Things You'll Need
Scale
Wire brush
Calipers

Knowing how to measure rust can help you understand how damaged a piece of metal is. Measuring rust may also be an important step in a science project or examination of what materials to use for a project. You can measure the amount of rust in several ways, but this measurement can be a rough estimate.
Measuring Rust Damage
Step 1
Inspect the rusted area to determine the extent of the rust over the surface of the metal and the depth of the deterioration.
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Step 2
Measure the depth of the rust by comparing how much of the metal is corroded away as compared with an unrusted portion of the metal or an original piece of the same metal.
Step 3
Measure the dimensions of the rusted area to calculate how much of the metal is covered in rust.
Measuring Amount of Metal Rusted
Step 1
Record the weight of the rusted metal. Use ounces, grams or any other appropriate unit of weight.
Step 2
Remove the rust from the metal with a wire brush.
Step 3
Weigh the piece of metal without the rust using the same units of measurement.
Step 4
Subtract the difference between the rusted metal and the metal without rust to measure how much of the metal has rusted.
Warning
Be careful when working with rusted items. Handling rusty metal and being cut or scratched can lead to tetanus.