Percent concentration calculator
Prepare w/v, w/w and v/v percent solutions — solve the solute, the total, or the percent — and convert between % w/v, mg/mL, g/L, % w/w and ppm, with the density asked for only where the chemistry needs it.
The formula
% = solute / total × 100
- % w/v
- grams of solute per 100 mL of final solution — the usual meaning for a solid dissolved in a liquid
- % w/w
- grams of solute per 100 g of final solution — how assays and concentrated reagents are labelled
- % v/v
- mL of solute per 100 mL of final solution — liquids diluted into liquids
Worked example
0.9% saline, then a w/w → w/v conversion
500 mL of 0.9% w/v NaCl: 0.9 g per 100 mL × 5 = 4.5 g of NaCl, dissolved and made up to 500 mL in a volumetric flask.
Converting a 10% w/w HCl solution (density 1.048 g/mL) to volume-based units: % w/v = 10 × 1.048 = 10.48% w/v, which is 104.8 g/L. Without the density, w/w and w/v are not interconvertible — that is why the converter asks for it.
Common pitfalls
Reading w/w as w/v (or the reverse)
A 10% w/w reagent is not 10 g per 100 mL — it differs by the solution density. For dense reagents the gap is far from negligible; check which convention the protocol or label uses before weighing anything.
% v/v does not survive mixing
Adding 30 mL of water to 70 mL of ethanol does not give 100 mL — mixing volumes are not additive. Dilute the 70 mL to the 100 mL mark instead; that is what 70% v/v means, and it is why this converter refuses v/v conversions rather than shipping a silently wrong number.
ppm here is a mass fraction
The ppm in this converter is mass-per-mass (1% w/w = 10,000 ppm), exact by definition. Reading ppm as mg/L assumes a dilute aqueous solution with density 1 — the ppm/ppb converter treats that assumption explicitly.
Dissolve, then fill to volume
w/v and v/v percents are defined against the final solution volume. Dissolve the solute in less solvent than the target, then make up to the mark — adding the full solvent volume to the solute gives a different, wrong concentration.