What is a kilowatt-hour (kWh)?

A kilowatt-hour is the energy delivered by 1 kilowatt of power over 1 hour, equal to exactly 3,600,000 joules (3.6 MJ). It is the standard unit for electricity billing.

What is the difference between a calorie and a Calorie (kcal)?

The 'food Calorie' (capital C) used on nutrition labels is actually a kilocalorie (kcal): 1 kcal = 1,000 cal = 4,184 J.

How many joules are in a BTU?

1 International Table BTU (BTU_IT) equals 1,055.05585262 joules. It is widely used in HVAC and US heating/cooling specifications.

What is an electronvolt (eV) used for?

The electronvolt is a tiny energy unit used in atomic, nuclear and particle physics. 1 eV = 1.602176634 × 10⁻¹⁹ joules (CODATA exact value).

Energy Converter

Free energy unit converter. Convert between J, kJ, MJ, cal, kcal, Wh, kWh, BTU, ft·lb and eV with NIST-grade precision.

Convert between joules, calories, kWh, BTU, electronvolts and more.

E_{t o} = E_{f r o m} \times \frac{f _{f r o m}}{f _{t o}}

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