Sheet Metal Flat Pattern Calculator

Calculate preliminary developed blank length from bend geometry, material K-factor and folded-part dimensions.

ENGINEERING PRINCIPLE

Sequential folded profiles and developed blanks

A sequential profile contains one more flange than bends. Each bend has independent angle, radius, direction and bend length, so the folded drawing, dynamic table, bend allowances and flat pattern are all derived from the same profile data.

FORMULA & SYMBOLS

BAᵢ = θᵢ(Rᵢ + Kt); Lflat = Σ flange lengths − Σ BDᵢ

BAᵢ = bend allowance for bend i (mm)
θᵢ = bend angle (radians)
Rᵢ = inside radius (mm)
K = K-factor
t = sheet thickness (mm)

LIVE SEQUENTIAL PROFILE

Flanges and bends

Set the bend count first. The editable profile retains inactive rows when you reduce then increase the count.

MATERIAL & PROFILE

Material contextSheet thickness mmSource-controlled K-factorPart / bend width mmNumber of bends

DYNAMIC FLANGE & BEND TABLE

Flange 1length mm

Bend 1Angle °Radius mmDirectionBend length mm

Flange 2length mm

Bend 2Angle °Radius mmDirectionBend length mm

Flange 3length mm

PROJECT TONNAGE BASIS

Source-controlled tensile strength MPaV-die opening mmBend methodMachine allowance %

Correct the engineering inputsK-factor must be between 0 and 1.

Enter approved K-factor and tensile-strength data for the supplied sheet condition. K-factor, bend allowance and tonnage inputs must be validated against the actual material, tooling and approved shop data before manufacture.

FOLDED PROFILE + FLAT PATTERN

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Enter valid positive dimensions to render the engineering drawing.