GUIDE
Measuring area
on a PDF.
Getting a square-metre or square-foot figure off a PDF plan, in a way you can defend later.
Set the scale first — always
A PDF holds geometry in points, not metres. Until you calibrate the sheet, every area is meaningless. Enter the drawn scale (1:100, 1/4" = 1'-0"), or better, click two ends of a known dimension and type the real distance. Do it per sheet: a detail at 1:20 and a plan at 1:100 in the same file need separate calibrations. Full guide to calibrating.
Two ways to take the area
- Trace it. Click each corner of the room and close the shape. Best where the boundary is irregular or partly implied. Snapping to the drawing's own lines keeps corners honest.
- Fill it. With Dynamic Fill, click once inside an enclosed room and the tool follows the walls to find the boundary. Best for ordinary rooms, and far faster across a floor plan. If a doorway leaves the room open, close the gap with a boundary stroke and click again.
Either way you get the area and the perimeter from one shape — useful when the same room needs both flooring and skirting.
Take the deductions
Columns, shafts, and anything else that is not floor comes out as a deduction: draw it on the area and it is subtracted, shown in the total and carried into the export. This is better than measuring around an obstruction, because the deduction is visible and checkable later.
Name the areas so the totals add up
Give each area a subject — "Ground-floor flooring", "Acoustic ceiling" — and, if the job needs it, a space such as "Room 101". The summary then subtotals by subject and space, so a floor of rooms becomes a handful of numbers rather than forty rows.
Check yourself
Measure one room whose area you already know, or check a dimension after calibrating. A systematic error in the scale shows up immediately and costs nothing to fix; discovered after the estimate goes out, it costs a great deal.
Get the numbers out
Export the summary as CSV for the estimate, or export the drawing as a PDF with the measurements on it — as editable annotations for a colleague, or flattened for a client. Try it on the sample drawing without an account.
Worked example: flooring with a deduction
For an illustrative rectangular room 5 m long and 4 m wide, the gross floor area is 20 m². A 1 m × 1 m shaft deducts 1 m², leaving 19 m². Calibrate first, trace the room, add the shaft as a deduction and check the summary against this calculation. These are assumed dimensions, not quantities from the sample screenshot.
Try it on the sample drawing
Redline runs in the browser — nothing to install. Open the demo to try tools on a sample drawing. Demo edits are temporary; your own files, saving, signatures, exporting, printing and downloads come with the seven-day trial, which takes no card. After it you keep Redline Free, or choose Pro at $15 a month or $150 a year. Compare the plans.
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