How to use (3 steps)
- Select nucleic acid type (dsDNA, etc.) and length (bp/nt).
- Enter one known value among ng/µL, nM, or copies/µL.
- Other values are calculated automatically. Enter volume to see totals.
Input (type, length, concentration)
Results (ng/µL, nM, copies)
Results will appear here.
—————————
How it’s calculated
- Molecular weight = length × factor (approx.)
mol/L = g/L ÷ molecular weightcopies/L = mol/L × Avogadro's constant- Entering volume yields total ng, total pmol, and total copies.
How to use this DNA/RNA concentration converter
Use this page when you need to convert between ng/µL, nM, and copies/µL for a known fragment length. Enter volume if you also need tube totals.
When to start from ng/µL, nM, or copies/µL
- Start from ng/µL when you have NanoDrop, Qubit, or library QC mass concentration.
- Start from nM when you are planning dilutions, pooling libraries, or matching molar input across samples.
- Start from copies/µL when you need template copy estimates for qPCR, standards, or spike-in calculations.
What changes the result most
- Length: longer fragments have higher molecular weight, so the same ng/µL becomes fewer nM and fewer copies/µL.
- Type: dsDNA, ssDNA, RNA, and oligos use different mass-per-base factors.
- Volume: volume does not change concentration, but it does change total ng, pmol, and copies in the tube.
Common lab mistakes to avoid
- Using the wrong fragment length after trimming adapters or primers.
- Mixing dsDNA and RNA assumptions when converting mass to molar units.
- Treating rounded display numbers as exact values for final pipetting decisions.
- Comparing concentrations across tools without checking their molecular-weight convention.
Worked example
If you have a 500 bp dsDNA fragment at 10 ng/µL, this tool converts it to nM and copies/µL using the fragment length and dsDNA mass factor. Add a tube volume to see total mass, total pmol, and total copies for dilution or pooling.
See also
FAQ
What is 10 ng/µL in nM?
It depends on fragment length and nucleic acid type. The same 10 ng/µL gives a much higher nM value for a short fragment than for a long amplicon or transcript.
How are copy numbers calculated?
The tool converts mass concentration to molar concentration through molecular weight, then multiplies the molar amount by Avogadro's constant to get copies.
Why do factors differ between dsDNA and RNA?
Average molecular weight per base or base pair differs by nucleic acid type. This tool uses standard approximate factors for dsDNA, ssDNA, RNA, and oligos.
Can I convert without length (bp/nt)?
Length is needed to estimate molecular weight. If you know the exact molecular weight, enter it directly as g/mol.
What does entering volume show?
It calculates total mass, total pmol, and total copies in the entered volume, which is useful for tube totals, aliquots, and dilution planning.
What does the share URL include?
It restores input values (type, length, units, etc.).
How to choose the right output first
For qPCR and standards
If you are preparing standards or template estimates, copies/µL is often the target output. Start from ng/µL or nM, then convert to copies/µL only after confirming fragment length and whether the molecule is dsDNA, ssDNA, or RNA.
For NGS and dilution workflows
If you are pooling libraries or targeting equal molar input, nM is usually the output you need first. Convert from ng/µL using the fragment length that matches the actual insert or library size distribution used in the workflow.
For quick sanity checks
If another tool gives a very different answer, compare the fragment length, nucleic acid type, and molecular-weight convention first. Check those assumptions before deciding one result is wrong.
Related tools
- NGS library concentration (ng/µL → nM) | dilution | CalcBEConvert library mass concentration to nM, then check dilution and pooling targets for sequencing prep.
- A260 Calculator (DNA/RNA Concentration & Purity) | CalcBEEstimate nucleic-acid concentration and purity from absorbance before converting to molar or copy-based units.
- DNA assembly mix calculator (Gibson/Golden Gate) | CalcBEPlan backbone and insert amounts after converting your stock concentrations to a comparable molar basis.
- qPCR standard curveTurn copy-number assumptions into standard-curve checks and dilution-series planning for qPCR runs.
- Centrifuge converter (rpm ↔ RCF ×g) | by rotor radius | CalcBECheck centrifuge settings alongside sample-prep steps when you move between concentration and cleanup workflows.
Feedback
Let us know issues or improvement ideas to help refine this tool.