Mass Percent Calculator

About the Mass Percent Calculator

Mass percent (weight percent) expresses the fraction of a component in a mixture or compound as a percentage of the total mass.

How to use this calculator

1. Enter the mass of the component you want to measure, in grams or another consistent unit.
2. Enter the total mass of the sample, using the same unit.
3. Use the calculator to compute \(\frac{m_{component}}{m_{total}} \times 100\).
4. Check the result, which is the mass percent of that component.

The formula explained

The formula computes the percentage of the total mass that comes from one component. It turns a part-to-whole ratio into a percent so it is easier to interpret and compare.

• \(m_{component}\) = the mass of the component or substance you are measuring
• \(m_{total}\) = the total mass of the entire sample or mixture

Step by step method

1. Find the mass of the component and the total mass.
2. Divide the component mass by the total mass.
3. Multiply by \(100\) to convert the decimal to a percent.

Worked example

Problem. A mixture has a salt mass of \(12\) g and a total mass of \(80\) g. What is the mass percent of salt?

1. Use the formula \(\%\,mass = \frac{m_{component}}{m_{total}} \times 100\).
2. Substitute the values: \(\%\,mass = \frac{12}{80} \times 100\).
3. Compute \(\frac{12}{80} = 0.15\), then \(0.15 \times 100 = 15\).

Tips and common mistakes

• Make sure both masses use the same unit before calculating, because the ratio only works correctly when the units match.
• Do not confuse mass percent with percent by volume, they measure different things.

Frequently asked questions