Drawing scales explained: 1:50, 1:100 and more

A scale like 1:100 means one unit on the drawing stands for 100 of the same units in real life. It's simple, but it only holds when the drawing is at the size it was made for.

Scale	1 cm on paper is	Typically used for
1:20	20 cm	Details, joinery, kitchens
1:50	50 cm	Floor plans of houses and flats, sections
1:100	1 m	Floor plans and elevations of larger buildings
1:200	2 m	Site layouts, block plans
1:500 and 1:1250	5 m and 12.5 m	Site and location plans

Why the paper size matters

A drawing marked “1:100 at A3” is only 1:100 when it's printed or viewed at A3. On A4 it's about 1:141; with “fit to page” it could be anything. Always check the paper size next to the scale.

Measuring a scaled PDF in ScaleDraw

PDF pages keep their real paper size when you import them. After pressing Calibrate and drawing a line, you can type the printed ratio (for example 100 for 1:100) instead of a length, and the whole page is set to that scale. If you're not sure the PDF was exported at its true size, calibrate on a known dimension instead. That works whatever happened to the file.

Step by step: measure a PDF plan to scale.

Questions

Is 1:50 bigger than 1:100?

Yes. At 1:50 things are drawn twice as large as at 1:100, so 1:50 shows more detail.

What does NTS mean?

Not to scale. Measurements taken from it are only a guide.