Tool
Carbon equivalent (Ceq) calculator
Enter the element percentages from your plate's mill test certificate to calculate carbon equivalent using the IIW formula and get general weldability guidance.
IIW carbon equivalent formula
Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15
Load a typical composition
These are typical mid-range values within the grade's specified chemistry, for illustration only — not a specific heat's actual analysis. Always calculate Ceq from the numbers on your own mill test certificate.
Carbon (C) is required. Other elements default to 0 if left blank.
Exact preheat temperature depends on section thickness, hydrogen level and joint restraint, not on Ceq alone. Confirm against the actual mill test certificate's Ceq, the joint's welding procedure specification (WPS), and classification-society requirements — this tool is for general reference, not a substitute for a proper WPS.
This calculator gives a general reference value based on the chemistry you enter and is not a formal quotation or a welding procedure. For pricing and lead times against your exact specification, request a formal quotation