Floor plan scale calculator
Measured a wall on the drawing? Get its real length at 1:50, 1:100 or any scale. Or find the scale of a plan from one dimension written on it.
Scale
On the drawing → real
In reality
Find the scale
The scale is
How plan scales work
A scale of 1:100 means every length on the drawing is a hundredth of the real one. To get a real length, multiply what you measured on the paper by the scale’s second number; to draw something, divide. Keep the units the same on both sides: 36 mm on a 1:100 plan is 3,600 mm, which is 3.6 m.
The scale printed on a plan is only true on paper at the size it was drawn for, usually A3 or A4. A PDF on screen or a plan printed “fit to page” has a different scale, so check it against a dimension written on the drawing before relying on it. More on reading the numbers in how to read floor plan dimensions and how to read a floor plan.
Questions, answered
What does 1:100 mean on a floor plan?
One unit on the drawing is 100 of the same units in reality: 1 cm on the plan is 100 cm, or 1 m, in the flat. At 1:50, 1 cm is 50 cm; at 1:200, 1 cm is 2 m.
How do I find the scale of a floor plan with no scale written on it?
Measure on the drawing a wall whose real length is written beside it, then divide the real length by the drawn one, in the same units. A 3.6 m wall drawn 36 mm long is 3,600 ÷ 36 = 1:100. The calculator’s third box does exactly this.
Can I scale a plan I see on a screen?
Not by its printed scale: zooming changes the size on screen. Use a known dimension instead, such as a written room size or a door, about 80–90 cm wide in most flats, and work out the scale from that.
What are the usual scales for house plans?
1:50 for a single flat or room in detail, 1:100 for a whole flat or house floor, 1:200 or 1:500 for a building or site. US plans write scales as 1/4″ = 1′-0″ (which is 1:48) or 1/8″ = 1′-0″ (1:96).
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