How It Works
This calculator works in 4 steps.
Enter stock and target concentrations
Type C₁ and C₂ in the same unit.
Enter the final volume (V₂)
Type the total volume to prepare.
Compute the stock volume (V₁)
The calculator solves V₁ = C₂V₂ / C₁ in the background.
Read the diluent volume
The calculator returns V₂ − V₁ in mL, L, and US fl oz, with a note on the additive-volume assumption.
The Formula
The formula subtracts the stock volume from the final volume.
V_diluent = V₂ − V₁V_diluent = V₂ × (1 − C₂ / C₁)- V_diluent:
- Volume of water, buffer, or solvent to add
- V₂:
- Final volume
- V₁:
- Stock volume
- C₁ / C₂:
- Stock and target concentrations
For 250 mL of 1× buffer from 5× stock, V₁ = 50 mL and V_diluent = 250 − 50 = 200 mL (6.76 US fl oz).
Conversion Table
The conversion table gives the diluent in mL and US fluid ounces for 6 dilution factors and final volumes.
| Dilution | Final volume | Stock volume | Diluent (mL) | Diluent (US fl oz) |
|---|---|---|---|---|
| 10× | 100 mL | 10 mL | 90 mL | 3.043 fl oz |
| 5× | 250 mL | 50 mL | 200 mL | 6.763 fl oz |
| 10× | 1,000 mL | 100 mL | 900 mL | 30.43 fl oz |
| 4× | 40 mL | 10 mL | 30 mL | 1.014 fl oz |
| 1,000× | 10 mL | 0.01 mL | 9.99 mL | 0.3378 fl oz |
| 5× | 500 mL | 100 mL | 400 mL | 13.53 fl oz |
1 US fl oz = 29.5735 mL. Values assume additive volumes.
What Is the Diluent Volume Calculator?
The Diluent Volume Calculator is a dilution tool that returns the volume of water, buffer, or solvent to add to a stock, under the assumption that stock and diluent volumes add. The tool subtracts the stock volume from the final volume to give the diluent volume.
Additive volume holds for most dilute aqueous solutions. Ethanol-water, concentrated acid-water, and sugar-syrup mixtures shrink on mixing, so the diluent value is an estimate for those systems. For exact work, the calculator recommends filling to the mark in a volumetric flask (quantum satis, q.s.) instead of adding a measured diluent volume.
Common Uses
There are 5 main uses of this calculator.
Buffer mixing
Technicians measure water for 10× to 1× buffer dilutions in graduated cylinders.
Graduated-cylinder preparation
Users without volumetric flasks add a measured diluent volume to a measured stock.
Cleaning solutions
Facility staff measure water for concentrate-to-ready-to-use dilutions.
Media preparation
Cell culture labs measure base medium for supplement additions.
Dispenser setup
Operators set a bottle-top dispenser to the diluent volume for repeated batches.