How do I make 100 mL of 10% serum medium?

Use 10 mL of serum and 90 mL of medium: 100% × V1 = 10% × 100 mL gives V1 = 10 mL. Adding 10 mL of serum to a full 100 mL of medium would give only about 9.09%.

Does C1V1 = C2V2 work with percentages?

Yes, as long as C1 and C2 are the same kind of percentage (both w/v or both v/v). The percent unit cancels out just like molarity does.

What does 1% w/v mean?

1% weight per volume is 1 g of solute in 100 mL of final solution, which is 10 g/L or 10 mg/mL. For example, 10% w/v SDS is 100 g made up to 1 L.

Percent Solution Dilution Calculator (% w/v and % v/v)

How the percent solution dilution calculator works

Percent solutions dilute exactly like molar ones. As long as the stock and the target use the same kind of percentage, the unit cancels and the familiar equation applies:

C1 (%) × V1 = C2 (%) × V2

Choose V1 in the calculator above, enter the stock percentage as C1, the target percentage as C2 and the final volume as V2. The result is the volume of stock to measure, and the line below it gives the diluent needed to make up the final volume.

Kinds of percent concentration

Notation	Meaning	Example
% w/v	grams of solute per 100 mL of solution	10% w/v SDS = 100 g made up to 1 L
% v/v	mL of liquid solute per 100 mL of solution	10% v/v serum in culture medium
% w/w	grams of solute per 100 g of solution	used for some concentrated acids

The 10% w/v SDS example comes from Promega’s guide to making a complex solution. Because 1% w/v is 1 g per 100 mL, it equals 10 g/L or 10 mg/mL. The calculator uses that relation only when you combine a percentage with a mass unit on the main dilution calculator; on this page both sides are percentages, so v/v works just as well. Do not mix w/v and v/v in one calculation: they are not interchangeable unless you also know the density of the solute.

Worked percent dilution examples

Serum in culture medium (v/v). To make 100.0 mL of medium containing 10% serum, the Irvine Valley College cell culture text uses 10.0 mL of serum and 90.0 mL of basal medium. That is the default problem above: 100% × V1 = 10% × 100 mL, so V1 = 10 mL. The same text points out a classic mistake: adding 10.0 mL of serum to a full 100.0 mL of medium gives 110 mL at only 9.09%.

Diluting a strong solution with water. A water-treatment example on LibreTexts Workforce mixes 250 mL of a 65% solution with 700 mL of water. The total is 950 mL, so C2 = 65% × 250 ÷ 950 ≈ 17%. Switch the calculator to solve for C2 to check it.

“Make up to” versus “add to”

The serum example shows why the wording of a recipe matters:

Make up to volume: measure V1 of stock, then add diluent until the total reaches V2. This is what C1V1 = C2V2 assumes.
Add to a volume: adding V1 to a full V2 of diluent produces V1 + V2 in total, and the percentage comes out lower than planned.

For accurate % solutions, especially w/v, dissolve or mix in less than the final volume and then bring the solution up to the mark in a volumetric flask or graduated cylinder.

Convert a ratio such as 1:4 into amounts: dilution ratio calculator
Plan several percent dilutions in a row: serial dilution calculator
Work in molarity instead: M1V1 = M2V2 calculator

Percent Solution Dilution Calculator