Convert Energy Units
Conversion Result
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Overview
Energy spans units from physics (J), food (Cal), HVAC (BTU), electricity billing (kW·h), to high‐energy physics (eV), industry (boe, therm), chemical (CHUIT), volumetric gas (scf), mechanical (ft·lbf), and more. This tool converts any of them instantly online.
Formula & Methodology
All conversions use joules as the pivot:
$$ E_{\!J} = E_{\text{input}} \times f_{\text{from}}, \quad E_{\text{out}} = \frac{E_{\!J}}{f_{\text{to}}} $$
| Unit | Symbol | → J | Note |
|---|---|---|---|
| Joule | J | 1 | SI base unit |
| Kilowatt-hour | kW·h | 3.6×10⁶ | Electricity billing unit |
| Calorie | Cal | 4184 | Food-energy unit (kcal) |
| BTU | BTU | 1055.056 | Heating/cooling |
| Electronvolt | eV | 1.602×10⁻¹⁹ | Particle physics |
| Celsius heat unit | CHUIT | 4184 | Same as 1 dietary Calorie |
| Standard cm³ atm | cc atm | 101325 × 10⁻⁶ | 1 cm³ of air at STP |
| Standard ft³ atm | scf | 101325 × 0.0283168 | 1 ft³ of air at STP |
| Standard yd³ atm | scy | 101325 × 0.764555 | 1 yd³ of air at STP |
| Foot-pound force | ft·lbf | 1.3558179 | Mechanical work |
| Foot-poundal | ft·pdl | 0.04214 | CGS mechanical |
| Imp gal atm | imp gal atm | 101325 × 0.0045461 | Imperial gallon of air at STP |
| US gal atm | US gal atm | 101325 × 0.00378541 | US gallon of air at STP |
| Hartree | Eh | 4.359744e-18 | Atomic unit of energy |
| Erg | erg | 1e-7 | CGS energy |
| Horsepower-hour | hp·h | 2.685e6 | Engine work |
| In-pound force | in·lbf | 0.1129848 | Small mechanical |
| Kilocalorie | kcal | 4184 | Same as Cal |
| kW·h (BOTU) | B.O.T.U. | 3.412e6 | US Board of Trade |
| Litre-atm | l·atm | 101325 | Gas work |
| Quad | quad | 1.055e18 | US energy industry |
| Rydberg | Ry | 2.179872e-18 | Atomic physics |
| Therm (E.C.) | thermEC | 1.055e8 | European gas |
| Thermie | th | 4.1868e6 | Metric ton‐calorie |
| TCE | TCE | 2.94e10 | Tonne coal eq. |
| toe | toe | 4.1868e10 | Tonne oil eq. |
| Ton TNT | tTNT | 4.184e9 | Explosive yield |
| Watt-second | W·s | 1 | Same as Joule |
Examples
- 10 kW·h → J: 10 × 3.6×10⁶ = 3.6×10⁷ J
- 500 Cal → kW·h: (500×4184)/3.6×10⁶ ≈ 0.582 kW·h
- 2 quad → J: 2×1.055×10¹⁸ = 2.11×10¹⁸ J
Use Cases
- Convert your food calories into joules for scientific work.
- Compare household electricity usage (kW·h) with fuel oil equivalents (boe).
- Switch between engineering units (BTU, Cal, J) quickly.
Frequently Asked Questions
Why convert all via joules?
Joule is the SI base unit for energy, ensuring consistency and accuracy across any system.
What is a barrel of oil equivalent?
A barrel-of-oil equivalent (boe) is a standardized unit—≈5.86 GJ—used to compare diverse energy sources on a common basis.
How accurate are these factors?
We use exact ISO & NIST conversion factors; industrial units (boe, therm) are approximate to the nearest GJ or MJ.
Can I add more units?
Yes—just edit the `toJoules` object in the JS to include your custom factor.
Why pivot through joules?
Joule is the SI base unit; all other factors convert to/from it for maximum accuracy.
What is CHUIT?
The Celsius heat unit (Intl. Table) equals 4184 J—same as the dietary Calorie.
How to customize units?
Edit the toJoules mapping in energy-converter.js to add your own.