Mole Calculator
Convert grams to moles, moles to grams, or solve for molar mass when two of the three values are known. This page is built for chemistry homework, lab prep, and fast unit-checked conversions between amount and mass.
Edited by Gail Joyce
Gail Joyce edits core chemistry calculator pages for formula clarity, unit consistency, and practical classroom and lab-use readability.
This calculator page is maintained by the Chemistry Calculators editorial team. The mole formulas, Avogadro-related explanations, worked examples, and unit guidance on this page are reviewed against standard general chemistry equations and commonly used chemistry reference material before major updates.
When to Use This Mole Calculator
Use this page when you already know any two of these three values: mass, moles, and molar mass. It is best for grams-to-moles conversions, checking stoichiometry setup, and confirming lab-prep amounts once the compound's molar mass is known.
This page does not replace a full stoichiometry solver, a particle-count converter, or a chemical-formula parser. Use it when the job is a direct relationship between mass, moles, and molar mass.
Homework conversions
Check grams-to-moles or moles-to-grams steps before moving into a larger stoichiometry problem.
Lab preparation
Use it when weighing out a target amount of substance from a known molar mass.
Molar mass checks
Use it to confirm whether your mass and mole values imply a reasonable molar mass for the compound.
Mole Calculator
Convert between moles and grams using molar mass. Enter any two values to calculate the third.
Scope: this calculator is for direct mass-mole-molar-mass relationships. It is not a chemical formula parser or a full stoichiometry reaction solver.
Table of Contents
Quickly navigate to different sections of this guide. Click any item below to jump to that section.
Understanding Mole Conversions
The mole is the bridge between the microscopic world of particles and the mass you can actually measure in the lab. One mole represents 6.022 × 10²³ particles, and each substance has its own molar mass that tells you how many grams correspond to one mole.
That is why the same relationship keeps appearing in chemistry problems: moles, mass, and molar mass are linked directly. Once you know any two of those values, the third can be solved without extra reaction chemistry.
Common Mole Values Reference Table
| Substance | Formula | Molar Mass (g/mol) | 1 Mole = ? Grams |
|---|---|---|---|
| Water | H₂O | 18.015 | 18.015 g |
| Sodium Chloride | NaCl | 58.44 | 58.44 g |
| Carbon Dioxide | CO₂ | 44.01 | 44.01 g |
| Glucose | C₆H₁₂O₆ | 180.16 | 180.16 g |
| Calcium Carbonate | CaCO₃ | 100.09 | 100.09 g |
| Sulfuric Acid | H₂SO₄ | 98.08 | 98.08 g |
| Ammonia | NH₃ | 17.03 | 17.03 g |
| Ethanol | C₂H₅OH | 46.07 | 46.07 g |
How to Use the Mole Calculator
Use the calculator like a standard chemistry setup: pick the missing quantity, enter the two known values, and keep the units in grams and grams per mole before you calculate.
Choose what you want to solve for
Select moles, mass, or molar mass so the calculator knows which field should remain unknown.
Enter the two values you already know
Fill in any two of the three core values. For example, enter mass and molar mass to solve for moles.
Check the units before calculating
Use grams for mass and grams per mole for molar mass. Convert kilograms or milligrams before you run the calculation.
Calculate and review the relationship
Use the result to confirm the value makes chemical sense, then move on to your stoichiometry or lab-prep step if needed.
Formulas and Equations
The relationship between moles, mass, and molar mass is straightforward. Our Mole Calculator uses these formulas to provide accurate results:
Basic Mole Formula
Where:
n = Number of moles (mol)
m = Mass in grams (g)
M = Molar mass in grams per mole (g/mol)
This is the fundamental equation for converting between mass and moles. It tells you that moles equal mass divided by molar mass. The calculator uses this formula to find moles when you provide mass and molar mass.
Rearranged Formulas
You can rearrange the mole formula to solve for mass or molar mass:
To find mass:
Multiply moles by molar mass to get mass in grams. This is useful when you know how many moles you have and need to find the mass.
To find molar mass:
Divide mass by moles to get molar mass. Use this when you know the mass and number of moles but need to find the molar mass.
Avogadro's Number
One mole contains exactly Avogadro's number of particles:
This constant relates the number of particles to moles. For example, one mole of water contains 6.022 × 10²³ water molecules. This number is essential for understanding the connection between macroscopic measurements and atomic-scale quantities.
Worked Examples
Step-by-step solutions demonstrating how to convert between moles and grams. These examples show you how to use the Mole Calculator effectively and demonstrate the calculation process for various scenarios.
Example 1: Converting Grams to Moles
Scenario: How many moles are in 36.0 grams of water (H₂O)? Molar mass of H₂O = 18.015 g/mol
Solution:
Use the formula n = m / M
n = 36.0 g / 18.015 g/mol = 1.998 mol ≈ 2.00 mol
Answer: Moles = 2.00 mol
Example 2: Converting Moles to Grams
Scenario: What is the mass of 0.5 moles of sodium chloride (NaCl)? Molar mass of NaCl = 58.44 g/mol
Solution:
Use the formula m = n × M
m = 0.5 mol × 58.44 g/mol = 29.22 g
Answer: Mass = 29.22 g
Example 3: Finding Molar Mass
Scenario: A sample contains 2.0 moles of a compound and weighs 180.16 grams. What is the molar mass?
Solution:
Use the formula M = m / n
M = 180.16 g / 2.0 mol = 90.08 g/mol
Answer: Molar Mass = 90.08 g/mol
Example 4: Large Quantities
Scenario: How many moles are in 1.0 kg of glucose (C₆H₁₂O₆)? Molar mass = 180.16 g/mol
Solution:
First convert kg to g: 1.0 kg = 1000 g
Use the formula n = m / M
n = 1000 g / 180.16 g/mol = 5.55 mol
Answer: Moles = 5.55 mol
Example 5: Small Quantities
Scenario: What is the mass of 0.001 moles of carbon dioxide (CO₂)? Molar mass = 44.01 g/mol
Solution:
Use the formula m = n × M
m = 0.001 mol × 44.01 g/mol = 0.04401 g
Answer: Mass = 0.04401 g
Example 6: Multiple Steps
Scenario: A chemist needs 0.25 moles of calcium carbonate (CaCO₃) for an experiment. How many grams should they weigh out? Molar mass = 100.09 g/mol
Solution:
Use the formula m = n × M
m = 0.25 mol × 100.09 g/mol = 25.0225 g ≈ 25.02 g
The chemist should weigh out approximately 25.0 grams of CaCO₃.
Answer: Mass = 25.02 g
Example 7: Real-World Application
Scenario: A pharmaceutical company needs to produce pills containing 0.01 moles of aspirin (C₉H₈O₄). How many grams of aspirin are needed per pill? Molar mass = 180.16 g/mol
Solution:
Use the formula m = n × M
m = 0.01 mol × 180.16 g/mol = 1.8016 g ≈ 1.80 g
Each pill should contain 1.80 grams of aspirin to provide the correct dosage.
Answer: Mass = 1.80 g per pill
Common Mole Mistakes to Avoid
Using the wrong mass unit
Convert kilograms or milligrams to grams before using the calculator so the formula stays consistent.
Entering the wrong molar mass
Check the compound formula carefully. A wrong molar mass will make every later stoichiometry step wrong too.
Using this page for particle counts or full reaction stoichiometry
This tool is strongest for direct mass-mole-molar-mass relationships. Use a dedicated stoichiometry or particle-count tool when the problem goes beyond that scope.
Frequently Asked Questions
These are the questions users most often need when converting between grams, moles, and molar mass.
What is a mole in chemistry?
A mole is a unit that represents 6.022 × 10²³ particles. It lets chemists connect particle counts to measurable mass.
How do I convert grams to moles?
Divide the mass in grams by the molar mass in grams per mole. That is the formula n = m / M.
How do I convert moles to grams?
Multiply the number of moles by the molar mass. That is the formula m = n × M.
What if I do not know the molar mass?
Use a molar mass reference or a molar mass calculator first. This page assumes the molar mass is already known if you are solving for grams or moles.
Can I use this page for stoichiometry?
Yes, for the conversion step inside a stoichiometry problem. Use a dedicated stoichiometry calculator once you need mole ratios from a balanced reaction.
What units should I use?
Use grams for mass, moles for amount, and grams per mole for molar mass. Convert other units before calculating.
References and Further Reading
For more in-depth information about moles, Avogadro's number, and related chemistry topics, consult these authoritative sources:
| Resource | Description | Category |
|---|---|---|
| ChemLibreTexts: General Chemistry | Open general chemistry reference material covering moles, mass relationships, and stoichiometry setup | General Chemistry |
| NIST Chemistry WebBook | Standard reference data for chemical compounds and molar masses | Chemical Data |
| PubChem | Database of chemical properties including molar masses | Chemical Data |
| Brown, T. L., et al. (2017). Chemistry: The Central Science | Textbook treatment of mole concepts, molar mass, and introductory stoichiometry | Textbook |