Press Brake Tonnage Calculator
Air-bending force from thickness, die opening, bend length and tensile strength — the chart formula every brake operator uses.
The 1.42 coefficient is the classic air-bending chart constant for a V-die with standard friction — the same number behind the tonnage chart riveted to your machine. Force grows with the SQUARE of thickness but only linearly with length, which is why a short flange in 6 mm plate can out-pull a full-length bend in 2 mm. Always check the result against both the machine rating and the centimetre-rated tooling load limit.
Formula
Note: Chart starting value for air bending only — bottoming and coining need 3–10× more force. Verify against your machine's rated capacity and the per-metre limit stamped on the tooling.
Air-bending force from thickness, die opening, bend length and tensile strength — the chart formula every brake operator uses. A free machinist & fabrication essentials tool — no sign-up, no upload, instant results in your browser.
About Press Brake Tonnage Calculator
Press Brake Tonnage Calculator computes the governing relationship P [N/mm = kN/m] = 1.42 · UTS · S² / V ; total [t] = P·L / g live as you type. The 1.42 coefficient is the classic air-bending chart constant for a V-die with standard friction — the same number behind the tonnage chart riveted to your machine. Force grows with the SQUARE of thickness but only linearly with length, which is why a short flange in 6 mm plate can out-pull a full-length bend in 2 mm. Always check the result against both the machine rating and the centimetre-rated tooling load limit. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Press Brake Tonnage Calculator
- 1Enter your values — Material thickness, Die opening (V), Bend length, Tensile strength (UTS) (sensible defaults are pre-filled).
- 2Read the live results: Force per metre, Total force, Recommended V (8×S), Approx. inside radius.
- 3Check the "with your numbers" line to see P [N/mm = kN/m] = 1.42 · UTS · S² / V ; total [t] = P·L / g substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Press Brake Tonnage Calculator?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula P [N/mm = kN/m] = 1.42 · UTS · S² / V ; total [t] = P·L / g with authoritative sources cited on the page (Machinery's Handbook, 31st ed.; Bystronic / Amada press-brake air-bending force charts)
- ✓The 1.42 coefficient is the classic air-bending chart constant for a V-die with standard friction — the same number behind the tonnage chart riveted to your machine.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the press brake tonnage calculator use?+
It evaluates P [N/mm = kN/m] = 1.42 · UTS · S² / V ; total [t] = P·L / g, exactly as published. Sources: Machinery's Handbook, 31st ed.; Bystronic / Amada press-brake air-bending force charts. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
The 1.42 coefficient is the classic air-bending chart constant for a V-die with standard friction — the same number behind the tonnage chart riveted to your machine. Chart starting value for air bending only — bottoming and coining need 3–10× more force. Verify against your machine's rated capacity and the per-metre limit stamped on the tooling.
When is this calculator the right tool for the job?+
Air-bending force from thickness, die opening, bend length and tensile strength. Force grows with the SQUARE of thickness but only linearly with length, which is why a short flange in 6 mm plate can out-pull a full-length bend in 2 mm. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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