10
%
0.1
100,000
ppm
90
g
100
g/kg
10
%
0.1
100,000
ppm
90
g
100
g/kg
The Mass Percent Calculator (also called weight percent or w/w%) determines the percentage of a component's mass relative to the total mass of a solution or mixture. Mass percent is defined as: mass% = (mass of solute / mass of solution) x 100. It is one of the most intuitive and widely used ways to express concentration in chemistry, food science, pharmacy, and industry. Unlike molarity, mass percent does not depend on temperature (since masses do not change with temperature). Common examples include: rubbing alcohol (70% isopropanol), household bleach (~5% NaOCl), and saline solution (0.9% NaCl). This calculator also converts the result to parts per million (ppm) for trace-level concentrations and shows the mass of solvent for convenience.
The mass percent formula is straightforward:
Mass % = (mass of solute / mass of solution) x 100
Important notes:
The calculator also provides:
Related concentration expressions:
To convert mass percent to molarity, you also need the solution density and solute molar mass: M = (mass% x density x 10) / molar mass.
A mass percent of 10% means that 10 grams of solute are present in every 100 grams of solution. Values close to 0% indicate very dilute solutions (the ppm output is more useful here). Values near 100% indicate nearly pure solute with very little solvent. The ppm output is particularly useful when mass percent values are very small (less than 0.1%), as seen in water quality analysis and trace element measurements.
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25 g sugar dissolved in 100 g water gives a total solution mass of 125 g. Mass% = (25/125) x 100 = 20%. This is a moderately concentrated sugar solution.
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0.005 g of contaminant in 1000 g (1 kg) of water. Mass% = 0.0005%, or equivalently 5 ppm. EPA drinking water standards for many contaminants are in the 1-10 ppm range.
Mass fraction is the decimal form (0 to 1) of mass percent. If mass% = 20%, then mass fraction = 0.20. Mass fraction is preferred in scientific calculations, while mass percent is more intuitive for practical applications.
In common usage, yes. Strictly speaking, mass is a measure of matter (grams) while weight is a force (newtons). However, since weight is proportional to mass on Earth, mass percent and weight percent give identical numerical values.
Molarity = (mass% x density x 10) / molar mass. For example, 36% HCl with density 1.18 g/mL: M = (36 x 1.18 x 10) / 36.46 = 11.65 mol/L. You need the solution density for this conversion.
1 ppm = 0.0001 mass%. Or equivalently, 1 mass% = 10,000 ppm. Parts per million is used for trace concentrations where mass percent values would be inconveniently small numbers.
No. Since masses are independent of temperature (unlike volumes), mass percent remains constant regardless of temperature. This is an advantage over molarity, which changes as the solution expands or contracts with temperature.
No. Mass percent ranges from 0% (no solute) to 100% (pure solute). If your calculation gives a value over 100%, the mass of solute has been entered as greater than the total solution mass, which is physically impossible.
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