Kfactor Calculator
Plan your materials specifications project with our free kfactor calculator. Get precise measurements, material lists, and budgets.
Reviewed by Abdullah, Technical Content Specialist
Formula
K-Factor = Neutral Axis Offset / Material Thickness
The K-factor equals the distance from the inside surface of the bend to the neutral axis, divided by the material thickness. It determines the bend allowance through the formula: BA = (Bend Angle in radians) x (Inside Radius + K-factor x Thickness). Common values range from 0.33 for tight bends to 0.50 for gentle bends.
Worked Examples
Example 1: K-Factor for 2mm Steel at 90 Degrees
Problem:Find the K-factor and bend allowance for 2mm mild steel with a 3mm inside bend radius at 90 degrees.
Solution:R/t ratio = 3/2 = 1.5 (between 1 and 2)\nK-factor = 0.38\nNeutral axis radius = 3 + (0.38 x 2) = 3.76 mm\nBend Allowance = (90 x pi/180) x 3.76 = 5.906 mm
Result:K-factor = 0.38, Bend Allowance = 5.906 mm
Example 2: Tight Bend in Thin Aluminum
Problem:Calculate K-factor for 1mm aluminum with 0.5mm inside radius bent to 120 degrees.
Solution:R/t ratio = 0.5/1 = 0.5 (less than 1, tight bend)\nK-factor = 0.33\nNeutral axis radius = 0.5 + (0.33 x 1) = 0.83 mm\nBend Allowance = (120 x pi/180) x 0.83 = 1.738 mm
Result:K-factor = 0.33, Bend Allowance = 1.738 mm
References
Reviewed by Abdullah, Technical Content Specialist · Editorial policy