Energy Converter

Convert between joules, calories, kilocalories, kilowatt-hours, BTU, and foot-pounds instantly.

Energy Converter

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Value

From Joules Calories (small cal) Kilocalories (food Calories) Kilowatt-hours BTU Foot-pounds

To Joules Calories (small cal) Kilocalories (food Calories) Kilowatt-hours BTU Foot-pounds

Converted value

239.01 cal

The "Calories" on food labels are kilocalories (1,000 small calories) - a common point of confusion.

The formula

Result = Value x (joules per "From" unit) / (joules per "To" unit)

Example

1,000 joules converts to about 239.01 calories, or 0.239 kilocalories, or roughly 0.000278 kilowatt-hours.

Step-by-step guide

1. Enter the value you want to convert.
2. Choose the "from" and "to" units.
3. Read the converted result.

Why "Calories" on food labels aren't the same as scientific calories

This is a genuinely common point of confusion: the "Calories" printed on nutrition labels (with a capital C) are actually kilocalories - 1,000 times larger than the small calorie (lowercase c) used in chemistry and physics. A food item listing "200 Calories" contains 200,000 small calories, or about 836,800 joules. This calculator clearly separates the two so you can convert accurately in either context.

Common mistakes

Confusing food Calories (kilocalories) with scientific calories - a factor-of-1,000 error that matters a lot for nutrition-related calculations.

Mixing up kWh (a unit of energy, what your electric bill charges for) with kW (a unit of power/rate) - they're related but not interchangeable without also knowing the time duration involved.

Frequently asked questions

What's a kilowatt-hour, in simple terms?

It's the energy used by a 1,000-watt device running for one hour - it's the standard unit electric utilities use for billing, since it directly ties power draw to time.

What is a BTU used for?

BTU (British Thermal Unit) is commonly used to describe heating and cooling capacity in HVAC systems - see our BTU Calculator for estimating the heating/cooling capacity a room needs.

How is energy different from power?

Energy is a total quantity (like joules or kWh), while power is a rate - energy used or produced per unit of time (like watts). See our Power Converter for converting between power units specifically.

Related calculators

See the full list of Converters, or try:

• Power Converter
• BTU Calculator