Why does changing the span leave deduction unchanged?

Deduction belongs to the bend geometry and process. Longer straight flanges change the developed blank length but do not change that bend’s allowance or setbacks.

What is a virtual sharp?

It is the intersection of the extended outside flange faces. Outside flange dimensions use this intersection even though the actual corner is rounded.

Must the two setbacks be identical?

Use the measured values for the specified bend. A symmetric bend ordinarily has matching setbacks, but this calculation accepts separately supplied values on a consistent geometry basis.

Can I reuse a deduction for another bend angle?

Only when your calibrated data confirms it. Bend allowance and outside setbacks vary with bend angle, so a deduction for one angle can produce an incorrect blank at another.

Welding & Fabrication calculator

Bend Deduction Calculator

Calculate bend deduction from outside setbacks and the developed bend allowance. Enter the outside flange span and matching measured bend data.

What this calculator does

Find the deduction from outside flange dimensions and the resulting developed blank length.

Formula used

Total setbacks = first setback + second setback
Bend deduction = total setbacks − bend allowance
Flat length = outside span − bend deduction

Inputs explained

Outside-Mold-Line Span: Sum of both flange lengths measured to the virtual sharp.
First Outside Setback: Distance from first tangent point to the virtual sharp.
Second Outside Setback: Distance from second tangent point to the virtual sharp.
Bend Allowance: Neutral-axis developed length for this same bend.

How to use the result

Best suited to Outside-Dimension flat Layout, measured bend data check.
Measured data must match material, tooling and bend angle. This does not derive the setbacks from tooling or predict springback.

Current U.S. benchmarks

The producer price index for steel mill products stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. Quotes priced off last quarter's material cost miss this move.
Industrial electricity averages 9.77 cents per kWh across the U.S. (EIA, Jul 2026), up 4.7% from a year earlier. Energy-intensive steps carry this directly into unit cost.
U.S. iron and steel import customs value ran $2.2B in Aug 2026 (Census International Trade). The U.S. ran a trade deficit of $0.6B in the category that month. This dollar total mixes price, quantity, product mix, origin, and timing; it does not measure physical import volume or prove a tariff or reshoring effect.
The U.S. has 53,790 fabricated metal products establishments employing about 1,441,471 workers (Census County Business Patterns, 2023).

Common questions

Why does changing the span leave deduction unchanged? Deduction belongs to the bend geometry and process. Longer straight flanges change the developed blank length but do not change that bend’s allowance or setbacks.
What is a virtual sharp? It is the intersection of the extended outside flange faces. Outside flange dimensions use this intersection even though the actual corner is rounded.
Must the two setbacks be identical? Use the measured values for the specified bend. A symmetric bend ordinarily has matching setbacks, but this calculation accepts separately supplied values on a consistent geometry basis.
Can I reuse a deduction for another bend angle? Only when your calibrated data confirms it. Bend allowance and outside setbacks vary with bend angle, so a deduction for one angle can produce an incorrect blank at another.

Last reviewed 2026-10-06.