Advanced Oligonucleotide Concentration Calculator

Calculator Form

Sample Name

Oligonucleotide Type

1 A260 Conversion Factor (µg/mL)

Typical values: ssDNA 33, dsDNA 50, RNA 40.

Measured A260

Baseline A320 Correction

Dilution Factor

Path Length (cm)

Extinction Coefficient (L·mol⁻¹·cm⁻¹)

Molecular Weight (g/mol)

Available Volume (µL)

A280 Reading

A230 Reading

Replicate A260 Values

Formula Used

1) Corrected absorbance: Corrected A260 = A260 − A320

2) Mass concentration: Concentration (µg/mL or ng/µL) = Corrected A260 × Dilution Factor × Conversion Factor ÷ Path Length

3) Molar concentration: Molarity (mol/L) = (Corrected A260 × Dilution Factor ÷ Path Length) ÷ Extinction Coefficient

4) Convert to micromolar: µM = mol/L × 1,000,000

5) Total nmol: nmol = µM × Volume(µL) ÷ 1000

6) Purity ratios: A260/A280 = Corrected A260 ÷ A280, and A260/A230 = Corrected A260 ÷ A230

How to Use This Calculator

Enter the sample name, select the oligonucleotide type, and provide a suitable A260 conversion factor. Then enter your measured A260, baseline A320 correction, dilution factor, path length, extinction coefficient, molecular weight, and available volume.

Add A280 and A230 readings to review purity ratios. You can also enter three replicate A260 values to assess repeatability through average, standard deviation, and coefficient of variation.

Press Calculate Concentration. The result appears above the form under the header, along with a detailed results table, interpretation notes, and a Plotly graph. Use the CSV and PDF buttons to export your output.

Example Data Table

Sample	A260	A320	Dilution	Ext. Coeff.	MW	Volume	A280	A230
Oligo Sample A	1.25	0.02	50	180000	6500	120 µL	0.68	0.55
Primer Mix B	0.92	0.01	40	155000	7200	80 µL	0.49	0.44
RNA Probe C	1.48	0.03	60	205000	8400	150 µL	0.81	0.71

Frequently Asked Questions

1. What does this calculator estimate?

It estimates oligonucleotide mass concentration, molar concentration, total amount, total mass, replicate consistency, and purity ratios using absorbance-based laboratory inputs.

2. Why is baseline correction included?

Baseline correction removes background absorbance. Subtracting A320 helps reduce turbidity or instrument noise effects before calculating concentration and purity ratios.

3. What conversion factor should I use?

Common values are 33 for ssDNA, 50 for dsDNA, and 40 for RNA. Use a custom value when your protocol or vendor provides a different factor.

4. Why is the extinction coefficient necessary?

The extinction coefficient links absorbance to molar concentration through Beer-Lambert relationships. Without it, the calculator cannot estimate concentration in molar units.

5. What do the purity ratios indicate?

A260/A280 helps flag protein contamination, while A260/A230 helps detect salts, solvents, or other carryover substances that can affect downstream performance.

6. Why are replicate readings useful?

Replicates improve confidence. Their average, standard deviation, and coefficient of variation reveal whether the spectrophotometer readings are stable and repeatable.

7. Is ng/µL the same as µg/mL?

Yes. Numerically, 1 ng/µL equals 1 µg/mL. Laboratories often use either notation depending on reporting style and workflow.

8. Can this replace a lab instrument report?

No. It supports interpretation and planning. Final reporting should still follow your instrument output, laboratory SOP, and validated analytical workflow.