A mole is the chemist's counting unit, about 6.022 times 10 to the 23 particles. The mass of one mole of a substance in grams is its molar mass.

What is the moles formula?

Moles equals mass in grams divided by molar mass in grams per mole. Rearranged, mass equals moles times molar mass, and molar mass equals mass divided by moles.

Where do I get the molar mass?

Use the molar mass calculator with the chemical formula, then bring that number here. For example, water has a molar mass of about 18.015 grams per mole.

Moles Calculator

This moles calculator converts between mass, moles and molar mass, the three quantities tied together by the rule that moles equals mass divided by molar mass. The mole is the chemist's way of counting particles, with one mole being about 6.022 times 10 to the power 23 atoms or molecules, and it is the unit that every balanced chemical equation is written in. Since you cannot count molecules directly but you can weigh a sample, converting between the mass on the balance and the number of moles is the single most common calculation in chemistry, the starting point for working out reacting quantities, yields and concentrations. You pick which quantity to solve for, the moles, the mass or the molar mass, then enter the other two. To find moles the calculator divides the mass in grams by the molar mass in grams per mole; to find the mass it multiplies moles by molar mass; and to find the molar mass it divides the mass by the moles. If you do not yet know the molar mass of your compound, work it out from the formula using the molar mass calculator and bring that figure here. Enter your two known values to see the result straight away.

Solve for

Mass (g)

Molar mass (g/mol)

Moles

0.999 mol

moles

Mass is in grams and molar mass in grams per mole. Estimate only.

How it works

The calculator uses moles equals mass over molar mass. To find moles it divides the mass by the molar mass, to find the mass it multiplies the moles by the molar mass, and to find the molar mass it divides the mass by the moles. The value you are solving for is hidden so you only enter the two known quantities.

Worked example

18 grams of water, which has a molar mass of about 18.015 grams per mole, is 18 divided by 18.015, which is very close to 1 mole.

Related calculators

Molar Mass Calculator: molar mass from a formula.
Molarity Calculator: concentration.
Dilution Calculator: dilute a stock.
pH Calculator: acidity.

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.