Scale Converter
Drawing and real-world lengths at any architectural scale
A ratio like 2:1 enlarges; 1:100 reduces. Pick a preset or type your own.
Measure any feature on a drawing, map or model, then enter the length it represents in reality. The scale is calculated for you.
Convert freely between a scale ratio, a percentage and a decimal factor — handy for photocopier enlarge / reduce and image resizing.
Edit any field — the others follow. 50% = 1:2 = 0.5× (half size); 200% = 2:1 = 2× (double size).
Which scale fits your sheet?
The real-world length above, converted to paper lengths at every common scale. Click a row to load that scale.
| Scale | On paper |
|---|---|
| 1:1 Current | – |
| 1:2 Current | – |
| 1:5 Current | – |
| 1:10 Current | – |
| 1:20 Current | – |
| 1:25 Current | – |
| 1:50 Current | – |
| 1:100 Current | – |
| 1:200 Current | – |
| 1:250 Current | – |
| 1:500 Current | – |
| 1:1000 Current | – |
| 1:1250 Current | – |
| 1:2500 Current | – |
Quick examples at this scale
How typical real-world objects measure on your drawing.
Common scales
Tap any scale to load it into the converter.
How the scale converter works
A scale tells you how many real-world units fit into one unit on a drawing. At 1:100, one centimetre on paper stands for one metre on site, so every measurement is reduced one hundred times. This converter turns drawing measurements into real sizes — and back again — for any metric, imperial, engineering, model or map scale.
Use Convert length to read a drawing or lay one out, Find the scale to discover the ratio of an unlabelled plan, and Scale factor to switch between ratios, percentages and the multipliers used for photocopier enlarge / reduce and image resizing. Nothing is uploaded — every calculation runs instantly in your browser.
Frequently asked questions
What does a scale like 1:50 mean?
It means one unit on the drawing represents fifty of the same units in reality. One centimetre on the page is 50 cm (half a metre) on site; one inch is 50 inches. The drawing is drawn at one-fiftieth of full size.
How do I find the scale of an unmarked drawing?
Open the Find the scale tab, measure any feature you know the real size of, and enter both lengths. The tool divides the real length by the drawing length to give the ratio and suggests the nearest standard scale.
What is a scale factor in percent?
The percentage is the drawing size as a share of the real size. 1:2 means the drawing is 50% of full size; 2:1 means it is 200% — twice full size. The Scale factor tab converts between ratio, percentage and decimal in one step.
Can I convert imperial architectural scales?
Yes. Scales such as ¼″ = 1′-0″ are listed under Architectural (imperial) with their ratio equivalent (1:48). Pick one and the converter handles inches, feet and metric units together.
Which model and railway scales are supported?
Diecast and plastic-kit scales (1:18, 1:24, 1:35, 1:48, 1:72…) and model-railway gauges (G, O, OO, HO 1:87, TT, N 1:160, Z 1:220) are all built in, plus map scales from 1:1 000 to 1:250 000.