dilution factor calculator

What is a dilution factor?

A dilution factor tells you how much a solution has been diluted. In practical lab terms, it is the ratio of the final volume to the original aliquot volume. If your dilution factor is 10, your final solution is ten times more dilute than the starting stock.

Core equations

• Dilution factor (DF): DF = C1 / C2
• Dilution law: C1V1 = C2V2
• Stock volume needed: V1 = (C2 × V2) / C1
• Diluent volume: Vdiluent = V2 − V1

How to use this dilution factor calculator

1. Enter your starting concentration (C1).
2. Enter your desired concentration (C2).
3. Enter your desired final volume (V2).
4. Click Calculate to get DF, stock volume, and diluent volume.

This tool assumes you are performing a true dilution (C1 > C2). If C2 is greater than C1, you would need concentration steps rather than dilution.

Example calculations

Example 1: 1:10 style dilution

Suppose you have a 100 mg/mL stock and you want 10 mg/mL final concentration with a total volume of 50 mL.

• DF = 100 / 10 = 10
• V1 = 50 / 10 = 5 mL stock
• Diluent = 50 − 5 = 45 mL

So you mix 5 mL stock + 45 mL diluent.

Example 2: Small-volume prep

If C1 = 2,000 ng/µL, C2 = 200 ng/µL, and V2 = 100 µL:

• DF = 10
• V1 = 10 µL stock
• Diluent = 90 µL

Serial dilution quick notes

For serial dilutions, multiply factors across steps:

• 1:10 followed by 1:10 gives an overall 1:100 dilution.
• 1:5 followed by 1:20 gives an overall 1:100 dilution.

Serial dilution is often preferred when a single-step dilution would require pipetting very tiny volumes.

Common mistakes to avoid

• Mixing units: Keep concentration units consistent between C1 and C2.
• Wrong ratio interpretation: 1:10 does not mean 1 + 10; it means total is 10 parts.
• Rounding too early: Keep extra decimal places, then round at the end.
• Pipetting below instrument limits: Use serial dilution when needed.

When this calculator is most useful

This tool is ideal for molecular biology, microbiology, analytical chemistry, and classroom labs where you need quick and reliable dilution planning. It helps reduce setup errors and saves time when preparing standards, reagents, and sample working solutions.