# DNA Molar Concentration Calculator (µg/mL → nM) Mass-to-molar DNA conversion: nM = (µg/mL × 10⁶)/(Da-per-bp × bp) with 650 Da/bp dsDNA and 330 Da/nt ssDNA, plus µM, pmol/µL, total pmol, and molecules/µL via Avogadro. Warns about the µM-vs-nM 1000× slip. NEB NEBioCalculator / Promega BioMath derived. Educational use only. > Canonical page: https://elysiatools.com/en/tools/molar-dna-concentration - **Category:** Education - **Keywords:** dna molar concentration, µg/ml to nm, dna nm calculator, pmol dna calculator, 650 daltons per base pair, 330 da per nucleotide, dsdna molecular weight, dna molecules per microliter, avogadro dna copies, molar insert concentration, molecular biology, lab calculator ## Overview Convert DNA mass concentration in µg/mL (numerically equal to ng/µL) into nM, µM, and pmol/µL using average molecular masses for dsDNA or ssDNA. Enter the DNA length and optionally the sample volume to calculate total pmol and molecule counts. This calculator is intended for education and experimental planning. ## Inputs - **DNA Concentration (µg/mL = ng/µL)** (number): Mass concentration of the DNA sample. 1 µg/mL is numerically identical to 1 ng/µL. - **DNA Type** (select): dsDNA averages 650 Da/bp; ssDNA averages 330 Da/nt (NEB convention). - **DNA Length (bp)** (number): Full length of the DNA molecule in base pairs (nt for ssDNA). - **Sample Volume (µL, optional)** (number): Volume of the sample in µL; enter 0 to skip the total-pmol calculation. - **Decimal Places** (number) ## When to use - Convert a measured DNA concentration from µg/mL or ng/µL to nM before setting up a molecular biology reaction. - Calculate molar amounts for PCR fragments, inserts, plasmids, or ssDNA based on DNA length and type. - Estimate total pmol and DNA molecule counts when the sample volume is known. ## How it works - Enter the DNA concentration in µg/mL; this value is numerically identical to ng/µL. - Select dsDNA, using 650 Da/bp, or ssDNA, using 330 Da/nt. - Enter the full DNA length in bp or nt. - Optionally enter the sample volume to calculate total pmol; the results also report µM, pmol/µL, and molecule counts. ## Use cases - Convert purified PCR fragment concentrations into molar concentrations for reaction planning. - Compare molar amounts of dsDNA and ssDNA molecules with different lengths. - Estimate total DNA quantity and molecule counts in a measured sample volume. ## Frequently asked questions ### What formula does the calculator use? It uses nM = (µg/mL × 10⁶) ÷ (Da per bp or nt × DNA length). ### What mass value is used for dsDNA? The calculator uses an average molecular mass of 650 Da per base pair. ### What mass value is used for ssDNA? The calculator uses an average molecular mass of 330 Da per nucleotide. ### Is 1 µg/mL equal to 1 ng/µL? Yes. These concentration units are numerically identical. ### What happens if I leave sample volume at zero? The calculator skips the total-pmol calculation while still reporting concentration-based results. ## Related tools - [PCR Annealing Temperature Calculator (Ta = Tm − 5°C)](https://elysiatools.com/en/tools/annealing-temperature-calculator): PCR Ta by the simple rule (lower primer Tm − 5°C) or the Rychlik 1990 formula (0.3·Tm_primer + 0.7·Tm_product − 14.9), with a ±3°C gradient window and primer-Tm mismatch warning. Derived from Rychlik 1990, Innis & Gelfand 1990, Lorenz 2012. 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