Connect mass, moles, and entities
The mole calculator provides two common routes to amount of substance. Choose mass and molar mass when a sample has been weighed, or choose entity count when atoms, molecules, ions, or formula units are known. The result always reports moles and the equivalent number of named entities. Keeping the entity label visible matters because one mole of molecules and one mole of atoms contain the same number of counting objects but can represent different total atoms and masses.
Calculate moles from sample mass
For the mass route, use n = m/M. Grams divided by grams per mole leave moles. A sample mass of 18.015 g with a molar mass of 18.015 g/mol represents 1 mol. The molar mass must belong to the same substance and chemical form as the sample. Hydrates, isotope-labelled compounds, salts, mixtures, and impure reagents may require a different value or an additional correction rather than the shortest familiar formula.
Calculate moles from particle count
For the entity route, use n = N/NA with the exact Avogadro constant 6.02214076 × 10²³ mol−1. Dividing that exact number of named entities returns 1 mol. The page accepts scientific notation because laboratory-scale counts are often extremely large. If a problem asks for atoms inside molecules, the molecule count must be multiplied by the formula subscripts in a second step; the entity conversion alone does not infer chemical composition.
Verify both conversion paths
Multiply the mole result by molar mass to reverse the mass path, or multiply it by the Avogadro constant to reverse the entity path. The original value should return within display rounding. For a mole amount near one, the entity count should be near 10²³. Zero mass or zero entities correctly gives zero moles, but a zero molar mass is invalid. Keep significant figures from the measured quantity even though the Avogadro constant itself is exact.
Counting scope and private calculation
The calculator does not identify a substance, calculate its molar mass from a name, determine concentration, predict reaction yield, or decide which reactant is limiting. It performs the relationship selected by the user and relies on the stated entity definition. A copied answer should retain the entity label and chemical identity so the number is not reused with a different counting basis. Laboratory decisions require verified substance data and appropriate procedures.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.