Bend Allowance Chart
A bend allowance chart is a starting reference for flat patterns. The exact value still depends on bend angle, inside radius, thickness and K-factor.
bend allowance chart bend allowance reference bend allowance formula inside radius k-factor
Bend allowance formula
BA = theta * (R + K * t)
Chart inputs
- theta: bend angle in radians.
- R: inside bend radius.
- t: sheet thickness.
- K: neutral-axis factor for the setup.
Use measured K
For production flat patterns, back-solve K from a test coupon instead of relying on a generic chart value.
Related pages
- Sheet-metal K-factor calculator - back-solve K from a measured bend allowance or coupon.
- Bend allowance calculator - use a known K-factor to calculate bend allowance.
- Bend deduction calculator - convert between outside dimensions and flat length.
- What is K-factor? - neutral-axis explanation and formula context.
- Bend allowance K-factor - relationship between neutral axis and bend allowance.