ISO 15550 establishes the framework for ISO engine power measurement standards. It specifies standard reference conditions and methods of declaring the power, fuel consumption, lubricating oil consumption and test methods for internal combustion engines in commercial production using liquid or gaseous fuels.

ISO 15550 applies to reciprocating internal combustion engines (spark-ignition or compression-ignition engines) but excluding free piston engines rotary piston engines. These engines may be naturally aspirated or pressure-charged either using a mechanical pressure-charger or turbocharger.

ISO 15550 applies to engines used for land, rail-traction and marine use; the propulsion of automotive vehicles; motorcycles; the propulsion of agricultural tractors and machines; the propulsion of earth-moving machinery; the propulsion of recreational craft or other small marine craft up to 24 m hull length.

It may be applied to engines used to propel road construction machines, industrial trucks and for other applications where no suitable International Standard for these engines exists. It may also be applied to tests performed both on a test bed at a manufacturer's works as well as on site.