Percentage Solution Calculator

A percentage solution calculator finds how concentrated a dissolved substance is in a solution, expressed as a percentage. The dissolved substance is called the solute. The calculator divides the solute's mass by the solution's total volume and multiplies by 100, giving a result in weight/volume percent, written as % w/v.

What Is a Percentage Solution?

A percentage solution states how much solute sits in a solution, as a percentage. The most common form in labs and pharmacies is weight/volume percentage (% w/v): the number of grams of solute in every 100 milliliters of the finished solution.

A 10% w/v solution contains 10 grams of solute in a total volume of 100 milliliters. Those 10 grams are not added to 100 ml of solvent. Instead, the solute is dissolved in a smaller amount of solvent first, then more solvent is added until the total volume reaches 100 ml. This "dissolve, then top up" method matters because the solute itself takes up space in the final volume.

Percentage solutions (% w/v) are used in:

Pharmacy, for creams, oral solutions, and injections
Medicine, for local anesthetics and antiseptics
Laboratories, for buffers, stains, and culture media
Food science, for brines, syrups, and pickling liquids
Agriculture, for fertilizer and pesticide dilutions
Industry, for cleaning solutions, plating baths, and coolants

Percentage Solution Formula

The formula for percentage concentration by weight/volume is:

Percentage Concentration (% w/v) = (Mass of Solute in g ÷ Volume of Solution in ml) × 100

Mass of solute: the weight of the dissolved substance, in grams. It cannot be negative.
Volume of solution: the total volume of the finished solution, in milliliters. It must be greater than zero.

If the volume entered is zero or negative, there is no valid percentage to show. The calculator displays a message instead of a number: "Total volume must be greater than zero." If the solute mass entered is negative, it shows "Amount of solute cannot be negative."

How to Calculate Percentage Concentration: Example

A technician dissolves 5 grams of a compound in enough water to make 250 milliliters of solution.

Percentage Concentration = (5 g ÷ 250 ml) × 100 = 2.00%

The solution is 2.00% w/v.

The formula can also be rearranged to find the solute mass needed for a target percentage:

Mass of Solute (g) = (Percentage × Volume) ÷ 100

Example: to prepare 50 ml of a 2% solution, the mass needed is (2 × 50) ÷ 100 = 1 gram.

Using the Calculator

Enter the solute mass in grams and the total solution volume in milliliters. The result updates as the values change.

Results normally show two decimal places, such as 2.00%.
If the result is greater than 1000%, it is shown in scientific notation instead, such as 1.20e+3% for a result of 1200%.
A bar chart shows the solute as a share of the total volume. The bar turns red and reads ">100%" once the percentage passes 100.
The copy button copies the result exactly as displayed, including the % sign.
A volume of zero or less does not cause an error message about calculation failure. It produces a plain validation message asking for a volume greater than zero.
A result above 100% is mathematically valid but usually signals a mixed-up unit, such as entering liters where milliliters were expected.

Related Concentration Units

Percentage (w/v) is one of several ways to express how concentrated a solution is.

Molarity (M): moles of solute per liter of solution. Used in chemical reactions and stoichiometry.
Molality (m): moles of solute per kilogram of solvent. Does not change with temperature, because it is based on mass rather than volume.
Parts per million (ppm): mass of solute per million parts of solution. Used for very small amounts; 1 ppm equals 0.0001%.
Weight/weight percentage (% w/w): grams of solute per 100 grams of solution. Common for creams and ointments.
Volume/volume percentage (% v/v): milliliters of solute per 100 ml of solution. Used for liquid mixtures, such as the alcohol content of a drink.

Frequently Asked Questions

What is a percentage solution?

A percentage solution states the amount of solute in a solution as a percentage of the total volume or mass. The weight/volume form (% w/v) gives grams of solute per 100 milliliters of solution.

How do you calculate the percentage of a solution?

Divide the solute mass in grams by the solution volume in milliliters, then multiply by 100. For example, 10 grams of salt in 200 milliliters of solution gives (10 ÷ 200) × 100 = 5%.

What is the difference between w/v, w/w, and v/v?

w/v is grams of solute per 100 ml of solution. w/w is grams of solute per 100 grams of solution. v/v is milliliters of solute per 100 ml of solution, used when both the solute and the solvent are liquids.

Why is my result over 100%?

A result over 100% means the solute mass in grams is larger than the solution volume in milliliters. This is mathematically valid but usually means a unit was entered wrong, such as liters instead of milliliters.

How do I prepare a 10% solution?

Multiply the target percentage by the target volume and divide by 100. For 500 ml of a 10% solution: (10 × 500) ÷ 100 = 50 grams of solute. Dissolve the 50 grams in less than 500 ml of solvent, then add solvent until the total reaches 500 ml.

Can this calculator be used for liquid solutes?

This calculator computes weight/volume percentage, which treats the solute as a measured mass. For a liquid solute measured by volume, use volume/volume percentage instead: (volume of solute ÷ volume of solution) × 100.

Percentage Solution Calculator | w/v Concentration