Dilution Calculator
How much stock to dilute, the final volume, or the strength you end up with, by C1V1 = C2V2 in any concentration unit, with the water to add.
Result
Stock solution, V1: 12.3077 fl oz
Arithmetic only. For how to handle and mix a product safely, follow its label or safety data sheet.
- Final volume, V2
- 16 fl oz (2 cup, 473.1765 mL)
- Diluent to add
- 3.6923 fl oz (0.4615 cup, 109.1946 mL)
- Dilution factor
- 1.3
- Parts of diluent per part of stock
- 0.3
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How to use the Dilution Calculator
- Choose the unknown, the stock volume, the final volume, the final concentration or the stock concentration.
- Enter the other three, with both concentrations in the same unit, whether that is percent, ppm, mg/mL or mol/L.
- Read the unknown, the diluent to add, and the dilution as a factor and as parts of diluent per part of stock.
The formula
C1 × V1 = C2 × V2V1 = C2 × V2 ÷ C1 V2 = C1 × V1 ÷ C2C2 = C1 × V1 ÷ V2 C1 = C2 × V2 ÷ V1diluent to add = V2 − V1dilution factor = C1 ÷ C2 = V2 ÷ V1The amount of dissolved substance, concentration times volume, is the same before and after adding solvent. That single fact gives all four arrangements. Volumes can be entered in fluid ounces, cups, quarts, gallons, millilitres or litres and are converted before the calculation.
Dilution only weakens
Adding solvent can only lower a concentration, so the page refuses a target above the stock and a stock volume larger than the final volume. If you need a stronger solution, you need a stronger stock or to add more of the substance itself.
How this differs from the molarity page
The molarity calculator also solves C1V1 = C2V2, in moles per litre, alongside working out molarity from a mass and molar mass. This page takes any concentration unit, can also solve for the stock strength, and gives the diluent to add and the mixing ratio.
With your numbers
- C1 × V1 = C2 × V2: 91 × 12.3077 fl oz = 70 × 16 fl oz
- Diluent = V2 − V1 = 3.6923 fl oz
- Dilution factor = C1 ÷ C2 = 1.3
Quick reference
Arithmetic only. For how to handle and mix a product safely, follow its label or safety data sheet.
| Example | Result |
|---|---|
| 91% to 70%, 500 mL | Stock solution, V1: 384.6154 mL |
| 10 mL of 5 M to 0.5 M | Final volume, V2: 100 mL |
| 1 cup of 12.5% made up to 1 gallon | Concentration: 0.78125 |
| Stock for 250 mL at 0.5 from 25 mL | Concentration: 5 |
| 1,000 ppm to 50 ppm, 1 L | Stock solution, V1: 50 mL |
| 10x buffer to 1x, 16 fl oz | Stock solution, V1: 1.6 fl oz |
Common questions about the Dilution Calculator
- How much stock do I need to make a weaker solution?
- Multiply the final volume by the final concentration and divide by the stock concentration: V1 = C2 × V2 ÷ C1. Then add diluent until the total reaches V2. To make 500 mL at 70 from a stock at 91, that is 384.6 mL of stock made up to 500 mL, which needs about 115.4 mL of diluent.
- Does the unit of concentration matter?
- No, as long as both concentrations use the same one. The unit cancels out of C1 ÷ C2, so percent, parts per million, milligrams per millilitre and moles per litre all work. Mixing units, such as a stock in percent and a target in ppm, gives a wrong answer by a factor of 10,000.
- What do dilution factor and "1 part to 9 parts" mean?
- The dilution factor is how many times weaker the result is: C1 ÷ C2, which equals V2 ÷ V1. A tenfold dilution takes 1 part of stock and 9 parts of diluent, 10 parts in all. Labels that say "1:10" can mean either 1 part in 10 or 1 part to 10, so check which one a label means before mixing.
- Can I use this for rubbing alcohol or bleach?
- For the arithmetic, yes. For alcohol, the result is close but not exact, because alcohol and water take up slightly less space mixed than apart, so the final volume comes out a little short. The page does not recommend a strength for any cleaning, disinfecting or medical use; follow the product label for that.