Percent Solution Calculator (w/v, w/w, v/v)

A percent solution tells you how much solute is in 100 parts of solution, but “parts” can mean three different things. Weight/volume (w/v) percent is grams of solute per 100 mL of solution – physiological saline is 0.9% w/v NaCl, 0.9 g in every 100 mL. Weight/weight (w/w) percent compares masses and is used for concentrated acids, alloys and foods. Volume/volume (v/v) percent compares volumes and is used for liquids dissolved in liquids – the alcohol content of drinks, for instance.

Mixing up the three is one of the commonest sources of error, because they only agree for dilute aqueous solutions with a density close to 1 g/mL. A 40% w/w sugar syrup is not 40% w/v, and 40% v/v ethanol is about 34% w/w because ethanol is lighter than water.

Choose the type you need. The calculator also shows the w/v result as g/L and parts per million, the amount of solute in any volume you choose, and – in the two preparation modes – the mass of solute to weigh out for a target percentage.

How to use the Percent Solution Calculator

1. Calculate
2. Mass of solute
3. I know the mass of
4. Mass of solution
5. Mass of solvent
6. Solute amount given as
7. Volume of solute
8. Mass of solute
9. Density of solute
10. Target percentage
11. Volume of solution
12. Total mass of solution
13. Show the solute in a volume of

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

How it works

Pick the kind of percentage, then enter the amounts of solute and solution. Always use the total amount of solution (solute plus solvent) in the denominator, not the solvent alone. For v/v you can enter the solute volume directly or its mass and density, and the calculator converts mass to volume.

Worked example

w/v: 12 g of glucose made up to 250 mL gives 12 ÷ 250 × 100 = 4.8% w/v, or 48 g/L (48,000 ppm); 100 mL of it contains 4.8 g. w/w: the same 12 g in a 150 g solution is 12 ÷ 150 × 100 = 8% w/w. v/v: 31.56 g of ethanol (density 0.789 g/mL) is 40.0 mL; made up to 250 mL that is 16.0% v/v. Preparation: 500 mL of 0.9% w/v saline needs 0.9 × 5 = 4.5 g NaCl; 200 g of a 5% w/w solution needs 10 g of solute and 190 g of water.

Which percentage to use

Tips

• Use the final volume of the solution, not the volume of solvent added, for molarity.
• For dilutions, C₁V₁ = C₂V₂ only holds when both concentrations use the same unit.
• Add acid to water, never water to acid.
• Everything is calculated in your browser.

Common mistakes to avoid

• Mixing w/w, w/v and v/v percentages.
• Forgetting that pH is logarithmic – one unit is a tenfold change in [H⁺].
• Using pKa where Ka is asked for (or the other way round).

Inputs explained

What each result means

• Concentration (w/v) = [Mass of solute]÷[Volume of solution]÷10
• Mass per volume = [Mass of solute]÷[Volume of solution]
• Parts per million (mg/L) = [Mass of solute]÷[Volume of solution]×1000
• Solute in the chosen volume = [Mass of solute]÷[Volume of solution]×[Show the solute in a volume of]
• Concentration (w/w) = [Mass of solute]÷[Mass of solution used]×100
• Mass of solvent = [Mass of solution used] – [Mass of solute]
• Parts per million by mass = [Mass of solute]÷[Mass of solution used]×1e6
• Concentration (v/v) = [Solute volume (L)]÷[Volume of solution]×100
• Volume of solute = [Solute volume (L)]
• Solvent to make up to volume (approx.) = [Volume of solution] – [Solute volume (L)]
• Solute to weigh out = [Target percentage]÷100×[Volume of solution]×1000
• Solute to weigh out = [Target percentage]÷100×[Total mass of solution]
• Solvent to add = [Total mass of solution] – [Target percentage]÷100×[Total mass of solution]
• Mass per volume = [Target percentage]×10