Is this calculation free and private?

Yes, 100% of calculations execute locally in your web browser. No inputs or personal data are stored or transmitted.

What do I need to enter?

Just Sheet Thickness T, Bend Angle B, Inside Bend Radius R, Neutral Axis K-Factor and Outside Flange Leg A and a few optional settings. Every field has a sensible default you can start from.

Is my data uploaded anywhere?

No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.

Does it work on a phone?

Yes. The layout adapts to small screens and needs no app or signup.

Sheet Metal Bend Allowance & Flat Pattern Calculator

Calculate bend allowance (BA), bend deduction (BD), outside setback (OSSB), and flat blank length from material thickness and K-factor.

100% free
Private in browser
No signup
No watermarks

Sheet Thickness T (Inches, e.g. 16ga=0.060)

Bend Angle B (° usually 90°)

Inside Bend Radius R (Inches)

Neutral Axis K-Factor (e.g. 0.44)

Outside Flange Leg A (Inches)

Outside Flange Leg B (Inches)

Bend Allowance BA (Inches)

0.188

Bend Deduction BD (Inches)

0.118

Outside Setback OSSB (Inches)

0.153

Calculated Flat Blank Length (Inches)

4.882

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About Sheet Metal Bend Allowance & Flat Pattern Calculator

Calculate bend allowance (BA), bend deduction (BD), outside setback (OSSB), and flat blank length from material thickness and K-factor. Enter Sheet Thickness T, Bend Angle B and Inside Bend Radius R and the tool works out Bend Allowance BA, Bend Deduction BD and Outside Setback OSSB straight away. Everything runs in your browser, so your data never leaves your device.

How to use Sheet Metal Bend Allowance & Flat Pattern Calculator

Enter Sheet Thickness T, Bend Angle B and Inside Bend Radius R.
Adjust the remaining options (Neutral Axis K-Factor and Outside Flange Leg A) to match your case.
Read Bend Allowance BA, Bend Deduction BD and Outside Setback OSSB in the results panel — copy or download what you need.

Key features

Shows Bend Allowance BA (Inches)
Shows Bend Deduction BD (Inches)
Shows Outside Setback OSSB (Inches)
6 adjustable inputs, results update as you type
No signup, no limits

Frequently asked questions

Is this calculation free and private?: Yes, 100% of calculations execute locally in your web browser. No inputs or personal data are stored or transmitted.
What does the Sheet Metal Bend Allowance & Flat Pattern Calculator give me?: It works out Bend Allowance BA, Bend Deduction BD, Outside Setback OSSB and Calculated Flat Blank Length, updating live as you change the inputs.
What do I need to enter?: Just Sheet Thickness T, Bend Angle B, Inside Bend Radius R, Neutral Axis K-Factor and Outside Flange Leg A and a few optional settings. Every field has a sensible default you can start from.
Is my data uploaded anywhere?: No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.
Does it work on a phone?: Yes. The layout adapts to small screens and needs no app or signup.

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