# Uniform Corrosion Rate Calculator (Weight Loss) Uniform corrosion rate by weight loss per ASTM G1: CR (mm/a) = 87.6 × ΔW / (ρ × A × t), with ΔW in mg, ρ in g/cm³, A in cm², t in hours. Also reports mpy (mils/year = mm/a × 39.37) and an indicative NACE-style carbon-steel rating (excellent/good/fair/poor). Used for immersion tests and coupon exposure. > Canonical page: https://elysiatools.com/en/tools/corrosion-rate-calculator - **Category:** Math & Numbers - **Keywords:** corrosion rate, weight loss, uniform corrosion, ASTM G1, NACE, mm per year, mpy, mils per year, coupon test, immersion test, materials engineering ## Overview Calculate uniform corrosion rate from specimen mass loss using the ASTM G1 weight-loss formula. Enter mass loss, material density, exposed area, and exposure time to get corrosion rate in mm/a, mpy, and an indicative carbon-steel rating. ## Inputs - **Mass loss ΔW (mg)** (number): Mass lost from the specimen in milligrams, measured by weighing before/after the test. - **Density ρ (g/cm³)** (number): Material density in g/cm³. E.g. carbon steel ≈ 7.85, stainless 304 ≈ 8.0, aluminum ≈ 2.70, copper ≈ 8.96. - **Exposed area A (cm²)** (number): Total exposed specimen surface area in cm². Include all wetted faces. - **Exposure time t (h)** (number): Exposure duration in hours. E.g. 24 (1 day), 720 (30 days), 8760 (1 year). - **Decimal Places** (number) ## When to use - Estimate uniform corrosion from an immersion or coupon exposure test. - Convert measured specimen mass loss into mm/a and mils per year. - Compare a calculated carbon-steel corrosion rate with indicative excellent, good, fair, or poor bands. ## How it works - Enter the specimen mass loss in milligrams, density in g/cm³, exposed area in cm², and exposure time in hours. - The calculator applies CR (mm/a) = 87.6 × ΔW / (ρ × A × t). - It converts the result to mpy using mpy = mm/a × 39.37. - It returns the calculated values and an indicative NACE-style carbon-steel rating, rounded to the selected decimal places. ## Use cases - Materials engineers can calculate corrosion rates from weight-loss coupon measurements. - Laboratories can report immersion-test results in both mm/a and mpy. - Corrosion analysts can review indicative carbon-steel severity bands for measured exposure data. ## Frequently asked questions ### What inputs are required? Enter mass loss in mg, density in g/cm³, exposed area in cm², and exposure time in hours. ### What formula does the calculator use? It uses CR (mm/a) = 87.6 × ΔW / (ρ × A × t), based on the ASTM G1 weight-loss calculation. ### What does mpy mean? mpy means mils per year, a corrosion-rate unit calculated as mm/a × 39.37. ### What is the corrosion rating based on? The tool provides an indicative NACE-style rating band intended for carbon steel: excellent, good, fair, or poor. ### Can I control the displayed precision? Yes. 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