Resuspension Calculator

Calculate how much solid to resuspend in a given volume to achieve your target concentration. Perfect for preparing oligonucleotide and reagent stock solutions.

Amount of solid to resuspend

Volume to resuspend in

Desired final concentration

MW of the compound

If using stock solution

Calculated if solving for dilution

Resuspension Formula: Mass to Resuspend: Mass (mg) = Conc (mM) × Volume (mL) × MW (g/mol) / 1000 Final Concentration: Conc (mM) = Mass (mg) × 1000 / (MW × Volume (mL)) Volume to Use: Volume (mL) = Mass (mg) × 1000 / (MW × Conc (mM)) Percent Solution (w/v): % = Mass (g) / Volume (L)
Example 1 (Standard Resuspension): MW = 500 g/mol Volume = 10 mL Target = 50 mM Mass = 50 × 10 × 500 / 1000 = 250 mg Example 2 (Oligonucleotide): 20-base DNA oligo, MW = 6100 g/mol Target = 100 µM = 0.1 mM Volume = 1 mL (1000 µL) Mass = 0.1 × 1 × 6100 / 1000 = 0.61 mg = 610 µg Example 3 (Find Concentration): Mass = 25 mg, MW = 327.7 g/mol Volume = 5 mL Conc = 25 × 1000 / (327.7 × 5) = 15.26 mM Example 4 (Small volume): 1 mg of enzyme, MW = 50,000 g/mol Target = 10 µM Volume = 1 × 1000 / (50000 × 0.01) = 2 mL

What is resuspension in chemistry?

Resuspension is the process of dissolving a solid compound into a solvent to create a solution of known concentration. It is commonly used in molecular biology and biochemistry to prepare stock solutions of oligonucleotides, enzymes, and other reagents. The formula is typically in units of mM (millimolar).

How do I calculate how much solid to add?

Use: Mass (mg) = Concentration (mM) × Volume (mL) × MW (g/mol) / 1000. For example, to make 10 mL of 100 mM solution of a 500 g/mol compound: Mass = 100 × 10 × 500 / 1000 = 500 mg. Always add solid to the solvent, not the other way around.

What is a typical stock solution concentration?

Common stock concentrations are 10 mM, 100 mM, or 1 M depending on the compound. For oligonucleotides, typical working stocks are 10-100 µM. Higher concentrations reduce storage volume but may have solubility limitations. Check the specific compound's solubility guidelines.

Why is molecular weight important for resuspension?

Molecular weight determines how many moles are in a given mass. Different compounds with the same mass but different MW will give different concentrations. For oligonucleotides (DNA/RNA), MW depends on length and base composition, typically ~300-400 g/mol per base pair.

How do I resuspend an oligonucleotide?

Calculate MW using the sequence (each base ~330 g/mol for DNA, ~350 for RNA). Use the formula: mass (µg) = pmol × MW (g/mol) × 10⁻⁶. Or use concentration formula: resuspend to 100 µM by adding µL = pmol/100. Most oligo suppliers provide MW and resuspension instructions with the product.

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