Sheet Metal Bend Calculator

Calculate Bend Allowance (BA), Bend Deduction (BD), and total flat pattern length for your sheet metal parts.

°
Flange Dimensions (Optional)
Used to calculate the Total Flat Pattern Length.
Bend Results
Bend Allowance (BA)

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in
Bend Deduction (BD)

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in
Total Flat Pattern Length

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in
Bend Geometry
T R L1 L2
What is K-Factor?

When sheet metal is bent, the inside compresses and the outside stretches. The neutral axis is the plane in the material that does neither. The K-Factor is the ratio of the neutral axis distance from the inside bend radius to the material thickness ($K = t / T$).

Bend Allowance vs. Deduction
  • Bend Allowance (BA): The length of the arc of the neutral axis. This is the amount of material actually required for the bend.
  • Bend Deduction (BD): The amount to subtract from the sum of the two outside flange lengths to find the flat pattern length ($Flat = L1 + L2 - BD$).
Note: Exact K-factors depend on the tooling (V-die opening), material grain direction, and the specific press brake. Test bends are always recommended.