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To convert from calorie (cal) to Joule (J), use the following formula:
With is the ratio between the base units Joule (J) and calorie (cal).
Let's convert 5 calorie (cal) to Joule (J).
Using the formula:
Therefore, 5 calorie (cal) is equal to Joule (J).
Here are some quick reference conversions from calorie (cal) to Joule (J):
| calories | Joules |
|---|---|
| 0.000001 cal | J |
| 0.001 cal | J |
| 0.1 cal | J |
| 1 cal | J |
| 2 cal | J |
| 3 cal | J |
| 4 cal | J |
| 5 cal | J |
| 6 cal | J |
| 7 cal | J |
| 8 cal | J |
| 9 cal | J |
| 10 cal | J |
| 20 cal | J |
| 30 cal | J |
| 40 cal | J |
| 50 cal | J |
| 100 cal | J |
| 1000 cal | J |
| 10000 cal | J |
For all Energy converters, choose units using the From/To dropdowns above.
At its core, a calorie (cal) is a fundamental unit of energy.
While we often talk about "calories" in our food, it's essential to understand precisely what they represent.
Have you ever noticed the term "calorie" on a nutrition label? What you're actually looking at is a kilocalorie (kcal).
One kilocalorie (or "food calorie") is equal to 1,000 of the smaller, scientific calories.
The scientific definition of a single, "small" calorie (cal) is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius.
Knowing this difference is key to accurate calorie counting and managing your energy intake for your health and fitness goals.
Scientists use two primary methods to determine the number of calories in food:
The Bomb Calorimeter: This is the most precise method. It involves an instrument that measures the total heat released when a food sample is burned completely.
The Atwater System: This is a more common and practical method. It calculates the total energy by using average values: 4 calories per gram for carbohydrates and proteins, and 9 calories per gram for fats.
Calories aren't just for food—they are a universal measure of energy. Anything that stores and releases energy has a calorie value.
For example, you might be surprised to learn that a single gallon of gasoline contains over 31 million calories!
This shows that a calorie is simply a standard unit for potential energy, whether it's fueling your body or powering a car.
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.