# How do you calculate dilution factor?

Mar 22, 2014

You divide the final volume by the initial volume.

#### Explanation:

$\text{DF} = {V}_{f} / {V}_{i}$

EXAMPLE 1:

What is the dilution factor if you add a 0.1 mL aliquot of a specimen to 9.9 mL of diluent?

Solution:

${V}_{f} = \text{aliquot volume + diluent volume" = "(0.1 + 9.9) mL" = "10.0 mL}$

"DF" = V_f/V_i = (10.0 cancel("mL"))/(0.1cancel("mL")) = 100

You have diluted the sample by a factor of 100.

The dilution factor is often used as the denominator of a fraction.

For example, a $\text{DF}$ of 100 means a 1:100 dilution.

EXAMPLE 2:

How would you make 500 mL of a 1:250 dilution?

Solution:

$\text{DF} = {V}_{f} / {V}_{i}$

V_i = V_f/("DF") ="500 mL"/250 = "2.00 mL"

Pipet 2.00 mL of your stock solution into a 500 mL volumetric flask.