Percent Concentration

General Chemistry • Solutions and Their Physical Properties

Written by STEM Calculators Team Published October 25, 2025 Updated February 24, 2026

Percent Concentration

Percent type Solve for

For % (w/w): \( \%=\frac{m_\text{solute}}{m_\text{solution}}\times 100 \). In “Percent” mode, give solute mass and either solvent mass or total mass.

Solute mass \(m_s\) (g) Solvent mass \(m_v\) (g) (optional in Percent mode) Total mass \(m_\text{tot}\) (g) (optional in Percent mode)

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Percent Concentration — Quick Reference

“Percent concentration” expresses the ratio of a solute amount to the whole solution, scaled by 100. The most common variants are mass percent (% w/w), volume percent (% v/v), mass/volume percent (% w/v), and mole percent.

Definitions

Mass percent (% w/w): \[ \%(\text{w/w}) = \frac{m_\text{solute}}{m_\text{solution}}\times 100. \]
Volume percent (% v/v): \[ \%(\text{v/v}) = \frac{V_\text{solute}}{V_\text{solution}}\times 100. \]
Mass/Volume percent (% w/v): \[ \%(\text{w/v}) = \frac{m_\text{solute}\,[\mathrm{g}]}{V_\text{solution}\,[\mathrm{mL}]}\times 100. \]
Mole percent: \[ \%(\text{mole}) = \frac{n_\text{solute}}{n_\text{solute}+n_\text{solvent}}\times 100. \]

Rearrangements (vertical form)

Given target %, find required solute (w/w or v/v):

\[ \begin{aligned} \% &= \frac{\text{solute}}{\text{total}}\cdot 100 \\ \text{solute} &= \frac{\%}{100}\,\text{total} \end{aligned} \]

Given target %, find total and solvent (w/w or v/v):

\[ \begin{aligned} \% &= \frac{\text{solute}}{\text{total}}\cdot 100 \\ \text{total} &= \frac{100}{\%}\,\text{solute} \\ \text{solvent} &= \text{total} - \text{solute} \end{aligned} \]

Mass/volume (% w/v):

\[ \begin{aligned} \%(\text{w/v}) &= \frac{m_s}{V_{\text{tot}}}\cdot 100 \\ m_s &= \frac{\%}{100}\,V_{\text{tot}},\quad V_{\text{tot}} = \frac{100}{\%}\,m_s \end{aligned} \]

Mole %: identical rearrangements with \(n_s\) and \(n_{\text{tot}}\).

Notes

Use consistent units (e.g., grams with grams, mL with mL). For % w/v, use grams and milliliters as defined.
For mole %, masses may be converted to moles by \( n = \dfrac{m}{M} \).
Percent is unitless; always report with the percent sign.

Frequently Asked Questions

What is percent concentration in chemistry?

Percent concentration expresses the ratio of solute to the entire solution multiplied by 100. Common forms are mass percent (w/w), volume percent (v/v), mass/volume percent (w/v), and mole percent.

How do you calculate mass percent and volume percent?

Mass percent uses % = (m_solute / m_solution) x 100 and volume percent uses % = (V_solute / V_solution) x 100. The solution amount is the total (solute + solvent) for the chosen basis.

What does mass/volume percent (w/v) mean?

Mass/volume percent is defined as % (w/v) = (m_solute in g / V_solution in mL) x 100. It is often interpreted as grams of solute per 100 mL of final solution volume.

How is mole percent calculated and how do I convert from mass?

Mole percent is % = n_solute / (n_solute + n_solvent) x 100. If you start from mass, convert using n = m/M, where M is the molar mass determined from the chemical formula.

Why do the solute and solvent units need to match?

In percent calculations, the ratio must compare the same type of quantity (grams with grams, mL with mL, or moles with moles). Mixing units breaks the ratio and leads to incorrect percent concentration.

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#	Component	Formula	Amount type	Value	Units
1	Solute	M = — g·mol⁻¹			mol
2	Solvent	M = — g·mol⁻¹			mol

Percent Concentration

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