How to Measure a Corner and Find the Miter Angle
Short answer: measure the corner angle, then cut each of the two pieces at half of it. A 90° corner needs two 45° cuts; a 135° corner needs two 67.5° cuts. Measure the real corner, because walls are rarely exactly square.
Step 1: measure the corner
Hold the phone flat against the wall or lay it on the floor in the corner. Put the protractor's vertex in the corner and line one arm along each wall. Or take a photo looking straight down into the corner and measure on the photo.
Step 2: halve it
Each piece takes half the corner. Examples: 90° → 45°, 92° → 46°, 120° → 60°, 135° → 67.5°.
Step 3: set the saw
Many miter saws read 0° for a square cut. On those, the setting is 90° minus the half angle: a 46° miter is a 44° setting. Make a test cut on scrap and check the fit before cutting the good piece.
Doing it with Anglora
Anglora shows the measured angle and the other angle at once, so you can read the corner directly. Save it as "hall corner" with a note of the half angle, and it will be there when you get to the saw.
Frequently asked questions
My walls are not square. What do I do?
Measure the real corner, for example 92°, and cut each piece at half of it, 46°. On a miter saw set to 0° for square, that is a 44° setting (90 − 46).
Is the miter angle the same for inside and outside corners?
Yes, each piece is cut at half the corner angle; only the direction of the cut flips.
How do I measure a corner I cannot reach?
Take a straight-on photo looking down into the corner and measure it on the photo.
Related guides
- How to Measure an Angle With Your Phone (3 Ways)
- How to Find Roof Pitch With Your Phone (Degrees, %, x/12)
Get Anglora: protractor, camera angle finder and level (Google Play)