Concentration Calculator
Calculate molarity and solution concentration from moles and volume, or from mass and molar mass. Solve for concentration, moles, volume, mass, or molar mass with unit support.
Amount of solute in moles (or mmol, µmol).
Volume of solution. Must be greater than zero.
Enter the required values to calculate concentration
Table of Contents
What is Concentration?
Concentration describes how much solute is dissolved in a given amount of solution. In chemistry, the most common measure is molarity (molar concentration). Key ideas:
- Molarity (M) = moles of solute ÷ liters of solution
- 1 M = 1 mol/L; 1 mM = 0.001 mol/L
- Mass concentration (e.g. g/L, mg/mL) expresses solute mass per solution volume
- Molarity depends on total solution volume, not solvent volume alone
If you know the mass of solute and its molar mass, you can find moles (n = m ÷ M) and then molarity (C = n ÷ V). This links mass-based measurements to molar concentration.
Concentration calculations are essential for preparing lab solutions, titrations, cell culture media, and any workflow where you need a specific amount of dissolved substance.
C = n / V
How it Works
Pick how you want to calculate, choose what to solve for, then enter the other known values:
- Moles & volume: Use when you know amount of substance and solution volume
- Mass & molar mass: Use when you weighed solid solute and know its formula weight
- Solve for concentration, moles, volume, mass, or molar mass depending on what is unknown
The calculator automatically:
- Converts units (M, mM, µM, nM, L, mL, µL, g, mg, mol, mmol)
- Computes molarity from C = n/V or C = m/(M×V)
- Shows derived moles and mass concentration (g/L) when applicable
- Updates results as you change inputs
All calculations assume a homogeneous solution and that volume additivity is approximately valid (typical for dilute aqueous solutions).
Formulas
Molarity (from moles)
C = n / V
Where n is moles of solute and V is volume of solution in liters.
Molarity (from mass)
C = m / (M × V)
Where m is mass of solute, M is molar mass (g/mol), and V is solution volume in liters.
Moles from molarity
n = C × V
Rearrange molarity to find amount of substance when concentration and volume are known.
Mass concentration
Mass conc. = m / V (g/L)
Mass per volume (e.g. g/L) is independent of molar mass and useful for many lab protocols.
Examples
Example 1: 1 M solution from moles
Given: n = 0.5 mol, V = 500 mL = 0.5 L
Calculation: C = 0.5 / 0.5 = 1 M
Example 2: NaCl from mass
Given: m = 5.844 g NaCl, M = 58.44 g/mol, V = 100 mL = 0.1 L
Calculation: n = 5.844/58.44 = 0.1 mol; C = 0.1/0.1 = 1 M
Example 3: Find volume for 0.25 M
Given: n = 0.1 mol, C = 0.25 M
Calculation: V = n/C = 0.1/0.25 = 0.4 L (400 mL)
Common Use Cases
- Lab solution prep: Make 500 mL of 0.1 M NaCl from stock or solid
- Titration: Confirm analyte or titrant concentration before a procedure
- Biochemistry: Prepare buffers and reagents at defined molarity
- Education: Practice stoichiometry and concentration unit conversions
- Pharmacy: Relate mass doses to molar concentration in formulations
- Quality control: Verify batch concentration from mass and volume records
Frequently Asked Questions
Molarity (M) is moles per liter of solution. Molality (m) is moles per kilogram of solvent. Molarity changes with temperature because volume changes; molality does not. This calculator uses molarity.
Divide mass by molar mass to get moles (n = m/M), then divide moles by volume in liters (C = n/V). Or use one step: C = m/(M×V).
Yes. 1 mg/mL = 1 g/L. Both express mass concentration. To get molarity from mass concentration, you also need molar mass: C (mol/L) = (mass conc in g/L) / M.
Use total volume of the final solution when molarity is specified. For precise work, dissolve solute and dilute to a marked volume (volumetric flask).
Molarity: M, mM, µM, nM. Volume: L, mL, µL. Mass: g, mg, µg, kg. Amount: mol, mmol, µmol. Molar mass is in g/mol.