Scale Calculator — real ⇄ drawing size
Convert between real-world and drawing dimensions at any scale (1:50, 1:100, custom) for architecture and models.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Convert between real-world size and drawing size at a chosen scale. Edit either length — the other updates instantly.
About this tool
This scale calculator converts between real-world measurements and drawing or model dimensions at any ratio, such as 1:50, 1:100 or a custom scale you type in. Enter a real length to get its size on the plan, or a drawing length to get the true dimension — ideal for architecture, blueprints, maps and scale models. Every calculation runs instantly in your browser.
Frequently asked questions
How does a scale like 1:100 work?
A ratio of 1:100 means one unit on the drawing represents 100 of the same units in reality, so 1 cm on paper equals 100 cm — one metre — in the real world. Enter either the real or the drawing length and the calculator multiplies or divides by the scale factor to give you the other, in whatever unit you choose.
Can I use it for maps and model kits too?
Yes. The same math applies to map scales, model railways and miniatures — just enter the ratio printed on the map or kit, such as 1:25000 or 1:48. You can also mix units, for example entering a real distance in metres and reading the model size in millimetres.
Is my data sent anywhere?
No. The scale calculator runs entirely in your browser as plain arithmetic, so the numbers you type are never sent to or stored on any server.