Percent Solution Calculator
Work out how much solute and solvent you need for a percent solution by weight/volume, weight/weight or volume/volume. You can also find the percentage of a solution you already mixed, or dilute a stronger stock to a lower percentage.
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Adds molarity for w/v solutions, e.g. NaCl 58.44
Converts the solvent mass to a volume
How to use the Percent Solution Calculator
- Choose a task: make a solution, find the percentage of a solution, or dilute a stock.
- Pick the percent type: w/v for a solid in a liquid by volume, w/w for everything by mass, v/v for a liquid in a liquid.
- Enter the target percentage and the final amount you want, or the amounts you already have.
- Press Calculate to get the amount of solute and solvent with the formula.
- Check the table for other batch sizes, or Copy the recipe.
Percent solution formulas
- % w/v = grams of solute ÷ mL of solution × 100. Solute needed = % × final volume (mL) ÷ 100.
- % w/w = grams of solute ÷ grams of solution × 100. Solvent = total mass − solute mass.
- % v/v = mL of solute ÷ mL of solution × 100.
- Dilution: C₁ × V₁ = C₂ × V₂, so the stock needed is V₁ = C₂ × V₂ ÷ C₁.
- w/v to molarity: M = (% × 10) ÷ molar mass.
Common percent solutions
| Solution | Type | Per 100 mL (or 100 g) | Per 1 L (or 1 kg) |
|---|---|---|---|
| Normal saline, 0.9% NaCl | w/v | 0.9 g NaCl | 9 g NaCl (0.154 M) |
| Agarose gel, 1% | w/v | 1 g agarose | 10 g agarose |
| Glucose (dextrose), 5% | w/v | 5 g glucose | 50 g glucose (0.278 M) |
| Sodium hydroxide, 10% | w/v | 10 g NaOH | 100 g NaOH (2.5 M) |
| Simple syrup, 50% sugar | w/w | 50 g sugar + 50 g water | 500 g sugar + 500 g water |
| Brine, 10% salt | w/w | 10 g salt + 90 g water | 100 g salt + 900 g water |
| Isopropyl alcohol, 70% | v/v | 70 mL alcohol, water to 100 mL | 700 mL alcohol, water to 1 L |
| Glycerol, 50% | v/v | 50 mL glycerol, water to 100 mL | 500 mL glycerol, water to 1 L |
Tips for accurate solutions
- Make up to volume. For w/v and v/v solutions, dissolve the solute first and then add solvent until you reach the final volume, ideally in a volumetric flask or graduated cylinder.
- Weigh for w/w. Weight percent does not depend on temperature or volume changes, which makes it the most reliable for syrups, brines and stock reagents.
- Watch for hydrates. If your chemical is a hydrate (for example CuSO₄·5H₂O), the percentage usually refers to the anhydrous compound; scale the mass by the ratio of molar masses.
- Percent of what? A "10% solution" with no label usually means w/v for solids in water and v/v for liquids. Write the type on the label to avoid confusion.
Frequently asked questions
What does % w/v mean?
Weight/volume percent is the grams of solute per 100 mL of final solution. A 5% w/v solution has 5 g of solute in every 100 mL, which is 50 g per liter.
How do I make a 10% w/v solution?
Weigh 10 g of solute for every 100 mL of final volume, dissolve it in somewhat less solvent, then add solvent until you reach the final volume. For 500 mL that is 50 g of solute made up to 500 mL.
What is the difference between w/v, w/w and v/v?
w/v is grams of solute per 100 mL of solution, w/w is grams of solute per 100 g of solution and v/v is milliliters of liquid solute per 100 mL of solution. Use w/w when both amounts are weighed and v/v for mixtures of liquids such as alcohol and water.
How do I make 70% alcohol from 95% alcohol?
Use C₁V₁ = C₂V₂: for 1,000 mL of 70%, you need 70 × 1,000 / 95 ≈ 737 mL of 95% alcohol, then add water up to 1,000 mL. Because ethanol and water shrink a little when mixed, fill to the final volume rather than adding exactly 263 mL of water.
How do I calculate the percentage of a solution?
Divide the amount of solute by the amount of whole solution and multiply by 100. For example, 5 g of salt dissolved in 95 g of water is 5 / (5 + 95) × 100 = 5% w/w.
How do I convert % w/v to molarity?
Multiply the percentage by 10 to get grams per liter, then divide by the molar mass. A 0.9% w/v NaCl solution is 9 g/L ÷ 58.44 g/mol ≈ 0.154 M.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.