Calculator Inputs
Use mass data, OD260 data, or a manual stock value. The calculator will also plan a target dilution.
Example data table
| Oligo | Length | Mass | Volume | MW | EC | A260 | Mass-Based Stock | OD-Based Stock | 2 µM in 100 µL |
|---|---|---|---|---|---|---|---|---|---|
| DNA Primer A | 25 nt | 50 µg | 500 µL | 7600 g/mol | 220000 | 0.58 | 13.1579 µM | 2.6364 µM | 15.2000 µL stock |
| RNA Probe B | 30 nt | 25 µg | 250 µL | 9600 g/mol | 285000 | 0.72 | 10.4167 µM | 2.5263 µM | 19.2000 µL stock |
Formula used
1) Amount from mass and molecular weight
Moles = Mass (g) ÷ Molecular Weight (g/mol)
2) Total nanomoles recovered
nmol = Moles × 109
3) Mass-based stock concentration
Concentration (M) = Moles ÷ Volume (L)
Concentration (µM) = Concentration (M) × 106
4) OD260-based concentration
Concentration (M) = A260 ÷ (Extinction Coefficient × Path Length)
5) Dilution planning
C1V1 = C2V2
Stock Volume Needed = (Target Concentration × Final Volume) ÷ Stock Concentration
Diluent Volume = Final Volume − Stock Volume Needed
How to use this calculator
- Enter the oligo name, type, and sequence length for record keeping.
- Provide mass, chosen mass unit, resuspension volume, and molecular weight for mass-based stock concentration.
- Enter extinction coefficient, A260, and path length when you want an absorbance-based concentration estimate.
- Optionally enter a manual stock concentration if your lab already verified the stock independently.
- Set the target concentration and target final volume for dilution planning.
- Press the calculate button to show results above the form.
- Review the result table, graph, and selected stock source.
- Use the CSV or PDF buttons to save a bench-friendly summary.
Frequently asked questions
1) What does this oligo concentration calculator estimate?
It estimates total nanomoles, stock concentration from mass, concentration from OD260, and the exact stock and diluent volumes needed for a target dilution.
2) Which stock concentration does the calculator use for dilution planning?
It uses the manual stock value first. If that is missing, it falls back to the mass-based concentration. If mass data cannot support the calculation, it uses the OD260-based concentration.
3) Why is molecular weight important?
Molecular weight converts a measured mass into moles. Without it, the calculator cannot estimate molar concentration accurately from dry mass and resuspension volume.
4) What is the extinction coefficient used for?
The extinction coefficient links absorbance to concentration through the Beer-Lambert relationship. It is required when using A260 readings to estimate oligo concentration.
5) Can I use this for DNA and RNA oligos?
Yes. The calculator is suitable for DNA primers, RNA oligos, probes, and similar short nucleic acid preparations, provided the molecular weight and extinction coefficient are appropriate.
6) Why might mass-based and OD260-based results differ?
They can differ because absorbance also reflects purity, contaminants, path length accuracy, and instrument handling. Dry mass recovery can also vary from the synthesis or shipping label.
7) What happens if the target concentration exceeds the stock concentration?
The calculator flags a warning because simple dilution cannot create a stronger solution than the stock. In that case, you need a more concentrated stock or less final volume.
8) Are the download buttons useful for lab records?
Yes. The CSV file is helpful for spreadsheets and batch documentation. The PDF version is better for printing, sharing, or attaching calculation notes to experiment records.