Convert between mass, moles, and particles using Avogadro's constant (NA = 6.02214076 × 1023 mol-1). Includes substance presets, substance database, and step-by-step working.
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Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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Avogadro’s number is the exact count of elementary entities in one mole: 6.02214076 × 10²³ mol⁻¹, one of the seven defining constants of the International System of Units since 2019 . It is the bridge between a weighable mass and a countable number of atoms, molecules, ions, or formula units.
The constant has no uncertainty. That’s a recent change. Before 2019, the mole was tied to the mass of carbon-12, and Avogadro’s number was measured with an error bar. Now it’s fixed, just like the speed of light. The IUPAC Gold Book defines the mole by this exact number, and the BIPM SI Brochure lists it among the defining constants. For everyday lab work the practical difference is small, but at four or more significant figures it matters. The linked-field design of this calculator means you never have to decide which conversion to apply first, the tool handles the order based on your source field.
Click into any one of the three linked fields and type a positive number. The other two fields fill in automatically. You don’t choose a mode or press a calculate button.
Select a substance preset, or leave it on Water and type a custom molar mass in g/mol.
Click into the moles, mass, or particles field. The one you click gets a red border.
Type a positive value. The field you’re editing shows a “source” badge.
Watch the other two fields populate with converted values as you type.
Scan the hero panel for the particle count in scientific notation, then check the breakdown table for the formula used at each step.
Every conversion passes through moles. If you type into mass, the tool divides by molar mass to get moles, then multiplies by Avogadro’s constant to get particles. If you type into particles, it runs the same path in reverse.
Formula: N = n × N_A
Formula: n = m / M
Formula: m = n × M
N is the particle count, n is moles, m is mass in grams, M is molar mass in g/mol, and N_A is 6.02214076 × 10²³ mol⁻¹. The calculator accepts scientific notation in every linked field, so 6.022e23 and 6.022 × 10^23 both parse. It rounds displayed values to four decimal places by default and keeps full precision internally; you can change the display precision up to eight decimal places. It does not support unit switching. Molar mass must be in g/mol, mass in grams, and particle count as a dimensionless number. If the molar mass field is invalid, the moles and particles fields still update, but mass shows N/A and the verdict banner tells you what’s missing.
Suppose you have 36.03 g of water and need the molecule count. Click into the mass field and type 36.03. The molar mass is already set to 18.015 g/mol from the Water preset. The tool divides 36.03 by 18.015 to get 2.000 mol, then multiplies by Avogadro’s constant. The moles field updates to 2.0000, and the particles field to 1.2044e+24. The hero panel shows 1.2044 × 10²⁴ particles.
Now click into the moles field and change it to 0.5000. The mass drops to 9.0075 g, and the particle count drops to 3.0111 × 10²³. The source badge moves to moles. Same three quantities, different starting point, no mode change required. The step-by-step table reflects the new path: mass = n × M ran first, then N = n × N_A.
The linked-field design matches workflows where the starting quantity shifts from one task to the next. A lab tech might weigh a solid on Monday and prepare a molecule-count standard on Tuesday. The same tool covers both without a mode reset.
A compounding pharmacist converting a weighed lipid mass to a molecule count for a nanoparticle formulation uses Avogadro’s number after dividing by molar mass. A quality-control analyst checking a batch record against a specification written in formula units can type the mass and read the particle count directly. Molar quantities appear constantly in pharmacy because “0.01 mol per litre” is easier to handle than the raw particle count per litre .
An analyst preparing a calibration standard often starts with a target concentration in moles per litre, then weighs the solid. The linked fields let them type the moles, read the required mass, and adjust the balance without re-entering the substance. A typical standard might call for 2.50 × 10⁻⁴ mol of potassium dichromate; the mass field returns the amount to weigh.
Students rotating through experiments meet problems phrased as masses one week and particle counts the next. A linked calculator removes the mode-selection step and keeps attention on the conversion logic. An instructor can demonstrate that 0.500 mol of sucrose is 171.15 g and 3.011 × 10²³ molecules by typing any one of those values and watching the other two follow.
Researchers converting mass loss to atom count in thermogravimetric analysis move between the balance reading and the number of atoms removed. The exact Avogadro constant matters when the mass change is small and the atom count is the reported quantity. A 0.001 g mass loss in a metal sample translates to a specific atom count only if the constant is treated as exact.
This table lists molar masses for substances in the calculator’s preset database. Values are calculated from IUPAC 2021 standard atomic weights and rounded to three decimal places.
| Substance | Molar mass (g/mol) |
|---|---|
| Water (H₂O) | 18.015 |
| Carbon dioxide (CO₂) | 44.010 |
| Sodium chloride (NaCl) | 58.440 |
| Glucose (C₆H₁₂O₆) | 180.156 |
| Sucrose (C₁₂H₂₂O₁₁) | 342.297 |
| Ethanol (C₂H₅OH) | 46.069 |
| Hydrogen gas (H₂) | 2.016 |
| Oxygen gas (O₂) | 31.998 |
| Nitrogen gas (N₂) | 28.014 |
| Methane (CH₄) | 16.043 |
| Ammonia (NH₃) | 17.031 |
| Iron (Fe) | 55.845 |
Exactly 6.02214076 × 10²³ elementary entities. That number is the Avogadro constant expressed in mol⁻¹, fixed by the 2019 SI definition. The entities can be atoms, molecules, ions, or formula units.
It’s the number of things in a mole. A dozen means 12; a mole means 6.02214076 × 10²³. The linked calculator uses it to convert between particle count and moles without a mode switch.
Type the mass into the mass field. The calculator divides by molar mass to get moles, then multiplies by Avogadro’s number to get molecules. The moles and particles fields update automatically.
Since 20 May 2019, the Avogadro constant is one of the seven defining constants of the SI, with the exact value 6.02214076 × 10²³ mol⁻¹ and no uncertainty. The mole is defined by fixing this number, not by a physical artifact .
About 3.34 × 10²² molecules. Type 1 into the mass field with Water selected; the calculator returns approximately 0.0555 mol and 3.34 × 10²² molecules.
Avogadro’s number converts moles to particles and is the same for every substance. Molar mass converts moles to grams and is different for each substance. The linked fields apply both in sequence, depending on which field you edit.
Yes. For ionic compounds, the “particle” is a formula unit. One mole of NaCl contains 6.022 × 10²³ formula units, not individual NaCl molecules.
1 mole of O₂ molecules contains 6.022 × 10²³ molecules. Because each molecule has two oxygen atoms, it contains 1.204 × 10²⁴ oxygen atoms. The calculator reports molecule count, not atom count, so multiply by atoms per molecule if you need atoms.
The calculator divides by Avogadro’s number to get moles, then multiplies by molar mass to get mass. The source badge moves to the particles field. You don’t need to change any settings.
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