Scale Conversion Calculator
Convert between real-world and model dimensions at any scale ratio, translate architectural scales, and apply the n² and n³ factors to area, volume and weight.
The converted length in every unit
- Millimetres (mm)114.942529
- Centimetres (cm)11.494253
- Metres (m)0.114943
- Inches (in)4.525296
- Feet (ft)0.377108
- Yards (yd)0.125703
Divide the real dimension by 87 to get the model dimension.
What the scale means
- 1 metre of the real thing = 11.4943 mm on the model
- 1 foot of the real thing = 0.137931 inches on the model
- Nearest architectural scale: ⅛" = 1'-0" (1:96)
- Area scales by the square: 7,569× smaller on the model
- Volume and weight scale by the cube: 658,503× smaller
A solid model in the same material would weigh 0.00227789 in the same unit — weight follows the cube of the scale, which is why models are so much lighter than people expect.
Imperial architectural scales
| Drawing scale | Ratio | 1 metre becomes |
|---|---|---|
| 3" = 1'-0" | 1:4.00 | 250 mm |
| 1½" = 1'-0" | 1:8.00 | 125 mm |
| 1" = 1'-0" | 1:12.00 | 83.333 mm |
| ¾" = 1'-0" | 1:16.00 | 62.5 mm |
| ½" = 1'-0" | 1:24.00 | 41.667 mm |
| ⅜" = 1'-0" | 1:32.00 | 31.25 mm |
| ¼" = 1'-0" | 1:48.00 | 20.833 mm |
| 3⁄16" = 1'-0" | 1:64.00 | 15.625 mm |
| ⅛" = 1'-0" | 1:96.00 | 10.417 mm |
| 3⁄32" = 1'-0" | 1:128.00 | 7.813 mm |
| 1⁄16" = 1'-0" | 1:192.00 | 5.208 mm |
What is the Scale Conversion Calculator?
The ByteTools Scale Conversion Calculator turns a scale ratio into an answer. Type 1:87, 1/24 or just 87, give it a length in any unit, and it divides or multiplies to get the other dimension — real to model, model to real, or straight from one scale to another so you can work out what an HO building becomes in N gauge.
- Real-to-model, model-to-real and scale-to-scale conversion in one place
- Accepts 1:87, 1/24 or a bare number, with 27 modelling and drawing presets
- Answers shown in millimetres, centimetres, metres, inches, feet and yards at once
- Names the nearest imperial architectural scale and flags exact matches
- Area factor n² and volume/weight factor n³, with a weight conversion box
- Reference table of imperial architectural scales from 3" = 1'-0" to 1/16" = 1'-0"
How to use the Scale Conversion Calculator
- 1
Pick a direction: real to model, model to real, or between two scales.
- 2
Type the scale as 1:87, 1/24 or 87 — or choose one from the presets dropdown.
- 3
Enter the length, the unit you measured in, and the unit you want the answer in.
- 4
Read the converted length plus the area and volume factors in the summary tiles.
- 5
Enter a real-world weight to see what a solid model would weigh, and check the architectural scale table below.
About the Scale Conversion Calculator
The ByteTools Scale Conversion Calculator turns a scale ratio into an answer. Type 1:87, 1/24 or just 87, give it a length in any unit, and it divides or multiplies to get the other dimension — real to model, model to real, or straight from one scale to another so you can work out what an HO building becomes in N gauge.
It also does the two things people forget. Architectural scales like ¼" = 1'-0" are really 1:48, and 1:100 is exactly 1 cm to the metre; the tool shows those equivalences and names the closest imperial drawing scale to whatever ratio you enter. And because area scales by n² while volume and weight scale by n³, it prints both factors and will scale a real-world weight down for you.
Every calculation runs locally in your browser with JavaScript, so nothing you type is uploaded and the page works offline once it has loaded. The converted length is shown in millimetres, centimetres, metres, inches, feet and yards simultaneously, which saves the second conversion step that usually follows a scale calculation on a workbench or a drawing board.
Frequently asked questions
What does a scale of 1:87 mean?
It means the real object is 87 times larger than the model, so you divide every real dimension by 87. A 10 metre real building becomes 114.9 mm at 1:87, which is HO scale — the most common model railway scale in the world.
What is 1/4 inch equals 1 foot as a ratio?
It is 1:48. One foot is 12 inches, drawn as a quarter of an inch, so the ratio is 12 ÷ 0.25 = 48. In the same way ⅛" = 1'-0" is 1:96 and 1" = 1'-0" is 1:12. The calculator names the nearest architectural scale for any ratio you enter.
How do you convert a model from one scale to another?
Multiply by the first scale factor to get back to full size, then divide by the second. Going from 1:87 to 1:160 means multiplying by 87 ÷ 160 = 0.544. Choose Convert a model between two scales and the tool combines both steps into a single factor for you.
Why does a scale model weigh so much less than the scale suggests?
Because weight follows volume, which scales by the cube of the ratio, not the ratio itself. At 1:87 a solid model is 87³ = 658,503 times lighter, so a 1,500 kg car becomes about 2.3 grams. Length shrinks by 87, area by 7,569 and weight by 658,503.
What scale is 1 cm to 1 metre?
That is 1:100, because there are 100 centimetres in a metre. It is the standard scale for building plans in metric countries. Likewise 1 mm to 1 metre is 1:1000, and 1:50 means 2 cm on the drawing stands for one metre.
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