Scale Converter

How to use

1. 1Pick a mode: scale to real size, real size to scale, or find the scale.
2. 2For the first two modes, set the scale as model side to real side, or tap a preset like HO 1:87.
3. 3Enter your measurement and choose its unit, then choose the unit for the answer.
4. 4To find a scale, enter one length on the model or drawing and the matching real length in any units.
5. 5Read the result and scale factor, then copy any value you need.

About this tool

Scale Converter answers the three questions that come up whenever a real object is shrunk or grown onto a model, a map, or a drawing. Scale to real size takes a measurement you read off the model, map, or blueprint and a scale ratio such as 1:87, then reports the full real-world size, with the answer shown both in the unit you measured in and in any unit you choose, so 100 mm at 1:87 becomes 8.7 metres. Real size to scale works the other way: type a real length and a scale and the tool tells you exactly how big to draw or build it, which is what you need when laying out a floor plan at 1:100 or cutting parts for a 1:24 model. Find the scale derives the ratio for you: enter one length measured on the model or drawing and the matching real length, in any two units, and it computes the scale ratio and scale factor, reducing it to a clean 1:N or N:1 form and telling you whether the drawing is a reduction or an enlargement. The scale is expressed as model side to real side, so an enlargement like 2:1 is handled as naturally as a reduction like 1:160. A unit menu covers millimetres, centimetres, metres, kilometres, inches, feet, yards, and miles, and mixed units are fine because every value is converted through millimetres internally, so you can read centimetres on a map and get the distance in kilometres or miles. Preset buttons fill in common model railroad scales (N, HO, OO, O), popular model and dollhouse scales, map scales, and architectural drawing scales so you do not have to remember the numbers. Everything is computed in your browser with plain arithmetic; the measurements you enter are never uploaded.

Free to use. Works in your browser. No signup, no login.