Pitting resistance equivalent number (PREN) is a predictive measurement of a stainless steel’s resistance to localized pitting corrosion.
This calculator is based on following formula:
PREN = %Cr + 3.3 x (%Mo + 0.5%W) + 16 x %N (equals formula %Cr + 3.3 x %Mo + 16 x %N when %W is not to be included.