How It Works
This calculator works in 4 steps.
Enter the master stock
Type the reconstituted stock, such as 100 µM.
Enter the working stock target
Type the working strength and volume, such as 10 µM in 100 µL.
Enter reaction details
Type the reaction volume and the final primer concentration from the protocol.
Read the volumes
The calculator returns master-to-working volumes and the µL of working stock per reaction.
The Formula
The formula applies C₁V₁ = C₂V₂ twice: once for the working stock and once for the reaction.
V_master = C_work × V_work / C_masterV_primer = C_final × V_rxn / C_work- C_master:
- Master stock (µM)
- C_work:
- Working stock (µM)
- C_final:
- Final primer concentration in the reaction (µM)
- V_rxn:
- Reaction volume
A 25 µL reaction with 0.4 µM primer from a 10 µM working stock needs 0.4 × 25 / 10 = 1 µL of each primer.
Conversion Table
The conversion table gives master stock and water volumes for 6 working stock preparations.
| Master stock | Working stock | Working volume | Master stock volume | Water |
|---|---|---|---|---|
| 100 µM | 10 µM | 100 µL | 10 µL | 90 µL |
| 100 µM | 10 µM | 200 µL | 20 µL | 180 µL |
| 100 µM | 20 µM | 100 µL | 20 µL | 80 µL |
| 100 µM | 5 µM | 50 µL | 2.5 µL | 47.5 µL |
| 200 µM | 10 µM | 100 µL | 5 µL | 95 µL |
| 50 µM | 10 µM | 100 µL | 20 µL | 80 µL |
What Is the PCR Primer Dilution Calculator?
The PCR Primer Dilution Calculator is a tool that prepares primer working stocks from a master stock and returns the primer volume per reaction for a specified final concentration. A 10 µM working stock is made from 10 µL of 100 µM master stock plus 90 µL water.
PCR reactions often use 0.1 to 1.0 µM of each primer in the final mix; the reaction protocol sets the value. 1 µL of 10 µM primer in a 50 µL reaction gives 0.2 µM. The calculator covers both steps: master stock to working stock, and working stock to reaction.
Common Uses
There are 5 main uses of this calculator.
Endpoint PCR
Users prepare working primers for routine amplification.
qPCR
Labs set primer levels for SYBR Green and probe assays.
Colony PCR
Users prepare primers for many small reactions.
Site-directed mutagenesis
Researchers set mutagenic primer amounts.
Primer optimization
Developers test 0.1 to 0.9 µM primer grids.