PSI to Bar Converter: Tire Pressure, Air Compressors, Scuba Tanks, Water Systems, and US Pressure Reference
Convert PSI to bar instantly. 1 psi = 0.068948 bar. 32 psi = 2.206 bar (most common US car tire). 1 bar = 14.504 psi. 3,000 psi = 206.84 bar (scuba tank). Residential water max 80 psi = 5.516 bar. Includes kPa, Pa, and atm outputs. TPMS thresholds, NHTSA standards, OSHA limits, NFPA 99 medical gas reference. Free PDF and batch converter.
PSI to Bar Calculator
Enter a pressure to convert
Car tire: 30-36 psi (2.07-2.48 bar). Shop air: 90-125 psi. Scuba: 3,000 psi = 206.84 bar. EU tire spec in bar: 2.2 bar = 31.9 psi.
US Pressure Reference Chart (0-130 psi, hover for bar)
PSI and Bar: The Two Pressure Languages American Technicians Must Speak
PSI, pounds per square inch, is the everyday pressure unit Americans encounter on tire sidewalls, air compressor gauges, garden hose connectors, and water pressure gauges behind every laundry room wall. It is derived from the US customary force unit (pound-force, lbf) divided by area in square inches, and it is the dominant pressure unit across US automotive, plumbing, industrial, and consumer product standards. Bar, on the other hand, is the metric unit that appears on European vehicle tire placards, international diving equipment, EU-sourced industrial machinery, and foreign regulatory documents. With roughly 1 bar equaling 14.504 psi, the two units are close enough that any American who works with imported equipment, follows international specifications, or travels internationally will need to convert between them fluently. The conversion appears in daily life more often than most people realize: the TPMS warning light on a car purchased in Europe, the diving computer switching to bar at a Caribbean resort, the tire pressure label on a bicycle purchased from an EU distributor, or a European industrial machine’s pressure gauge showing bar at a US manufacturing facility.
The exact definition of psi traces to two international standards locked in by NIST SP 811 (Guide for the Use of the International System of Units). First: 1 pound-force = 0.45359237 kilograms-mass times 9.80665 m/s squared (standard gravity) = 4.4482216152605 N exactly. Second: 1 square inch = 0.0254 m squared = 0.00064516 m squared exactly. Therefore: 1 psi = 4.4482216152605 N / 0.00064516 m squared = 6,894.757293168 Pa exactly to the significant figures NIST publishes. Since 1 bar = 100,000 Pa exactly (defined by the International Bureau of Weights and Measures BIPM), we get: 1 psi = 6,894.757293168 / 100,000 = 0.068947572931684 bar. And: 1 bar = 100,000 / 6,894.757293168 = 14.503773773… psi (non-terminating, requiring Big.js precision). All the practical results from tire pressure conversions to scuba tank gauge readings flow from these two anchored definitions.
How This PSI to Bar Converter Works
Enter any pressure in psi or bar. The converter outputs all five pressure units simultaneously: bar (primary when converting from psi), psi (primary when converting from bar), kPa (kilopascals, the standard metric engineering unit in North America for tire pressure and plumbing), Pa (pascals, SI base unit), and atm (standard atmospheres, used in diving and atmospheric science). The context panel below the results identifies what your pressure reading means in the real US world: whether it is in flat-tire territory, ideal tire pressure range, residential water pressure, hospital medical air range, air compressor output, or scuba tank fill pressure. The color-coded chart shows seven common reference pressures from 15 psi (TPMS alert zone) up to 125 psi (air compressor maximum), with green highlighting the safe tire pressure window (28-36 psi), red marking dangerously low pressure below 25 psi, and orange covering the industrial range above 36 psi. The batch converter accepts up to 20 pressures at once, outputting bar, psi, kPa, Pa, and atm for every input, useful for converting an entire fleet vehicle tire pressure schedule or a compressed air system pressure profile in a single pass.
US Pressure Reference: PSI to Bar Across Common American Applications
| Application | PSI Range | Bar Range | kPa Range | US Standard |
|---|---|---|---|---|
| Passenger car tire (cold) | 30-36 psi | 2.07-2.48 bar | 207-248 kPa | DOT door-jamb placard |
| SUV / light truck tire | 35-45 psi | 2.41-3.10 bar | 241-310 kPa | DOT FMVSS 110 |
| TPMS low-pressure alert | ~25% below placard | ~1.56-1.86 bar | ~156-186 kPa | NHTSA FMVSS 138 |
| Road bicycle tires | 90-130 psi | 6.21-8.96 bar | 621-896 kPa | Manufacturer sidewall |
| MTB / gravel tires | 20-35 psi | 1.38-2.41 bar | 138-241 kPa | Rider preference + rim |
| Residential water (min) | 20 psi | 1.38 bar | 138 kPa | UPC Section 608.1 |
| Residential water (ideal) | 40-60 psi | 2.76-4.14 bar | 276-414 kPa | IRC P2903.3.1 |
| Residential water (max) | 80 psi | 5.52 bar | 552 kPa | UPC 608.2 / IRC P2903.3.1 |
| Hospital medical air | 50-55 psi | 3.45-3.79 bar | 345-379 kPa | NFPA 99 Section 5.1.3 |
| Shop air (tool operating) | 90-100 psi | 6.21-6.89 bar | 621-689 kPa | OSHA 29 CFR 1910.242 |
| Air compressor cutoff | 125-135 psi | 8.62-9.31 bar | 862-931 kPa | Manufacturer spec |
| Scuba cylinder (full fill) | 3,000 psi | 206.84 bar | 20,684 kPa | ANSI / CGA, PADI standards |
Three Real US Examples Using PSI to Bar Conversion
Car Owner Checking Tire Pressure After Buying an Imported European Vehicle with Bar Placard
A family in Charlotte, North Carolina just purchased a used BMW 3 Series imported from Germany. Opening the driver’s door, they find the tire pressure placard (required by FMVSS 110 on all vehicles sold in the US) stamped in bar units as the European specification: Front 2.2 bar, Rear 2.5 bar, at maximum load 2.7 bar. Their home garage air gauge reads in psi. Converting: 2.2 bar times 14.5038 psi/bar = 31.908 psi, rounded to 32 psi for the front tires. 2.5 bar times 14.5038 = 36.260 psi, rounded to 36 psi for the rear. 2.7 bar times 14.5038 = 39.160 psi for the maximum load rating. They inflate the front to 32 psi and rear to 36 psi cold (before driving, in the morning when tires have not heated up from use), which is the correct practice per NHTSA guidelines. Note: tire pressure increases roughly 1 psi for every 10 degrees Fahrenheit of temperature rise, so a tire inflated to 32 psi at 60 degrees Fahrenheit in the morning may read 34-35 psi after highway driving, which is still within acceptable range.
Homeowner Installing a Pressure-Reducing Valve on a High-Pressure City Water Supply
A homeowner in Phoenix, Arizona tests their incoming city water pressure with a gauge and reads 95 psi. Their plumber explains that the International Residential Code (IRC P2903.3.1) and Uniform Plumbing Code (UPC 608.2) require a pressure-reducing valve (PRV) when static water pressure exceeds 80 psi (5.516 bar) at the point of entry, because higher pressure stresses pipe fittings, appliances, and washing machine hoses. Converting for comparison: 95 psi times 0.068948 = 6.550 bar = 655.1 kPa. The recommended PRV setpoint per IRC is 50-60 psi (3.447-4.137 bar). After installing the PRV set to 60 psi (4.137 bar), the household appliances including the water heater, dishwasher, and irrigation system operate within design parameters, extending their service life. The previous 95 psi supply was putting nearly 20% excess stress on rated 80-psi fittings, risking pinhole leaks in copper supply lines and premature washing machine solenoid valve failure.
Scuba Instructor Teaching a New Diver to Read Pressure Gauges in Both PSI and Bar
A PADI-certified instructor in Key West, Florida is teaching an open-water diver course to a student who dives in the US but plans to dive in Europe later. US dive shops fill aluminum 80 tanks to 3,000 psi (the standard fill per ANSI/CGA standards). European dive operations fill steel tanks to 200-300 bar (European standard: 200 bar = 2,900.8 psi; 300 bar = 4,351.1 psi). The instructor teaches two key conversions: 3,000 psi ÷ 14.5038 = 206.84 bar (so a US-filled tank reads 207 bar on a European gauge). Rule of thirds for air planning: start with 3,000 psi (206.8 bar), plan to turn back at 2,000 psi (137.9 bar), reach surface with at least 1,000 psi (68.9 bar). European equivalent rule in bar: start 200 bar, turn at 130 bar, surface with 65+ bar. The instructor also explains that dive computers display psi or bar depending on the unit setting, and divers who switch between US and European operations must always verify which unit their computer is displaying before the dive to avoid misreading remaining air supply.
Four Expert Tips on PSI and Bar for US Homeowners, Drivers, and Technicians
NHTSA TPMS: The 25% Rule and Cold vs Hot Inflation
The National Highway Traffic Safety Administration (NHTSA) mandated TPMS (Tire Pressure Monitoring System) on all new passenger vehicles sold in the US starting September 2007 (FMVSS 138). The system must illuminate the low-pressure warning light when any tire is 25% or more below the vehicle’s recommended cold inflation pressure listed on the door-jamb placard. For a vehicle with 32 psi (2.206 bar) recommended front pressure, 25% below = 32 minus 8 = 24 psi (1.655 bar). For 35 psi (2.413 bar) SUV rear, 25% below = 35 minus 8.75 = 26.25 psi (1.810 bar). Always inflate to the placard psi (or bar equivalent), not the tire sidewall maximum pressure (that is the maximum safe cold pressure, not the recommended pressure). Cold inflation means tires that have been sitting for at least three hours or driven less than one mile at low speed.
Residential Water Pressure: The 80 psi / 5.52 bar Hard Limit and When to Install a PRV
Both the Uniform Plumbing Code (UPC, adopted in most western US states) and the International Residential Code (IRC, adopted in most eastern US states) cap static water pressure at 80 psi (5.516 bar) at the building service entry. Cities with high-pressure distribution systems (common in hilly areas like San Francisco, Seattle, and Denver neighborhoods at low elevation) may deliver 80-120 psi to homes without a PRV. Beyond 80 psi, washing machine hose connections (rated 80-150 psi burst) are at elevated risk, water heater pressure relief valves may drip, and even ice maker lines can split. A pressure-reducing valve (PRV) costs $75-200 in parts and 1-2 hours of plumber labor to install on the main supply line, with a setpoint adjusted to 50-60 psi (3.45-4.14 bar). The investment typically pays for itself in extended appliance life and avoided water damage repair costs. Use a standard psi gauge (widely available for $10-20 at hardware stores) on any outdoor hose bib to check your home’s inlet pressure.
OSHA’s 30 PSI Rule for Compressed Air Chip-Clearing
OSHA Standard 29 CFR 1910.242(b) states that compressed air used for cleaning purposes shall be reduced to less than 30 psi (2.069 bar) at the dead end of the nozzle when it is used for chip-clearing. This regulation exists because high-pressure air can inject through skin or drive debris into eyes at pressures above 30 psi. Many shop workers routinely use compressed air at 90-125 psi (6.21-8.62 bar) line pressure for cleaning machine parts, thinking it is safe if the nozzle is held at a distance. OSHA’s violation citations in woodworking and metal shops frequently cite this rule. Compliant air cleaning guns have a pressure-relief hole in the nozzle tip that prevents dead-end pressure from exceeding 30 psi even when connected to a 100 psi (6.895 bar) supply line. Converting 30 psi to bar: 30 times 0.068948 = 2.069 bar, a value that appears on EU-sourced OSHA-compliant air gun specifications.
Hospital Medical Gas: NFPA 99 Requires 50-55 PSI (3.45-3.79 Bar) at the Outlet
NFPA 99 (Health Care Facilities Code), published by the National Fire Protection Association and adopted in most US states for hospital and ambulatory surgical center facilities, specifies that Level 1 medical compressed air systems must deliver 50-55 psi (3.447-3.792 bar) at the outlet station (wall outlet or ceiling pendant) under peak demand flow conditions. This standard applies to surgical suites, intensive care units, emergency departments, and other critical care areas. Medical air is not the same as industrial compressed air: it is filtered to medical-grade purity, dried to a specific dew point, and monitored continuously for purity and pressure. Understanding the psi-to-bar conversion is essential for biomedical equipment technicians (BMET) who service medical gas equipment purchased internationally or for facilities that cross-reference international HTM 02-01 (UK) standards, which specify medical air at 4 bar (58.0 psi) compared to the US 50-55 psi (3.45-3.79 bar).
PSI and Bar in HVAC Refrigerant Systems and Automotive Applications
HVAC Refrigerant Pressures: R-410A and R-22 in PSI and Bar
HVAC technicians working on US residential air conditioning systems routinely deal with refrigerant pressures in psi on US manifold gauge sets, but when cross-referencing European technical documents or using imported equipment, bar conversions are necessary. R-410A (the dominant US residential refrigerant since the 2010 R-22 phaseout): low-side pressure at 70 degrees F ambient = 118-125 psi (8.14-8.62 bar); high-side pressure at 95 degrees F ambient = 350-400 psi (24.1-27.6 bar). R-22 (older systems still in service): low-side at 70F = 58-68 psi (4.0-4.69 bar); high-side = 230-270 psi (15.9-18.6 bar). R-32 and R-454B (newer low-GWP alternatives now entering the US market under EPA SNAP approval, and already dominant in EU residential equipment since 2015): R-32 operates at similar pressures to R-410A, around 120-135 psi (8.27-9.31 bar) low side at moderate ambient conditions, and 400-470 psi (27.6-32.4 bar) high side at peak summer load. European service documentation for these refrigerants specifies pressures in bar, requiring US technicians to convert. A manifold gauge reading of 125 psi (8.62 bar) on the low side of an R-410A system at 70 degrees F ambient indicates proper operation within the typical 118-130 psi (8.14-8.96 bar) range.
Automotive Hydraulic and Fuel System Pressures
Modern vehicle systems involve a wide range of pressures that US technicians encounter in psi and must often convert to bar for international service manuals. Engine oil pressure: normal operating range 25-65 psi (1.72-4.48 bar), with a low-oil-pressure warning typically at 7-15 psi (0.48-1.03 bar). Coolant system (radiator cap pressure): 13-16 psi (0.90-1.10 bar) for most passenger vehicles. Power steering hydraulic: 1,000-1,500 psi (68.9-103.4 bar) at full lock. Fuel injection pressure: port injection 40-60 psi (2.76-4.14 bar); direct injection 1,500-3,000 psi (103.4-206.8 bar) at idle, up to 3,000-3,600 psi (206.8-248.2 bar) at full load. Automatic transmission line pressure: 60-200 psi (4.14-13.79 bar) depending on gear and load. CVT (continuously variable transmission) line pressure in modern vehicles: 200-500 psi (13.79-34.47 bar), higher than traditional automatics due to the hydraulic clamping force required on the belt/chain pulley system. Brake master cylinder: 800-1,200 psi (55.2-82.7 bar) during normal braking, up to 2,000+ psi (137.9+ bar) in emergency stops. European service manuals for vehicles such as BMW, Mercedes-Benz, and Volkswagen specify all these pressures in bar, making the 1 bar = 14.504 psi conversion a daily tool for import vehicle technicians working in the US.
Bicycle Tire Pressure: The PSI to Bar Gap Between US and European Riders
Road and mountain bicycle tires in the US are consistently inflated and discussed in psi, while European cycling culture uses bar. A Michelin Power Road tire sidewall reads “Max 8 bars” in European distribution but “Max 116 psi” on US packaging for the same tire. Converting the most common road cycling pressures: 90 psi = 6.205 bar; 100 psi = 6.895 bar; 110 psi = 7.584 bar; 120 psi = 8.274 bar; 130 psi = 8.963 bar. For tubeless road setups: 70-85 psi = 4.826-5.861 bar. Gravel bike tubeless: 35-55 psi = 2.413-3.792 bar. Mountain bike trail tubeless: 22-30 psi front, 24-32 psi rear = 1.517-2.068 bar front, 1.655-2.206 bar rear. US bicycle floor pumps have dual-scale gauges showing both psi and bar, with most gauges accurate to plus or minus 2 psi (0.138 bar) at calibrated conditions. For competitive cycling, many professional teams use digital pressure gauges accurate to 0.5 psi (0.034 bar) for optimal tire setup, especially in time trials where rolling resistance differences of 0.5 psi matter at the watt level. The SRAM AXS tire pressure calculator and Continental tire pressure app both offer psi and bar input, reflecting the dual-unit reality of modern cycling globally.
Industrial Pneumatics: US Shop Air Standards and ASME/ISO Pressure Ratings
American industrial facilities almost universally plumb compressed air at 90-125 psi (6.21-8.62 bar) working pressure. The Compressed Air and Gas Institute (CAGI), based in Cleveland, Ohio, publishes performance data sheets for air compressors in both cfm (cubic feet per minute) and l/min (liters per minute), and pressure in both psi and bar, to serve US domestic and export markets. Key US industrial pneumatic reference pressures in psi and bar: ASME pressure vessel rating stamps on air receiver tanks appear in psi (typically 200 psi = 13.79 bar maximum allowable working pressure for a standard 80-gallon shop tank). ANSI/ASME B16.5 flange pressure ratings are in Class designations (150, 300, 600, 900, 1500, 2500) that map to temperature-dependent psi and bar limits. A Class 150 carbon steel flange at 68F: 285 psi (19.65 bar). A Class 300 at 68F: 740 psi (51.02 bar). ISO 4414 (pneumatic fluid power general rules) specifies design and operating pressures in bar; US engineers working with ISO-spec European machinery must convert to bar for compliance documentation while operating the equipment at equivalent US psi settings.
Natural Gas and Propane Pressures in the US: Low psi, High Safety Stakes
Natural gas distribution to US homes operates at dramatically lower pressures than compressed air or water systems, yet the psi-to-bar conversion remains important for gas appliance technicians who service or import European-spec equipment. Residential natural gas service pressure at the meter: 0.25 psi (0.017 bar) typical, ranging up to 2 psi (0.138 bar) in some neighborhoods with older low-pressure distribution mains. Gas appliance manifold pressure: 3.5 inches water column (in WC) = 0.127 psi (0.00874 bar) for natural gas on most US appliances. Propane (LP) appliance manifold pressure: 10 to 11 inches WC = 0.362-0.398 psi (0.025-0.027 bar). Residential gas regulator outlet pressure: 5-7 in WC = 0.181-0.253 psi (0.012-0.017 bar). Medium-pressure commercial gas: 2-5 psi (0.138-0.345 bar). High-pressure commercial: 5-60 psi (0.345-4.137 bar). The primary regulatory body for US gas systems is the American Gas Association (AGA), and installation codes follow NFPA 54 (National Fuel Gas Code) and NFPA 58 (Liquefied Petroleum Gas Code). European gas pressure specifications typically reference millibar (mbar): 1 mbar = 0.001 bar = 0.01450 psi. The UK gas supply pressure is 21 mbar (0.021 bar = 0.305 psi), requiring a pressure conversion when a US technician services a UK-spec gas appliance imported to the United States or compares appliance ratings between the two standards.
Quick Reference: Common PSI to Bar Conversions
| PSI | Bar | kPa | atm | US Context |
|---|---|---|---|---|
| 1 psi | 0.06895 bar | 6.895 kPa | 0.06805 atm | 1 psi = 6,894.757 Pa (NIST) |
| 15 psi | 1.034 bar | 103.4 kPa | 1.020 atm | TPMS low-pressure warning zone |
| 30 psi | 2.069 bar | 206.8 kPa | 2.041 atm | OSHA 30 psi chip-clear limit | car tire low |
| 32 psi | 2.206 bar | 220.6 kPa | 2.177 atm | Most common US passenger car cold inflation |
| 35 psi | 2.413 bar | 241.3 kPa | 2.381 atm | US SUV and light truck typical |
| 55 psi | 3.792 bar | 379.2 kPa | 3.742 atm | NFPA 99 hospital medical air upper limit |
| 80 psi | 5.516 bar | 551.6 kPa | 5.442 atm | UPC/IRC residential water pressure maximum |
| 125 psi | 8.618 bar | 861.8 kPa | 8.503 atm | Air compressor cutoff (typical consumer unit) |
| 3,000 psi | 206.843 bar | 20,684 kPa | 204.1 atm | Standard US scuba cylinder full fill (ANSI) |
Frequently Asked Questions About PSI and Bar Conversion
1 psi = 0.068947572931684 bar. Derived: 1 psi = 6,894.757293168 Pa (NIST SP 811) ÷ 100,000 Pa/bar (exact definition of bar). Also: 1 psi = 6.895 kPa = 0.06805 standard atmospheres. Quick rule: multiply psi by 0.0689 for approximate bar. Reverse: 1 bar = 14.5038 psi (multiply bar by 14.504).
30 psi = 30 × 0.068948 = 2.0684 bar = 206.84 kPa. This is a reference pressure in two important US contexts: the OSHA 29 CFR 1910.242 chip-clearing limit of 30 psi (2.07 bar) dead-end nozzle pressure, and the lower boundary of the typical US passenger car tire cold inflation range (30-36 psi = 2.07-2.48 bar). A tire at exactly 30 psi is within the acceptable range for most compact and mid-size cars but at the low end. TPMS would not alert at 30 psi unless the placard calls for 40+ psi (trucks).
Multiply psi by 0.068948: bar = psi × 0.068948. More precisely: bar = psi × 6894.75729316836 / 100000. The exact derivation per NIST SP 811: 1 lbf = 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N. 1 in² = 0.00064516 m². 1 psi = 4.4482216152605 / 0.00064516 = 6,894.757 Pa. 1 bar = 100,000 Pa (BIPM). So 1 psi = 6894.757 / 100000 bar = 0.068948 bar. Quick mental estimate: divide psi by 14.5 to get approximate bar.
100 psi = 100 × 0.068948 = 6.8948 bar = 689.476 kPa. This is at the lower end of the typical shop air tool operating range (90-125 psi = 6.21-8.62 bar). Most air-powered tools (nail guns, impact wrenches, air ratchets, spray guns) are designed for 90-100 psi input. Air compressor tanks typically cycle between 100 psi (cutout shutoff may be 125-135 psi). HVAC R-410A refrigerant low-side pressure at 70 degrees F ambient: 118-130 psi (8.14-8.96 bar).
1 bar = 14.503773773… psi (non-terminating). Rounded: 14.5038 psi. 1 bar = 100,000 Pa (exact). Since 1 psi = 6,894.757 Pa, dividing 100,000 / 6,894.757 = 14.5038. Quick rule: multiply bar by 14.5 for approximate psi. Common reference: 2 bar = 29.008 psi (close to typical US car tire minimum); 2.5 bar = 36.259 psi (common European SUV tire spec); 3 bar = 43.511 psi (common European truck tire).
2.5 bar = 2.5 × 14.5038 = 36.259 psi, rounded to 36 psi. European tire placards on SUVs, crossovers, and sport models frequently specify 2.3-2.5 bar (33.4-36.3 psi) for the rear tires and 2.2-2.4 bar (31.9-34.8 psi) for the front. When filling an EU-spec vehicle at a US gas station, convert the bar value on the door placard to psi and use the psi gauge on the US air machine. 2.5 bar = 36 psi is an easy mental conversion: 2.5 × 14.5 = 36.25 ≈ 36 psi.
35 psi = 35 × 0.068948 = 2.4132 bar = 241.32 kPa. This is the typical cold inflation pressure for many US SUVs, crossovers, and light trucks (Ford Explorer, Chevy Equinox, Toyota Highlander commonly specify 35 psi). On a European tire pressure gauge or a European vehicle service manual, this corresponds to 2.4 bar. When cross-checking tire specs: 35 psi is just below the 2.5 bar (36.3 psi) common in European SUV specs, so these vehicle types align closely across US and EU recommended pressures.
80 psi (5.516 bar) is the maximum static water pressure allowed at the building service entry per UPC Section 608.2 and IRC P2903.3.1, both of which are adopted in most US jurisdictions. At the point of use (individual fixtures), the maximum is also 80 psi per UPC. If your city supply exceeds 80 psi, a pressure-reducing valve (PRV) is required. The recommended operating range per IRC P2903.3.1 is 40-80 psi (2.76-5.52 bar). The minimum flow pressure required at fixtures (faucets, showers) is 20 psi (1.38 bar) at peak demand. Converting: 80 psi = 552 kPa; 40 psi = 276 kPa; 20 psi = 138 kPa.
3,000 psi = 3,000 × 0.068948 = 206.843 bar. The standard US scuba fill is 3,000 psi for aluminum cylinders (AL80, the most common recreational dive cylinder holding 77.4 cubic feet at 3,000 psi). European dive operations fill steel cylinders to 200-300 bar: 200 bar = 2,900.8 psi; 232 bar (the European HP standard) = 3,364.9 psi; 300 bar = 4,351.1 psi. A diver trained in the US reading 206 bar on a European gauge knows they have the equivalent of a US 3,000 psi full fill. Down to 100 bar = 1,450 psi, which is the US “turn around” pressure for most recreational dives using the rule of thirds on a 3,000 psi fill.
6 bar = 6 × 14.5038 = 87.023 psi = 600 kPa exactly. This appears in several European specifications for US technicians: residential water heater relief valve setting in Europe is typically 6-8 bar (87-116 psi) versus 150 psi (10.34 bar) in the US; European gas pressure regulators for high-pressure commercial applications reference 6 bar output; European industrial pneumatic systems often operate at 6 bar (87 psi) line pressure, close to the US 90-100 psi shop air standard.
125 psi = 125 × 0.068948 = 8.619 bar = 861.8 kPa. This is the typical maximum output pressure for consumer and contractor-grade portable air compressors (DeWalt, Makita, Craftsman, Rolair models). The compressor’s pressure switch cuts off the motor at 125-135 psi (8.62-9.31 bar) and restarts it when pressure drops to 90-100 psi (6.21-6.89 bar). At 125 psi tank pressure, the tool air supply regulator is usually set to deliver 90 psi (6.21 bar) to tools. European compressors specify output in bar and commonly have a maximum of 8-10 bar (116-145 psi).
Both measure pressure (force per unit area). PSI (pounds per square inch) is a US customary unit: 1 lbf of force applied over 1 square inch. Bar is a metric unit: 1 bar = 100,000 Pascals = 100,000 N/m². Standard atmospheric pressure at sea level is 14.696 psi = 1.01325 bar = 101,325 Pa. 1 bar is slightly less than standard atmosphere (about 0.987 atm). For everyday purposes: 1 bar ≈ 14.5 psi; 1 psi ≈ 0.069 bar. Bar is widely used internationally (EU tire specs, diving, meteorology). PSI dominates in the US across automotive, plumbing, and industrial applications.
40 psi = 40 × 0.068948 = 2.758 bar = 275.8 kPa. This pressure appears in several US standards: the minimum recommended static water supply pressure for residential service per IRC (40 psi minimum for adequate flow at fixtures). Many truck tires (pickup trucks, full-size vans) specify 40-45 psi (2.76-3.10 bar) cold inflation. Full-size SUVs (Suburban, Expedition, Tahoe) often specify 38-42 psi (2.62-2.90 bar). Converting: 40 psi in bar = 2.758, which rounds to 2.8 bar on a European gauge.
Check the door-jamb sticker (required on all US vehicles by FMVSS 110) for the exact psi or bar recommended for your specific vehicle and tire size. Typical US passenger car placard values in bar: compact cars 2.0-2.2 bar (29-32 psi); mid-size cars 2.1-2.4 bar (30-35 psi); SUVs 2.3-2.7 bar (33-39 psi); pickup trucks 2.6-3.1 bar (38-45 psi). Do not use the tire sidewall number (that is the maximum pressure, not the recommended). Check cold: in the morning before driving, or if the car has been parked 3+ hours. Tire pressure drops about 1 psi (0.069 bar) for every 10 degrees Fahrenheit of temperature drop, so winter pressure checks are especially important.
0.5 bar = 0.5 × 14.5038 = 7.252 psi = 50 kPa. This is a very low pressure for most mechanical applications, but relevant in a few US contexts: residential natural gas service pressure at the meter ranges from 0.25-2 psi (0.017-0.138 bar); a completely flat car tire has only 0 psi above atmospheric (0 bar gauge); 0.5 bar (7.25 psi) represents dangerous underinflation for all vehicle types. In HVAC: vacuum is sometimes measured in bar absolute (below atmospheric), and 0.5 bar absolute = 50 kPa absolute = roughly 15 in/Hg vacuum, relevant for system evacuation procedures.
Yes, this converter uses Big.js arbitrary-precision arithmetic and the exact NIST SP 811 derivation: 1 psi = 6,894.75729316836 Pa (from 1 lbf = 0.45359237 kg × 9.80665 m/s² = 4.44822162 N, divided by 1 in² = 0.00064516 m²). 1 bar = 100,000 Pa (exact BIPM definition). Key verified results: 32 psi = 2.20632 bar; 2.2 bar = 31.908 psi; 80 psi = 5.51581 bar; 3,000 psi = 206.843 bar. Sources: NIST SP 811; BIPM; NHTSA FMVSS 138; UPC 2021; NFPA 99 2021; OSHA 29 CFR 1910.242.
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This PSI to bar converter is provided for educational and informational purposes only. The conversion factor 1 psi = 6,894.75729316836 Pa is derived from exact NIST SP 811 definitions (1 lbf = 0.45359237 kg × 9.80665 m/s²; 1 in² = 0.0254² m²). The bar is defined as exactly 100,000 Pa per BIPM. All conversions use Big.js arbitrary-precision arithmetic. Tire pressure recommendations cited (32 psi, 35 psi, 2.2 bar) are illustrative of common values; always use your specific vehicle’s door-jamb placard value for actual tire inflation. TPMS thresholds reflect NHTSA FMVSS 138 requirements for vehicles sold in the US after September 2007; older vehicles do not have TPMS. Residential water pressure limits (80 psi / 5.52 bar) reflect UPC 2021 and IRC 2021 standards; local codes may vary. Medical gas pressures (50-55 psi per NFPA 99) are for US Level 1 systems; international standards differ. OSHA 29 CFR 1910.242 chip-clearing limit (30 psi dead-end) reflects federal US regulations; some states have additional requirements. Scuba pressures are for reference only; always follow your certifying agency’s (PADI, SSI, NAUI, IANTD) training and your equipment manufacturer’s fill specifications; have cylinders inspected and hydrostatically tested per DOT regulations. Pneumatic system pressures (CAGI, ISO 4414, ASME) cited for educational context; qualified technicians and licensed engineers should design and service compressed air systems to applicable codes. Content reviewed by the USCalculators.com editorial team. References: NIST SP 811; BIPM; NHTSA FMVSS 138; UPC 2021; IRC 2021; NFPA 99 2021; NFPA 54; OSHA 29 CFR 1910.242; CAGI; ASME B16.5; ISO 4414.