Offline
No internet, no account required.
IRC
Validated against the standard.
PDF export
Pro-only. Generate professional reports.
$2.99 Pro
Lifetime unlock. No subscriptions.
How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
Get a code-checked result
Instant answer with a clear PASS / FAIL and the exact IRC reference behind every number.
Save & export
Keep a history of calculations and export a clean PDF report to share or attach to a permit (Pro).
What this calculator does
Corners are rarely a perfect 90°. This app gives the miter (and bevel) angles to join two pieces at any corner, and handles compound angles for crown molding, so joints close tight.
The basics
- For a flat butt joint, the miter angle = corner angle ÷ 2 (a 90° corner is a 45° miter).
- Out-of-square corners — measure the actual corner and the app splits it.
- Crown molding — the app gives the compound miter and bevel from the spring angle and the corner.
Worked example
An out-of-square corner measuring 86° needs a miter of 86 ÷ 2 = 43° on each piece. A 92° corner needs 46° cuts — small differences that show badly if you cut a flat 45.
Related calculators
Measure runs with the trim and molding calculator and lay out stairs with the stair calculator.
Angle and miter FAQ
How is the miter angle found?
For a simple joint it is half the corner angle, so a 90° corner is a 45° miter. The app splits any measured corner, including out-of-square ones.
Does it do compound angles for crown?
Yes. Enter the crown's spring angle and the corner angle and it returns the saw's miter and bevel settings for a compound cut.
Can it handle non-90 corners?
That's the point — measure the real corner angle and the app gives the exact cut for each piece so the joint closes.
Does it work offline?
Yes, it runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
Get Angle Miter Calc on your phone
Free with rewarded ads · $2.99 lifetime Pro · iOS & Android. Works 100% offline on the job site.