A single-bend calculation reference
Unfold the model.
Keep the assumptions.
Separate bend allowance from bend deduction. Calculate a conditional ideal flat length from your dimensions and an explicitly entered K-factor.
Entered bend model
One constant-thickness, constant-radius bend. The example K = 0.4 illustrates arithmetic; it is not a recommendation.
Plain decimals, up to 12 fractional places. A/B/R: 0–1,000,000 mm equivalent. Thickness: 0.000001–10,000 mm. Each leg must reach its unrounded setback; neutral radius must be positive. Software bounds do not establish process limits.
Conditional ideal result
Illustrative schematic: angle follows the input; other proportions are exaggerated. Outer tangent points T1/T2 and virtual sharp V define the outside legs. The rust arc represents the assumed neutral axis.
≈ outputs use numerical π/tangent and round to 6 decimal places. Small positive values can round to zero. The report retains exact canonical inputs. No manufacturing tolerance is implied.
Allowance follows the neutral arc
BA = θ × π / 180 × (R + Kt). With R = 2, t = 1, K = 0.4 and θ = 90°, the allowance is approximately 3.769911 mm.
Deduction removes the overlap
BD = 2 × SB − BA. The default setback is exactly 3 mm, giving deduction approximately 2.230089 mm.
Flat length uses both straight legs
27 + 37 + 3.769911 gives approximately 67.769911 mm. The same model gives 30 + 40 − 2.230089.
A model to inspect, not a shop guarantee
The entered linear K-factor model omits springback, tooling, corner relief, collision and manufacturing tolerance. It does not determine whether a real part can be formed or meets a standard. Read the definitions, two worked examples and model limits →
Why is the K-factor not chosen for me?
The factor represents a neutral-axis assumption. It can depend on material and process behaviour, which this calculator does not identify. The initial 0.4 value demonstrates the equations only.
Do my dimensions leave the calculator?
The application calculates and exports locally without sending measurements or saving browser storage. Hosting receives ordinary page requests. See privacy details.