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PCR Reaction Dilution Factor Estimator

The PCR Reaction Dilution Factor Estimator calculates the dilution factor produced by combining a measured aliquot of stock material with diluent. It reports both the fold dilution and the fraction of stock present in the final mixture, which helps with preparing PCR-related working solutions or checking a planned dilution step.

The calculation is purely volumetric: it does not assume a particular primer, template, buffer, or analyte. Use volumes in the same unit, and interpret the result alongside the concentration or protocol requirements for the material being diluted.

Inputs

µL
µL
Result
—
Dilution factor
Final volume—
Stock fraction—
Stock : final ratio—

1. Enter the stock aliquot
Enter the amount of the original solution used in the dilution.

2. Enter added diluent
Use the volume of water, buffer, or other diluent added to that aliquot.

3. Keep units consistent
Both inputs must use the same volume unit; the displayed labels use microliters.

4. Read the fold dilution
A 10× result means the final concentration is one tenth of the starting concentration, assuming ideal mixing and no reaction.

5. Use with concentration calculations
Multiply the starting concentration by the stock fraction, or divide by the dilution factor, to estimate final concentration.

Final volume = Stock volume + Diluent volume Dilution factor = Final volume ÷ Stock volume Stock fraction (%) = Stock volume ÷ Final volume × 100

Where:

  • Stock volume — aliquot taken from the original solution
  • Diluent volume — volume added to dilute the stock
  • Final volume — sum of stock and diluent volumes
  • Dilution factor — fold increase in volume relative to the stock aliquot

Assumptions: Volumes are assumed additive and the solute is assumed to remain fully mixed with no loss or reaction during dilution.

What the result means

The final solution contains one tenth of the original stock concentration if the solute behaves conservatively during dilution.

Dilution factor is unitless; both entered volumes must use the same unit.

Given:

  • 10 µL stock
  • 90 µL diluent

Calculation:
Final volume = 10 + 90 = 100 µL
Dilution factor = 100 ÷ 10 = 10×
Stock fraction = 10 ÷ 100 × 100 = 10%

Result:
10× dilution

Interpretation:
The final solution contains one tenth of the original stock concentration if the solute behaves conservatively during dilution.

Is a 1:10 dilution the same as a 10× dilution?

In this calculator, yes: one part stock in ten total parts corresponds to a 10× dilution factor. Be careful with informal “1:10” notation because some protocols use ratio wording differently.

Can I use milliliters instead of microliters?

Yes mathematically, as long as both volume inputs use the same unit. The numeric dilution factor is unitless, although the interface displays final volume in µL.

What happens if I add no diluent?

The dilution factor is 1× and the stock fraction is 100%. That means the solution has not been diluted.

Does dilution factor depend on starting concentration?

No. The factor comes from the volume ratio alone. Starting concentration is needed only when you want to calculate the resulting concentration.

Can this model serial dilutions?

Use the calculator for each step or multiply the individual dilution factors to obtain the overall fold dilution. Verify that each step is mixed and prepared as intended by your protocol.