Energy Converter
Joules vs. Calories: The Great Confusion
Energy comes in many forms—heat, electricity, movement, and food. Because different scientists discovered these at different times, we ended up with different units for everything.
The biggest source of confusion is the word "Calorie."
• small calorie (cal): Used in chemistry. The energy to heat 1 gram of water by 1°C.
• Food Calorie (kcal): Used on nutrition labels. It is equal to 1,000 small calories.
If a candy bar label says "200 Calories" (capital C), it actually contains 200,000 physics calories (cal). Our converter distinguishes between "Gram Calories" (cal) and "Food Calories" (kcal) to ensure your math is right.
Electricity: Joules and Kilowatt-hours
In the metric system (SI), the standard unit of energy is the Joule (J). However, a Joule is extremely small. It takes about 100 Joules just to lift an apple one meter in the air.
Because a house uses billions of Joules a month, utility companies use the Kilowatt-hour (kWh).
- 1 kWh = 3,600,000 Joules
Seeing "3.6 Million Joules" on your electric bill would be scary, so they shorten it to "1 kWh."
Heating & Cooling: What is a BTU?
If you are buying an Air Conditioner in the US or UK, you will see it rated in BTUs (British Thermal Units). This is an old imperial unit representing the energy required to heat one pound of water by 1°F.
Common conversion: 12,000 BTU is generally referred to as a "1-Ton" AC unit.
Unit Comparison Cheat Sheet
| Unit | Joules Equivalent (Approx) | Typical Use |
|---|---|---|
| 1 Joule | 1 J | Physics class (SI Base Unit) |
| 1 Calorie (cal) | 4.18 J | Chemistry labs |
| 1 BTU | 1,055 J | Heaters / AC Units |
| 1 Food Calorie (kcal) | 4,184 J | Diet & Nutrition |
| 1 kWh | 3,600,000 J | Home Electricity Bills |