Bend Radius Calculator
Bend calculator
Arc length, tangent length, cut length, D-of-bend and wall factor for a single bend between two straight legs. Inches or millimetres.
Results
- Arc length (in the bend) CLR × θrad
- Tangent length CLR × tan(θ/2)
- Cut length
- Straight before bend Mark from end A to the bend start
- D of bend CLR ÷ OD
- Wall factor OD ÷ wall
- Outside / inside radius CLR ± OD/2
- Outer-wall stretch (theoretical) OD ÷ (2 × CLR); ignores neutral-axis shift
Geometry is exact for the inputs. Real bends also stretch or "gain" slightly depending on machine and die, so calibrate with a test piece before cutting expensive tube.
Springback from your test bend
There is no reliable universal springback table for tube — it changes with material batch, wall, radius and machine. Bend a scrap piece, measure it, and let the numbers tell you how far to over-bend.