Resuspension Calculator
Use this resuspension calculator to work out the buffer volume for a lyophilized oligo, primer or peptide. Enter the mass, molecular weight, and the concentration you want (µM) — it returns the volume of water or buffer to add.
Enter mass, molecular weight, and the concentration you want to get the buffer volume to add.
How to resuspend a lyophilized sample
Resuspension is just making a solution at a known concentration from a dry amount. First convert the mass to moles, then divide by the target molarity:
Equivalently, if you already know the amount in nmol, the volume is nmol ÷ µM × 1000. The molecular weight is in g/mol (Daltons) and should come from your vendor spec sheet.
Worked example
A primer of 100 µg with MW 6600 g/mol to reach 100 µM: volume = 100 × 1,000,000 ÷ (6600 × 100) ≈ 151.5 µL of buffer (that is about 15.15 nmol).
Related tools
To go from mg/mL to molarity, use the mg/mL ⇆ molarity calculator. To then dilute the stock down, use the dilution calculator.
Frequently asked questions
›How do I resuspend a lyophilized oligo to 100 µM?
Convert the amount to nmol, then divide by the target µM and multiply by 1000. For a mass in µg, nmol = mass ÷ MW × 1000, so the volume in µL is (mass × 1,000,000) ÷ (MW × target µM). Add that many µL of buffer or nuclease-free water.
›What is the resuspension formula?
Volume (µL) = mass (µg) × 1,000,000 ÷ (molecular weight × target concentration in µM). Equivalently, µL = nmol ÷ µM × 1000. It gives the buffer volume to reach the concentration you want.
›What molecular weight should I use for an oligo?
Use the exact MW from your synthesis or spec sheet (in g/mol / Daltons). A rough estimate for single-stranded DNA is length × 330 g/mol per base, but the vendor value is more accurate, especially with modifications.
›Water or buffer for resuspension?
TE buffer (10 mM Tris, 1 mM EDTA) is common for long-term storage because EDTA chelates nucleases; nuclease-free water is fine for short-term use. This calculator only gives the volume — the diluent choice is yours.
Related calculators
Solve C₁V₁ = C₂V₂ for any unknown — stock concentration, volume, or final concentration.
Find molarity from mass and molecular weight, or the mass needed for a target molarity.
Convert between moles, volume, and molar concentration (mol/L) in any direction.
Turn a 1:N ratio into exact stock + solvent volumes for any final amount.
Dilute a stock solution to a target concentration with full unit switching.
Convert mg/mL to molarity (and back) using molecular weight — both directions.