NUM8ERS Tutoring Center Dubai logo – you can count on us
Book Now
Sign In

⚡ Energy Conversion Calculator 2026

Convert between 90+ energy units — Joules, BTU, kWh, Calories, and more

1 joule = 0.000948 BTU
Formula: value × 0.000948

📊 All Conversions

Common Energy Conversions

From To Multiply by
1 kWh Joules 3,600,000
1 kWh BTU 3,412.14
1 BTU Joules 1,055.06
1 Calorie (food) Joules 4,184
1 calorie (small) Joules 4.184
1 therm BTU 100,000
1 eV Joules 1.602×10⁻¹⁹
1 horsepower-hour Joules 2,684,520

Understanding Energy Units

⚡ Joule (J)

The SI unit of energy. 1 joule = 1 watt-second = 1 Newton-meter. Named after James Prescott Joule. Used in physics and engineering worldwide.

🔥 BTU

British Thermal Unit — energy to raise 1 lb of water by 1°F. Common in HVAC, heating, and US energy ratings. 1 BTU ≈ 1,055 joules.

🔌 Kilowatt-hour

kWh is standard for electricity billing. 1 kWh = 3.6 MJ = 3,412 BTU. Measures energy consumed over time (power × time).

🍎 Calorie

Small calorie (cal): raises 1g water by 1°C. Large Calorie (kcal): food energy = 1,000 small calories. 1 kcal = 4,184 J.

Frequently Asked Questions

How do I convert energy units?
Use our calculator above: enter a value, select source and target units. The formula is Result = Value × (FromFactor ÷ ToFactor). All units convert through joules as the base unit.
How do I convert joules to BTU?
Divide by 1,055.06. Formula: BTU = Joules ÷ 1,055.06. Example: 10,000 J = 9.48 BTU. Or multiply by 0.000948.
How do I convert BTU to joules?
Multiply by 1,055.06. Formula: Joules = BTU × 1,055.06. Example: 100 BTU = 105,506 J ≈ 105.5 kJ.
How do I convert kWh to joules?
Multiply by 3,600,000. Formula: J = kWh × 3,600,000. This is because 1 kWh = 1,000 W × 3,600 seconds = 3.6 MJ.
How do I convert calories to joules?
Small calorie: Multiply by 4.184. Food Calorie (kcal): Multiply by 4,184. Example: 100 kcal = 418,400 J = 418.4 kJ.
What is the difference between calorie and Calorie?
Small calorie (cal): energy to heat 1g of water by 1°C. Large Calorie (Cal or kcal): food energy = 1,000 small calories. Food labels use kcal.
What is a BTU?
British Thermal Unit — the energy needed to raise 1 pound of water by 1°F at sea level. Used in HVAC, heating, and appliance ratings (especially in USA).
How many BTU in a kWh?
1 kWh = 3,412.14 BTU. This is useful for comparing electric and gas heating costs. To convert kWh to BTU, multiply by 3,412.
What is an electronvolt (eV)?
Electronvolt is energy gained by one electron accelerated through 1 volt. 1 eV = 1.602×10⁻¹⁹ joules. Used in atomic/nuclear physics. 1 MeV = 10⁶ eV.
What is a therm?
1 therm = 100,000 BTU = 105.5 MJ. Used for natural gas billing. A dekatherm = 10 therms. Common in US energy industry.
How do I convert horsepower-hours to joules?
Multiply by 2,684,520. 1 hp·h = 2.685 MJ = 0.7457 kWh. Used for mechanical energy output over time.
What is a quad (Q)?
Quad = 10¹⁵ BTU = 1.055 exajoules. Used for national/global energy statistics. US uses ~100 quads/year total energy.
How do fuel energy equivalents work?
Fuel units express energy content of specific fuels. Example: 1 gallon of gasoline ≈ 120 MJ ≈ 33.4 kWh. Varies by fuel type and grade.
What is tonne of oil equivalent (toe)?
1 toe = 41.868 GJ = 11,630 kWh. Standard for comparing different fuels. 1 tonne of coal equivalent (tce) = 29.3 GJ.
Why are there different calorie definitions?
Different reference temperatures: 15°C calorie, IT calorie (international), thermochemical calorie. Differences are small (~0.1%). IT calorie is most common.
What is a watt-second?
1 watt-second = 1 joule exactly. Power (watts) × time (seconds) = energy (joules). Similarly, watt-hour = 3,600 joules.
How accurate is this energy converter?
Uses precise conversion factors from NIST and international standards. Results shown with appropriate precision. For critical applications, verify with official standards.