idt resuspension calculator - Aaron Graves, PhDude Replica

IDT Oligo Resuspension Calculator

Enter the oligo amount from your IDT datasheet and your desired stock concentration. Optionally, calculate a working dilution and aliquot plan.

Oligo Amount (nmol) *

Use the "nmol delivered" or "Total nmol" value.

Desired Stock Concentration (µM) *

µM is equivalent to pmol/µL for oligo prep calculations.

Resuspension Buffer

Optional Working Concentration (µM)

Optional Final Working Volume (µL)

Optional Aliquot Size (µL)

What this IDT resuspension calculator does

If you order DNA oligos from IDT, one of the first practical questions is simple: How much liquid do I add to reach my desired stock concentration? This calculator answers that instantly. You input the oligo amount in nmol and your desired stock concentration in µM, and it returns the exact volume of water or buffer to add.

It also helps with two common follow-up tasks:

Preparing a lower-concentration working solution from your stock.
Estimating how many aliquots you can make from the final stock volume.

Core formula used

The math is based on unit conversion and the standard dilution equation.

Resuspension volume (µL) = (nmol × 1000) / desired concentration (µM)
Since 1 nmol = 1000 pmol and 1 µM = 1 pmol/µL.

Dilution equation for working solution: C₁V₁ = C₂V₂
V₁ = (C₂ × V₂) / C₁

Step-by-step usage guide

1) Find your oligo amount

Open your IDT order details or tube documentation and identify the amount in nmol. Enter that number directly.

2) Choose your stock concentration

Common stock choices include 100 µM or 10 µM, depending on downstream protocol needs. Higher stock concentrations reduce storage volume and can be convenient for long-term use.

3) Select your resuspension buffer

The calculator supports water, TE, or IDTE labels for your notes. The chosen buffer does not change the math, but it helps generate clear instructions in your results.

4) (Optional) Plan a working dilution

If your assay needs a lower concentration, enter a working concentration and final working volume. The calculator tells you how much stock and buffer to mix.

Example calculation

Suppose your oligo amount is 25 nmol and you want a 100 µM stock:

Resuspension volume = (25 × 1000) / 100 = 250 µL

If you then need 100 µL of 10 µM working solution from that 100 µM stock:

V₁ = (10 × 100) / 100 = 10 µL stock
Add 90 µL diluent

Best practices for oligo resuspension

Spin tubes briefly before opening to collect dried oligo at the bottom.
Use low-bind tubes for very low-volume work.
Mix thoroughly (pipette up/down or gentle vortex) and allow complete dissolution.
Label tubes with concentration, date, and buffer.
Aliquot stocks to reduce freeze-thaw cycles.

Choosing water vs TE buffer

Nuclease-free water is common for immediate short-term use. TE (or IDTE) offers improved stability for many applications because EDTA can help protect oligos from nucleases. The right choice depends on your protocol and whether EDTA is compatible with downstream enzymatic reactions.

Common mistakes this calculator helps prevent

Mixing up nmol and µmol units.
Using concentration units inconsistently.
Attempting to make a working concentration higher than the stock by dilution alone.
Forgetting to account for final working volume.

Quick FAQ

Is µM the same as pmol/µL here?

Yes. For these oligo calculations, 1 µM equals 1 pmol/µL, which keeps the math straightforward.

Can I use this for RNA oligos?

The concentration-volume math is the same. Still, RNA handling requires stricter RNase-free technique and storage considerations.

What if my desired working concentration is higher than stock?

You cannot reach a higher concentration through dilution. You would need a more concentrated stock or to re-prepare from dried material if available.

This tool is designed to be a practical lab helper for everyday oligonucleotide preparation, dilution, and aliquot planning.