PREN Calculator
| Grade | Typical PREN |
|---|---|
| SS 304 Stainless Steel | 18 – 20 |
| SS 304L Stainless Steel | 18 – 20 |
| SS 316 Stainless Steel | 23 – 25 |
| SS 316L Stainless Steel | 23 – 25 |
| SS 316Ti Stainless Steel | 23 – 25 |
| SS 317 Stainless Steel | 28 – 30 |
| SS 317L Stainless Steel | 28 – 30 |
| SS 904L Stainless Steel | 32 – 36 |
| Duplex 2205 Stainless Steel | 34 – 35 |
| Super Duplex 2507 Stainless Steel | ≥ 40 (typically 41 – 43) |
| SS 254 SMO Stainless Steel | 42 – 45 |
| Inconel 625 | ≈ 51 |
| Incoloy 825 | ≈ 30 – 33 |
| Hastelloy C22 | ≈ 65 – 70 |
| Hastelloy C276 | ≈ 68 – 76 |
How it works
PREN = Cr + 3.3 × (Mo + 0.5 × W) + 16 × N. It's a ranking index for pitting resistance, not a design value. See the PREN guide.
Frequently asked questions
Is this tool free to use?
Yes. All Bright Tubes tools are free and run in your browser, and nothing you enter is stored.
Which densities are used?
Typical densities for each grade from our grade database, for example 7.85 g/cm³ for carbon steel, about 8.0 for austenitic stainless steel and 4.51 for CP titanium.
Is this calculator accurate enough for purchasing?
It gives theoretical values from nominal dimensions and typical density. Actual weights vary within manufacturing tolerances, so use them for estimates, not for design or invoicing.