that allow comparison of ring strains are obtained by measuring per methylene group (CH₂) of the molar heat of combustion in the cycloalkanes.

:_combustion per CH₂ − 658.6 kJ = strain per CH₂

The value 658.6 kJ per mole is obtained from an unstrained long-chain alkane.

Cycloalkanes generally have less ring strain than cycloalkenes, which is seen when comparing cyclopropane and cyclopropene.

Angle strain in alkenes

Cyclic