Where do I measure the straight lengths?

Measure each straight from the finished end to the bend tangency point. Add those lengths; dimensions to a theoretical sharp corner include a setback and cannot be entered directly.

Is the centerline always the neutral axis?

No. The centerline is a layout approximation for a round tube. Tight bends, wall changes and distortion can shift the neutral axis, so verify the cut length with your established bend method.

Does this predict springback?

No. Enter the finished bend angle and specified radius. Springback compensation depends on your material, tooling and process; it needs trial data or a validated bending model.

Does zero stock margin pass?

Yes, it exactly covers the entered layout and trim. It leaves no extra stock for uncertainty, so use the allowance your proven cut plan requires.

Tube, Pipe & Profile Forming calculator

Bend Stock Allowance Margin Calculator

Check stock length for one circular bend using its centerline arc and tangent straights. Enter the usable cut length, bend geometry and planned end trim.

What this calculator does

Check whether a cut length covers one circular tube bend, tangent straights and your planned trim.

Formula used

Bend arc (mm) = centerline radius × bend angle × pi ÷ 180
Required cut (mm) = tangent straights + bend arc + total trim
Stock margin (mm) = available cut − required cut
Stock margin (%) = stock margin ÷ required cut × 100

Inputs explained

Available Cut Length: Usable stock length from your cut plan.
Tangent Straight Length: Sum of straight sections between ends and bend tangency points.
Centerline Bend Radius: Radius to the tube centerline from the bend drawing.
Bend Angle: Finished direction change from the drawing.
Total Trim: Combined end trim from the proven cut plan.

How to use the result

Best suited to One-Bend cut Plans, tube bend tryout.
Springback, ovalization and neutral-axis movement can change the actual developed length. Clamp waste must already be excluded from usable stock.

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.

Common questions

Where do I measure the straight lengths? Measure each straight from the finished end to the bend tangency point. Add those lengths; dimensions to a theoretical sharp corner include a setback and cannot be entered directly.
Is the centerline always the neutral axis? No. The centerline is a layout approximation for a round tube. Tight bends, wall changes and distortion can shift the neutral axis, so verify the cut length with your established bend method.
Does this predict springback? No. Enter the finished bend angle and specified radius. Springback compensation depends on your material, tooling and process; it needs trial data or a validated bending model.
Does zero stock margin pass? Yes, it exactly covers the entered layout and trim. It leaves no extra stock for uncertainty, so use the allowance your proven cut plan requires.

Last reviewed 2026-10-06.