Loschmidt’s number

chemistry

Also known as: Loschmidt number

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June 30, 2026

Quick Summary

Loschmidt number refers to the number of molecules within a specific volume of an ideal gas under standard conditions of 0°C and 1 atmosphere. This value is approximately 2.7 x 10¹⁹ molecules per cubic centimeter.1

The concept is named after Austrian physicist Joseph Loschmidt, who made significant contributions to chemistry and physics. Loschmidt was the first to accurately estimate the size of air molecules and the number of molecules in a gram-mole, a quantity now known as the Avogadro constant. His work also advanced the understanding of aromatic hydrocarbons and chemical bonding.2

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Summary of numerical magnitudes
…is often referred to as Loschmidt’s number for this reason. In current English-language scientific literature, Loschmidt’s number is usually taken to mean the number of gas molecules in one cubic centimetre at 0° C and one atmosphere pressure (2.687 × 10¹⁹ molecules per cubic centimetre).
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…is often referred to as Loschmidt’s number for this reason. In current English-language scientific literature, Loschmidt’s number is usually taken to mean the number of gas molecules in one cubic centimetre at 0° C and one atmosphere pressure (2.687 × 10¹⁹ molecules per cubic centimetre).
Read More