Energy Conversion Calculator

The Energy Conversion Calculator converts any energy value between 14 units — from everyday units like kilocalories (kcal) and kilowatt-hours (kWh) to scientific ones like electron volts (eV) and physics staples like joules (J) and BTU. Enter your Value to Convert, then select your From Unit and To Unit to get the Converted Value, plus the exact Conversion Factor and result in Scientific Notation.

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Conversion Factor

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Scientific Notation

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Frequently Asked Questions

What is the difference between calories and kilocalories?

A kilocalorie (kcal) is equal to 1,000 calories. The 'calories' listed on food labels are actually kilocalories. One food calorie equals 4,186.8 joules.

How do you convert joules to calories?

To convert joules to calories, divide by 4.184. For example, 1,000 joules equals approximately 239.0 calories. This uses the thermochemical calorie definition.

What is the relationship between BTU and joules?

One British Thermal Unit (BTU IT) equals 1,055.06 joules. BTU is commonly used in heating and cooling applications, while joules are the SI unit for energy.

How many joules are in a kilowatt-hour?

One kilowatt-hour (kWh) equals 3,600,000 joules or 3.6 megajoules. This is the amount of energy consumed by a 1,000-watt device running for one hour.

What is an electron volt and how does it compare to joules?

An electron volt (eV) is a very small unit of energy used in atomic and nuclear physics. One eV equals approximately 1.602 × 10⁻¹⁹ joules.

Why are there different types of BTU measurements?

Different BTU types (IT, th, mean, 39°F, 59°F) exist due to varying temperature conditions and standards. The International Table (IT) BTU is most commonly used today.

What is a therm and when is it used?

A therm is a unit of energy equal to 100,000 BTU or approximately 105.5 megajoules. It's commonly used by natural gas utilities for billing purposes.

How accurate are these energy conversions?

These conversions use internationally accepted conversion factors and are accurate to many decimal places. The precision shown depends on the units being converted and their inherent measurement standards.