Power density

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Power density
SI unitW/m3
In SI base unitskg·m−1s−3
Derivations from
other quantities

Power density is the amount of power (time rate of energy transfer) per unit volume.[1]It is typically measured in watts per cubic meter (W/m³) and represents how much power is distributed within a given space. In various fields such as physics, engineering, and electronics, power density is used to evaluate the efficiency and performance of devices, systems, or materials by considering how much power they can handle or generate relative to their size or volume.[2]

In energy transformers including batteries, fuel cells, motors, power supply units, etc., power density refers to a volume, where it is often called volume power density, expressed as W/m3.

In reciprocating internal combustion engines, power density (power per swept volume or brake horsepower per cubic centimeter) is an important metric, based on the internal capacity of the engine, not its external size.


Storage material Energy type Specific power (W/kg) Power density (W/m3)
Hydrogen (in star) Stellar fusion 0.00184 276.5
Plutonium Alpha decay 1.94 38,360
Supercapacitors Capacitance up to 15000 Variable
Lithium-ion Chemical ~250–350 ~700

See also[edit]


  1. ^ Jelley, N. A. (Nicholas Alfred), 1946-. A dictionary of energy science. Oxford. ISBN 978-0-19-182627-6. OCLC 970401289.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  2. ^ "Power density - Energy Education". energyeducation.ca. Retrieved 2024-01-25.