How to Use the Oligo Concentration Calculator

Select the calculation method – Absorbance, Sequence, Weight, or Unit Converter.
Enter your values – Input A260 reading, nucleotide sequence, weight, or volume.
Get instant results – Molarity, molecular weight, extinction coefficient, and Tm.
Adjust parameters if needed – Modify dilution factors, path length, or extinction coefficient.

Accurately Determine Oligonucleotide Concentration for Your Experiments

The Oligo Concentration Calculator is a powerful and easy-to-use tool designed for researchers, molecular biologists, and lab technicians. It provides precise calculations for DNA and RNA oligonucleotides using multiple input methods. Whether you are working with absorbance readings from a spectrophotometer, a known nucleotide sequence, or a dry oligonucleotide sample, this calculator ensures accurate results in seconds.

Key Features of the Oligo Concentration Calculator

Fast and reliable results

• Uses Beer-Lambert’s Law for spectrophotometry-based calculations.
• Calculates molarity, mass concentration, and OD260 values.
• Supports nucleotide sequences, molecular weight, and dilution factors.

Multiple calculation methods

• Absorbance-based calculation using spectrophotometry (A260 method).
• Sequence-based calculation from nucleotide composition.
• Weight-based calculation from dry oligonucleotide mass.
• Unit converter for interconverting molar and mass concentrations.

Comprehensive data output

• Computes molecular weight, extinction coefficient, and melting temperature (Tm).
• Provides instant unit conversions for precise experimental setups.

User-friendly interface

• Simple and intuitive input fields.
• Dark mode for comfortable usage.
• Interactive tabs for switching between calculation modes.

Optimized for laboratory research

• Ideal for qPCR, sequencing, hybridization assays, and oligonucleotide resuspension.
• Useful for preparing working solutions with accurate concentrations.

For those working with reconstitution procedures, the Peptide Reconstitution Calculator provides a similar approach for peptide solutions.

How to Calculate Oligo Concentration

1. Absorbance-Based Calculation (A260 Method)

If you have a spectrophotometer reading at 260 nm, this method determines the oligonucleotide concentration using Beer-Lambert’s Law:

Concentration= A260×Dilution Factor/Path Length x Extinction Coefficient

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Example Calculation

• A sample of single-stranded DNA has an A260 of 1.0.
• The extinction coefficient for ssDNA is 33 µg/mL per A260.
• If the sample was not diluted and measured in a 1 cm cuvette, the concentration is 33 µg/mL.

This method is particularly useful when preparing diluted solutions for further use. If you need to dilute your oligonucleotide to a specific working concentration, try the Oligo Dilution Calculator.

2. Sequence-Based Calculation

If you have the nucleotide sequence of your oligonucleotide, this method calculates:
Molecular weight
Extinction coefficient for absorbance-based quantification
Melting temperature (Tm) for hybridization efficiency
Molar concentration based on weight and volume

Example Calculation

• A 20-base single-stranded DNA sequence is entered.
• The molecular weight is calculated as ~6000 g/mol.
• If 10 nmol is dissolved in 100 µL, the final concentration is 100 µM.

To further analyze the sequence composition, including GC content, use the GC Content Calculator.

3. Weight-Based Calculation

If you have a dry oligonucleotide sample, this method calculates the final concentration based on:
Weight (µg, mg, nmol, pmol)
Molecular weight of the oligo
Resuspension volume

Example Calculation

• 1 µg of an oligonucleotide (MW = 6000 g/mol) is dissolved in 100 µL.
• The resulting concentration is 1.67 µM.

Accurate resuspension of oligonucleotides is critical for maintaining experimental reproducibility. If you need assistance in determining the best volume for resuspending your sample, use the Resuspension Calculator.

4. Unit Conversion

This tool converts between:
Mass concentration (µg/µL, µg/mL)
Molar concentration (µM, nM, pmol/µL)
Optical density (OD260 to concentration)

Example Conversion

• A 50 µM oligonucleotide solution needs to be converted to µg/mL.
• Given a molecular weight of 6000 g/mol, the result is 300 µg/mL.

If you are working with other types of solution dilutions, the Solution Dilution Calculator can assist with precise volume adjustments.

Practical Applications of the Oligo Concentration Calculator

1. qPCR and RT-PCR

• Ensures correct primer concentration for amplification reactions.
• Converts OD260 values into molar concentration for precise dilutions.

2. Genetic Research and Sequencing

• Helps prepare oligo stock solutions for DNA/RNA sequencing protocols.
• Assists in calculating molar ratios for hybridization experiments.

3. Oligonucleotide Synthesis and Purification

• Determines purity and concentration of synthesized oligonucleotides.
• Normalizes oligos from different synthesis batches.

4. Pharmaceutical and Biotech Industries

• Supports formulation of custom nucleic acid-based drugs.
• Calculates RNA concentrations for therapeutic applications.

Frequently Asked Questions (FAQs)

1. What are the default extinction coefficients for DNA and RNA?

• Single-stranded DNA: 33 µg/mL per A260
• Double-stranded DNA: 50 µg/mL per A260
• Single-stranded RNA: 40 µg/mL per A260

2. What is the standard path length for absorbance measurements?

• The standard cuvette path length is 1 cm.

3. How do I determine molecular weight from a sequence?

• Each nucleotide base has a specific molecular weight:
  • dA = 313.2 g/mol
  • dT = 304.2 g/mol
  • dG = 329.2 g/mol
  • dC = 289.2 g/mol

4. Can I convert OD260 to µg/mL?

• Yes. Use the conversion factor for your oligo type:
  • ssDNA: 1 OD260 = 33 µg/mL
  • dsDNA: 1 OD260 = 50 µg/mL
  • RNA: 1 OD260 = 40 µg/mL