The percentage of mass is a useful tool in research, scientific hypotheses and the analysis of various substances, since it allows knowing the amount of a substance in relation to the rest of the sample. This measure is used in many fieldsincluding the pharmaceutical industry, food technology, chemistry and biology, among others.
In this sense, it is important know how the percentage of mass is calculated and how it is used in different contexts. This text will address this measure in detail and its application in different areas of science.
Mass Percentage Definition
Percentage by mass, also known as percentage by weight, is a measurement used to express the amount of a substance in a sample in terms of the mass of that substance, relative to the total mass of the sample.
The percentage by mass is an important measurement in chemistry and related sciences, since it allows to know the proportion of a substance in a sample and make comparisons between different parties of a sample or chemical element.
What is the formula to get the percentage of the mass?
The formula for obtaining mass percentage, also known as percent by mass or weight percentageis the next:
 mass percentage = (mass of the substance / total mass of the sample) x 100%
In this formula, ‘mass of the substance’ refers to the amount of the substance in question found in the sample, while ‘total mass of the sample’ refers to the total mass of the sample, including the mass of the substance and any other substances present in it. For example, if you have a sample that weighs 50 grams and contains 10 grams of substance ‘A’, the formula to calculate the percentage by mass of substance ‘A’ would be as follows:
 Mass percentage of substance A = (10g / 50g) x 100% = twenty%
It’s important to put attention on the percentage by mass is always expressed in percentage, that is, as a value ranging from 0 to 100%. In mass percentage, the commonly used derived units are as follows:

Percentage (%): It is the unit used to express the percentage of mass. It represents the proportion of the mass of the component in relation to the total mass of the sample, expressed as a percentage.

Gram (g): is the base unit used to express the mass of the sample and the component. The gram is a unit of the metric system and is defined as one thousandth of a kilogram.

kilogram (kg): It is a unit of mass of the decimal metric system, commonly used to express the mass of objects either substances on a large scale.

Milligram (mg): It is a unit of mass of the decimal metric system, used to express small masses. A milligram is one thousandth of a gram.

Microgram (µg): It is a unit of mass of the decimal metric system, used to express very small masses. A microgram is one millionth of a gram.
What is the percentage by mass of a solution?
The percentage by mass of a solution refers to the amount of solute present in a given amount of solution, expressed as a percentage of its total mass. The formula to calculate the percentage by mass of a solution is the following:
 mass percentage of solution = (solute mass / mass of solution) x 100%
In this formula, ‘mass of the solute’ refers to the amount of solute present in the solution, while ‘mass of the solution’ refers to the amount of solute present in the solution. total mass of solutionthat is, the mass of the solute plus the mass of the solvent.
For example, if you have a solution of sodium chloride (NaCl) with a total mass of 250 grams and you know that it contains 25 grams of NaCl, you can Calculate the percentage by mass of the solution. as follows:
Mass percentage of NaCl solution = (25g / 250g) x 100% = 10%
That is, 10% of the total mass of the solution is made up of NaCl. The mass percentage of a solution is an important measurement in chemistry and is used to express the concentration of a solution in an easily understandable and comparable way.
How to convert a percentage of mass to volume?
To convert a percentage of mass to volume, it is necessary to know the density of the substance in question. Density is a measure of the mass per unit volume of a substance and is expressed in units of mass/volume as g/mL or kg/L. The formula to convert a percentage of mass to volume is as follows:
 Volume of the substance = (mass of the substance / substance density)
To calculate the volume of the substance it is necessary to know its mass and its density. Once you have the density, you can divide the mass of the substance by its density to get its volume.
For example, if you have a sample that weighs 20 grams and you know that 40% of the mass of the sample corresponds to the substance in question, and you know the density of the substance as 1.5 g/mL, you can calculate the volume as follows:
 mass of the substance = (40% x 20g) = 8g
 Volume of the substance = (8g / 1.5g/mL) = 5.33mL
That is, the volume of the substance in question is 5.33 mL. It is important to note that this formula is only applicable if density is known of the substance in question.
Examples of situations in which it is useful to take the percentage of the mass
The calculation of the percentage of the mass commonly used in chemistry and in industry for a variety of purposes. Some examples of situations where mass percentage is used include:
 in chemical analysis: The percentage by mass is used to express the concentration of solutions in some chemical compound or mixtures of substances in analytical chemistry. For example, it can be used to calculate the concentration of an analyte in a blood sample or to determine the amount of carbon or contaminants present in a soil sample.
 in food processing: The percentage by mass is used in the food industry to express the amount of nutrients, such as proteins, carbohydrates or fats, present in food. For example, it can be used to calculate protein content in a protein bar, fat content in a dairy product.
 In the production of medicines: The percentage by mass is used to express the concentration of an active ingredient in a medicine. For example, it can be used to calculate the concentration of an antibiotic in a solution for injection or the amount of an active substance in a tablet.
 in the manufacture of materials: Percentage by mass is used to express the amount of a substance present in a material, such as fiber content in a fabric or the amount of additives in a polymer.