Calculadora de Porcentagem em Massa
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
% = (m_soluto / m_solução) × 100
About this calculator
The Mass Percentage Calculator is a practical tool to determine the concentration of a solution expressed as mass/mass percent (% m/m). This quantity indicates how many grams of solute are dissolved in 100 grams of solution. The calculation is simple: divide the mass of the solute by the total mass of the solution and multiply by 100. For example, a solution with 20 g of salt in 80 g of water has a total mass of 100 g, resulting in 20% m/m salt.
Use this calculator whenever you need to prepare solutions with a defined concentration in laboratories, industries, or even at home, such as making oral rehydration solution or diluting chemicals. The formula % = (m_solute / m_solution) × 100 is the basis, but remember that the mass of the solution is the sum of the solute and solvent masses. The tool streamlines the process, avoiding manual errors and ensuring accuracy.
Essential precautions: ensure masses are in the same unit (grams, kilograms, etc.). Mass percentage is dimensionless but always refers to mass. Do not confuse with volume/volume or mass/volume percentages. In very dilute solutions, the percentage may be very small; use appropriate decimal places. This calculator is ideal for students, technicians, and chemistry professionals.
Frequently asked questions
What does % m/m mean?
% m/m means mass by mass percentage, i.e., grams of solute per 100 grams of solution.
Can I use different units, like kg and g, in the same calculation?
No. The masses of solute and solution must be in the same unit for the correct calculation.
How do I calculate the mass of the solution if I only have the masses of solute and solvent?
The mass of the solution is the sum of the masses of solute and solvent. For example, 10 g salt + 90 g water = 100 g solution.
Does this calculator work for volume concentration?
No. It is specific for mass concentration. For volume, use the volume/volume percentage calculator.
Can the result be greater than 100%?
No, because the mass of the solute can never exceed the mass of the solution. The maximum is 100% when the solution is pure solute.