Four corners describe how the reference plane has been distorted by perspective.
PHOTO MEASURE · FREE
Measure a flat area from a single photo.
For patios, lawns, floors and walls: photograph the surface, mark a known rectangle on the same plane, then trace the area you need. WorkedItOut perspective-corrects the surface before calculating.
1
Take or upload a good photoGet the whole area in frame. Avoid extreme angles and very wide-angle/zoom shots.
For the best result
✓ Reference rectangle must lie flat on the area being measured
✓ Use the largest known rectangle you can
✓ Keep all 4 reference corners clearly visible
✕ Don't use a vertical fence panel to scale a horizontal lawn
Your photo will appear here.
Reference: tap the 4 corners clockwise around your known rectangle.
2
Calibrate perspectiveUse something rectangular whose real size you know.
Examples: one paving slab, a rectangular mat, sheet of board, or a rectangle you've measured. It must be on the same plane as the target.
0 / 4 reference corners marked
3
Trace what you needTap around the outside edge of the patio, lawn, floor or wall.
Use more points for irregular shapes. WorkedItOut will transform those points onto the calibrated flat surface.
0 target points marked
Waiting for a photoUpload an image to begin.
Why four reference points?
A single length only provides scale at one part of a perspective photo. A known rectangle gives WorkedItOut enough information to correct the perspective of that flat plane before measuring the traced shape.
The corrected result is useful for planning quantities, but camera/lens and point-placement errors still matter.
A reference on a wall cannot calibrate a floor or lawn. Use a reference lying on the surface you're measuring.