Selected: OO Scale (1:76)
Enter a real-world measurement and your chosen scale. The app converts everything to millimetres first, then divides by the scale number to find the model size.
A note on figure heights: model figure height may be measured to the top of the head or to eye level, depending on the manufacturer. Always check the manufacturer's stated measurement convention before comparing scales.
All measurements are converted to millimetres before calculating, and results are rounded to two decimal places. Zero or negative values are not accepted.
How scale conversion works
Every conversion in this tool uses the same three relationships. The scale denominator is the number after the 1: — 76 for OO, 87 for HO, 148 for UK N.
Real size ÷ scale denominator = model size
Use it to check a figure or kit, or to scratch-build to scale.
Model size × scale denominator = real size
Use it to work out what a model represents.
Current scale denominator ÷ target scale denominator × 100 = STL resizing percentage
Use it to reprint an STL at a different scale.
Worked examples
Real size to model size
A person who is 1,800 mm tall becomes a 23.68 mm figure at 1:76 scale.
Calculation: 1,800 ÷ 76 = 23.68 mm.
Find a model's scale
A 25 mm figure representing a person who is 1,800 mm tall is at 1:72 scale.
Calculation: 1,800 ÷ 25 = 72, giving a scale of 1:72.
Resize an STL to another scale
To change a model from 1:35 to 1:48, set your slicer's uniform scale to 72.92% of its original size.
Calculation: 35 ÷ 48 × 100 = 72.92%.
Common questions
- How do I convert a real size to a model size?
- Divide the real measurement by the scale denominator. A 1,800 mm person at 1:76 is 1,800 ÷ 76 = 23.68 mm.
- How do I work out what scale a model is?
- Divide the real size by the measured model size. A 25 mm figure representing a 1,800 mm person is 1,800 ÷ 25 = 72, so the scale is 1:72.
- What percentage do I resize an STL by?
- Divide the current scale denominator by the target scale denominator and multiply by 100. Going from 1:35 to 1:48 is 35 ÷ 48 × 100 = 72.92%.
- Why do two figures sold as the same size differ in height?
- Manufacturers quote figure height in different ways — often to eye level rather than the top of the head — and body proportions vary between sculptors. Check the stated convention before comparing.