Carbon Equivalent Calculator
Estimate a steel alloy’s Carbon Equivalent (CE) value using the widely-used IIW formula, a common gauge of weldability and hardenability.
What Is Carbon Equivalent?
Carbon Equivalent (CE) is a single number that combines a steel’s alloying elements into an estimate of how it will behave during welding, mainly its risk of hydrogen cracking and the hardenability of the heat-affected zone.
The IIW Formula
This calculator uses the International Institute of Welding (IIW) formula, one of the most widely referenced: CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, where each element is entered as a weight percentage from the steel’s mill certificate or material spec.
As a rough general guide, steels with CE below about 0.40 are usually considered readily weldable without special precautions, while higher values increasingly call for preheat or controlled cooling to avoid cracking. This is a general planning and educational estimate only — always follow the welding procedure specification (WPS) and codes applicable to your project, and consult a qualified welding engineer for critical work.