Step 1: Identify the sample (solute) volume
This is the volume of the original solution you are diluting.

Step 2: Determine the total volume
Total volume = Sample volume + Diluent (e.g., water, saline)

Step 3: Apply the formula

DF = \frac{\text{Total Volume}}{\text{Sample Volume}}

Step 4: Express the result
Write as a ratio (e.g., 1:10, 1:100)

2. Practice Problems

Problem 1:
You mix 2 mL of sample with 8 mL of diluent.

• Total volume = 10 mL

• DF = 10 / 2 = 5
  👉 Answer: 1:5 dilution

Problem 2:
You add 1 mL of serum to 99 mL of diluent.

• Total volume = 100 mL

• DF = 100 / 1 = 100
  👉 Answer: 1:100 dilution

Problem 3:
You dilute 0.5 mL of sample with 4.5 mL of saline.

• Total volume = 5 mL

• DF = 5 / 0.5 = 10
  👉 Answer: 1:10 dilution

Problem 4 (Serial Dilution):
You perform two consecutive 1:10 dilutions.

• First dilution = 1:10

• Second dilution = 1:10
  👉 Overall DF = 10 × 10 = 100 (1:100)

3. Interpreting Results

• DF = 1: No dilution (original sample)

• Small DF (e.g., 1:2, 1:5): Slight dilution (still relatively concentrated)

• Large DF (e.g., 1:100, 1:1000): Highly diluted (very low concentration)

Key Interpretation Rule

• The higher the dilution factor, the lower the concentration of the final solution.

Clinical/Lab Insight

• If results are too high, dilute more (increase DF)

• If results are too low, dilute less

• Always multiply the final result by the DF to get the original concentration