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Dilution Factor Calculator

Calculate dilution factor ratios (S:D and S:T) from stock, dilutant, and total volumes with real-time results.

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Dilution Factor Calculator

The Dilution Factor Calculator computes stock-to-dilutant (S:D) and stock-to-total (S:T) ratios from solution volumes. Dilution factor notation tells you how much stock solution is present relative to dilutant added or to the final total volume.

Given stock volume $V_{stock}$, dilutant volume $V_{dilutant}$, and total volume $V_{total}$:

$$V_{total} = V_{stock} + V_{dilutant}$$

$$S:D = V_{stock} : V_{dilutant}$$

$$S:T = V_{stock} : V_{total}$$

The concentration dilution factor is $DF = V_{total} / V_{stock}$. For example, mixing 10 mL stock with 90 mL dilutant gives S:D = 1:9 and S:T = 1:10.

For related calculations, see our Dilution Calculator and Serial Dilution Calculator.

Frequently Asked Questions

What is the difference between S:D and S:T?

S:D compares stock volume to dilutant volume only. S:T compares stock volume to the final total solution. For 10 mL stock plus 90 mL dilutant, S:D is 1:9 while S:T is 1:10.

What does a 1:10 dilution factor mean?

A 1:10 S:T dilution factor means one part stock in ten parts total solution. The stock is 10 times more concentrated than the final working solution.

How do I calculate dilution factor from volumes?

Add stock and dilutant to get total volume. Divide stock by dilutant for S:D, or stock by total for S:T. Simplify the ratio by dividing both sides by their greatest common factor.

Can I use any volume units?

Yes, as long as all three volumes use the same unit. The ratios are dimensionless and identical whether you use mL, µL, or liters.