DNA/Molarity Calculator
Enter the mass, molecular weight, and volume to find the resulting molar concentration.
How molarity is calculated
Molarity (M) is moles of solute per liter of solution: M = mass(g) / (molecular weight(g/mol) × volume(L)). This calculator handles the unit conversions internally, taking mass in milligrams and volume in milliliters for convenience.
For DNA and RNA specifically, the molecular weight depends on the exact sequence and length — an average base pair weight (around 650 g/mol for double-stranded DNA) is commonly used for a quick estimate, but precise work should use the exact molecular weight for your specific sequence.
Frequently asked questions
What's a typical molecular weight to use for DNA?
For double-stranded DNA, roughly 650 g/mol per base pair is a common estimate, so multiply this by the number of base pairs for an approximate total molecular weight. For a precise value, use software or a reference table based on the exact sequence.
Why does this calculator show both M and mM?
Molar (M) concentrations are often very small in molecular biology work — nanomolar and micromolar ranges are common — so millimolar (mM, one-thousandth of a mole per liter) is frequently a more convenient and readable unit for everyday lab calculations.
Can I use this for solutions other than DNA?
Yes — this calculates molarity for any solute given its mass, molecular weight, and solution volume, making it useful for general chemistry and biology lab work, not just nucleic acids.