Pipe Bending Calculator

The three numbers you reach for when bending: Bend allowance (BA) is the material the bend will consume along the neutral axis — BA = π / 180 × angle × (R + k × OD) × 180 / π × 1 — but the quick version in inches is (angle ÷ 360) × 2π × (R + k × OD). Setback is how far back you place the bend mark from the target line so the finished pipe lands at the correct end dimension. Outside arc is the total material path along the outside of the bend. This calculator shows all three for every angle.

Pipe fitters use 22.5° bends for small offsets because the math is clean: run length between two 22.5° bends equals the offset distance × 2.414. For 45° it is offset × 1.414. General: L = offset ÷ sin(angle/2). If you know offset and angle this calculator gives you the intermediate pipe length instantly — no trigonometry in the field.

When you need a tight elbow radius on site without a pipe bender, you cut a straight pipe into ring segments at angles A = 360° / N (where N is the number of segments) and miter each ring at half that angle so when you rotate them they form the bend. The cut angle per ring is A/2 and the centerline radius R = pipe_OD × 1.5 for standard long radius. This tool shows both the miter angle and the segment count.

All three words for the same thing: the mitered end cut on a pipe that branches into another pipe. The cope height h = pipe_OD × tan(θ/2), where θ is the branch angle. The distance from the pipe end to the start of the cope on the branch pipe is h / tan(θ/2). This calculator gives the cope height at 45° and 90° — the two angles you see 90% of the time in handrails and framed steel.

Strip width = circumference = π × OD (all in the same unit). If you are shearing sheet metal and rolling it into pipe, the finished pipe inside diameter is OD − 2 × wall — so strip width for the ID you want is π × (ID + 2 × wall). This calculator's circumference number IS the strip width for a one-piece roll, and that is why strip-width questions show up on pipe calculators.

When you bend metal, it springs back a few degrees after the ram releases — steel ≈ 1.5°, aluminum ≈ 0.8°, stainless ≈ 2.5°. To hit a finished 90° you bend 91.5° on steel. This tool shows the adjusted angle you should program the bender for, not just the finished angle you need. Skip it and your handrail ends up off by a degree or two — enough to be visible.