Press brake

Press Brake Tonnage 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 air-bending tons per foot and total machine tonnage from thickness, V-die opening, bend length, and a material multiplier. Use the result to plan tooling and machine selection — never as a final load number.

mild steel16 ga0.0598 in1.519 mm

Interactive calculator

Press Brake Tonnage Calculator

Tons per foot5.73 tons/ft
Total tonnage22.92 tons
Material multiplier1x

Static reference

Common V-die and tonnage combinations

Swipe table horizontally for more columns.

GaugeThicknessRecommended VInside radius estimate48 in bend tonnage
20 ga0.0359 in / 0.912 mm0.2154 in0.0345 in13.76 tons
16 ga0.0598 in / 1.519 mm0.3588 in0.0574 in22.92 tons
12 ga0.1046 in / 2.657 mm0.6276 in0.1004 in40.1 tons
10 ga0.1345 in / 3.416 mm1.076 in0.1722 in38.67 tons

Formula used

What this calculator computes

T_ft = (575 × M × t²) / V
T_ft
Tons per foot of bend length (tons/ft)
575
Empirical air-bend constant for mild steel in imperial units (—)
M
Material multiplier vs mild steel (1.0 baseline) (ratio)
t
Material thickness (in)
V
V-die opening (top width of the female die) (in)
  • The 575 constant is a widely circulated shop rule of thumb for air bending mild steel with t and V in inches and the result in tons per foot. It is not from a single normative standard — manufacturer charts vary.
  • Metric inputs are converted to inches before the formula runs; the constant itself remains imperial-rooted.
  • Material multipliers shipped with this calculator are starting estimates per family/temper — see /reference/data-sources/.
T_total = T_ft × (L / 12)
T_total
Total tonnage required for the bend length (tons)
T_ft
Tons per foot of bend length (from the formula above) (tons/ft)
L
Bend length (in)

Worked example

One numeric walk-through

Inputs

Thickness t
0.125 in (1/8")
V-die opening V
1.000 in
Bend length L
48 in (4 ft)
Material multiplier M
1.0 (mild steel baseline)

Steps

  1. t² = 0.125 × 0.125 = 0.015625.
  2. T_ft = (575 × 1.0 × 0.015625) / 1.0 = 8.984 tons/ft.
  3. T_total = 8.984 × (48 / 12) = 35.94 tons.

Result

About 9 tons/ft and 35.9 tons total for this 4-ft bend. Verify against the press brake's rated tonnage AND against the punch and die tooling load ratings before forming.

Common mistakes

Things to check before trusting the number

Related calculators

Move between connected shop calculations

TonnageV-die openingBend allowanceMinimum bend radiusData sources

FAQ

Specific checks for this calculator

Is press brake tonnage calculated per foot?

Most air-bending charts start with tons per foot, then multiply by bend length in feet to estimate total required tonnage. This calculator does both steps.

Why is stainless tonnage higher than mild steel?

Stainless typically has higher tensile strength and work-hardening behavior, so the calculator applies a multiplier (~1.5× for 304, ~1.6× for 316) versus the mild-steel baseline.