Set the scale on a PDF drawing, and know you can trust it
You set the scale of a PDF drawing in pdf2takeoff by clicking both ends of a dimension you know and typing its length, by picking a standard scale such as 1:100, or by letting it read the scale straight off the title block. It then checks your scale against the sheet and shows whether to trust it. Free, in your browser, with nothing uploaded.
How to set the scale of a PDF drawing
- Open the drawing. Drop the PDF into pdf2takeoff. It renders on your machine; nothing is uploaded.
- Click a known dimension. Press C and click both ends of a long printed dimension or a length you know, such as a 6000 mm wall.
- Enter the length, a preset or Auto-read. Type the real length in mm, cm, m, in or ft, pick a standard scale from the list, or click Auto-read from sheet to read the printed dimension or the title-block scale.
- Choose one page or the whole set. Leave Apply this scale to every page in the set ticked for a uniform set, or untick it so this sheet keeps its own scale.
- Check the scale chip. The chip in the top bar shows the scale and where it came from. A tick means it matches the title block or the doors measure like doors; check scale means something disagrees.
Which scales are built in?
Metric 1:50, 1:100, 1:200 and 1:500; imperial architectural 1/16″, 1/8″ and 1/4″ = 1′-0″; and engineering 1″ = 10′, 20′ and 30′. Anything else: calibrate from a dimension. A preset is only right at the paper size the drawing was made for, so a dimension is safer when a sheet may have been printed smaller.
How does Auto-read work?
Auto-read uses on-device OCR. If you have clicked a dimension, it reads the number printed beside it (for example 12.00) and fills in the length for you to check before you apply it. If not, it looks for the scale note, such as SCALE 1:100, and applies that ratio. The first use downloads the OCR language pack (about 4 MB, then cached); the drawing itself never leaves your machine.
How do I know the scale is right?
Many takeoff errors start with a wrong scale. After you calibrate from a dimension, pdf2takeoff checks your scale against the sheet, and the chip in the top bar shows the result:
- matches title block: your scale agrees with the scale printed on the sheet.
- doors check out: there is no printed scale to compare with, but the sheet's doorways come out door-sized at your scale.
- check scale: something disagrees. The message says by how much and names the likely slip: a sheet printed at reduced size, millimetres read as metres, inches as feet, or a dimension like 1200 misread as 1:200.
Without a check, the chip says where the scale came from: from title block, from a dimension, set by hand or, for a DXF, from drawing units.
Can one sheet have more than one scale?
Yes. Every page keeps its own scale, so a set with a 1:100 plan and a 1:50 detail sheet measures correctly. When a detail drawn at another scale sits on the same sheet, press W, outline it as a viewport and pick its scale: measurements inside the region resolve to that scale automatically. The same 100 pt line reads 1.76 m inside a 1:50 viewport and 3.53 m at 1:100.
FAQ
What is the most accurate way to calibrate a PDF drawing?
Click the longest dimension you can find, end to end, and zoom in for the clicks: a small slip matters less over a long distance.
Can I use a printed ratio like 1:100 on a scan or image?
Only when the scan states its resolution (300 dpi, for example), because a ratio needs the paper size. Most photos and screenshots do not, so pdf2takeoff refuses the preset rather than give wrong lengths, and you calibrate from a dimension instead.
What if the sheet was printed at a different size?
Calibrating from a dimension gives correct lengths whatever the print size. If the title block says 1:100 but the page is an A3 print of an A1 drawing, the chip shows check scale and names the likely cause, so trust the dimension, not the printed ratio.
Do DXF files need calibrating?
No. A DXF opens at a standard scale worked out from its own units, and the chip says from drawing units. If the file does not state its units, pdf2takeoff estimates them from the drawing size and asks you to check a known dimension.
Calibrate your drawing
Open a PDF and set its scale in under a minute, or try the sample drawing, which has two sheets at different scales.
Related guides
- Measure area on a PDF drawing: room areas in one click, plus lengths and perimeters.
- DXF takeoff without AutoCAD: open a DXF with its scale already set.
- Takeoff from photos and scans: images, scanned PDFs, phone photos and screenshots.
- pdf2takeoff home: free construction takeoff software that runs in your browser.