2017 Two-V Die, 60°
Amada-style die with 16 mm and 20 mm V openings and a listed 60 T/m maximum.
From $241 CAD
View Two-V Die →Press Brake Tonnage Calculator & Air-Bending Guide
Use this press brake tonnage calculator to estimate the air-bending force required from material thickness, bend length, V-die opening and material type. It reports US tons per foot, total US tons, metric tonnes, force in kN, estimated natural inside radius and minimum flange. Use the result for planning only, then confirm the job with the machine and tooling manufacturers' charts.
Air bending only: Do not use this calculator for bottoming, coining, hemming, offset tools, off-center loading or special forming. Never exceed the rating of the press brake, ram, holder, punch or die. The lowest rated component controls.
Press Brake Tonnage Calculator
Enter the actual job dimensions. The default example is 3 mm mild steel, a 24 mm V opening and a 1,000 mm bend.
Load per foot--
Total required load--
Metric load / force--
Estimated inside radius--
Estimated minimum flange--
V opening ratio / starting V--
Enter values and calculate.
How Press Brake Tonnage Is Calculated
For common mild-steel air bending, Mate Precision publishes the imperial relationship below. The calculator applies the formula in inches and US tons, then converts the result for metric users.
US tons per foot = 575 × material factor × thickness2 ÷ V opening
Thickness and V opening are in inches. Total tonnage equals tons per foot multiplied by bend length in feet.
Thickness and V opening are in inches. Total tonnage equals tons per foot multiplied by bend length in feet.
The mild-steel baseline assumes approximately 60,000 psi tensile strength. Mate's reference chart uses factors of 0.50 for aluminum, 1.00 for mild steel and 1.50 for stainless steel. Those are planning factors, not a substitute for the actual alloy specification.
What Changes the Required Bending Force?
| Input | Effect on estimated force | Important check |
|---|---|---|
| Material thickness | Force rises with thickness squared. | Use measured thickness, not nominal gauge alone. |
| Bend length | Total force rises directly with bend length. | Check machine capacity over the actual working length. |
| V opening | A wider opening reduces air-bending force. | It also changes radius and minimum flange. |
| Material strength | Higher tensile strength requires a higher factor. | Confirm the actual grade and temper. |
| Forming method | Bottoming and coining can require far more force. | This calculator is not valid for those methods. |
V Opening, Inside Radius and Minimum Flange
A safe setup cannot be selected from tonnage alone. Wilson Tool's reference chart pairs force with V opening, estimated inside radius and minimum flange. Mate publishes natural-radius starting factors of about 0.156× V for cold-rolled steel, 0.14× V for aluminum and 0.21× V for stainless. The common minimum-flange reference is about 0.707× V for a 90-degree air bend.
Use the V-die opening guide to select a starting opening before calculating force.
How to Use the Calculator Safely
- Confirm that the operation is air bending.
- Enter measured material thickness and the full bend length.
- Enter the exact V opening on the selected die.
- Select the closest reference material, then compare with the actual grade.
- Check estimated inside radius and minimum flange against the drawing.
- Compare total load and load per foot with the machine, holder, punch and die ratings.
- Review off-center or short-section loading with the manufacturers.
- Make a controlled test bend using the facility's approved procedure.
Worked Example: 3 mm Mild Steel
For 3 mm mild steel, a 24 mm V opening and a 1,000 mm bend, the imperial formula is evaluated after unit conversion. The result is approximately 8.49 US tons per foot and 27.85 US tons total over 1,000 mm. The estimated natural inside radius is about 3.74 mm and the reference minimum flange is about 16.97 mm. These are planning estimates; a manufacturer's chart may round or adjust the result.
Manufacturer References
- Mate Precision air-bending force charts - formula, material factors, radius and flange references.
- Wilson Tool air-bending force chart - V-opening and safe tool-selection reference.
- Cincinnati press brake tonnage calculator guidance - air-bending scope and application limits.
Press Brake Tooling to Compare
Calculator results do not establish compatibility. Verify tooling style, dimensions, V opening, angle and load rating before ordering.
3161 Self-Centering Die, 88°
Single-V insert with a 10 mm opening for compatible lower holders.
From $250 CAD
View Self-Centering Die →
1324 Gooseneck Punch, 86°
Wila-style return-flange clearance option with a listed 65 T/m maximum.
From $503 CAD
View Gooseneck Punch →
Need the tooling checked against your job?
Send the machine and holder model, material grade, thickness, bend length, V opening and part drawing.
Request a Tooling Review or Quote
Send the machine and holder model, material grade, thickness, bend length, V opening and part drawing.
Request a Tooling Review or Quote
Press Brake Tonnage FAQ
How much tonnage does a press brake need?
It depends on material strength, thickness, V opening and bend length. Calculate total load and load per foot, then verify both against the machine and tooling manufacturers' ratings.
Does a wider V die reduce tonnage?
Generally yes in air bending, but it also increases the natural inside radius and minimum supported flange.
Can this calculator be used for stainless steel?
It provides a 1.5 reference factor from Mate's chart. Actual stainless grades vary, so confirm the tensile strength and approved manufacturer chart.
Can it calculate bottoming or coining force?
No. The calculator is for air bending only. Bottoming and coining use different force relationships and can require substantially more load.
Continue learning: Read the complete tooling selection guide or compare press brake tooling styles.
Flat-pattern planning: Continue with the press brake bend allowance, K-factor and bend deduction guide.
Plan Bend Radius and Springback
Learn how the V opening and material affect natural inside radius, why a bend opens after unloading, and how to confirm compensation with a controlled test coupon.
Compare Tonnage by Material and Thickness
Use the metric and imperial air-bending charts for mild steel, stainless and aluminum, then enter the exact bend length in the calculator.