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To convert from Joule (J) to Watt-second (Ws), use the following formula:
To convert from Joule (J) to Watt-minute (Wm), use the following formula:
To convert from Joule (J) to Watt-hour (Wh), use the following formula:
To convert from Joule (J) to Milliwatt-hour (mWh), use the following formula:
To convert from Joule (J) to Kilowatt-hour (kWh), use the following formula:
To convert from Joule (J) to Megawatt-hour (MWh), use the following formula:
To convert from Joule (J) to Gigawatt-hour (GWh), use the following formula:
To convert from Joule (J) to Kilojoule (kJ), use the following formula:
To convert from Joule (J) to Megajoule (MJ), use the following formula:
To convert from Joule (J) to Gigajoule (GJ), use the following formula:
To convert from Joule (J) to calorie (cal), use the following formula:
With is the ratio between the base units calorie (cal) and Joule (J).
To convert from Joule (J) to Kilocalorie (kcal), use the following formula:
With is the ratio between the base units calorie (cal) and Joule (J).
The joule (J), as part of the International System of Units (SI), is a fundamental unit used to measure energy.
Whether you're discussing the electricity that powers your home, the work done by a machine, or the energy you get from food, the joule is the universal standard.
Key Takeaways:
A joule (J) represents the amount of work done when a force of one newton moves an object by one meter.
This is formally expressed as:
1 J = 1 N·m
To make that simpler, think of it this way: lifting a small apple (which weighs about one newton) one meter straight up requires about one joule of energy.
This direct link between force, distance, and energy makes the joule a cornerstone unit in physics and engineering.
It's easy to mix up joules and watts, but the key difference is time.
Specifically, one watt is equal to one joule of energy transferred per second (1 W = 1 J/s).
For example, a 100-watt light bulb uses 100 joules of electrical energy every second it is on.
While many food labels use calories (specifically kilocalories, or kcal), the official SI unit for food energy is the joule.
The conversion is straightforward:
1 food calorie (kcal) ≈ 4,184 joules or 4.184 kilojoules (kJ)
Using joules and kilojoules (kJ) provides a universal, scientific standard for measuring the energy we get from food. This is why you will often see "kJ" on nutrition labels in many parts of the world.