Min Bend Radius Calculator
Determine the smallest safe inside bend radius for your material and thickness before the outside fibers crack.
Using this calculator responsibly
The Min Bend Radius calculator is an engineering aid for checking a shop-floor estimate before a setup, quote, or process review. Enter values in the units shown, confirm material properties against the applicable specification, and keep a record of the assumptions used. Calculator output does not override machine capacity, tooling limits, part requirements, or a qualified engineer's approval.
Before using a result in production, repeat the calculation with the extreme values allowed by the print or process window. Check that the selected material, thickness, geometry, and safety factor reflect the actual job. If a result approaches a press, die, fastener, or machine limit, stop and verify it with the equipment manufacturer or responsible engineer.
Inputs and results
Read every field label before entering data and avoid mixing inch and metric values. A useful result should be traceable to the job number, revision, material certification, and machine or tooling record. Treat warnings, invalid ranges, and unusual outputs as reasons to inspect the inputs rather than as values to work around.
Bending too tight cracks the outer fibers. The minimum inside radius is a multiple of thickness that depends on the material’s ductility and bend orientation relative to grain.
Bending across (transverse to) the grain allows a tighter radius than bending along it.
Formula: Min inside radius ≈ k × Thickness (k set by material & grain)
Worked example
- Soft aluminum may allow k ≈ 0 (near-zero radius); a hard temper may need k ≈ 3.
- For 0.060 in stock at k = 1, hold a minimum inside radius of about 0.060 in.