PREN Value Calculator & CEV Calculator

On this page we offer you various PREN value calculators and CEV calculators. The PREN value calculators allow you to calculate the corrosion resistance of steel, the CEV calculators are used to determine the carbon equivalent.

For the conversion of metres and kilograms as well as the determination of the weight of bent parts and bars, you will find further calculators on our weight calculator page.

PREN value calculator


The term PREN stands for Pitting Resistance Equivalent Number and is a unit of measurement that indicates the corrosion resistance of stainless steel. The test methods are specified in ASTM-48 of the international standardization organization ASTM International.

Corrosion resistance increases with the PREN value. PREN values above 32 are considered seawater resistant.

We offer you two different PREN calculators that differ in how tungsten (W%) is taken into account.

The PREN value is calculated using the formula:

PREN = 1 × %Cr + 3.3 × %Mo + 16 × %N (w/w)


PREN calculator without W%

PREN Calculator with W%


CEV calculator


The CEV value  (Carbon Equivalent Value) is used to determine the carbon equivalent of steel in relation to other alloy components. The CEV value is particularly important for assessing the weldability of the material, as this largely depends on the carbon content. With a carbon content of 0.2%, there is good weldability, but this can be influenced by other alloying components.  

We offer you two calculators to calculate the CEV value.

The CEV calculator IIW follows the formula of the International Welding Institute and assumes a carbon content of +0.18%:

CEV (%) = %C + %Mn/6 + (%Cu + %Ni)/15 + (%Cr + %Mo + %V)/5

The CEV calculator, which follows the Ito-Bessyo formula, can be used for steels with a carbon content below 0.18%. The Ito-Bessyo formula is:

CEV (%) = %C + %Si/30 + (%Mn + %Cu + %Cr)/20 + %Ni/60 + %Mo/15 + %V/10 + 5(%B)

Since there is no general formula for the different steels, we would like to point out that we cannot assume any liability for our information.

CEV calculator based on the formula of the International Welding Institute (I.I.W.)


CEV calculator after Ito-Bessyo formula