Scale Converter
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the scale (the N in 1:N).
- Enter either the real size or the model size to get the other.
How it works
Model size = real size ÷ scale; real size = model size × scale. Both use the same unit.
Worked example
1:87 (HO), real 4350 mm. Model size = 50 mm.
Common mistakes
- Mixing units between the real and model figures — keep both the same.
- Entering the scale as a ratio (1:87) instead of just the number (87).
Frequently asked questions
What does 1:87 mean?
The model is 1/87th of the real object — 87 mm in real life becomes 1 mm on the model.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.