Oligonucleotide Resuspension Calculator
Calculate the diluent volume needed to prepare an oligo stock at a chosen molar concentration.
Inputs
Live result
Equivalent values
| Quantity | Base value | Equivalent 1 | Equivalent 2 |
|---|---|---|---|
| Oligo amount | 60 nmol | 60,000 pmol | 0.06 µmol |
| Concentration | 40 µM | 40,000 nM | 0.04 mM |
| Diluent volume | 1,500 µL | 1.5 mL | 0.0015 L |
How to use the oligonucleotide resuspension calculator
What this calculator does. This tool estimates the volume of diluent needed to dissolve a known molar amount of a dried oligonucleotide and obtain a selected molar concentration. It is useful for preparing DNA or RNA primer stocks, checking a vendor-provided resuspension instruction, planning aliquots, and converting between common laboratory units. It does not choose the correct buffer, confirm that the oligo has fully dissolved, account for evaporation or pipetting loss, or replace a validated laboratory protocol.
When to use it. Use the calculator when a tube label or certificate of analysis gives an oligo amount in pmol, nmol, or µmol and you need a stock in nM, µM, or mM. It is also helpful when standardizing several primers to one stock concentration, checking whether a required volume is practical for your pipette, or documenting preparation values before entering the laboratory. Integrated DNA Technologies describes 100 µM as a common versatile stock concentration in its oligo resuspension guidance, while your application may require a different concentration.
How to calculate. The calculator opens with a complete demonstration: 60 nmol at 40 µM produces 1,500 µL. The Excel button is ready immediately for that example. To use your own values:
- Replace Oligo amount with the quantity shown on the tube or certificate, then select pmol, nmol, or µmol.
- Enter the Desired concentration and choose nM, µM, or mM.
- Choose the Diluent volume display unit. Read the required volume and the equivalent-unit table.
- Select Download Excel to export the current validated inputs and results. Select Reset to clear the demonstration values; after reset, Excel export remains disabled until complete valid values are entered again.
Input guide. Oligo amount is required and accepts a positive decimal using a period as the decimal separator, such as 60 nmol or 500 pmol. Increasing the amount while holding concentration constant increases the required volume proportionally. Do not enter mass units such as ng because this calculator works with molar amount. Desired concentration is also required and must be positive, for example 40 µM or 100 µM. A higher desired concentration needs less diluent for the same amount; a lower concentration needs more. Do not confuse µM with mM, which differs by a factor of 1,000. Diluent volume display unit is a required presentation choice. It can show the same physical volume in µL, mL, or L and does not alter the calculation.
Output guide. Diluent volume required is the calculated amount of liquid to add. It is an exact unit conversion from the entered molar quantity and concentration, subject to the accuracy of the inputs and practical laboratory handling. Canonical amount shows the amount converted to nmol, and Canonical concentration shows the concentration converted to µM. The summary pills repeat the active amount, concentration, and result. The Equivalent values table lists the same amount, concentration, and volume in three common units; zero or negative values are rejected because they do not describe a usable resuspension calculation.
Worked example. With 60 nmol and a target of 40 µM, the formula in nmol, µM, and µL is volume = amount × 1,000 ÷ concentration. Therefore, 60 × 1,000 ÷ 40 = 1,500 µL, which is also 1.5 mL. This matches the first-open result, the equivalent-values table, and the exported workbook. For practical handling, choose a diluent and mixing method appropriate to the oligo and downstream application. Thermo Fisher Scientific provides additional oligonucleotide handling protocols.
Formula and unit logic
The familiar laboratory shortcut follows directly from the base equation. Because 1 nmol divided by 1 µM equals 1,000 µL, the calculator can use volume in µL = amount in nmol × 1,000 ÷ concentration in µM. Internally, however, it converts every input to moles and moles per liter first. This makes pmol, nmol, µmol, nM, µM, mM, µL, mL, and L interchangeable without changing the physical result.
Molarity expresses amount of substance per solution volume. For more background on common oligo concentration units, see IDT's guide to oligo quantification units. The calculator assumes the final solution volume is approximately the added diluent volume, which is standard for this type of preparation calculation.
Practical interpretation and common mistakes
Check pipetting practicality. A mathematically correct volume may be awkward or outside the accurate range of available pipettes. In that case, consider a different stock concentration or a validated staged preparation rather than rounding aggressively.
Common errors include reading pmol as nmol, selecting mM instead of µM, entering a concentration from a downstream working reaction rather than the desired stock, and assuming every oligo should use the same buffer. Buffer choice depends on chemistry, storage, nuclease sensitivity, and downstream use. Some protocols use TE buffer, while others use molecular-biology-grade or nuclease-free water. A published example in the NIH-hosted literature shows DNA and siRNA being resuspended in different media for different workflows, illustrating why the calculation and the buffer decision are separate steps: see the resuspension methods described in this research article.
After adding diluent, follow your validated procedure for mixing, brief centrifugation, incubation, storage, and aliquoting. The calculator gives the target volume but cannot verify recovery, purity, degradation, or the actual concentration after handling. When concentration accuracy is critical, confirm it with the analytical method specified by your laboratory or supplier.