Sheet Metal Bend Calculator

About this resource

This workbook calculates the flat pattern for a single bend from the material thickness, inside bend radius, bend angle and K-factor. It returns bend allowance, bend deduction, setback, outside setback, neutral-axis radius and the flat length for two outside leg dimensions.

A reference table gives indicative K-factor ranges for cold-rolled steel, stainless steel, aluminium and copper alloys, with a clear note that the value must be confirmed by a test bend or the material supplier.

The calculator is intended for estimating and checking flat patterns before production. Springback, material thinning, multi-bend parts and tooling-specific behaviour are outside its scope and must be handled in the CAM or nesting workflow.

What is included

• Sheet Metal Bend Calculator — XLSX · Single-bend calculator with input cells, bend results, K-factor reference table, assumptions, unit notes, instructions and licence sheets. · Editable

• Bend allowance, bend deduction, setback and outside setback
• Flat length from two outside leg dimensions
• Neutral-axis radius and angle in radians
• Indicative K-factor ranges for common materials
• Assumptions, unit notes, instructions and licence sheets

Software compatibility

• Microsoft Excel: Excel 2016 or later, desktop or Microsoft 365 · required · edit · tested by author — Uses standard trigonometric and conversion functions.
• LibreOffice Calc: 7.6 or later · optional · edit · format based expectation — Opens normally; confirm the printed layout before production use.

Prerequisites and technical context

Intended audience

working-engineer, engineering-team, early-career-engineer

Prerequisites

• Material thickness and inside bend radius from the drawing or tooling
• A K-factor for the material and process, confirmed by test bend where possible

Unit systems

• Metric: mm and degrees

Assumptions

• Single bend with constant thickness and constant inside radius
• Bend angle below 180°
• Flat length measured along the neutral axis
• K-factor represents the neutral-axis position for the material and process
• Springback and material thinning are not modelled

Technical notes

• Bend allowance = θ (rad) × (R + K·T).
• Bend deduction = 2 (R + T) tan(θ/2) for angles below 180°.
• Flat length = outside leg A + outside leg B − bend deduction.
• For multi-bend parts, calculate each bend and subtract each bend deduction once.

References

• No external standards or references listed.

Scope and limitations

Included

• Bend allowance, bend deduction, setback and outside setback
• Flat length from two outside leg dimensions
• Neutral-axis radius and angle in radians
• Indicative K-factor ranges for common materials
• Assumptions, unit notes, instructions and licence sheets

Not included

• Multi-bend parts and bend sequencing
• Springback compensation and tooling selection
• Material thinning, cracking and minimum bend radius limits
• CAM programming, nesting and laser or punch path generation
• Production approval of a flat pattern

Limitations

• The result depends on the K-factor, which varies with material, temper, tooling and die width.
• Confirm the K-factor with a test bend or the material supplier before releasing a flat pattern.
• Do not use the calculator as the only check for safety-critical formed parts.

Author and review information

Author / publisher: Engineering Resources

Review status: Author checked

The bend geometry follows the standard neutral-axis formulation used in sheet-metal practice. K-factor ranges are indicative values compiled for common materials and processes, not certified tooling data.

Review scope: Formulas, worked defaults and stated assumptions were checked against the classical equations named on each sheet. No independent third-party review was commissioned.

Licence and permitted use

Single-user commercial licence

One named user may use this resource on any number of their own devices for commercial and educational engineering work. Resale, redistribution, publication, sublicensing and inclusion in a paid course or product are not permitted. Adapted copies remain subject to the same terms.

• Use on your own projects, including paid client work
• Use for teaching and internal training
• Adapt the formulas and layout for your own internal templates
• Keep a personal or company archive copy for business continuity

Not permitted

• Reselling, sublicensing or distributing the file
• Publishing the file on a website, shared drive or marketplace
• Including the file in a paid course, product or template pack
• Removing the licence, attribution or version notices

Delivery

Orders are confirmed by email before payment. After payment clears, the workbook is sent as a secure download link with the licence and a short getting-started note. Usually within one business day.