What Is Mass/Volume Percent (w/v%)?
Mass/volume percent, written as w/v%, is a common way to express the concentration of a solution. It tells you how many grams of solute are dissolved in 100 milliliters of solution. For example, a 5% w/v saline solution contains 5 grams of sodium chloride in every 100 mL. This unit is widely used in chemistry, biology, pharmacy, and medicine because it conveniently mixes a solid mass with a liquid volume.
How to Use This Calculator
Enter the mass of solute in grams and the volume of the solution in milliliters. The calculator divides the mass by the volume and multiplies by 100 to return the w/v% concentration. Make sure your units are grams and milliliters — if you have different units, convert first (1 L = 1000 mL, 1 kg = 1000 g).
The Formula Explained
The equation is:
$$\text{w/v \%} = \frac{\text{Mass of solute (g)}}{\text{Volume of solution (mL)}} \times 100$$
The factor of 100 scales the ratio so the answer is expressed per 100 mL, matching the definition of percent. Note that the volume used is the volume of the final solution, not just the volume of solvent added.
Worked Example
Suppose you dissolve 8 grams of glucose in enough water to make 250 mL of solution. The w/v% is:
$$\left(\frac{8\ \text{g}}{250\ \text{mL}}\right) \times 100 = 0.032 \times 100 = \textbf{3.2\% w/v}$$
So the solution is 3.2% glucose by mass/volume.
FAQ
Is w/v% the same as g/100 mL? Yes — a 1% w/v solution is exactly 1 gram per 100 mL.
How do I convert w/v% to grams per liter? Multiply the w/v% by 10. A 5% w/v solution equals 50 g/L.
Why use the final solution volume? Adding solute can slightly change the total volume, so concentration is defined relative to the final, fully mixed solution volume for accuracy.
