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Chemistry

Mole Calculator

Moles from mass and molar mass. Free online Mole Calculator. Calculate mole online — fast, accurate, mobile-friendly, no signup needed.

Moles
0.999167

Derivation

  1. ├── 01Givenm = 18, mm = 18.015
  2. ├── 02Formulae.m / e.mm
  3. ├── 03Substitutee.18 / e.18.015
  4. └── 04Compute Moles0.999167
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§01What is

Understanding the Mole Calculator

The Mole Calculator computes Moles from 2 inputs: mass (g), molar mass (g/mol). Moles from mass and molar mass.

Chemistry turns grams and moles into reactions. Getting the stoichiometry, dilutions, or concentrations right is the difference between a lab result you can trust and one you can’t reproduce. The Mole Calculator sits in that toolkit — it moles from mass and molar mass. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

e.m / e.mm

Where

m
Mass (g)
mm
Molar mass (g/mol)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: Mass (g) = 18, Molar mass (g/mol) = 18.015.

  1. 01Start by noting the input — Mass (g): 18.
  2. 02Start by noting the input — Molar mass (g/mol): 18.015.
  3. 03Substitute these values into the formula: e.m / e.mm
  4. 04Compute Moles: the calculator returns 0.999167.
  5. 05Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common Mole Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

Mass (g) halved

m = 9 (from 18)

Keep every other input at its default and halve the mass (g). See how moles responds.

  1. 01New Mass (g): 9
  2. 02Baseline Moles: 0.999167
  3. 03New Moles: 0.499584
  4. 04Moles decreases by 50% → use this sensitivity to plan for real-world variation.
02 · PATTERN

Mass (g) doubled

m = 36 (from 18)

Keep every other input at its default and double the mass (g). See how moles responds.

  1. 01New Mass (g): 36
  2. 02Baseline Moles: 0.999167
  3. 03New Moles: 1.99833
  4. 04Moles increases by 100% → use this sensitivity to plan for real-world variation.
03 · PATTERN

Molar mass (g/mol) halved

mm = 9.0075 (from 18.015)

Keep every other input at its default and halve the molar mass (g/mol). See how moles responds.

  1. 01New Molar mass (g/mol): 9.0075
  2. 02Baseline Moles: 0.999167
  3. 03New Moles: 1.99833
  4. 04Moles increases by 100% → use this sensitivity to plan for real-world variation.
04 · PATTERN

Molar mass (g/mol) doubled

mm = 36.03 (from 18.015)

Keep every other input at its default and double the molar mass (g/mol). See how moles responds.

  1. 01New Molar mass (g/mol): 36.03
  2. 02Baseline Moles: 0.999167
  3. 03New Moles: 0.499584
  4. 04Moles decreases by 50% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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