Does a right-angle bend use 90 degrees here?

Enter approximately 1.5708 radians for a right-angle bend. This input uses the angle turned through by the sheet from its original flat position.

Where does my K-factor come from?

Use a bend coupon or established bend table for the same material, thickness, radius and tooling. K represents neutral-axis depth divided by sheet thickness.

Can I add allowance to outside flange dimensions?

Use straight lengths measured to bend tangent points when adding allowance. Outside dimensions measured to the virtual sharp require the corresponding bend deduction.

Does this predict the radius after bending?

No. Enter the final inside radius from your process data or formed measurement. Tooling geometry, material behavior and springback determine the actual formed radius.

Welding & Fabrication calculator

Sheet Metal Bend Allowance Calculator

Calculate the developed length through one sheet metal bend. Enter bend rotation in radians, final inside radius, measured thickness and a calibrated K-factor.

What this calculator does

Find the neutral-axis length consumed by a sheet metal bend from calibrated geometry.

Formula used

Neutral-axis depth = K-factor × sheet thickness
Neutral-axis radius = inside radius + neutral-axis depth
Bend allowance = bend rotation in radians × neutral-axis radius

Inputs explained

Bend Rotation: Angle turned through by the sheet, measured in radians.
Inside Bend Radius: Final inside bend radius from the drawing or formed coupon.
Sheet Thickness: Measured sheet thickness for the bending setup.
K-Factor: Neutral-line depth divided by thickness from calibrated bend data.

How to use the result

Best suited to flat blank Development, bend table calibration.
Does not predict springback or minimum safe bend radius. Hems and complex formed corners need process-specific bend data.

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

Does a right-angle bend use 90 degrees here? Enter approximately 1.5708 radians for a right-angle bend. This input uses the angle turned through by the sheet from its original flat position.
Where does my K-factor come from? Use a bend coupon or established bend table for the same material, thickness, radius and tooling. K represents neutral-axis depth divided by sheet thickness.
Can I add allowance to outside flange dimensions? Use straight lengths measured to bend tangent points when adding allowance. Outside dimensions measured to the virtual sharp require the corresponding bend deduction.
Does this predict the radius after bending? No. Enter the final inside radius from your process data or formed measurement. Tooling geometry, material behavior and springback determine the actual formed radius.

Last reviewed 2026-10-06.