Thickness · R · Angle
Mistake: Changing units and assuming the entered numbers were converted.
Fix: Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
Archive · Free
Sheet-metal bend flat planner
Calculate bend allowance, setback, deduction and flat length from shop dimensions.
This tool is archived. Recheck its method and dated data before use.
01Enter your values
Runs in your browserRuns offline in your browser. Once the page and required files have loaded, processing needs no internet.
02Sheet-metal bend flat planner
Runs in your browser
How it works
Calculate bend allowance, setback, deduction and flat length from shop dimensions.
BA = θ(R + KT); OSSB = (R + T)tan(θ/2); BD = 2OSSB − BA; flat = A + B − BD
Runs in your browser
Discovery source
Your data stays yours
Inputs are processed on this page and are never sent to a server.
About this tool
Use tool ↑Calculate bend allowance, setback, deduction and flat length from shop dimensions.
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
- Enter your values
- Unit for every dimension
- Thickness
- R
- Angle
- K
- A
- B
- Calculation method
BA = θ(R + KT); OSSB = (R + T)tan(θ/2); BD = 2OSSB − BA; flat = A + B − BD
- Example scenario · Result
77.131194 mm
Calculation method
- Convert the bend angle from degrees to radians: θ = angle × π / 180.
- The neutral-axis radius is R + Kt; multiplying by θ gives bend allowance.
- Outside setback is (R + t) × tan(θ/2).
- Bend deduction is twice setback minus allowance.
- Subtract that deduction from the sum of the two outside leg dimensions to obtain flat length.
BA = θ(R + KT); OSSB = (R + T)tan(θ/2); BD = 2OSSB − BA; flat = A + B − BD
Sheet-metal bend flat planner
- Unit for every dimension
- mm
- Thickness
- 1.5
- R
- 2
- Angle
- 90 °
- K
- 0.42
- A
- 50
- B
- 30
Result
77.131194 mm
Frequently asked questions
Is the K-factor selected automatically?
No. Enter the factor established for the material and bending setup; the tool performs geometry only.
Where does my data go?
Calculations run on your device. Form inputs are not sent to a server.
Terms and definitions
Enter your values
- Measurement system
The initial choice follows your browser region. Your choice is remembered on this device. Gallons are US gallons. Switching units keeps your numbers unchanged and interprets them in the new unit.
Numbers stay unchanged. Check the new unit and enter the intended measurement, or select an example for that system.
- Unit for every dimension
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor.
Choose the mode that matches the data you entered.
Options: mm · in
- Thickness
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor.
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.0001 · Maximum: 100000 mm
- R
Inside bend radius, not outside radius
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0 · Maximum: 100000 mm
- Angle
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor.
Enter a numerical value for this quantity. Use the unit shown beside this field. °
Minimum: 0.01 · Maximum: 179.9 °
- K
Neutral-axis distance from the inside face divided by thickness
Enter a ratio or multiplier; 0.5 means one half, not 50.
Minimum: 0 · Maximum: 0.5
- A
First outside leg dimension to the virtual intersection
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.0001 · Maximum: 1000000 mm
- B
Second outside leg dimension to the virtual intersection
Enter a numerical value for this quantity. Use the unit shown beside this field. mm / in
Minimum: 0.0001 · Maximum: 1000000 mm
Result
- Result
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
- BA
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
- BD
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
- OSSB
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
- Value
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
- Lflat
Uses outside leg dimensions, inside radius, thickness, bend angle and your proven K-factor. Validate the K-factor with the actual material, tooling and process.
Calculated from your entries using the method below.
Common mistakes and quick fixes
Is the K-factor selected automatically?
Mistake: Treating a result as valid outside the described scope.
Fix: No. Enter the factor established for the material and bending setup; the tool performs geometry only.
Limits and key assumptions
- No. Enter the factor established for the material and bending setup; the tool performs geometry only.
- Validate the K-factor with the actual material, tooling and process.
- Displayed results may be rounded; rounding does not add measurement precision.