Energy Calculator
Calculate energy consumption and convert between energy units
Energy Calculator
Calculate energy consumption from power and time (E = P × t), or convert between different energy units such as joules, kilowatt-hours, calories, BTU, electronvolts, and more.
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🧮 Energy Calculator
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🔄 Energy Unit Converter
Convert between different units of energy.
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📋 Common Energy Consumption Reference
| Activity / Device | Power (W) | Time | Energy (kWh) |
|---|---|---|---|
| 💡 LED Light Bulb | 10 | 8 hours | 0.08 |
| 💻 Laptop Computer | 65 | 8 hours | 0.52 |
| 📺 Television (55") | 120 | 4 hours | 0.48 |
| ❄️ Refrigerator | 150 | 24 hours | 3.60 |
| 🧹 Vacuum Cleaner | 1,200 | 30 min | 0.60 |
| 🔥 Space Heater | 1,500 | 4 hours | 6.00 |
| 🌀 Central A/C | 3,500 | 8 hours | 28.00 |
| 👕 Clothes Dryer | 5,000 | 1 hour | 5.00 |
| ⚡ Electric Oven | 2,500 | 1 hour | 2.50 |
| 📱 Smartphone Charging | 5 | 2 hours | 0.01 |
📚 Understanding Energy
What is Energy?
Energy is the capacity to do work. In physics, it is measured in joules (J). Energy can take many forms including kinetic, potential, thermal, electrical, chemical, and nuclear. Energy can be converted from one form to another but cannot be created or destroyed (law of conservation of energy).
Energy vs Power
Power is the rate at which energy is produced or consumed. Energy equals power multiplied by time (E = P × t). For example, a 100-watt light bulb running for 10 hours uses 1,000 watt-hours (1 kWh) of energy. Power is measured in watts; energy is measured in joules or watt-hours.
Kilowatt-Hours (kWh)
The kilowatt-hour (kWh) is the most common unit for measuring electrical energy consumption. It is equal to 3,600,000 joules or 3,412 BTU. Electricity bills are typically measured in kilowatt-hours, making it the standard unit for household energy usage.
Energy Unit Conversions
There are many units for measuring energy, each commonly used in different fields and contexts.
Joule (J)
The SI unit of energy. One joule is equal to the energy transferred when a force of one newton moves an object one meter. 1 J = 1 N·m = 1 kg·m²/s².
Calorie (cal) / Kilocalorie (kcal)
The calorie is the energy needed to raise the temperature of 1 gram of water by 1°C. Food calories (Calories) are actually kilocalories. 1 cal = 4.184 J; 1 kcal = 4,184 J.
British Thermal Unit (BTU)
The energy needed to raise the temperature of 1 pound of water by 1°F. Commonly used in heating and cooling systems. 1 BTU = 1,055.06 J.
Electronvolt (eV)
The energy gained by an electron moving through a potential difference of 1 volt. Used in particle physics and atomic-scale processes. 1 eV = 1.602 × 10⁻¹⁹ J.
Quick Conversion Reference
Kilowatt-hour to joule
Kilowatt-hour to BTU
Kilocalorie to joule
BTU to joule