Queendom Tools

Corrosion Rate Calculator

For materials scientists reducing weight-loss coupon measurements to a reportable rate, this converts W, A, T and D straight into mm/y and mpy with the ASTM G31 constant already built in, so you never hand-carry 8.76e4 or 3.45e6 through a spreadsheet again. ASTM G31 corrosion rate CR = (K * W) / (A * T * D), with K = 8.76e4 for mm/y or 3.45e6 for mpy (W in g, A in cm2, T in hours, D in g/cm3).

Corrosion Rate (mm/y): — Corrosion Rate (mpy): —

Formula: CR = (K * W) / (A * T * D)
Substituted (mm/y): (8.76e4 * —) / (— * — * —)
Substituted (mpy): (3.45e6 * —) / (— * — * —)

Disclaimer: for preliminary estimation only, not a substitute for review by a qualified/licensed engineer.

How to Use This Calculator

  1. Enter the coupon weight loss W in grams.
  2. Enter the exposed surface area A in cm².
  3. Enter the exposure time T in hours.
  4. Enter the material density D in g/cm³ — the mm/y and mpy rates update as each field is filled.

FAQ

Q: What is the ASTM G31 corrosion rate formula?

A: CR = (K × W) / (A × T × D), where K = 8.76e4 gives the rate in mm/y and K = 3.45e6 gives it in mpy when W is in grams, A in cm², T in hours and D in g/cm³.

Q: Which units do I enter for weight loss, area, time and density?

A: Weight loss in grams, exposed area in cm², exposure time in hours and density in g/cm³ — the constants 8.76e4 and 3.45e6 are only valid with exactly that unit set.

Q: Why do mm/y and mpy come out of the same four inputs?

A: Only the constant K changes between the two outputs: 8.76e4 for mm/y and 3.45e6 for mpy, with W, A, T and D identical in both.

Q: Why does the calculator refuse a zero exposure time or zero area?

A: Because A × T × D sits in the denominator of CR = (K × W) / (A × T × D), so a zero area, time or density makes the rate undefined — enter the actual exposed area and exposure hours.