Mass Percent Calculator
Find the mass percent (% w/w) of a solute in a solution from the solute mass and either the solvent mass or the total solution mass.
Second input
g
g
Percent of the solution mass made up by the solute
10%
SoluteSolute
10%
Solvent
90%
- 1
Total solution mass
solute + solvent = 5 + 45 = 50 - 2
Mass percent (% w/w)
5 ÷ 50 × 100 = 10
How does this calculator work?
Mass percent (% w/w) equals the mass of solute divided by the total mass of solution, multiplied by 100. The solution mass is the solute mass plus the solvent mass. Enter the solute mass and either the solvent or total solution mass, and the calculator returns the percent by mass of the solute.
Formula
How this is calculated
Mass percent, also called percent by mass or weight percent (% w/w), expresses the mass of a solute as a fraction of the total mass of the solution. Enter the mass of the solute, then choose whether you know the mass of the solvent or the mass of the whole solution. If you supply the solvent mass, the calculator adds it to the solute mass to get the total solution mass (mass of solution = mass of solute + mass of solvent).
The result is computed as (mass of solute ÷ mass of solution) × 100. Because the ratio is a ratio of masses, the units cancel and the answer is a pure percentage — any consistent unit (grams, kilograms, milligrams) works as long as both masses use the same unit. Here values are entered in grams for convenience.
All masses must be non-negative, and the solution mass must be greater than zero to avoid dividing by zero. When you provide the total solution mass directly, the solvent mass is back-calculated as solution minus solute, so the solute mass must not exceed the solution mass.
Frequently asked questions
Mass percent uses the masses of solute and solution, while volume percent uses volumes. Mass percent is preferred for solids and when precise, temperature-independent values are needed, since mass does not change with temperature.
Either works. The total solution mass equals the solute mass plus the solvent mass, so the calculator lets you enter whichever you know and derives the other.
No, as long as the solute and solution masses use the same unit. The units cancel in the ratio, so the result is always a percentage.
Also known as
TG we-Calculate Editorial Team. (2026). Mass Percent Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/mass-percent-calculator
TG we-Calculate Editorial Team. "Mass Percent Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/mass-percent-calculator.
TG we-Calculate Editorial Team, "Mass Percent Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/mass-percent-calculator
@misc{wecalculate_mass_percent_calculator, title = {Mass Percent Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/mass-percent-calculator}}, year = {2026}, note = {TG we-Calculate} }
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