Corrosion Rate Calculator

Work out corrosion rate instantly with clear inputs, formula shown and shareable results.

About Corrosion Rate Calculator

The weight loss coupon method converts mass lost into a uniform thickness loss rate: mils per year = 534 W / (D A T), with W in milligrams, density in g/cm³, area in square inches and time in hours. The 534 constant carries all the unit conversions. A rate below 5 mpy is generally considered good service.

Formula

Corrosion rate

mpy = 534 x W / (D x A x T)

W: Mass loss, mg
D: Density, g/cm³
A: Area, in²
T: Time, h

Worked example

With the default values below, Corrosion Rate Calculator returns Corrosion rate of 2.268. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mass lossminimum 0.01 mg: 120 mg
Material densityminimum 0.1 g/cm³: 7.85 g/cm³
Exposed areaminimum 0.01 in²: 5 in²
Exposure timeminimum 0.1 h: 720 h

Results

Corrosion rate: 2.268 mils/year
Rate in metric units: 0.0576 mm/year
Rate in microns: 57.6 µm/year
Mass loss rate: 0.1667 mg/h

Step by step

1Values used
2Corrosion rate
3Corrosion rate= 2.268 mils/year
4Rate in metric units= 0.0576 mm/year
5Rate in microns= 57.6 µm/year
6Mass loss rate= 0.1667 mg/h

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Corrosion Rate figure worked out?

mpy = 534 x W / (D x A x T). The weight loss coupon method converts mass lost into a uniform thickness loss rate: mils per year = 534 W / (D A T), with W in milligrams, density in g/cm³, area in square inches and time in hours.

Does this catch pitting?

No. It assumes uniform attack. Localised pitting or crevice corrosion can perforate a wall while the average rate looks negligible, so coupons must also be examined visually.

What values do I need to enter?

This calculator takes 4 inputs: Mass loss, Material density, Exposed area, Exposure time. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.