Scale models, from model railroads to plastic kits and dollhouses, are labeled with a ratio such as 1:24 or 1:87. This calculator converts real dimensions to model size and back, for any scale.
What a scale means
A scale of 1:N means one unit on the model equals N of the same units on the real object. At 1:24, 1 inch on the model stands for 24 inches, or 2 ft, in reality.
model size = real size ÷ N, real size = model size × N
A 15 ft car is 180 in long; at 1:24 it becomes 180 ÷ 24 = 7.5 in. At 1:87 it is about 2.07 in.
Remember to use the same unit on both sides, or convert: the calculator takes the real size in feet and gives the model size in inches.
Common scales
| Scale | Typical use |
|---|---|
| 1:12 | dollhouses, large motorcycles |
| 1:18 and 1:24 | die-cast and kit cars |
| 1:35 | military vehicles and figures |
| 1:43 | collectible cars |
| 1:48 | aircraft, O-scale trains in the US |
| 1:64 | small die-cast cars, S scale trains |
| 1:72 | aircraft and military kits |
| 1:87 (HO) | the most popular model railroad scale |
| 1:160 (N) | compact model railroads |
| 1:220 (Z) | very small layouts |
| 1:350 and 1:700 | ships |
Model railroad gauges also set the track width: HO track is 16.5 mm between rails, representing standard gauge of 4 ft 8½ in.
Working back from a model
Measuring a model and multiplying by the scale gives the real size. This is useful to check a kit’s accuracy, to scratch-build a building that matches your layout or to size figures and accessories. A 1:87 figure of a 5 ft 10 in person is about 0.8 in tall.
Custom scales
Architects and engineers use scales such as 1:50, 1:100 or 1:500, and some hobbyists build to unusual ratios. Enter any N in the custom box to override the list.
Tips
- Area scales with the square of the ratio and volume with the cube: a 1:24 model has 1/576 the area and 1/13,824 the volume of the real thing.
- Mixing nearby scales, such as 1:72 and 1:76, is often fine for background pieces but noticeable side by side.