K-Factor (Bend Allowance) Calculator

Find bend allowance from K-factor.

Bend angle (degrees)

Inside radius

Material thickness

K-factor

Bend allowance 3.66

Formula: BA = (π/180) × angle × (IR + K × thickness)

Step-by-step with your numbers:

1. Values used:

2. Bend angle = 90 degrees

3. Inside radius = 2

4. Material thickness = 1

5. K-factor = 0.33

7. Bend allowance = 3.66

Did we solve your problem today?

Find the flat-pattern length needed for a sheet metal bend.

The math behind it

bend allowance = bend angle (radians) × (inside radius + K × thickness). K-factor ≈ 0.33 for common steel.

90° bend, IR 2 mm, 1 mm thick, K 0.33 → BA ~3.66 mm.

K-factor value?

It varies by material and bending method — 0.33 is common for mild steel.