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energy · International · Modern

joule

Jexact
Record
M029
Definition quality
Standardized
Conversion mode
multiplicative
Calculator
Fully calculable

Etymology/person-name origin not separately researched unless stated by standards history; current definition/conversion resolved.

Definition

SI derived unit of energy and work; 1 J = 1 N·m = 1 kg·m²·s⁻².

Reference value

One joule is equal to 1 joule.

History & use

The joule was defined in the international MKS electrical/mechanical system and the 1948 CGPM adopted joule as the unit for quantity of heat.

Modern use

Standard SI unit for energy, work, and heat.

Did you know?

Torque and energy share the same base dimensions, but SI convention uses newton-metre for torque rather than joule.

Sources & evidence

Source tier Tier A · confidence High

Related measurements

calorie

cal

energy · International · Modern / historical

The generic calorie is variant-dependent; NIST lists thermochemical, International Table, mean, 15 °C, and 20 °C calories.

variant

kilocalorie

kcal

energy · International · Modern / historical

A kilocalorie is 1000 calories, so its joule value depends on the calorie convention.

variant

British thermal unit

Btu

energy · International · Modern / historical

British thermal unit is variant-dependent; NIST lists IT, thermochemical, mean, and temperature-specific forms.

variant

electronvolt

eV

energy · International · Modern / historical

Non-SI unit accepted for use with the SI; 1 eV = exactly 1.602176634×10⁻¹⁹ J.

kilowatt-hour

kW·h

energy · International · Modern

1 kWh = exactly 3.6×10^6 J.