Energy Converter
Convert energy between joules, kilocalories, BTU, kilowatt-hours, electron volts, and foot-pounds. Calculate electricity cost from energy used and compare energy equivalents.
Converted Value
—
In Joules —
Extended More scenarios, charts & detailed breakdown ▾
Result
—
Professional Full parameters & maximum detail ▾
W
hrs
Energy
Energy Used (kWh) —
Energy in BTU —
Energy in kJ —
Cost & Equivalents
Electricity Cost —
Therms in Joules —
Physical Equivalent —
How to Use This Calculator
- Enter the energy value and select From unit.
- Select the To unit and click Calculate.
- Use All Units to see your value converted to all 6 common energy units simultaneously.
- Use Common Equivalents to see what 1 kWh equals in BTU, kcal, and joules.
- Use the Professional tab to calculate energy from power × time and find electricity cost.
Formula
Conversion via joules: Value × (J per unit from) ÷ (J per unit to)
Key factors: 1 kWh = 3,600,000 J | 1 BTU = 1,055.06 J | 1 kcal = 4,184 J | 1 cal = 4.184 J
Example
Example: 1 kWh → BTU = 3,600,000 ÷ 1,055.06 = 3,412 BTU. 1 kWh → kcal = 3,600,000 ÷ 4,184 = 860.4 kcal.
Frequently Asked Questions
- 1 kilowatt-hour (kWh) = 3,600,000 joules (3.6 MJ). This is the unit used on electricity bills. 1 kWh = 3,412 BTU = 860 kcal.
- 1 kWh = 3,412.14 BTU. This conversion is important for comparing electrical energy costs with heating fuel costs.
- A calorie (cal) is the energy to raise 1g of water by 1°C. A kilocalorie (kcal) = 1,000 calories. Food "Calories" (capital C) are actually kilocalories. 1 kcal = 4,184 joules.
- A British Thermal Unit (BTU) is the energy needed to raise 1 pound of water by 1°F. 1 BTU = 1,055.06 joules. BTUs are used to rate heating and cooling equipment.
- Multiply kWh used by your electricity rate ($/kWh). Example: A 1,500W heater running 8 hours uses 12 kWh. At $0.13/kWh, cost = 12 × 0.13 = $1.56.