Plan scale calculator
From the centimetre measured on paper to the real metre, and back.
Result
Indicative calculation, run in your browser. No data is sent anywhere.
A 1:100 scale means one centimetre on the drawing equals one metre on site. The rule is simple, but it breaks as soon as an A1 drawing is printed on A3: the scale in the title block is no longer right, and every measurement taken with a ruler is wrong.
The calculator works both ways: what a distance measured on paper is worth in reality, and what a known real distance should measure on paper. That second formula is the one that lets you check a print's actual scale against a dimension written on it.
You can also let the plan supply these figures for you.
Plan measurementFrequently asked questions
How do I recover the scale of a dubious print?
Take a dimension written on the drawing, measure the same distance with a ruler, and compare with the real-to-paper result. If the measurement does not match, the title block scale does not correspond to the print in your hands.
What about a PDF on screen?
On screen the notion of paper scale no longer applies: everything depends on the zoom. That is exactly the problem the scale calibration in the app solves, where two points and one known distance are enough to measure the rest of the drawing.
Which scales are offered?
The most common in building: 1:20 and 1:50 for details and construction drawings, 1:100 for floor plans, 1:200 and 1:500 for site plans, 1:1000 for location plans.