Photo Takeoff
Measure real distances from a site photo. Place a credit card or sheet of paper in the shot, mark its four corners to set the scale, then measure anything else in the same plane.
Select a photo to begin
Scale
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Mark all four corners of the reference object, clockwise from its top-left.
Measured distance
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Set the scale first.
Accuracy limits. This applies one uniform scale, so it is only valid when the reference object and the thing being measured sit in the same plane, with the camera roughly perpendicular. It does not correct perspective, so objects nearer the camera than the reference will read large and objects further away will read small. Treat results as a preliminary estimate and confirm anything load-bearing or cut-to-fit with a tape measure. Your photo is processed entirely on this device and is never uploaded.
How to use the Photo Takeoff
Photograph with a reference in shot
Place a bank card, A4 sheet or US Letter sheet flat on the same surface you want to measure, and shoot square-on to the surface.
Load the photo
Select the image. It is drawn onto a canvas in the page and never uploaded.
Calibrate against the reference
Choose which reference you used, then drag across its known edge. That sets the pixels-per-millimetre scale for the image.
Measure
Switch to measure mode and drag between any two points in the same plane to read the real distance.
Sanity-check one known dimension
Measure something whose size you already know. If that reads long, the shot was angled and every measurement is scaled with it.
Where this tool stops
It applies one uniform scale, so it is only valid where the reference and the thing being measured lie in the same plane with the camera roughly perpendicular. Angled shots read long.
Photo Takeoff — frequently asked questions
- How accurate is measuring from a photo?
- In a square-on shot with the reference on the same surface, a few percent is realistic — good enough to order materials, not good enough for a fabrication drawing. Accuracy degrades quickly with camera angle, because a single uniform scale cannot describe a perspective-distorted plane.
- Why do angled photos read long?
- A tilted camera foreshortens the image unevenly: the far part of the surface occupies fewer pixels per millimetre than the near part. Calibrating on the near part and measuring on the far part therefore over-reads. Correcting it properly needs a homography solved from four known points plus the camera's intrinsics, which is real photogrammetry — the tool says it cannot do that rather than returning a confident wrong number.
- What is the best reference object to include?
- A bank card, because ISO ID-1 is 85.60 mm everywhere in the world. A4 and US Letter are also offered and are better for large surfaces, since a bigger reference spreads the calibration error over more pixels.
- Does my photo get uploaded anywhere?
- No. The file is read by the browser into a canvas element on the page. There is no server, no upload endpoint and no storage — closing the tab discards it.
- Can I measure a wall from across the room?
- Only if the reference is on that wall, in the same plane, and you shot it square-on. A card on the floor cannot calibrate a wall — they are different planes, at different distances, with different scales.
- Can I measure an area rather than a length?
- Measure the two sides and multiply, which is also the honest way to do it: an area read directly from a photo compounds the perspective error in both directions at once.
- Why does the tool ask me to check a known dimension?
- Because it is the only way to catch a bad shot. If a door opening you know to be 762 mm reads 810, your scale is out by 6% and so is every other measurement in that image — better to find out before ordering.
- Does it work on an old photo from my phone's gallery?
- Yes, as long as a suitable reference object happens to be in the frame on the same surface. This is the main reason to drop a card into the shot whenever you photograph something on site — it costs nothing and makes the photo measurable later.
Turn this measurement into a quantity
A reading on its own does not order material. These calculators take what you just measured and give you quantities, cuts or cost.