IDT Resuspension Calculator

Professional DNA/RNA Oligo Dilution Tool for Laboratory Precision

Standard Resuspension Reference Table

Target Concentration (µM)	Volume for 25 nmol (µL)	Volume for 50 nmol (µL)	Volume for 100 nmol (µL)

Table 1: Calculated volumes for common IDT oligo scales using the idt resuspension calculator formula.

What is the IDT Resuspension Calculator?

The idt resuspension calculator is an essential tool for molecular biologists and genomic researchers. When you receive synthetic DNA or RNA from Integrated DNA Technologies (IDT), it typically arrives in a lyophilized (freeze-dried) state. To use these oligos in PCR, sequencing, or CRISPR applications, they must be dissolved in a specific volume of liquid—usually TE buffer or nuclease-free water—to reach a known molar concentration.

Using a dedicated idt resuspension calculator ensures that your master stocks and working dilutions are precise, preventing experimental failure due to inconsistent primer concentrations. Most labs aim for a 100 µM master stock, as it is easy to handle and stable for long-term storage at -20°C.

IDT Resuspension Calculator Formula and Mathematical Explanation

The math behind the idt resuspension calculator is based on the fundamental relationship between moles, volume, and molarity. The standard formula used is:

Volume (µL) = [Oligo Amount (nmol) × 1000] / Desired Concentration (µM)

Because 1 µM is equivalent to 1 nmol/mL, we multiply the nmol value by 1000 to convert the resulting volume into microliters (µL), which is the standard unit for pipetting in molecular biology labs.

Variables Table

Variable	Meaning	Unit	Typical Range
nmol	Amount of Oligo	Nanomoles	5 – 1000 nmol
µM	Target Molarity	Micromolar	10 – 200 µM
µL	Buffer Volume	Microliters	50 – 5000 µL

Practical Examples (Real-World Use Cases)

Example 1: Creating a 100 µM Stock

A researcher receives an oligo with a yield of 32.4 nmol. They want to create a standard 100 µM master stock. Using the idt resuspension calculator, the calculation is: (32.4 × 1000) / 100 = 324 µL. The researcher adds 324 µL of TE buffer to the tube, resulting in a 100 µM concentration.

Example 2: Diluting for Direct PCR Use

If a protocol requires a 20 µM working solution and the oligo amount is 15 nmol, the idt resuspension calculator provides: (15 × 1000) / 20 = 750 µL. Adding 750 µL of water directly to the lyophilized pellet provides the exact concentration needed for the reaction mix.

How to Use This IDT Resuspension Calculator

1. Locate the nmol amount on your IDT product label or specification sheet.
2. Enter this value into the “Oligo Amount” field of the idt resuspension calculator.
3. Select your desired final concentration (e.g., 100 µM for stocks or 10 µM for working solutions).
4. If your required concentration isn’t listed, select “Custom” and enter the value manually.
5. The idt resuspension calculator will instantly display the volume of buffer you need to add in microliters.
6. Use the “Copy Results” button to save the calculation for your lab notebook.

Key Factors That Affect IDT Resuspension Results

• Buffer Choice: Using TE buffer (10 mM Tris, 0.1 mM EDTA, pH 8.0) is recommended for long-term stability of DNA stocks compared to water.
• Pellet Solubility: Sometimes the DNA pellet sticks to the side of the tube. After adding buffer via the idt resuspension calculator, vortex briefly and centrifuge.
• Storage Temperature: Resuspended oligos should be stored at -20°C. Repeated freeze-thaw cycles can degrade the material.
• Pipetting Accuracy: For very small volumes (less than 20 µL), the margin of error increases significantly.
• Oligo Length: Very long oligos (ultramers) may take longer to fully dissolve in the volume calculated by the idt resuspension calculator.
• PH Levels: DNA is unstable in acidic conditions. Ensure your resuspension liquid has a pH between 7.5 and 8.5.

Frequently Asked Questions (FAQ)

What is the “10x Rule” in the idt resuspension calculator?

A common lab shortcut is to add a volume of buffer 10 times the number of nanomoles (e.g., 25 nmol → 250 µL) to achieve exactly 100 µM. The idt resuspension calculator automates this logic for any concentration.

Can I use water instead of TE buffer?

Yes, but only for short-term use. Water can be slightly acidic, which leads to depurination of the DNA over time. For stability, TE is preferred.

What if the volume is too small to pipette?

If the idt resuspension calculator suggests a volume under 10 µL, it is better to target a lower concentration (like 10 µM) to increase the volume and reduce pipetting error.

Is nmol the same as OD260?

No, OD260 measures optical density. While related to amount, the idt resuspension calculator specifically requires the molar amount in nanomoles.

How long should I wait after adding the buffer?

It is best to let the tube sit at room temperature for 15-30 minutes after using the idt resuspension calculator to ensure the pellet is fully hydrated.

Does the sequence of the DNA affect the volume?

The sequence affects the molecular weight and extinction coefficient, but since the idt resuspension calculator uses molarity (nmol), the sequence does not change the volume needed for a specific µM concentration.

What if I added too much liquid?

If you exceeded the volume suggested by the idt resuspension calculator, you can use a vacuum concentrator (SpeedVac) to dry the sample and start over.

Can this be used for RNA?

Yes, the idt resuspension calculator works perfectly for RNA oligos, though you must use RNase-free water or buffers.

Related Tools and Internal Resources

• Oligo Molecular Weight Calculator – Calculate the mass of your DNA sequences.
• Molarity to Mass Converter – Convert between different concentration units.
• Annealing Temperature Predictor – Determine the optimal Tm for your PCR primers.
• Serial Dilution Tool – Step-by-step guide for creating working concentrations.
• DNA Copy Number Calculator – Convert ng/µL to copies per microliter.
• Buffer Preparation Guide – How to mix 1X TE from 10X stocks.