DNA/RNA Concentration Calculator
Calculate the concentration of double-stranded DNA, single-stranded DNA, or RNA in your samples based on A260 absorbance and dilution factor.
Measurement Parameters
Specify absorbance, dilution factor, and sample type.
Nucleic Acid Concentration
* Equal to 250.0 ng/μL.
Linear Dynamic Range
Ensure A260 readings are between 0.10 and 1.00 for spectrophotometer detector linearity and Beer-Lambert compliance.
Nucleic Acid Extinction Coefficient Reference Matrix
| Nucleic Acid Molecule | A260 = 1.0 Equivalent Concentration | Extinction Coefficient (ε) | Expected A260/A280 Pure Ratio |
|---|---|---|---|
| Double-Stranded DNA (dsDNA) | 50 μg/mL (50 ng/μL) | 0.020 (μg/mL)⁻¹ cm⁻¹ | 1.80 |
| Single-Stranded DNA (ssDNA) | 33 μg/mL (33 ng/μL) | 0.030 (μg/mL)⁻¹ cm⁻¹ | 1.80 – 1.90 |
| Single-Stranded RNA (ssRNA) | 40 μg/mL (40 ng/μL) | 0.025 (μg/mL)⁻¹ cm⁻¹ | 2.00 |
| Oligonucleotides (Short Primers) | ~ 20 – 30 μg/mL | Sequence-specific (nearest-neighbor) | 1.80 – 2.00 |
Calculation Methodology & Biological Principles
Beer-Lambert Spectrophotometry
Absorbance at 260 nm correlates linearly with concentration within 0.1 to 1.0 OD.
Hyperchromic & Hypochromic Effects
Double-stranded base stacking decreases light absorption (hypochromicity). Denaturation into single strands increases A260 by ~30% (hyperchromicity).
Frequently Asked Questions
Why is 260 nm used to quantify nucleic acids? ▼
Purine and pyrimidine bases in DNA and RNA have maximum UV light absorption at 260 nm due to resonance in their conjugated ring structures.
What conversion factors are used for DNA and RNA? ▼
At 1.0 A260 unit (1 cm path length): Double-stranded DNA (dsDNA) = 50 μg/mL (50 ng/μL); Single-stranded DNA (ssDNA) = 33 μg/mL; RNA = 40 μg/mL.
How does dilution factor affect the concentration formula? ▼
If a sample is diluted prior to spectrophotometry (e.g. 10 μL sample into 90 μL water for a 1:10 dilution), the measured A260 is multiplied by 10 to yield the original stock concentration.
Related Calculators
View All Biology Tools →A260 Absorbance to Concentration
Calculate concentrations for DNA, RNA, and proteins using standard extinction coefficients.
A260/A280 Purity Ratio Calculator
Assess DNA and RNA purity from A260/A280 and A260/A230 absorbance ratios.
PCR Master Mix Calculator
Calculate reaction component volumes for single and multi-well PCR master mixes.