This calculator finds the percent purity of a sample, the proportion of it that is the substance you want, with the rest being impurities. Real chemical samples are rarely completely pure: a product from a reaction, a mineral ore, or a commercial chemical contains some unwanted material alongside the substance of interest. Percent purity expresses how much of the sample is the genuine substance, and it is an important quantity in chemistry, manufacturing and quality control, where the purity of a product determines its value and whether it meets specification. It also feeds into accurate calculations, since you must account for impurities when working out how much of a substance is really present. This calculator computes it. You enter the mass of the pure substance and the total mass of the sample, and the calculator returns the percent purity, the percentage of impurities, and the masses for reference. The results update as you type. Use it for chemistry study, for laboratory and quality work, or whenever you need to express how pure a sample is. The percent purity is the mass of the pure substance divided by the total sample mass, multiplied by one hundred, and the impurity percentage is simply the remainder. The pure mass is often found by analysis, for example by reacting the sample and measuring the product, or by separating and weighing the pure component. A high purity, close to one hundred percent, means almost all of the sample is the desired substance, while a lower figure indicates significant impurities. Purity matters because impurities can affect a substance's behaviour, and because they mean a given mass of sample contains less of the actual substance than its weight suggests, which must be allowed for in quantitative work. This simple percentage is one of the most practical measures of sample quality in the laboratory and industry.
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96%
percent purity
Impurities4%
Pure mass4.8
Total mass5
Percent purity = pure mass / total mass x 100. Impurity percentage is the remainder. Use the same units for both masses.
How it works
The percent purity is the mass of the pure substance divided by the total mass of the sample, multiplied by one hundred. The impurity percentage is one hundred minus the purity. Both masses must be in the same units, since they appear as a ratio and the units cancel.
Worked example
A 5.0 gram sample found to contain 4.8 grams of the pure substance has a percent purity of 4.8 divided by 5.0, times 100, which is 96 percent. The remaining 4 percent, 0.2 grams, is impurities.
