How Many Joules Are in a Kilocalorie?
Explore Kilocalorie
Convert joules, kilocalories, kilowatt-hours, BTUs, and more with our free energy converter. Essential for nutrition tracking, electricity bills, physics homework, and engineering calculations.
How it works
Energy units span a wide range. 1 food calorie (kcal) = 4,184 joules. 1 kWh = 3,600,000 joules — this is what your electricity meter counts. BTUs are used to rate heating and cooling equipment in the US.
Quick reference
Frequently Asked Questions
How many joules are in a calorie?
1 calorie (thermochemical) equals 4.184 joules. The food calorie (kilocalorie) equals 4,184 joules or 4.184 kJ.
What is the difference between a calorie and a kilocalorie?
A food calorie (written as "Calorie" with a capital C or "kcal") equals 1,000 small calories. Nutrition labels use kilocalories (kcal).
How many kJ are in 1 kcal?
1 kilocalorie (kcal) equals 4.184 kilojoules (kJ). Both are commonly used in nutrition: kcal in the US, kJ in Australia and many other countries.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is the energy used by a 1,000-watt appliance running for 1 hour. It equals 3,600,000 joules (3.6 MJ) and is the standard unit on electricity bills.
What is a BTU?
A British Thermal Unit (BTU) is the energy needed to heat 1 pound of water by 1°F. 1 BTU equals approximately 1,055 joules. BTUs are used to rate air conditioners and heating systems.
How much energy does a household use per day?
The average US household uses about 30 kWh (kilowatt-hours) of electricity per day, or about 900 kWh per month. European households use less — a typical German household averages about 10–12 kWh per day. In joules, 1 kWh = 3,600,000 J (3.6 MJ).
How many calories are in common foods?
Approximate food energy values: an apple ≈ 80 kcal, a slice of bread ≈ 80 kcal, a chicken breast (150 g) ≈ 165 kcal, a chocolate bar (50 g) ≈ 250 kcal, a Big Mac ≈ 550 kcal. Daily intake recommendations are typically 2,000 kcal for women and 2,500 kcal for men.
How much energy does a 60W light bulb use in a day?
A 60-watt bulb running for 8 hours uses 60 W × 8 h = 480 Wh = 0.48 kWh. An equivalent LED bulb at 8–9 watts uses about 64–72 Wh for the same light output — roughly 85% less energy. In joules: 0.48 kWh = 1,728,000 J (1.73 MJ).
How much energy is in a AA battery?
A standard AA alkaline battery stores about 3,000–3,500 mAh at 1.5V, which is roughly 16,000–19,000 joules (4.5–5.3 Wh). For comparison, a typical smartphone battery holds 10,000–15,000 J (2.8–4.2 Wh). A AA battery powers a TV remote for 6–12 months of normal use.
How much energy does a car engine produce?
A typical family car engine produces 100–150 kW (134–201 hp) of peak power. At highway cruising speed, it uses about 15–25 kW continuously. In energy terms, gasoline contains about 32 MJ per liter (8.6 kWh/L). A full 50-liter tank holds about 1,600 MJ of chemical energy, though engines convert only 20–35% of that into motion.