Whole House Generator Cost in 2026: Standby vs Portable by Size
A whole house standby generator costs $5,000 to $15,000 installed for a natural gas or propane unit in 2026. A 10 to 15 kW generator covers most homes; a 20 to 22 kW unit covers larger homes or homes with electric heating. Whole house generator cost includes the generator unit, automatic transfer switch, gas line extension, concrete pad, and installation labor. Portable generators that power selected circuits cost $500 to $3,500 for the unit and $500 to $1,500 for a manual transfer switch installation.
Power outages have become longer and more frequent in many US regions, driven by aging grid infrastructure and more severe weather events. A standby generator is the only power backup solution that truly functions as a whole house solution: it starts automatically within seconds of a utility outage, requires no manual setup, and runs as long as the fuel supply lasts. The cost is significant, but for homeowners with medical equipment, well pumps, sump pumps, or businesses run from home, the standby generator is a functional necessity rather than a luxury.
The generator sizing calculator estimates the kW output needed based on your home size and the loads you want to back up.
Open the Generator Calculator →Whole House Generator Installed Cost by Size in 2026
| Generator size | Covers | Installed cost | Typical homes |
|---|---|---|---|
| 7 to 9 kW | Essential circuits (lights, fridge, some AC) | $3,500 to $7,000 | Small homes; partial coverage only |
| 10 to 12 kW | Whole house (up to 1,500 sq ft with AC) | $5,000 to $9,000 | Small to medium homes; most popular size |
| 14 to 16 kW | Whole house (1,500 to 2,500 sq ft with AC) | $6,500 to $11,000 | Medium homes; covers all circuits |
| 20 to 22 kW | Whole house (2,500 to 3,500 sq ft with AC) | $8,500 to $13,500 | Large homes; electric heating included |
| 25 to 30 kW | Very large homes or light commercial | $12,000 to $20,000 | Large estate, home with EV charging |
Standby vs Portable Generator: Full Comparison
| Feature | Standby generator | Portable generator |
|---|---|---|
| Activation | Automatic (within 10-30 seconds) | Manual start; setup required |
| Fuel | Natural gas or propane (continuous supply) | Gasoline, propane, or dual-fuel |
| Runtime | Unlimited (gas line) or propane tank duration | 8-18 hours per tank |
| Coverage | Whole house; all circuits automatic | Selected circuits via transfer switch or cords |
| Equipment cost | $2,500 to $15,000 | $500 to $3,500 |
| Installation cost | $1,500 to $5,000 | $500 to $1,500 (transfer switch) |
| Annual maintenance | $150 to $300 (automatic weekly self-test) | Fuel stabilizer; annual carb service |
| Noise | Similar to central AC unit (65-70 dB) | Loud (70-85 dB); often restricted near homes |
For electrical panel capacity needed to connect a generator, our electrical panel cost guide covers the panel upgrade considerations when adding a generator transfer switch. For the lighting that will stay on during outages, our recessed lighting guide covers the wiring work alongside generator backup planning.
Fuel Type Comparison: Natural Gas vs Propane vs Diesel
| Fuel type | Availability | Fuel cost per hour (10 kW load) | Tank/supply needs | Notes |
|---|---|---|---|---|
| Natural gas | Urban and suburban areas with gas service | $0.80 to $1.40/hr | Continuous; no storage | Best option where available; never runs out |
| Propane | Any location; requires on-site tank | $1.50 to $2.80/hr | 250 to 1,000 gallon tank | Good for rural; monitor tank level |
| Gasoline | Portable generators only | $1.80 to $3.50/hr | 5 to 6 gallons/6-8 hrs | Difficult to store; supply uncertain in emergencies |
| Diesel | Commercial standby; some residential | $1.20 to $2.00/hr | 100 to 500 gallon tank | Most efficient; complex installation |
What Drives Whole House Generator Cost Variation
Gas line extension distance
A generator running on natural gas requires a gas line from the utility meter to the generator pad. If the generator is installed close to the meter (under 25 feet), this cost is minimal ($200 to $400). If the generator must be placed far from the meter (for aesthetic or noise reasons), each additional 10 feet of gas line adds $50 to $150 in material and labor. Propane-fueled generators avoid this consideration but require a propane tank installation: a 500-gallon propane tank installed runs $1,000 to $2,500 plus propane delivery cost.
Automatic transfer switch complexity
The automatic transfer switch (ATS) detects the utility outage and switches the home to generator power. A whole-house ATS (which connects at the main panel and transfers all circuits automatically) costs $800 to $2,500 installed. A load-center ATS that creates a critical circuits sub-panel (only selected circuits transfer) costs $400 to $1,200 installed and is used with smaller generators that cannot power the entire home. The whole-house ATS is the cleaner and more convenient solution for a properly sized generator.
Three Real Generator Installation Projects
Example 1: 10 kW natural gas standby in Raleigh, North Carolina
A homeowner in a suburb with natural gas service installing a whole house generator after experiencing 3 extended outages in 2 years (the longest lasting 9 days after a hurricane). Home: 1,600 sq ft, 3-bed/2-bath, central AC (3-ton). Load calculation: 10 to 12 kW required. Chosen: 12 kW natural gas standby generator. Generator unit: $3,200. Automatic whole-house transfer switch: $1,100. Concrete pad: $380. Gas line extension (30 feet): $450. Electrician and gas fitter labor (8 hours): $1,200. Permit: $125. Total: $6,455. The generator performs a 10-minute self-test every Sunday at 10 AM automatically. Annual maintenance contract: $185/year.
Example 2: 20 kW propane standby in rural Vermont
A homeowner in a rural area without natural gas service installing a standby generator for a 2,800 sq ft home with electric heat pump and well pump. Propane fuel required (no natural gas). 20 kW propane generator (needed for heat pump load): $5,800 unit. 500-gallon propane tank (installed): $1,800. Transfer switch (whole-house): $1,400. Concrete pad: $420. Labor (two days, licensed electrician and plumber for gas): $2,200. Permit: $180. Total: $11,800. Propane consumption at 50% load: approximately 2 gallons/hour. A 500-gallon tank provides roughly 250 hours of runtime at that load, or about 10 days of continuous operation. The homeowner maintains the tank at 40% minimum fill through the winter.
Example 3: Portable generator with transfer switch in Minneapolis, Minnesota
A homeowner wanting outage protection for a sump pump, refrigerator, and select lights without the cost of a full standby system. Chose a 7,500-watt dual-fuel (gas/propane) portable generator with a 6-circuit manual transfer switch. Generator: $980. Manual 6-circuit transfer switch (installed by electrician): $750. Generator cord (50-amp L14-30 connection): $80. Total: $1,810. The manual setup requires starting the generator, connecting the cord, and manually switching the transfer switch when an outage occurs. For a household where someone is always home and outages typically give a few minutes of warning (severe weather), this is an acceptable compromise that saves $5,000 to $10,000 versus a standby system.
The generator calculator estimates the kW size needed based on your home size and backup priority loads.
Calculate Generator Size and Cost →Frequently Asked Questions About Whole House Generator Cost
How much does a whole house generator cost installed?
A whole house standby generator costs $5,000 to $15,000 installed in 2026, including the generator unit, automatic transfer switch, concrete pad, gas line connection, and labor. A 10 to 12 kW natural gas generator for a 1,500 sq ft home typically runs $5,000 to $9,000. A 20 kW generator for a larger home with electric heating runs $8,500 to $13,500. Propane adds tank installation cost ($1,000 to $2,500) but avoids gas line extension cost.
What size whole house generator do I need?
Calculate the total wattage of all loads you want to run simultaneously. A 3-ton central AC draws 3,500 to 5,000 watts. A refrigerator draws 150 to 400 watts running. A well pump draws 750 to 1,500 watts. Lighting and small appliances add 2,000 to 4,000 watts. Add 25 percent for motor start-up surge. A 10 kW generator handles most homes under 1,500 sq ft with standard AC; a 14 to 20 kW handles larger homes or homes with electric heating. A load calculation from a licensed electrician gives the most accurate sizing.
Is a whole house generator worth the cost?
The financial case depends on outage frequency and duration in your area, and the cost of loss during outages. For a home with a freezer of food ($500 to $1,000 value), a sump pump preventing basement flooding ($10,000 to $50,000 risk), medical equipment, or a home-based business, a $7,000 to $10,000 standby generator pays back quickly in the first major avoidance event. For a home in an area with infrequent short outages and no special risk, the standby generator is a quality-of-life purchase rather than a financial calculation.
How long can a whole house generator run continuously?
A natural gas standby generator can run indefinitely as long as the utility continues to supply gas (outages rarely affect underground gas service even when power is out). A propane standby generator runs until the propane tank is empty; at typical home load, a 500-gallon propane tank lasts 5 to 14 days depending on load. Generator manufacturers recommend not running standby generators for more than 500 continuous hours without a service interval. In practice, few residential outages approach this duration.
What is an automatic transfer switch?
An automatic transfer switch (ATS) monitors utility power and automatically disconnects the home from the utility grid and connects it to the generator within 10 to 30 seconds of an outage. It prevents back-feeding utility lines (a safety requirement) and eliminates the need for manual action when power fails. The ATS also automatically returns the home to utility power when the outage ends and the utility is restored. Whole-house ATS connects at the main panel; critical-circuit ATS creates a sub-panel with selected circuits.
How much does generator maintenance cost?
Standby generator annual maintenance typically runs $150 to $300 for an oil change, filter replacement, spark plug check, battery test, and load test. Most standby generators run a weekly self-test for 10 to 20 minutes automatically, which keeps the engine lubricated and confirms operational readiness. Portable generator maintenance is similar in cost but more frequent if the generator sees significant use: annual carburetor cleaning, oil change, and fuel system service.
Does a whole house generator increase home value?
In regions with frequent power outages (hurricane zones, rural areas with aging infrastructure, areas prone to ice storms), a whole house generator is a meaningful selling point. In urban areas with reliable utility service, it is a niche feature that appeals to specific buyers but does not broadly increase appraised value. Remodeling magazine’s Cost vs Value report does not specifically include generators; anecdotal evidence from real estate agents in outage-prone markets suggests 50 to 70 percent cost recovery at resale.
Can I run my central air conditioner on a generator?
Yes, with a properly sized generator. A 3-ton central AC system draws 3,500 to 5,000 running watts and 7,000 to 9,000 start-up watts (compressor surge). A 10 kW generator can handle a 3-ton AC plus essential household loads simultaneously. A 5 to 7 kW generator typically cannot start a 3-ton AC system; it can run a window unit (1,200 to 1,800 watts) or a mini-split (600 to 1,500 watts). If whole-house AC backup is a requirement, size the generator accordingly in the load calculation before purchase.
Related Calculators and Guides
For generator installation standards and electrical connection requirements, the National Electrical Code (NFPA 70) Article 702 governs optional standby systems, and NFPA 110 covers emergency and standby power systems. The EPA Air Quality program regulates generator emissions; check local ordinances for noise and emissions restrictions in your area.