Convert molar concentration (molarity) between mol/L, mmol/L, mol/m³ and µmol/L.
Fluids • 6 units
All 6 units on the Molar Concentration Converter are defined against the Mole/meter³ (mol/m³), so each result is one conversion factor away from a single reference rather than the end of a chain of roundings.
The conversion this page is most often opened for is ready before you type anything: 1 mol/L = 1,000 mmol/L. Change either side and every row in the table recalculates with it.
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This table contains an identity that saves a step in almost every calculation: millimoles per litre and moles per cubic metre are numerically the same, so a clinical result in mmol/L can be dropped straight into an engineering expression written in SI. Above them, one mole per litre — one molar — is 1,000 mmol/L and 1,000 mol/m³, which is why the litre-based unit survives despite not being the SI choice.
Clinical chemistry converts between mass and molar units constantly, and there is no single factor that does it. Because the conversion runs through molar mass, glucose in mg/dL is divided by about 18.0 to reach mmol/L, while total cholesterol uses roughly 38.7 — the two differ purely because the molecules do. Any tool or table offering one universal mg/dL-to-mmol/L factor is quietly assuming a substance, which is why laboratory reports name the analyte alongside the unit.
Preparing a solution runs the same arithmetic forward: mass equals molarity times volume times molar mass, so 250 mL of 0.1 M sodium chloride needs 1.461 g of solute at 58.44 g/mol. The detail that trips people is what the volume refers to. Molarity is defined against the final volume of solution, not the volume of solvent added, which is why the preparation calls for a volumetric flask topped up to the mark rather than a measured quantity of water with solid stirred into it.
Quick reference — 1 Mole/liter (Molar) (mol/L) is equal to:
| Mole/meter³ | mol/m³ | 1,000 |
| Millimole/liter | mmol/L | 1,000 |
| Micromole/liter | µmol/L | 1,000,000 |
| Mole/decimeter³ | mol/dm³ | 1 |
| Mole/centimeter³ | mol/cm³ | 0.001 |
6 units of molar concentration, each a fixed multiple of the mol/m³. The table spans 1,000,000,000:1, from µmol/L (0.001 mol/m³) to mol/cm³ (1000000 mol/m³). Conversion is one multiplication into the base unit and one division out of it, with no lookup table and no approximation.
value_to = value_from × (factor_from ÷ factor_to)1 mol/m³ = 1 mol/m³1 mol/L = 1000 mol/m³1 mmol/L = 1 mol/m³1 µmol/L = 0.001 mol/m³1 mol/dm³ = 1000 mol/m³1 mol/cm³ = 1000000 mol/m³where:
Assumptions: Factors are exact definitions. Full double precision is carried internally and rounding is applied only for display.
Result25 mol/L = 25000 mmol/L
Molar concentration is amount of substance per unit volume, with an SI unit of mol/m³ that almost nobody uses. The working unit is molarity — moles per litre, written M — and one molar equals 1,000 mol/m³.
Molarity is the right unit whenever a reaction is what matters, because equal volumes of equal molarity contain equal numbers of reacting particles regardless of what they weigh. It has one genuine weakness worth knowing: because it is defined per unit volume, and volume changes with temperature, a solution's molarity drifts as it warms. Work requiring precision over a temperature range uses molality, defined per kilogram of solvent, which does not.