Mole Calculator
Start from mass, moles, particles, or gas volume — get all four with steps shown; formula-aware molar mass built in.
💡 The mole is chemistry's currency converter: one quantity in, all four out. Gas volume assumes STP (0 °C, 1 atm → 22.4 L/mol) and only applies to gases.
Amount of substance
1.99833 mol
M = 18.015 g/mol
Mass
36 g
Particles
1.203e+24
Gas @ STP
44.7627 L
Step-by-step working
1. n = mass ÷ M = 36 g ÷ 18.015 g/mol = 1.99833 mol
2. particles = n × Nₐ = 1.99833 × 6.022×10²³ = 1.2034e+24
3. gas volume at STP = n × 22.4 = 44.7627 L (if it's a gas)
🗺️ The mole map — every conversion goes through n
Mass (g)
÷ M → moles · × M ← moles
Moles (n)
the hub
Particles
× Nₐ ← moles · ÷ Nₐ → moles
Gas volume at STP joins the hub too: n × 22.4 L. There is no direct road between mass and particles — every route passes through moles.
⚠️ 22.4 L/mol is the traditional STP (0 °C, 1 atm) used in most Indian textbooks; IUPAC's current STP (1 bar) gives 22.7 L/mol. Use whichever your syllabus prescribes.
🧪One value in, all four out
The mole is chemistry's hub: mass, particle count, and gas volume all convert through it. Tell this calculator any one of the four — mass, moles, particles, or gas volume at STP — plus the substance (type a formula and the molar mass computes itself, or enter M directly), and it returns the other three with the conversion steps written out and the route through the mole map made visible.
📊Everything you'd want to know
- Start from any quantity: grams, moles, particles, or litres of gas at STP.
- Formula-aware: typing H2O sets M = 18.02 automatically (hydrates and brackets included); manual M overrides.
- Every conversion narrated — n = m/M, particles = n × Nₐ, V = n × 22.4 — ready to copy.
- The mole map shows why there's no direct road from mass to particles.
- Honest STP note: 22.4 L/mol (0 °C, 1 atm, the Indian-syllabus standard) vs IUPAC's 22.7.
🧮The maths
Avogadro's number is the bridge between the atomic world and the weighable one: 6.022×10²³ particles per mole, defined so that one mole of a substance weighs its molecular mass in grams.
💡Mole-problem survival kit
- Always convert to moles first — every stoichiometry path runs through n.
- The 22.4 L/mol shortcut applies only to gases at STP — liquids and solids never.
- Check units before dividing: mass in grams, M in g/mol.
- In reaction problems, mole ratios come from the balanced equation — use our Equation Balancer first.
💡 Frequently Asked Questions
How do I convert grams to moles?+
Divide mass by molar mass: n = m ÷ M. For 36 g of water, n = 36 ÷ 18.02 = 2 mol. Type the formula and this calculator finds M itself, then shows the division as a written step.
How many molecules are in one mole?+
6.022 × 10²³ — Avogadro's number. Multiply moles by it for particles: 2 mol of water contains about 1.2 × 10²⁴ molecules. The calculator does this conversion in both directions.
What is the volume of one mole of gas at STP?+
22.4 litres at the traditional STP (0 °C, 1 atm) used by most Indian boards; IUPAC's current definition (1 bar) gives 22.7 L. This applies to gases only — the calculator labels it accordingly.
How do I find the number of moles from particles?+
Divide by Avogadro's number: n = N ÷ 6.022×10²³. Three × 10²³ molecules is about 0.5 mol. Enter the particle count in the particles mode and everything else follows.
Why do all conversions go through moles?+
Because the mole is the defined link between particle counts and gram-scale masses. Mass→particles directly would need both M and Nₐ anyway — moles just makes the middle step explicit, which is also how examiners want the working shown.