Energy Converter
This energy converter turns any amount of energy into another unit instantly, moving between joules (J), kilojoules (kJ), calories (cal), kilocalories (kcal), watt-hours (Wh), kilowatt-hours (kWh) and British thermal units (BTU). Load the amount, state which unit you have it in and which one you want, and the converter recalculates without delay: just as handy for finding out how many kJ the kcal on a label are as for turning the kWh on your bill into BTU or joules.
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How it works
Each unit is pinned to the joule, so a nutrition label and an electricity bill end up on the same scale. Picture a chocolate bar marked 250 kcal: to read it in the kilojoules European packaging prints, the tool turns your figure into joules first (250 × 4184 = 1,046,000 J) and then divides by the target factor (÷ 1000 = 1046 kJ). The very same route handles a meter reading — a fridge that draws 0.4 kWh becomes 0.4 × 3,600,000 = 1,440,000 J, or about 344 kcal of heat. The factors are fixed (1 kJ = 1000 J, 1 kcal = 4184 J, 1 Wh = 3600 J, 1 kWh = 3,600,000 J, 1 BTU = 1055.06 J), which is what keeps a snack and a power bill perfectly comparable.
Common energy conversions at a glance
From a single snack to a full day of eating, here is how everyday calorie figures line up with kilojoules and the kilowatt-hours your electricity meter counts. Food labels use kcal (what most people simply call a "Calorie") or kJ; the last column shows that same energy the way a power company would bill it.
| kcal | kJ | kWh |
|---|---|---|
| 50 | 209.2 | 0.058 |
| 100 | 418.4 | 0.116 |
| 200 | 836.8 | 0.232 |
| 250 | 1046 | 0.291 |
| 300 | 1255.2 | 0.349 |
| 500 | 2092 | 0.581 |
| 600 | 2510.4 | 0.697 |
| 800 | 3347.2 | 0.930 |
| 1000 | 4184 | 1.162 |
| 1500 | 6276 | 1.743 |
| 2000 | 8368 | 2.324 |
| 2500 | 10460 | 2.906 |
| 3000 | 12552 | 3.487 |
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Preguntas frecuentes
- What is the difference between a calorie and a kilocalorie?
- A kilocalorie (kcal) is 1000 calories. Nutrition labels usually write "Calories" with a capital C, but they actually mean kilocalories. So a 200 "Calorie" snack is 200 kcal, which is 200000 small calories.
- How many joules are in 1 kWh?
- 1 kilowatt-hour equals exactly 3600000 joules (3.6 MJ). That is because 1 kWh is 1000 watts sustained for 3600 seconds, and 1 watt for 1 second is 1 joule.
- How many kcal are in 1 kJ?
- 1 kilojoule equals about 0.239 kilocalories. Since 1 kcal is 4.184 kJ, dividing 1 by 4.184 gives 0.239 kcal. To go the other way, multiply kcal by 4.184 to get kJ.
- What is a BTU?
- A British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit. It equals 1055.06 joules and is common in heating, air-conditioning and gas appliance ratings.
- How do I convert food kJ to Calories?
- Divide the kilojoules by 4.184. For example, a food listing 837 kJ has 837 ÷ 4.184 = about 200 Calories (kcal). Many labels show both values side by side.
- How much energy is a 2000-Calorie diet in kJ?
- A 2000 kcal daily intake equals 2000 × 4.184 = 8368 kJ, roughly 8.37 MJ. That is the same amount of energy an appliance would draw as 2.32 kWh, since 8368 kJ ÷ 3600 = 2.324 kWh — a neat way to picture a full day of food as an electricity figure.
- How much energy does a 2000 W heater use in one hour?
- Running 2000 watts for one hour uses 2 kWh, which is 7,200,000 J (7.2 MJ). Expressed as heat that is about 1721 kcal — more than a whole meal. To go from kWh to joules, multiply by 3,600,000.