Press brake dies
Compare single-V, multi-V, hemming, radius and special dies across supported clamping styles.
Browse press brake dies →Free fabrication calculator
Press Brake Tonnage Calculator
Estimate 90-degree air-bending force by material, thickness, bend length and V-die opening. Results include total US tons, metric tonnes, kN, tons per foot and tonnes per metre.
Enter the bend
Air bending only. Use measured material thickness and the actual die opening.
How this press brake tonnage calculator works
The calculator uses the same 90-degree air-bending relationship published in the Machinist’s Vault tonnage guide: US tons per foot = 575 × material factor × thickness² ÷ V opening. Thickness and V opening are converted to inches before the formula is applied.
Total load is the calculated linear load multiplied by the actual bend length. A machine can have enough total force while the tooling is still overloaded per foot or per metre, so both numbers must be checked.
See the full tonnage chart, worked examples and manufacturer references.
Documented V-opening starting points
- 1–2 mm sheet: approximately 6 × thickness
- 3–8 mm sheet: approximately 8 × thickness
- 10–12 mm sheet: approximately 10 × thickness
Gaps are intentional. The published guide does not prescribe a default ratio between those bands. Enter the manufacturer-approved opening instead of guessing.
Do not widen a die solely to reduce tonnage until inside radius, minimum flange, angle and drawing requirements have been checked.
Metric press brake tonnage table
Estimated metric tonnes per metre for 90-degree air bends. Multiply by bend length in metres for total metric tonnes.
| Thickness | V opening | Aluminum | Mild steel | Stainless |
|---|---|---|---|---|
| 1.0 mm | 6 mm | 5.6 t/m | 11.2 t/m | 16.8 t/m |
| 1.5 mm | 9 mm | 8.4 t/m | 16.8 t/m | 25.3 t/m |
| 2.0 mm | 12 mm | 11.2 t/m | 22.5 t/m | 33.7 t/m |
| 3.0 mm | 24 mm | 12.6 t/m | 25.3 t/m | 37.9 t/m |
| 4.0 mm | 32 mm | 16.8 t/m | 33.7 t/m | 50.5 t/m |
| 5.0 mm | 40 mm | 21.1 t/m | 42.1 t/m | 63.2 t/m |
| 6.0 mm | 48 mm | 25.3 t/m | 50.5 t/m | 75.8 t/m |
| 8.0 mm | 64 mm | 33.7 t/m | 67.4 t/m | 101.1 t/m |
| 10.0 mm | 100 mm | 33.7 t/m | 67.4 t/m | 101.1 t/m |
| 12.0 mm | 120 mm | 40.4 t/m | 80.9 t/m | 121.3 t/m |
Imperial press brake tonnage table
Estimated US short tons per foot for 90-degree air bends. Multiply by bend length in feet for total US tons.
| Gauge / thickness | Decimal | V opening | Aluminum | Mild steel | Stainless |
|---|---|---|---|---|---|
| 20 ga | 0.036 in | 0.250 in | 1.5 tons/ft | 3.0 tons/ft | 4.5 tons/ft |
| 18 ga | 0.048 in | 0.375 in | 1.8 tons/ft | 3.5 tons/ft | 5.3 tons/ft |
| 16 ga | 0.060 in | 0.500 in | 2.1 tons/ft | 4.1 tons/ft | 6.2 tons/ft |
| 14 ga | 0.075 in | 0.625 in | 2.6 tons/ft | 5.2 tons/ft | 7.8 tons/ft |
| 12 ga | 0.105 in | 0.750 in | 4.2 tons/ft | 8.5 tons/ft | 12.7 tons/ft |
| 10 ga | 0.135 in | 1.000 in | 5.2 tons/ft | 10.5 tons/ft | 15.7 tons/ft |
| 3/16 in | 0.188 in | 1.500 in | 6.8 tons/ft | 13.5 tons/ft | 20.3 tons/ft |
| 1/4 in | 0.250 in | 2.000 in | 9.0 tons/ft | 18.0 tons/ft | 27.0 tons/ft |
| 5/16 in | 0.313 in | 2.500 in | 11.3 tons/ft | 22.5 tons/ft | 33.8 tons/ft |
| 3/8 in | 0.375 in | 3.000 in | 13.5 tons/ft | 27.0 tons/ft | 40.4 tons/ft |
| 1/2 in | 0.500 in | 4.000 in | 18.0 tons/ft | 35.9 tons/ft | 53.9 tons/ft |
Match the calculation to real tooling
A force result is only useful after the opening, style, angle, radius, length and maximum linear-load rating are confirmed against the machine and drawing.
Press brake punches
Review straight, gooseneck, radius and application-specific punches by machine style.
Browse press brake punches →Complete tooling range
Shop punches, dies, adapters, clamps and accessories, or request help matching a bend.
View all press brake tooling →Press brake tonnage calculator FAQ
How accurate is a press brake tonnage calculator?
It is a planning estimate when the material factor, thickness, V opening and bend length match the job. Certified material strength, tooling condition, friction and machine setup can change the real load, so the approved machine and tooling data must be checked before production.
How much tonnage is needed to bend 1/4-inch mild steel?
Using the source guide’s 2-inch V opening and 60,000 psi mild-steel baseline, the estimate is approximately 18 US tons per foot. A six-foot bend therefore estimates to 108 US tons before machine and tooling verification.
Why does stainless steel require more tonnage?
The published planning chart uses a 1.5 stainless factor compared with the mild-steel baseline. Grade-specific tensile data is more accurate than treating every stainless alloy as identical.
Can I use this calculator for aluminum?
Yes, as a preliminary estimate using the published 0.5 planning factor. Alloy and temper strongly affect bending behaviour, radius and springback, so confirm the exact material.
Can this calculator be used for bottoming, coining or hemming?
No. The source guide covers 90-degree air bending only. Bottoming, coining, hemming, offset forming, off-centre loading and special tooling need process-specific manufacturer or engineering data.
Does a wider V opening reduce required force?
Yes. V opening is in the denominator of the air-bending formula, so a wider opening reduces estimated force. It also changes natural inside radius and minimum flange, which must be checked before changing the die.
Reviewed by
This calculator and guide are reviewed by Kartar Chalotra, Sales & Operations at Rise Tek Machinery.