Question 1

What energy units are supported?

Accepted Answer

The converter covers 23 units across four groups. SI / Metric: erg, joule (J), kilojoule (kJ), megajoule (MJ), gigajoule (GJ), watt-hour (Wh), kilowatt-hour (kWh), megawatt-hour (MWh). Caloric / Nutritional: thermochemical calorie (cal), IT calorie (cal_IT), thermochemical kilocalorie (kcal), IT kilocalorie / food Calorie (kcal_IT). Imperial / Mechanical: inch-pound (in·lbf), foot-pound (ft·lbf), BTU (IT), therm (US), horsepower-hour (hp·h). Scientific / Large Scale: electron-volt (eV), keV, MeV, GeV, ton of TNT, ton of oil equivalent (toe).

Question 2

What is the difference between a thermochemical calorie and an IT calorie?

Accepted Answer

The thermochemical calorie (cal_th) is defined as exactly 4.184 J and is used in chemistry and physics. The International Table calorie (cal_IT) is defined as exactly 4.1868 J and was historically used in steam engineering. The difference is only 0.1%, which is negligible for most purposes. Food labels use the kilocalorie (kcal), which equals 1,000 thermochemical calories = 4,184 J.

Question 3

What is BTU and when is it used?

Accepted Answer

A British Thermal Unit (BTU) is the energy required to raise 1 pound of water by 1 °F. The IT definition gives exactly 1,055.056 J. BTUs are the standard unit in North American HVAC, natural gas billing, and heating equipment ratings. Air conditioners and furnaces are commonly rated in BTU/h; natural gas utility bills often show usage in therms (= 100,000 BTU).

Question 4

What is a kilowatt-hour and how does it relate to joules?

Accepted Answer

A kilowatt-hour (kWh) is the energy consumed by a 1,000-watt device running for one hour. It equals exactly 3,600,000 joules (3.6 MJ). kWh is the standard unit on electricity bills worldwide. 1 kWh = 3,412.14 BTU = 859.845 kcal.

Question 5

What are electron-volts and why does the converter include them?

Accepted Answer

An electron-volt (eV) is the kinetic energy gained by one electron accelerating through a 1-volt potential difference. It equals exactly 1.602176634 × 10⁻¹⁹ J (exact by 2019 SI redefinition). eV, keV, MeV, and GeV are the standard energy units in atomic, nuclear, and particle physics - for example, chemical bond energies are a few eV while nuclear fission releases ~200 MeV per event.

Question 6

What is a ton of TNT?

Accepted Answer

A ton of TNT is a unit of explosive energy defined as exactly 4.184 × 10⁹ J (= 1 gigacalorie). It is not the actual energy of one ton of TNT detonation (which varies), but a conventional standard used to describe nuclear weapon yields, asteroid impact energies, and large industrial explosions. 1 kiloton of TNT = 4.184 TJ; 1 megaton = 4.184 PJ.

Question 7

How do I convert in the other direction?

Accepted Answer

Hover any result row and click the swap icon (⇅) to use that unit and value as the new input, reversing the conversion instantly. You can also click the ⇄ button between the From and To fields to swap both units while preserving the numerical result value.

Question 8

Is my data private?

Accepted Answer

Yes - all conversions happen entirely in your browser using JavaScript and exact mathematical constants. No data is ever sent to any server.

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