Molarity Calculator
Calculate the molarity of a solution from moles of solute (or mass and molar mass) and volume.
Moderate
At 0.5 mol/L, this solution reads as "Moderate" — general chemistry commonly treats solutions under 0.1 M as dilute and over 1 M as concentrated.
ƒShow your work
- 1Molarity = moles ÷ volume = 0.5 mol ÷ 1 L = 0.5 mol/L
About the Molarity Calculator
This calculator works out the molarity of a solution — how many moles of solute are dissolved per liter — either directly from a known moles figure, or from a mass and molar mass if you're starting from a scale reading instead of a moles count.
It's a standard tool in chemistry coursework and lab work: preparing a solution to a target concentration, checking a calculation before mixing reagents, or converting between a recipe given in grams and one given in molarity.
Switch the input mode depending on what you actually have on hand — moles directly, or mass plus the compound's molar mass — and the calculator handles the rest, including a quick read on whether the resulting solution counts as dilute or concentrated.
How it’s calculated
When starting from mass, moles are first found by dividing mass by molar mass (moles = mass ÷ molar mass) — molar mass is specific to each compound and can be found on a label, a safety data sheet, or calculated with the Molecular Weight Calculator.
Molarity itself is moles of solute divided by the solution's volume in liters (M = mol/L). General chemistry commonly treats concentrations under about 0.1 M as dilute and over 1 M as concentrated, which is the rough scale the gauge above reflects.
Frequently asked questions
What's the difference between molarity and molality?
Molarity is moles of solute per liter of solution (volume-based), while molality is moles of solute per kilogram of solvent (mass-based). Molarity is more common in general lab work, while molality is preferred when temperature changes might affect volume, since mass doesn't shift with temperature.
Where do I find a compound's molar mass?
It's usually printed on the reagent bottle's label or safety data sheet. If you only know the chemical formula, the Molecular Weight Calculator will compute it directly by summing each element's atomic weight.
How do I prepare a solution of a specific molarity?
Rearrange the molarity formula to solve for mass: mass = molarity × volume × molar mass. This calculator's mass-input mode does exactly that calculation in reverse — enter mass and molar mass to check the molarity a given amount will produce in your chosen volume.
Does molarity change if I dilute the solution?
Yes — adding solvent increases the volume while the moles of solute stay the same, which lowers the molarity proportionally. That relationship (M₁V₁ = M₂V₂) is the basis for calculating dilutions, though this calculator handles the base molarity formula rather than the dilution equation itself.
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