Percent Solution Calculator
Use this percent solution calculator to work out how much solute a solution needs. Choose % w/v (grams of solid per 100 mL) or % v/v (mL of liquid per 100 mL), enter the target percent and volume, and get the answer instantly.
Enter a target percent and a volume to see how much solute to use.
How percent solutions work
A percent solution states the amount of solute as a percentage of the total solution. There are three common conventions, and they are not interchangeable, so it always pays to know which one a recipe means.
- % w/v (weight/volume) ā grams of solute per 100 mL of solution. A 5% w/v solution holds 5 g in 100 mL. This is the usual choice when a solid is dissolved in a liquid.
- % v/v (volume/volume) ā millilitres of liquid solute per 100 mL of solution. 70% v/v ethanol means 70 mL of ethanol made up to 100 mL. Use it when mixing a liquid into a liquid.
- % w/w (weight/weight) ā grams of solute per 100 g of total solution. Common for ointments and concentrated mixtures where both components are weighed.
Because % w/v = g per 100 mL and % v/v = mL per 100 mL, scaling to any volume is just a proportion:
Worked example
Say you need 500 mL of 0.9% w/v saline. The grams of sodium chloride are (0.9 Ć· 100) Ć 500 = 4.5 g NaCl. Dissolve 4.5 g of NaCl in a little water, then top up to 500 mL ā that is standard physiological saline.
Related tools
- Working in parts per million instead? Use the ppm calculator.
- Diluting a stock to a lower concentration? Use the dilution calculator.
Frequently asked questions
āŗWhat is a % w/v (percent weight/volume) solution?
A % w/v solution expresses the mass of solute as grams per 100 mL of solution. So a 5% w/v solution contains 5 g of solute in every 100 mL. To find the grams you need, multiply the percent (divided by 100) by the solution volume in millilitres: grams = (% Ć· 100) Ć volume(mL). It is the standard way to describe a solid dissolved in a liquid, such as 0.9% w/v saline.
āŗWhat is the difference between % w/v and % v/v?
% w/v (weight/volume) measures grams of solute per 100 mL of solution and is used when a solid is dissolved in a liquid. % v/v (volume/volume) measures millilitres of liquid solute per 100 mL of solution and is used when a liquid is mixed into a liquid, such as 70% v/v ethanol. There is also % w/w (weight/weight), which is grams of solute per 100 g of total solution. Always check which one a recipe or protocol means, because the numbers are not interchangeable.
āŗHow do I make a percent solution?
For a % w/v solution, weigh out grams = (% Ć· 100) Ć volume(mL) of solute, dissolve it in a little solvent, then top up to the final volume in a volumetric flask. For a % v/v solution, measure mL solute = (% Ć· 100) Ć volume of the liquid solute and add solvent to reach the final volume. Topping up to volume ā rather than adding the full volume of solvent ā keeps the concentration accurate.
āŗIs this percent solution calculator free?
Yes. This percent solution calculator is completely free, runs entirely in your browser, needs no sign-up, and never sends your numbers to a server.
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