Applied to each strand; choose the chemistry of the DNA being measured.
Maximum 5,000,000 bases.
Enter your parameters to see conversion results
1. Calculate Moles of DNA
moles of DNA [mol] = DNA mass [g] / DNA molecular weight [g/mol]
This fundamental equation converts the physical mass of DNA to the number of moles using the molecular weight.
2. Calculate Moles of DNA Ends
moles of dsDNA ends [mol] = moles of dsDNA [mol] × 2
Each double-stranded DNA molecule has two ends (3' and 5' ends on each strand), important for ligation and enzymatic reactions.
3. Calculate DNA Copy Number
DNA copy number [molecules] = moles of DNA [mol] × 6.022e23 [molecules/mol]
Uses Avogadro's number to convert moles to actual number of DNA molecules, useful for qPCR and digital PCR applications.
4. Calculate DNA Molecular Weight
MW = both complementary strand residue sums − 123.92 + selected 5′ adjustments
The complementary strand is calculated base by base (A↔T and C↔G); it is not assumed to have the same composition as the entered strand.
Molecular weight is determined by summing the weights of all atoms (protons, neutrons, and electrons) in a molecule. For DNA, this is calculated by adding the molecular weights of each nucleotide in the sequence.
Converting between mass and moles requires knowing the molecular weight, which serves as the conversion factor between these two fundamental measurements.
📊 Average Method
When only sequence length is provided, the average nucleotide molecular weight is used:
Best for: Quick estimates and unknown sequences
🧬 Precise Method
When the actual sequence is provided, exact molecular weights are summed for each nucleotide:
Best for: Accurate calculations and known sequences
🔬 Strand Type Differences
Double-stranded DNA (dsDNA):
Single-stranded DNA (ssDNA):
🔬 The Mole Concept
In chemistry, a mole represents a specific quantity of substance containing Avogadro's number of particles (6.02214076 × 10²³), typically atoms or molecules.
Avogadro's Number (NA):
6.02214076 × 10²³ molecules/mol
This fundamental constant connects the microscopic world (individual molecules) with the macroscopic world (measurable quantities).
📊 Copy Number Determination
Copy number represents the actual count of DNA molecules in your sample. To calculate from moles, multiply by Avogadro's number:
Copy Number = Moles × 6.022 × 10²³
This calculation applies to both single-stranded (ssDNA) and double-stranded DNA (dsDNA) as it counts molecules, not individual nucleotides.
🧬 Understanding DNA 3'/5' Ends
DNA molecules have directional ends (3' and 5') that are critical for biological processes like ligation and enzymatic reactions:
Single-stranded DNA (ssDNA):
Each molecule has one 3' end and one 5' end
Moles 3'/5' ends = Moles ssDNA
Double-stranded DNA (dsDNA):
Two complementary strands, each with 3' and 5' ends
Moles 3'/5' ends = Moles dsDNA × 2
5′ End Chemistry:
The molecular-weight calculation uses the selected 5′-OH or 5′-monophosphate state for every strand.
Cloning & Ligation
Calculate insert:vector molar ratios (typically 3:1 or 5:1) for optimal ligation efficiency.
Library Preparation
Determine precise molarity for NGS library pooling to ensure uniform coverage across samples.
Digital PCR Standards
Convert copy number to concentration for preparing absolute quantification standards.
Calculate the correct molar ratios for insert and vector in ligation reactions
Convert mass measurements from spectrophotometry to molar concentrations
Calculate library concentrations in molarity for proper pooling and sequencing
Determine the number of DNA molecules in a sample for digital PCR or qPCR