Surface power density has the dimension mass per time cubed. The SI composite unit of surface power density is the watt per square meter.

Maple knows the units of surface power density listed in the following table.

An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively.  Refer to a unit in the Units package by indexing the name or symbol with the context, for example, langley[power]; or, if the context is indicated as the default, by using only the unit name or symbol.

The unit of surface power density is defined as follows.

A power langley is defined as a thermochemical calorie per square centimeter minute.