Take real measurements from scale drawings — right in your browser.
Drop in a floor plan, site plan or blueprint — PDF, JPG or PNG. Calibrate against one known dimension, then read distances, areas and angles straight off the drawing. Free, no account, and your files never leave your device.
- No sign-up
- Nothing uploads
- Works on phone & desktop
01 · How it works
From drawing to dimensions in under a minute
If the drawing is to scale, one known length unlocks every other measurement on the page.
Upload a plan
Drop in a PDF, JPG or PNG up to 30 MB — an architect's drawing, an estate agent's floor plan, or a straight-on photo of a paper plan. Multi-page PDFs become multi-page drawings.
Calibrate once
Draw a line over any dimension you already know — a labelled wall, a door width, a scale bar — and type its real length. Add more than one calibration and Scale Rule averages them.
Measure anything
Distances, running paths, room areas, angles — drawn on the plan, read out in metres or feet. Every shape stays editable, with full undo.
02 · What you get
Four tools and the workflow around them
Distance, path, area, angle
Point-to-point lengths, running polylines, polygon areas and three-point angles — with vertex snapping for clean lines.
PDF, JPG & PNG plans
PDFs render page-by-page in your browser at drawing-office resolution. No conversion step, no upload.
Robust calibration
Multiple calibrations per page are averaged, and Scale Rule warns you when they disagree enough to matter.
Editable measurements
Drag vertices, insert points mid-segment, rename, undo and redo. Your measurements are living objects, not burned-in ink.
Metric & imperial, exportable
Toggle m/ft per drawing. Copy a single value, or the whole list as TSV for a spreadsheet or Markdown for a doc.
Backup & restore
Export your whole library — drawings included — as a single file, and import it on any device. That file is yours; there is no cloud copy.
03 · Privacy
Your drawings never leave your device
Nothing uploads. Ever.
Scale Rule stores no user data, has no accounts and runs no analytics scripts — the web server's only job is delivering the app's files to your browser. Reading the file, rendering PDF pages, calibrating, measuring — all of it happens in your browser, and everything is stored only in your browser.
- No account — open the app and start measuring.
- No upload — plans are processed and stored locally (IndexedDB).
- No trackers — no analytics scripts, nothing follows you around.
- No lock-in — export everything to a plain JSON file, any time.
04 · FAQ
Frequently asked questions
How do I measure from a PDF floor plan?
Open Scale Rule, drop the PDF in, and each page is rendered in your browser. Draw a calibration line over any dimension you already know — a labelled wall, a door width, a scale bar — and type in its real length. From then on, every distance, path, area or angle you draw reads out in real-world units.
How accurate are the measurements?
As accurate as the drawing and your calibration. On a clean, to-scale plan with a careful calibration line, results are typically well within a percent or two. Treat them as estimates: always verify independently before making a purchase or construction decision.
Do my drawings get uploaded anywhere?
No. There is no account and no server-side storage — the server's only role is delivering the app's files. Your files are read, rendered and stored entirely in your browser (IndexedDB). Clearing the browser's site data deletes them — use the built-in backup export if a drawing matters to you.
Is Scale Rule really free?
Yes — free, with no account, no watermarks and no measurement limits. It runs entirely in your browser, so there is very little for us to pay for either.
What file types does it support?
PDF, JPG and PNG, up to 30 MB per file. Multi-page PDFs become multi-page drawings. A straight-on photo of a paper plan works too — calibrate against a known dimension in the photo.
Can I measure areas and angles, not just lengths?
Yes. Four tools: distance (two points), path (a running polyline), area (a polygon, e.g. a room or a plot) and angle (three points). Every shape stays editable afterwards — drag vertices, insert or remove points, undo and redo.
05 · Guides
Measuring know-how
Short, practical guides to getting trustworthy numbers off a drawing — browse them all.
- How to measure a PDF floor plan Upload, calibrate, measure — real dimensions in about a minute.
- Architectural scales explained 1:50, 1:100, ¼″ = 1′-0″ — what they mean and why screens break them.
- How to measure area on a plan Rooms, gardens and plots — trace a polygon, read m² or ft².
- Measuring from a photo of a plan When a phone photo is good enough, and how to shoot one that measures well.