Several different methods of calculating the carbon equivalent exist. The most commonly used are listed below (all values in wt%):
The two formulae specified in EN 1011-2:
CE = C + 1⁄6 Mn + 1⁄5 (Cr + Mo + V) + 1⁄15 (Ni + Cu)
CET = C + 1⁄10 (Mn + Mo) + 1⁄20 (Cr + Cu) + 1⁄40 Ni
For use in Method A and Method B respectively for the avoidance of hydrogen cracking. Note: CE (Method A) is described as being mainly for carbon manganese type steels, whereas CET (Method B) is described as being mainly for low alloy high strength steels. The two formulae have slightly different limits on the composition of the alloys they are applicable to. See the standard for further information.
The formula of the American Welding Society (AWS), given in AWS D1.1:
CE (AWS) = C + 1⁄6 Mn + 1⁄5 (Cr + Mo + V) + 1⁄15 (Ni + Cu) + 1⁄6 Si
And the Japanese Welding Engineering Society's critical metal parameter:
Pcm = C + 1⁄30 Si + 1⁄20 (Mn + Cu + Cr) + 1⁄60 Ni + 1⁄15 Mo + 1⁄10 V + 5B
Used for low C content alloys, typically wt% C less than 0.11.
An online carbon equivalent calculator is presented below, but an Excel spreadsheet is also provided here:
Enter the weight percentage values for each element into the relevant boxes and click ENTER to calculate the carbon equivalent.