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

Pick the percentage type, enter the target percentage and how much you need, and get the mass to weigh or volume to measure. Diluting from a concentrated stock works too.

Inputs

Percentage type

%

Results

Solute to weigh
0.9 g
Add solvent up to
100 mL

Formula

% w/v: Solute (g) = Percent × Total volume (mL) ÷ 100

% v/v: Solute (mL) = Percent × Total volume (mL) ÷ 100

% w/w: Solute (g) = Percent × Total volume (mL) × Density (g/mL) ÷ 100

Dilution: Stock (mL) = Target % × Total volume (mL) ÷ Stock % (C1V1 = C2V2)

Tip: For w/v, v/v and dilutions, dissolve or mix first, then add solvent up to the total volume rather than adding the full volume of solvent. For w/w, a blank density means 1.00 g/mL. Enter the real density for concentrated solutions.

You got this step right, but a whole experiment has dozens of linked parameters. Change one dilution factor and everything downstream has to be recalculated. In Vara the parameters of your whole experiment are connected, so changing one recalculates the rest automatically. Manage 3 experiments for free.

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FAQ

How much NaCl do I need for 100 mL of 0.9% saline?+
0.9% NaCl usually means % w/v, 0.9 g per 100 mL. Weigh 0.9 × 100 ÷ 100 = 0.9 g of NaCl, dissolve it in less than 100 mL of water, then bring the volume up to 100 mL.
How much glucose for 500 mL of a 5% glucose solution?+
As % w/v: 5 × 500 ÷ 100 = 25 g. Dissolve 25 g of glucose and bring it up to 500 mL. That assumes anhydrous glucose (MW 180.16). With glucose monohydrate (MW 198.17), weigh 25 × 198.17 ÷ 180.16 ≈ 27.5 g.
How do I make 100 mL of 70% ethanol from 95% ethanol?+
This is a dilution, so use C1V1 = C2V2: V1 = 70 × 100 ÷ 95 = 73.68 mL. Measure 73.68 mL of 95% ethanol and add water up to 100 mL. Ethanol and water shrink in volume when mixed, so adding 26.32 mL of water gives a little less than 100 mL. Bring it up to the mark instead of subtracting. Choose "Dilute from stock" in the calculator to work this out.
What is the difference between % w/v, % v/v and % w/w?+
% w/v is grams of solute per 100 mL of solution, the usual choice for solids (NaCl, BSA, agarose). % v/v is milliliters of solute per 100 mL of solution, used for liquids (ethanol, Triton X-100). % w/w is grams of solute per 100 g of solution, common on bottles of concentrated acids and ammonia. If a protocol does not say, a solid solute is usually meant as w/v.
Why does % w/w need a density?+
w/w is by mass, but you usually measure volume, and solution mass = volume × density. For 100 mL of a 10% w/w solution at 1.00 g/mL, the solution weighs 100 g: 10 g of solute and 90 g of solvent. At 1.10 g/mL it weighs 110 g: 11 g of solute and 99 g of solvent. Leaving density blank uses 1.00 g/mL, which only suits dilute aqueous solutions. If you set the total in grams, no density is needed.
What is the molarity of 0.9% NaCl?+
0.9% w/v is 9 g/L. Divide by the molecular weight of NaCl, 58.44, to get 0.154 mol/L, about 154 mM. Use the molarity calculator to convert between percent and molar concentrations.

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