Chemistry · Solutions
Percent solution calculator.
Work out how much solute to weigh or measure for a w/v, w/w or v/v percent solution of any final size.
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Percent solution formulas
A percent solution states solute per 100 parts of solution. % w/v is grams of solute per 100 mL of final solution, so 5 g in 100 mL is 5% w/v. % w/w is grams of solute per 100 g of final solution, and % v/v is mL of liquid solute per 100 mL of final solution. In every case, solute = percent / 100 x final amount.
Worked examples. 500 mL of a 10% w/v solution needs 10 / 100 x 500 = 50 g of solute, dissolved and made up to 500 mL. 250 g of a 20% w/w solution needs 50 g of solute plus 200 g of solvent. 100 mL of a 70% v/v solution needs 70 mL of the liquid, topped up to 100 mL with solvent.
For w/v and v/v, bring the mixture up to the final volume with solvent rather than adding a fixed solvent volume, because liquids and dissolved solids do not always add volumes exactly. Check the percent type on your protocol, since 5% could mean any of the three.
Frequently asked questions
What does % w/v mean?
Weight per volume: grams of solute per 100 mL of the finished solution. 5 g in 100 mL is 5% w/v.
What is the difference between w/w, w/v and v/v?
w/w is grams of solute per 100 g of solution, w/v is grams per 100 mL of solution, and v/v is mL of solute per 100 mL of solution.
Do I add the solute to 100 mL of water?
No. For w/v and v/v, dissolve the solute in some solvent, then add solvent until the total reaches the final volume. For w/w, weigh the solvent so the total mass is right.
How is a percent solution different from molarity?
A percent solution is based on mass or volume ratios, while molarity counts moles per litre. Use the molarity calculator to convert via molar mass.
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Lab safety and scope
This is arithmetic, not professional advice. Check every result against your own procedure, the safety data sheet (SDS) for each chemical, and your lab supervisor or instructor before you prepare, mix or dispose of anything. Verify values on the reagent bottle, since purity and hydration state change the real molar mass.