Bend Allowance Calculator (Sheet Metal)
Flat-pattern length through a bend from K-factor, radius and angle.
The neutral axis shifts inward when you bend — K marks where. Get K wrong by 0.05 and a four-bend box grows ~0.4 mm: enough to scrap precision enclosures.
Formula
Bend Allowance Calculator (Sheet Metal) is a free bend allowance for design engineers, metallurgists and QA inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Bend Allowance Calculator (Sheet Metal)
Flat-pattern length through a bend from K-factor, radius and angle. The calculation implements BA = θ·(R + K·t); BD = 2·OSSB − BA (Machinery's Handbook — sheet metal). The neutral axis shifts inward when you bend — K marks where. Get K wrong by 0.05 and a four-bend box grows ~0.4 mm: enough to scrap precision enclosures.
How to use Bend Allowance Calculator (Sheet Metal)
- 1Enter Sheet thickness in mm.
- 2Enter Inside bend radius in mm.
- 3Enter Bend angle in deg.
- 4Enter K-factor (Air bend 0.40–0.45 · bottoming 0.42 · coining 0.5).
- 5Read Bend allowance, Bend deduction instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Bend Allowance Calculator (Sheet Metal)?
- ✓Implements the standard formula — BA = θ·(R + K·t); BD = 2·OSSB − BA
- ✓Reference cited on-page: Machinery's Handbook — sheet metal
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Bend Allowance Calculator (Sheet Metal) use?+
It computes BA = θ·(R + K·t); BD = 2·OSSB − BA, per Machinery's Handbook — sheet metal. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
The neutral axis shifts inward when you bend — K marks where. Get K wrong by 0.05 and a four-bend box grows ~0.4 mm: enough to scrap precision enclosures.
Where do the material property defaults come from?+
Defaults are standard handbook values (ASM, manufacturer datasheets, the cited standard). Always substitute certified values from your material's test certificate for critical work.
Is the Bend Allowance Calculator (Sheet Metal) free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
Related Engineering tools
Reynolds Number Calculator
Compute Re from density, velocity, pipe diameter and viscosity — with instant laminar/turbulent classification.
● LiveLaminar vs Turbulent Flow Classifier
Classify hydraulic-oil or process-fluid flow regime from kinematic viscosity, line velocity and tube bore.
● LiveBernoulli Equation Solver
Solve downstream pressure between two points from velocities, elevations and fluid density (ideal, lossless).
● Live