Percentage of Volume Calculator
Find v/v% from a part volume and final volume for liquid mixes, gas mixes, lab notes, and class problems.
Result
20%
30 of 150 total volume is 20% by volume (v/v)
Quick Answer
Percent by volume is the part volume divided by the total volume, times 100, so 30 mL of alcohol in a 150 mL mix is (30 / 150) x 100, which is 20 percent v/v. Use the final total volume as the base. It reports a volume ratio, not a mass percent.
How A Percent By Volume Calculator Works, Step By Step
Percent by volume tells how much of a liquid or gas mix comes from one measured part. Chem labs often call this v/v%. The tool divides part volume by total volume, then multiplies by 100. Use one unit in both boxes, such as mL with mL. The result fits liquid mixes, gas mixes, and final bottle records. A v/v% result does not use mass, density, or moles. A w/w% result uses mass instead, so do not swap the two. Use this page when a class problem, label, or lab method gives measured volumes. The answer shows how much of the final mix comes from the chosen part. The same idea works for any unit pair as long as both fields use that unit.
Percent By Volume Calculator: The Formula Behind The Result
Part volume means the measured amount of the liquid or gas part. Total volume means the final measured amount of the whole mix. The result is v/v%, also written as volume by volume percent. Use one unit for both fields before you calculate. Do not place a mass value into a volume field.
- Percent by volume = (part volume ÷ total volume) × 100
Using The Percent By Volume Calculator: Step By Step
Inputs
- Part volume: the measured volume of the selected liquid or gas.
- Total volume: the final measured volume of the whole mix.
- Volume unit: use one unit for both volume fields.
Steps
- Enter the part volume.
- Enter the total volume.
- Check that both values use one unit.
- Run the calculator.
- Read the result as v/v%.
Percent By Volume Calculator In Practice: A Real Example
A liquid mix has 30 mL of alcohol in a final mix of 150 mL.
- Percent by volume = (30 ÷ 150) × 100.
- 30 ÷ 150 = 0.2.
- 0.2 × 100 = 20.
Percent by volume = 20% v/v, rounded to the nearest whole percent. The result does not say alcohol makes up 20% of the mass.
When To Use A Percent By Volume Calculator (Or Not)
Use percent by volume when the method measures parts by volume. Use v/v% for liquid mix notes, gas ratios, and final flask records. Keep w/w% for mass based work so the two lab notes stay clear. See the science calculators hub for related tools.
Assumptions
- Both volume values use one unit.
- Total volume is greater than zero.
- Part volume is included in the final volume.
- The output is a volume share shown as a percent.
- Rounding happens after the full math step.
Limitations
- This calculator does not convert mass to volume.
- This calculator does not use density.
- Mixed liquids may not add to a simple final volume.
- This calculator does not find molarity or stock dilution.
In Practice
The most common mistake is assuming volumes add up neatly, but mixing some liquids causes slight volume contraction, so the parts may not sum to the final volume exactly. Always measure the true final volume for the base. Also do not read a v/v percent as a mass percent; the two differ whenever densities differ.
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Frequently Asked Questions About Volume Percent Results
Is v/v% the same as percent by volume?
v/v% is the same common lab convention as percent by volume. Both compare part volume with total volume, then show the ratio as a percent.
How is v/v% different from w/w%?
v/v% compares volume with volume, while w/w% compares mass with mass. The two values use different bases and should not be swapped.
Should total volume mean solvent volume or final volume?
Total volume should mean the final measured volume of the whole mix. Using only solvent volume changes the base and can change the result.
Can this calculator handle gas mixtures?
This calculator can handle gas mix shares when both values use one volume basis. The result still represents v/v%, not mass percent.
Why can mixed liquid volumes be tricky?
Mixed liquids can be tricky because the final amount may not equal the sum of the separate liquids. Measure final volume when accuracy matters.
Sources
Last updated: . Reviewed for accuracy against the formula shown above.