Minimum Bend Radius Calculator

Formula

• R_min = (R/t factor) × thickness
• R/t from material table × method multiplier
• Springback ≈ base springback × (bend angle / 90°)

About this calculator

Part of our Sheet Metal Calculators collection. Bend allowance, K-factor, flat pattern length, and minimum bend radius.

How it works

Minimum inside radius equals material R/t factor times thickness, adjusted for temper and bending method. Springback estimate helps you plan overbend. Risk code flags when your chosen radius is tight for the material and process.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

Stainless 304, annealed, air bend, 2 mm thick, 90° bend.

1. Base R/t = 0.5 (SS304 annealed)
2. Air bend multiplier = 1.0
3. Min inside radius = 0.5 × 2 = 1.0 mm

Result: Minimum inside radius 1.0 mm, outside 3.0 mm, springback ~3°.

When to use

• Checking if a design radius will crack the material
• Planning press brake tooling selection
• Estimating springback before trial bends

Limitations

• Material table is indicative; verify with supplier data
• Grain direction and edge condition affect cracking
• Custom mode requires your own R/t from testing

FAQ

What does the risk label mean?

Low R/t (<0.3) may over-stress material; medium (0.3–1.5) is typical; high (>1.5) is generous and easier to form.

Air bend vs coining?

Coining uses higher force and smaller effective R/t multipliers. Air bend is most common on CNC brakes.

Why scale springback by angle?

Springback increases with bend angle. The estimate scales a 90° baseline to your entered angle.