Molarity Calculator – Moles, Mass and Volume
This molarity calculator handles the three everyday lab questions. Find the molarity of a solution from the mass of solute, its molar mass and the solution volume. Find how many grams to weigh out to make a solution of a target molarity. Or find the volume you need for a given mass and molarity. It shows the moles along the way so you can follow the steps, and it accepts milliliters or liters. If you do not know the molar mass, use the molar mass calculator linked below, then come back. Everything is calculated instantly in your browser.
Molarity Calculator
Find molarity, the mass to weigh out, or the volume of solution.
How to use the Molarity Calculator
- Choose what to find: molarity, mass or volume.
- Enter the known values, including the molar mass in g/mol.
- Pick mL or L for volume.
- Read the answer and the moles used.
Molarity formula
M = moles ÷ liters of solution, and moles = grams ÷ molar mass. So grams = M × liters × molar mass.
Features
- Molarity from mass and volume
- Grams needed for a target molarity
- Volume for a given mass
- Shows moles step by step
- mL or L
- Copy and print
Frequently asked questions
What is molarity?
Molarity (M) is moles of solute per liter of solution. A 1 M solution has 1 mole of solute in 1 liter of solution.
How do you calculate molarity?
Divide grams of solute by molar mass to get moles, then divide moles by liters of solution. 5.844 g of NaCl (58.44 g/mol) in 0.5 L is 0.2 M.
How many grams do I need for 250 mL of 0.5 M NaCl?
Mass = 0.5 mol/L × 0.25 L × 58.44 g/mol = 7.305 g.
Is molarity the same as molality?
No. Molarity uses liters of solution; molality uses kilograms of solvent.
Does temperature affect molarity?
Slightly, because solution volume changes with temperature. For most classroom work it is ignored.