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PCR Master Mix Calculator

Calculate PCR master mix component volumes for a batch of reactions.

About PCR Master Mix Calculator

Master mixes are prepared with an excess because pipetting loses volume at every transfer. Component volumes follow the dilution relationship, so each primer volume is the reaction volume scaled by the concentration ratio. Preparing a master mix rather than individual reactions is what makes replicates comparable, since every reaction then draws from identical reagent proportions.

Formula

PCR Master Mix

C₁V₁ = C₂V₂, so primer volume = reaction volume × final ÷ stock concentration

pipetting excess
Extra reactions prepared to cover dead volume, typically 10 per cent
master mix
Shared reagents prepared once and dispensed, reducing variability

Worked example

With the default values below, PCR Master Mix Calculator returns Total Master Mix Volume of 660.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Number of reactionsminimum 1
24
Volume per reactionminimum 1 uL
25 uL
Pipetting excessaccepts 0–50 %
10 %
Primer stock concentrationminimum 0.1 uM
100 uM
Primer final concentrationminimum 0.01 uM
0.5 uM

Results

Total Master Mix Volume
660.00 uL
Reactions Prepared Including Excess
26.40
Primer Volume per Reaction
0.125 uL
Total Primer Volume
3.300 uL
Nuclease-Free Water to Add
561.00 uL

Step by step

  1. 1Values used
  2. 2PCR Master Mix
  3. 3Total Master Mix Volume= 660.00 uL
  4. 4Reactions Prepared Including Excess= 26.40
  5. 5Primer Volume per Reaction= 0.125 uL
  6. 6Total Primer Volume= 3.300 uL
  7. 7Nuclease-Free Water to Add= 561.00 uL

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is PCR Master Mix calculated?

C₁V₁ = C₂V₂, so primer volume = reaction volume × final ÷ stock concentration Master mixes are prepared with an excess because pipetting loses volume at every transfer. Component volumes follow the dilution relationship, so each primer volume is the reaction volume scaled by the concentration ratio.

Why does PCR Master Mix matter?

Preparing a master mix rather than individual reactions is what makes replicates comparable, since every reaction then draws from identical reagent proportions.

What values do I need to enter?

This calculator takes 5 inputs: Number of reactions, Volume per reaction, Pipetting excess, Primer stock concentration, Primer final concentration. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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