DNA Concentration Calculator

What is DNA Concentration?

DNA concentration shows how much DNA exists in a sample. It helps you check sample strength, plan lab reactions, and use the right amount of DNA for your next step. The value may use ng/µL or another unit.

What is a DNA Concentration Calculator?

A DNA Concentration Calculator uses sample measurements to estimate DNA concentration. It can also calculate yield, purity ratios, and molarity for common nucleic acid samples. This saves time during routine lab checks.

How to calculate DNA Concentration manually

You can estimate DNA concentration from an A260 reading by using the correct factor and dilution value. For dsDNA, a common factor is 50 µg/mL per A260.

Formula

$C = A_{260} × F × DF$

Here, $C$ is concentration, $F$ is the nucleic acid factor, and $DF$ is the dilution factor. For dsDNA, $F = 50$.

Step by step guide

1. Record the A260 reading.
2. Select the correct nucleic acid type.
3. Use its matching A260 factor.
4. Multiply by the dilution factor.
5. Report the result in ng/µL.

Practical Example

If A260 = 0.8 for dsDNA and DF = 5:

$C = 0.8 × 50 × 5 = 200$ ng/µL.

This estimate assumes a suitable path length and a clean sample.

How to Calculate DNA Molarity

DNA molarity tells you the amount of DNA in moles within a given volume. You need concentration and molecular weight to calculate it.

Formula

$nM = \frac{C × 10^6}{MW}$

Here, $C$ is DNA concentration in ng/µL and $MW$ is molecular weight in g/mol. For dsDNA:

$MW ≈ length(bp) × 660$

Step by step guide

1. Record DNA concentration in ng/µL.
2. Find DNA length in base pairs.
3. Calculate molecular weight.
4. Divide $C × 10^6$ by molecular weight.
5. Report the result in nM.

Practical Example

For 100 ng/µL of 1,000 bp dsDNA:

$MW ≈ 1,000 × 660 = 660,000$ g/mol.

$nM = 100 × 10^6 ÷ 660,000 ≈ 151.5$ nM.

Runcell uses 660 g/mol per base pair for its dsDNA molecular weight assumption.

How to Calculate DNA Purity

DNA purity uses absorbance ratios to check whether other substances may affect your sample. A260/A280 and A260/A230 provide two useful checks.

Formula

$A_{260}/A_{280} = A_{260} ÷ A_{280}$

$A_{260}/A_{230} = A_{260} ÷ A_{230}$

Step by step guide

1. Record A260, A280, and A230.
2. Divide A260 by A280.
3. Divide A260 by A230.
4. Compare the ratios with suitable DNA quality ranges.
5. Recheck unusual results before using the sample.

Practical Example

If A260 = 1.8 and A280 = 0.9:

$A_{260}/A_{280} = 1.8 ÷ 0.9 = 2.0$.

The second ratio uses A260 divided by A230.

AAT Bioquest and Pearson both emphasize absorbance measurements and sample quality when estimating nucleic acid concentration

DNA Concentration Factors for dsDNA, ssDNA, RNA, and Oligos

A260 conversion factors differ by nucleic acid type. Use the correct factor for dsDNA, ssDNA, RNA, or oligos, and keep the sample assumptions consistent.

Note: A260 factors are estimates. Sample purity, sequence details, path length, and instrument limits can affect the final concentration result.