Molarity Calculator

mol

Molarity Calculator — M = m / (MW × V)

Enter any 3 of the 4 values to calculate the fourth. Select a common chemical below to auto-fill its molecular weight.

Common Chemical Preset (auto-fills MW)

Solve For

Mass (m)Known

Molecular Weight (MW)Known

Select a preset above to auto-fill

Volume (V)Known

Molarity / Concentration (M)Result

Significant Figures:

dil

Dilution Calculator — C1V1 = C2V2

Calculate how to dilute a stock solution to a working concentration. Enter any 3 of the 4 values to find the fourth.

Solve For

Stock Concentration (C1)Result

Stock Volume to Take (V1)Known

Final Concentration (C2)Known

Final Volume (V2)Known

ser

Serial Dilution Calculator

Calculate concentrations at each step of a serial dilution. Each step uses the same dilution factor.

Starting Concentration

Dilution Factor (e.g. 10 = 1:10)

Each step divides by this factor

Number of Steps

Volume per Step

Common Chemical Molecular Weights

Reference table of molecular weights for common laboratory chemicals. Click any row to use that MW in the molarity calculator.

Chemical	Formula	MW (g/mol)

Molarity Guide

Key Formulas

Molarity (M) = moles / volume (L)
Moles (n) = mass (g) / MW (g/mol)
Therefore: M = mass / (MW × Volume)

Rearranged:
Mass = M × MW × V
Volume = mass / (M × MW)
MW = mass / (M × V)

Dilution: C1 × V1 = C2 × V2

Concentration Units

M (Molar): mol/L — standard lab unit
mM (millimolar): 10³ M — common for enzyme kinetics
µM (micromolar): 10&sup6; M — drugs, hormones
nM (nanomolar): 10&sup9; M — antibodies, high-affinity ligands
pM (picomolar): 10² M — extremely dilute solutions
fM (femtomolar): 10&sup5; M — ultra-sensitive assays

1 M = 1,000 mM = 10&sup6; µM = 10&sup9; nM = 10² pM

Practical Lab Tips

Making a 1 M NaCl (MW 58.44) in 1 L:
Mass = 1 M × 58.44 g/mol × 1 L = 58.44 g
Weigh 58.44 g NaCl, dissolve in ~800 mL water, then make up to 1 L.

Diluting a stock: Always add solute/stock to solvent, not the other way around for concentrated acids.

Serial dilution: A 1:10 dilution repeated 8 times gives 10−8 × original concentration.

Terminology

Molar mass: mass of 1 mole of substance (g/mol) — preferred scientific term
Molecular weight: used interchangeably with molar mass in practice
Molarity: moles of solute per liter of solution
Molality: moles of solute per kg of solvent (differs at non-standard temp)
Normality: equivalents of solute per liter (used in acid-base/redox)
ppm: mg/L for dilute aqueous solutions
Avogadro's number: 6.022 × 10²³ particles/mol