Photo Angle Finder
Last updated: September 29, 2026
A photo angle finder measures angles that already exist inside an image: a snapshot of a roofline, a screenshot of a drawing, or a picture of the joint you are trying to match. Choose a file and a digital protractor appears on top of it, ready to drag into position and read.
The picture is decoded in your browser and held only in memory. It is never uploaded, stored or sent anywhere, so job-site photos, client interiors and confidential drawings can all be opened here without a second thought.
Angle Properties & Complementary
Keyboard Shortcuts:
Measurement History
Saved in this browser only - never uploaded.
| Time | Mode | Degrees | Radians | Slope |
|---|---|---|---|---|
| Every angle you lock is logged here. | ||||
How to measure an angle in a photo
Photo mode opens on this page. Pick a file with the browse button or drag the image straight onto the canvas – it is fitted to the workspace, and you can zoom with the wheel or a pinch and pan by dragging the image itself while the protractor overlay stays where you left it.
Move the vertex of the angle to the centre of the protractor, swing the baseline onto one edge, then bring the moving arm onto the second edge. The panel on the right reports degrees, radians and slope the moment the arm moves, and the fine-tune buttons let you finish the last fraction of a degree one hundredth at a time. Lock the reading when it looks right, then copy it into your notes or leave it in the history below.
Photos that measure well (and photos that do not)
The rule is the same as with a live camera: shoot square-on. A picture taken at an angle to the surface distorts it, and a wide-angle phone lens at close range bends straight lines near the edges of the frame. When you can, retake the shot from further back with the subject centred, and keep the horizon level.
Light and sharpness matter as much as position. A clean edge lets the overlay sit exactly on the line; a blurred or heavily compressed photo turns a crisp roofline into a band several pixels wide, and the reading drifts as you zoom. When you are measuring something that lives on a screen rather than in the real world – a screenshot of a plan, for instance – set the screen PPI in the calibration panel first so the tool can relate pixels to millimetres.
Typical jobs for a photo angle finder
Photograph the angles you cannot walk up to: the rake of a second-storey gable, the slope of a roof seen from the street, the corner behind a fitted unit. Carpenters use it to copy the angle of an existing skirt board, roofers to sanity-check a pitch from a listing photo, and students to check the angles printed in a photographed homework diagram.
It is also the quickest way to work from drawings: screenshot the plan, open it here, and read the angle straight off the screen instead of guessing at a printed scale. Locked readings accumulate in the measurement history under the canvas and export as a CSV file, so a session of measuring turns into a table you can paste into a quote.