Molarity, mg/mL & % Concentration Converter
Convert between molarity (M), mg/mL, μg/mL, and percentage concentrations (% w/v, v/v, w/w)
💡 Common Molecular Weights
Click to auto-fill the MW field above.
Buffers
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Sugars & Others
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ℹ️ Concentration Conversion Reference
What is Molarity?
Molarity (M) is the number of moles of solute per liter of solution. It is the most common way to express concentration in molecular biology and biochemistry.
M = mol / L = (mass in g) / (MW in g/mol × volume in L)
Common prefixes: 1 mM = 10⁻³ M, 1 μM = 10⁻⁶ M, 1 nM = 10⁻⁹ M
What is % w/v, % w/w, and % v/v?
% w/v (weight/volume): grams of solute per 100 mL of solution. Most common in biology. 1% w/v = 10 mg/mL = 10 g/L.
% w/w (weight/weight): grams of solute per 100 g of solution. Requires solution density. Used for concentrated acids, viscous solutions.
% v/v (volume/volume): mL of solute per 100 mL of solution. Used for liquid-liquid mixtures (e.g., ethanol, methanol). Cannot be converted to molarity without density information.
How to convert mg/mL to Molarity
To convert from mg/mL (mass concentration) to molarity (molar concentration), you need the molecular weight (MW):
Molarity (M) = concentration (mg/mL) / MW (g/mol)
For example: 5 mg/mL of glucose (MW = 180.16 g/mol):
5 / 180.16 = 0.02776 M = 27.76 mM
Common Mistakes
Forgetting molecular weight: mg/mL and molarity are fundamentally different units. Without MW, conversion is impossible.
Confusing % w/v and % w/w: A 10% w/v NaCl solution contains 10 g NaCl in 100 mL solution, while 10% w/w contains 10 g NaCl in 100 g solution. The difference matters for concentrated solutions.
Assuming 1 mg/mL = 1 mM: This is only true when MW = 1000 g/mol. Always check MW.