Sheet metal

Minimum Bend Radius Calculator

Estimate only: actual tonnage and radius depend on material tensile, grain direction, springback, and tooling condition. Verify machine capacity and tooling load limits before operation.

Estimate a starting minimum inside bend radius from material family, temper, and sheet thickness. The factor varies with grain direction and supplier; treat the result as a starting reference.

mild steel16 ga0.0598 in1.519 mm

Interactive calculator

Minimum Bend Radius Calculator

Minimum inside radius0.0598 in
Radius factor1T

Static reference

Common thickness, radius, and angle combinations

Swipe table horizontally for more columns.

GaugeThicknessInside radiusAngleBend allowanceBend deduction
16 ga0.0598 in / 1.519 mm0.0598 in / 1.519 mm45 deg0.0667 in0.0324 in
12 ga0.1046 in / 2.657 mm0.1569 in / 3.985 mm90 deg0.3155 in0.2075 in

Formula used

What this calculator computes

MBR = factor × t
MBR
Minimum inside bend radius (starting estimate) (in or mm)
factor
Material/temper-specific multiplier (xT) (ratio of t)
t
Material thickness (in or mm)
  • Factors shipped with this calculator are common shop starting values. Different mills, tempers, and coatings can need 0.5–2× this value.
  • Bends across the grain typically need a larger radius than bends with the grain — sometimes by 1×T or more.
  • Bend radius below the material's minimum risks cracking, tearing, or coating fracture.

Worked example

One numeric walk-through

Inputs

Material
6061-T6 aluminum
Thickness t
0.0508 in (16 ga aluminum, per gauges.json)
Material factor
3T (default for 6061-T6)

Steps

  1. MBR = 3 × 0.0508 = 0.1524 in.

Result

Starting minimum inside radius ≈ 0.152 in. Verify with the supplier's bend-radius chart and a coupon test before committing tooling.

Common mistakes

Things to check before trusting the number

Related calculators

Move between connected shop calculations

K-factorBend allowanceBend deductionFlat patternMinimum bend radiusReverse K-factorPress brake tonnageData sources

FAQ

Specific checks for this calculator

Why does 6061-T6 need a larger bend radius?

6061-T6 is heat-treated and harder than annealed or H-temper alloys; tighter radii concentrate strain and risk cracking. The default factor is a starting estimate.

Is minimum bend radius the same as V-die radius?

No. Minimum bend radius is a material strain limit. The produced inside radius in air bending is roughly 16% of the V-die opening, set by tooling, not by the material.