What this calculator does
DNA copy number from concentration works out dNA or RNA molecules per microlitre from concentration and fragment length. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulacopies/µL = (C·Nₐ) / (length_bp · w_bp · 10⁹), Nₐ = 6.02214076×10²³ /mol
The inputs explained
| Field | What to enter |
|---|---|
| Concentration (ng/µL) | A number, measured in ng/µL. Starts at 10. |
| Fragment length (bp (or nt)) | A number, measured in bp (or nt). Starts at 500. |
| Molecule type | Choose from dsDNA (660 Da/bp), ssDNA (330 Da/nt), ssRNA (340 Da/nt). |
| Sample volume (µL) | A number, measured in µL. Starts at 50. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with concentration
Every other input is held at the calculator’s starting values while concentration varies. Select any row to load that scenario into the calculator.
How the answer changes with concentration
| Concentration (ng/µL) | Copies per µL | Total copies in sample | Molecular weight used |
|---|---|---|---|
| 5 | 9,124,455,697 copies/µL | 456,222,784,800 copies | 660 Da per bp |
| 7.5 | 13,686,683,550 copies/µL | 684,334,177,300 copies | 660 Da per bp |
| 10 | 18,248,911,390 copies/µL | 912,445,569,700 copies | 660 Da per bp |
| 15 | 27,373,367,090 copies/µL | 1,368,668,355,000 copies | 660 Da per bp |
| 20 | 36,497,822,790 copies/µL | 1,824,891,139,000 copies | 660 Da per bp |
| 30 | 54,746,734,180 copies/µL | 2,737,336,709,000 copies | 660 Da per bp |