How to use
Choose whether the target diameter is inside, outside or neutral. Enter thickness, neutral-axis K, seam allowance and trim applied to each end.
Example calculation
Di = 500 mm, t = 2 mm, K = 0.5, s = m = 0 → Dn = 502 mm; L ≈ 1577.07951 mm.
Calculation method
Di: Dn = Di + 2Kt Do: Dn = Do − 2(1−K)t L = πDn + s + 2m
Calculation limits
K=0.5 assumes the middle surface. Springback, rolling-machine effects and weld shrinkage are not automatic; verify with a trial.