Cell Culture Molarity Calculator
Turn a mass of solute, its molecular weight and a solution volume into molarity for cell-culture media and buffers — with the result in mol/L, mM and µM plus total moles.
How it works
Moles = mass (g) ÷ molecular weight (g/mol) · Molarity (mol/L) = moles ÷ volume (L) · mM = mol/L × 1000
Molarity is moles of solute per litre of solution — the concentration unit behind almost every cell-culture medium, buffer and stock. Convert the weighed mass to grams, divide by the molecular weight to get moles, then divide by the volume in litres. Reagents for cells are often quoted in millimolar (mM) or micromolar (µM), which are simply the molarity scaled by 1,000 and 1,000,000.
Worked example
Weighing 500 mg (0.5 g) of glucose (180 g/mol) into 500 mL of medium gives 0.5 ÷ 180 = 0.002778 mol, and 0.002778 ÷ 0.5 L = 0.005556 mol/L — about 5.56 mM.
Sources: Molar concentration — Wikipedia
Frequently asked questions
How do I make a specific mM concentration?
Rearrange the formula: mass (g) = molarity (mol/L) × volume (L) × molecular weight. For 10 mM in 500 mL of a 180 g/mol solute, that is 0.01 × 0.5 × 180 = 0.9 g.
Does temperature change molarity?
Slightly. Molarity is defined per litre of solution, and volume expands with temperature, so a stock made at 4 °C is marginally more concentrated when warmed. For most cell-culture work the effect is negligible; molality avoids it entirely.
What molecular weight should I use for hydrates?
Use the molecular weight of the exact form you weigh out. Hydrated salts (for example CuSO₄·5H₂O) include the water of crystallisation in their molar mass, so using the anhydrous value would overshoot the concentration.
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Educational estimate, not medical or laboratory advice — verify formulas, units and assumptions for your specific organism or protocol.