Math
Molarity Calculator
Solve M = n / V for molarity, moles, or volume. Compute molarity from mass and molar mass, with mM, uM, ppm, and %w/v conversions.
Molarity Calculator (M = n / V)
Given moles and volume, compute M = n / V.
Amount of substance, n.
Total solution volume. mL is converted to liters internally.
Optional outside the mass mode. Enables grams, ppm, and %w/v.
Molarity (M)
0.5 mol/L
Molarity
0.5 mol/L
Millimolar
500 mM
Micromolar
500,000 uM
Moles
0.5 mol
Volume
1 L
Mass
29.22 g
Concentration (approx.)
29,220 ppm
Percent w/v (approx.)
2.922%
ppm and %w/v assume a dilute aqueous solution (density about 1 g/mL).
Frequently Asked Questions about the Molarity Calculator
What is molarity and how do you calculate it?
Molarity (M) is the concentration of a solution expressed as moles of solute per liter of solution: M = n / V. A 1 M solution contains 1 mole of solute in every liter of total solution volume.
How do I find molarity from mass and molar mass?
Switch the calculator to fromMass mode. Enter the solute mass in grams, its molar mass in g/mol, and the final solution volume. The calculator first converts mass to moles (n = mass / molar mass), then divides by volume in liters to give molarity.
What is the difference between molarity, millimolar, and micromolar?
They are the same quantity at different scales. 1 M = 1,000 mM = 1,000,000 uM. Millimolar (mM) is common in biology buffers, and micromolar (uM) shows up for drug concentrations and enzyme kinetics.
How do molarity, ppm, and percent w/v relate?
If you know the molar mass, you can convert molarity (mol/L) to grams per liter: g/L = M x molar mass. From there, ppm = g/L x 1000 and percent w/v = g per 100 mL = (g/L) / 10. These conversions assume a dilute aqueous solution with density close to 1 g/mL.
Do I have to enter volume in liters?
No. Pick liters (L) or milliliters (mL) from the unit selector next to the volume field. The calculator converts mL to liters internally before applying M = n / V.