Miniature Scale Converter for Wargaming and 3D Printing

Walk into a game store in Dallas or Minneapolis and you will almost certainly see two kinds of miniatures on the shelf: figures labeled 28mm and figures labeled 32mm. They are not the same thing, and they are not always compatible, even though both numbers suggest they should be close in size. The reason for this apparent contradiction is the distinction between nominal scale and actual scale, and it is the single most misunderstood concept in the hobby.

Scale in miniature gaming does not work the same way as scale in model trains or architectural models, and this distinction trips up even experienced hobbyists when they first start mixing terrain sources or cross-manufacturer figure ranges. A model railroad car at HO scale (1:87) is precisely 1/87th the size of the real locomotive it represents, measured in every dimension. A 28mm miniature, by contrast, uses a measurement convention that refers to the height of the figure from the base of the foot to the eye level, not the top of the head. The real-world person being represented is assumed to be roughly 1700mm tall to eye level (about 5 feet 7 inches), giving a scale ratio of approximately 1:60. But different manufacturers round this differently, and heroic sculpting further complicates matters.

True Scale Versus Heroic Scale: What the Numbers Really Mean

True scale miniatures reproduce real-world anatomy accurately at the stated ratio. Bolt Action WWII infantry, Infinity Corvus Belli figures, and historical ranges from companies like Perry Miniatures use true scale proportions. A 28mm true scale figure has anatomically realistic head, hand, and weapon sizes relative to its body.

Heroic scale miniatures deliberately exaggerate certain features. Games Workshop pioneered this approach in the 1980s for practical reasons: on a tabletop viewed from arm’s length, anatomically correct proportions look spindly and details become invisible. By making heads, hands, shoulder pads, and weapons 15 to 25 percent larger than anatomically correct, the figures read clearly even from several feet away and hold paint much better on fine detail areas. A 28mm heroic figure from the Warhammer 40,000 range is approximately 32mm to the top of the head (not the eye) and uses an effective scale ratio closer to 1:48 than the 1:56 that strict 28mm implies.

Railroad Terrain as Proxy: A Money-Saving Guide for US Gamers

One of the most overlooked facts in American tabletop gaming is that model railroad terrain and accessories can substitute directly for wargame terrain at corresponding scales. The National Model Railroad Association (NMRA) defines official scale ratios for HO (1:87), N (1:160), S (1:64), O (1:48), and G (1:22.5) scales through its standards documents S-1.2 and S-1.3. These are published US industry standards with precise mathematical definitions.

The overlap between railroad and gaming scales is extensive and commercially useful. O scale (1:48) matches almost exactly with 32mm heroic and 28mm heroic gaming figures. S scale (1:64) sits between 28mm true and 28mm heroic, making it useful for Bolt Action terrain on a budget. N scale (1:160) is a close match for 15mm gaming figures used in Flames of War and similar historical wargames. A model railroad building, bridge, or vehicle at the right scale costs a fraction of the equivalent terrain piece marketed specifically to wargamers, yet looks identical on the table. Major US retailers including Hobby Lobby, Michael’s, and online distributors like Woodland Scenics Direct carry O and N scale structure kits year-round. Specifically, Woodland Scenics O scale building kits and Walthers O scale accessories are consistently available at US hobby stores and are well-regarded by both railroad modelers and wargamers for their consistent quality and dimensional accuracy. The crossover savings are significant: a full 4-by-6-foot Warhammer 40K gaming board built primarily from O scale railroad kits can cost 60 to 70 percent less than an equivalent board built from dedicated wargame terrain.

3D Printing and the Slicer Percentage Problem

The explosion of 3D printing in the US miniature hobby community since 2020 has fundamentally changed how American hobbyists approach scale. A 2024 survey by the Tabletop Miniature Gaming community estimated that over 40 percent of active US wargamers now own at least one resin or FDM printer, and the number continues to grow. STL files sold on platforms like MyMiniFactory, Patreon, and Cults3D are designed at the sculptor’s preferred scale, which varies widely between creators. A file marketed as “28mm scale” might actually be designed to print at 32mm heroic, true 28mm, or any other interpretation of the measurement convention. Without a reliable conversion tool, hobbyists waste expensive resin on test prints that are clearly the wrong size.

When you want to print a file at a different scale than it was designed for, you need to calculate a percentage scaling factor to enter in your slicer software (Chitubox, Lychee, PrusaSlicer, or Bambu Studio). The formula is straightforward: divide the from-scale ratio by the to-scale ratio and multiply by 100. To rescale a 1:100 tank to work with 28mm true scale (1:56) figures, the calculation is (100/56) times 100, which equals 178.57 percent. An additional buffer of 0.1 to 0.5 percent compensates for the slight dimensional shrinkage that occurs when most resins cure, which is standard practice recommended by resin manufacturers like Elegoo, Anycubic, and AmeraLabs.

Mode 1: Real World to Model (Ratio Division)

The fundamental scale conversion formula divides the real-world dimension in millimeters by the scale ratio. For a 72-inch US door (1828.8mm) at 28mm heroic scale (effective ratio 1:48): 1828.8 divided by 48 equals 38.1mm. This is the height the doorway should measure on the model. The heroic toggle applies the corrected ratio for heroic-scale lines instead of the nominal stated ratio. The resin shrinkage buffer adds a small percentage to the result, compensating for the dimensional reduction that occurs when resin cures. All outputs are simultaneously shown in millimeters, centimeters, and inches.

Mode 2: Scale-to-Scale Rescaler (Ratio Division)

To convert between two scales, the slicer percentage equals the from-scale ratio divided by the to-scale ratio, multiplied by 100. This derives directly from the proportionality requirement that the real-world dimensions remain constant while the model dimensions change. The resin shrinkage buffer multiplies the result by (1 plus the shrink percentage/100). The chart in this mode shows how common reference figure heights transform across both scales simultaneously, giving a visual sanity check before committing to a print run.

Mode 3: Multi-Scale Comparison (Batch Ratio Division)

This mode divides the real-world dimension (in mm) by every scale ratio in the database simultaneously, producing a complete comparison table of 19 gaming and railroad scales in a single view. When you input a model dimension instead of a real-world dimension, the tool first reverses the calculation (multiplying by the stated scale ratio to recover the implied real-world dimension), then applies that recovered real-world value to all other scales. The railroad terrain proxy column uses a lookup table to flag the closest NMRA-standard railroad scale for each gaming scale, making it easy to shop for compatible terrain at model railroad retailers, craft stores, and hobby shops across the United States. The accompanying Chart.js bar chart renders all 19 results visually so you can immediately see which scales produce usable model dimensions for a given real-world object.