Calculate the developed flat length and material required for a sheet metal hem using thickness, hem size, bend radius and bend allowance.
Enter the dimensions and calculate.
What is a sheet metal hem? A hem is a folded sheet metal edge where the material is returned toward the sheet surface.
Why are hems used? Hems can improve edge safety, stiffness, appearance and resistance to handling damage.
Does the hem length equal the flat material consumed? Not necessarily. The developed length must account for the bend region and the actual geometry of the folded material.
Does material thickness matter? Yes. Thickness affects the physical geometry of the folded edge and the required bend allowance.
What bend allowance should I use? Use a validated bend allowance from your material, tooling and machine setup whenever possible.
Can this calculate a closed hem? Yes. Select the appropriate hem configuration and enter the required hem dimensions.
Is this suitable for production drawings? It can provide a useful estimate, but production-critical dimensions should be checked against actual bend tests, tooling data or a validated sheet-metal CAD model.