DNA ng / pmol / Copies Converter

About DNA ng / pmol / Copies Converter

This tool converts a nucleic acid amount between mass in nanograms, moles in picomoles and molecule count, using the molecule's length and type. Add a volume and it also gives molarity. It answers questions such as how many copies are in 100 ng of a plasmid insert, or what molar amount you are ligating.

How to use it

1. Enter the Mass in nanograms.
2. Enter the Length in base pairs for dsDNA, or nucleotides for ssDNA and RNA, and pick the Type.
3. Optionally enter a Volume in microliters to get molarity.
4. Read molecular weight, amount in pmol, molecule count and molarity in the Results panel and use Copy results to save them.

100 ng of a 1,000 bp fragment in 50 uL

100 ng, 1000 bp, dsDNA, 50 uL

650000 g/mol, 0.154 pmol, 9.265e+10 copies, 3.077 nmol/L

When to use it

• Working out insert-to-vector molar ratios for a ligation or Gibson assembly.
• Calculating copy number for a qPCR standard curve dilution series.
• Converting a library concentration and average fragment size into nanomolar for sequencing loading.
• Estimating how many template molecules a PCR reaction actually starts with.

Questions about DNA ng / pmol / Copies Converter

What molecular weights does it assume?

An average of 650 g/mol per base pair for dsDNA, 330 g/mol per nucleotide for ssDNA and oligos, and 340 g/mol per nucleotide for RNA. Molecular weight is length times that figure.

How accurate is that for a specific sequence?

It is an average, so individual molecules differ a little with base composition. For a short oligo where precision matters, use its actual composition instead of the average.

How is molarity calculated?

It divides the picomoles by your volume and rescales to nanomoles per liter, so it assumes all the mass is dissolved in that volume. Without a volume it shows a prompt instead.

What constant gives the copy number?

Picomoles are multiplied by 10 to the minus 12 and by Avogadro's number, 6.022 times 10 to the 23, so the result is the molecule count.

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