Calculator Inputs
Formula Used
Primer amount: pmol = nmol × 1000
Recommended stock volume: stock volume µL = primer pmol ÷ desired stock µM
Actual stock concentration: stock µM = primer pmol ÷ stock volume µL
Working dilution: V1 = C2 × V2 ÷ C1
V1 is stock transfer volume. C1 is stock concentration. C2 is target working concentration. V2 is final working volume.
Diluent volume: diluent µL = final working volume µL − stock transfer volume µL
How to Use This Calculator
- Enter the primer amount from the oligo tube label.
- Enter the desired stock concentration, such as 100 µM.
- Add a custom reconstitution volume only when needed.
- Enter the target working concentration and final tube volume.
- Add molecular weight when mass results are required.
- Press calculate and review the stock transfer volume.
- Use CSV or PDF download for lab documentation.
Example Data Table
| Primer Amount | Stock Target | Stock Volume | Working Target | Working Volume | Stock Transfer | Diluent |
|---|---|---|---|---|---|---|
| 10 nmol | 100 µM | 100 µL | 10 µM | 100 µL | 10 µL | 90 µL |
| 25 nmol | 100 µM | 250 µL | 10 µM | 200 µL | 20 µL | 180 µL |
| 5 nmol | 50 µM | 100 µL | 5 µM | 100 µL | 10 µL | 90 µL |
Primer Dilution Planning
Primer dilution is a common chemistry task in molecular biology. A dried primer arrives as an oligonucleotide pellet or film. The label often gives the amount in nanomoles. The first goal is to make a reliable stock solution. The second goal is to prepare a working solution for PCR, qPCR, sequencing, or cloning.
Why accurate dilution matters
Small concentration errors can change annealing behavior. They can also affect primer balance in multiplex reactions. A strong stock may be convenient, but it must be mixed well. A weak working tube may reduce freeze thaw damage to the main stock. This calculator helps link those choices in one place.
How the calculator helps
The tool accepts primer amount, desired stock concentration, working concentration, and final working volume. It can also estimate mass when molecular weight is provided. The main stock volume comes from the amount divided by concentration. The working transfer volume follows the dilution equation. The remaining volume is diluent. Percent error and final concentration are shown when practical.
Practical bench use
Spin the primer tube before opening it. Add nuclease free water or buffer to the dried material. Vortex or pipette mix gently. Let the tube sit for several minutes if the pellet is hard to see. Make a clear label with primer name, stock strength, date, and initials.
Good storage habits
Store concentrated stock in small aliquots when possible. Keep a separate working tube for daily use. Avoid repeated warming of the original stock. Use clean tips. Record every dilution in a notebook or electronic sheet. The CSV and PDF options help create that record.
Reading the results
A stock volume of 100 microliters for 10 nanomoles at 100 micromolar is common. A working dilution from 100 micromolar to 10 micromolar uses one part stock and nine parts diluent. Always check units before pipetting. Very small transfer volumes are hard to measure. Increase the final working volume when the stock transfer is below one microliter. This reduces pipetting error and improves repeatability. The calculator gives guidance, but laboratory judgment remains important. For sensitive assays, prepare fresh working dilution and compare primer pairs together. Matched concentrations make optimization easier and improve interpretation across repeated reaction runs later.
FAQs
What does this primer dilution calculator do?
It calculates stock reconstitution volume, actual stock concentration, working dilution volume, diluent volume, and optional mass values for primer preparation.
Why is primer amount entered in nanomoles?
Primer suppliers commonly report dried oligo amount in nanomoles. The calculator converts nanomoles to picomoles for direct concentration and volume calculations.
What stock concentration should I use?
Many labs prepare primer stocks at 100 µM. Your protocol may require another value, so always follow your laboratory standard.
What is a working primer solution?
A working solution is a lower concentration primer tube used for routine reactions. It protects the main stock from repeated handling.
Can I enter a custom stock volume?
Yes. Enter custom reconstitution volume when you already know the volume added to the dried primer. The calculator then finds actual stock strength.
When should molecular weight be entered?
Enter molecular weight when you need mass in micrograms or mass concentration in ng/µL. Leave it blank for molarity-only dilution work.
Why is my transfer volume very small?
A small transfer happens when stock concentration is much higher than working concentration. Prepare a larger working volume to reduce pipetting error.
Can I save the result?
Yes. Use the CSV button for spreadsheet records. Use the PDF button for a simple printable lab record.