Convert Watt-hour to Joule
1 watt-hour = 3,600 joule (J). For example, 10 watt-hour = 36,000 joule and 100 watt-hour = 360,000 joule. Type any value below to convert watt-hour to joule both ways — it runs entirely in your browser.
Quick answer: Watt-hour to Joule
1 Watt-hour = 3,600 Joule (Wh → J). To convert watt-hour to joule, multiply by 3,600. To convert joule to watt-hour, multiply by 0.0002777778. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common watt-hour-to-joule questions.
How to convert Watt-hour to Joule
To convert watt-hour to joule, multiply the number of watt-hour by the conversion factor 3,600, because 1 Wh = 3,600 J. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 J = 0.0002777778 Wh, so you divide by 3,600 (or multiply by 0.0002777778) to turn joule back into watt-hour.
J = Wh × 3,600 ·
Wh = J × 0.0002777778
- Write down the value you want to convert, in watt-hour.
- Multiply it by 3,600.
- The result is the same area/length/quantity expressed in joule.
Watt-hour to Joule — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 watt-hour is 18,000 joule because 5 Wh × 3,600 = 18,000 J.
| Watt-hour | Calculation | Joule |
|---|---|---|
| 1 Wh | 1 Wh × 3,600 = 3,600 J | 3,600 J |
| 2 Wh | 2 Wh × 3,600 = 7,200 J | 7,200 J |
| 3 Wh | 3 Wh × 3,600 = 10,800 J | 10,800 J |
| 5 Wh | 5 Wh × 3,600 = 18,000 J | 18,000 J |
| 7 Wh | 7 Wh × 3,600 = 25,200 J | 25,200 J |
| 10 Wh | 10 Wh × 3,600 = 36,000 J | 36,000 J |
| 12 Wh | 12 Wh × 3,600 = 43,200 J | 43,200 J |
| 15 Wh | 15 Wh × 3,600 = 54,000 J | 54,000 J |
| 20 Wh | 20 Wh × 3,600 = 72,000 J | 72,000 J |
| 25 Wh | 25 Wh × 3,600 = 90,000 J | 90,000 J |
| 50 Wh | 50 Wh × 3,600 = 180,000 J | 180,000 J |
| 100 Wh | 100 Wh × 3,600 = 360,000 J | 360,000 J |
Common Watt-hour to Joule conversions
These are the watt-hour-to-joule values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 watt-hour = 3,600 joule
- 2 watt-hour = 7,200 joule
- 2.5 watt-hour = 9,000 joule
- 3 watt-hour = 10,800 joule
- 4 watt-hour = 14,400 joule
- 5 watt-hour = 18,000 joule
- 6 watt-hour = 21,600 joule
- 7 watt-hour = 25,200 joule
- 8 watt-hour = 28,800 joule
- 9 watt-hour = 32,400 joule
- 10 watt-hour = 36,000 joule
- 12 watt-hour = 43,200 joule
- 15 watt-hour = 54,000 joule
- 20 watt-hour = 72,000 joule
- 25 watt-hour = 90,000 joule
- 30 watt-hour = 108,000 joule
- 50 watt-hour = 180,000 joule
- 75 watt-hour = 270,000 joule
- 100 watt-hour = 360,000 joule
- 200 watt-hour = 720,000 joule
- 500 watt-hour = 1,800,000 joule
- 1000 watt-hour = 3,600,000 joule
Watt-hour to Joule conversion chart (both directions)
The chart below converts watt-hour to joule and joule to watt-hour side by side, so it works whichever way you need. 1 watt-hour = 3,600 joule, and 1 joule = 0.0002777778 watt-hour.
| Watt-hour → Joule | Joule → Watt-hour |
|---|---|
| 0.25 Wh = 900 J | 0.25 J = 0.00006944444 Wh |
| 0.5 Wh = 1,800 J | 0.5 J = 0.0001388889 Wh |
| 1 Wh = 3,600 J | 1 J = 0.0002777778 Wh |
| 2 Wh = 7,200 J | 2 J = 0.0005555556 Wh |
| 3 Wh = 10,800 J | 3 J = 0.0008333333 Wh |
| 4 Wh = 14,400 J | 4 J = 0.001111111 Wh |
| 5 Wh = 18,000 J | 5 J = 0.001388889 Wh |
| 6 Wh = 21,600 J | 6 J = 0.001666667 Wh |
| 7 Wh = 25,200 J | 7 J = 0.001944444 Wh |
| 8 Wh = 28,800 J | 8 J = 0.002222222 Wh |
| 9 Wh = 32,400 J | 9 J = 0.0025 Wh |
| 10 Wh = 36,000 J | 10 J = 0.002777778 Wh |
| 12 Wh = 43,200 J | 12 J = 0.003333333 Wh |
| 15 Wh = 54,000 J | 15 J = 0.004166667 Wh |
| 20 Wh = 72,000 J | 20 J = 0.005555556 Wh |
| 25 Wh = 90,000 J | 25 J = 0.006944444 Wh |
| 30 Wh = 108,000 J | 30 J = 0.008333333 Wh |
| 40 Wh = 144,000 J | 40 J = 0.01111111 Wh |
| 50 Wh = 180,000 J | 50 J = 0.01388889 Wh |
| 75 Wh = 270,000 J | 75 J = 0.02083333 Wh |
| 100 Wh = 360,000 J | 100 J = 0.02777778 Wh |
| 150 Wh = 540,000 J | 150 J = 0.04166667 Wh |
| 200 Wh = 720,000 J | 200 J = 0.05555556 Wh |
| 250 Wh = 900,000 J | 250 J = 0.06944444 Wh |
| 500 Wh = 1,800,000 J | 500 J = 0.1388889 Wh |
| 1000 Wh = 3,600,000 J | 1000 J = 0.2777778 Wh |
Watt-hour vs Joule: which is bigger?
A watt-hour is the larger unit: one watt-hour equals 3,600 joules. Put another way, you need 3,600 joules to make a single watt-hour.
What is a Watt-hour? History, origin and usage
The watt-hour combines the watt — named after the Scottish engineer James Watt (1736-1819), improver of the steam engine — with the hour, giving the energy delivered by one watt of power sustained for one hour. It arose with the electrical industry as a convenient way to rate and bill energy rather than instantaneous power.
Watt-hours (and milliamp-hours, their close cousin) are the standard way to rate the capacity of batteries — from phones and laptops to power tools and electric-vehicle packs. The unit links power (watts) and time (hours) intuitively, making it easy to estimate how long a device will run.
Because power multiplied by time gives energy, a 10-watt device running for one hour uses 10 watt-hours — the same energy as a 100-watt device running for six minutes. A watt-hour equals exactly 3,600 joules, since an hour is 3,600 seconds.
What is a Joule? History, origin and usage
The joule is named after the English physicist James Prescott Joule (1818-1889), a Salford brewer’s son who, through painstaking experiments in the 1840s, measured the mechanical equivalent of heat and showed that work and heat are interchangeable forms of energy. The name was proposed by Wilhelm Siemens at an 1882 British Association meeting, and the joule was adopted as an international unit at the 1889 International Electrical Congress — just weeks before Joule himself died.
As the SI unit of energy, the joule underpins all of physics and engineering, measuring mechanical work, heat and electrical energy alike (one joule is also one watt-second). It appears on European food labels (usually as kilojoules), in battery specifications, and anywhere energy must be stated in coherent SI units.
One joule is roughly the energy needed to lift a small apple (about 100 grams) one metre against gravity, or the kinetic energy of a 56-gram tennis ball travelling about 6 m/s. Because one joule equals one newton-metre, the joule is dimensionally identical to the newton-metre of torque, yet the two describe different physical quantities.
Convert 1 Watt-hour to other units
It can help to see a watt-hour next to the other units it is commonly compared with. One watt-hour (Wh) is equal to:
| 1 Watt-hour equals | Unit |
|---|---|
| 3,600 J | Joule |
| 3,600 N·m | Newton-metre |
| 3.6 kJ | Kilojoule |
| 0.0036 MJ | Megajoule |
| 0.001 kWh | Kilowatt-hour |
| 0.000001 MWh | Megawatt-hour |
| 2,655.224 ft·lbf | Foot-pound |
| 22,469,430,000,000,000 MeV | Megaelectronvolt |
| 860.4207 cal | Calorie |
| 0.8604207 kcal | Kilocalorie |
| 3.412142 BTU | British Thermal Unit |
Convert 1 Joule to other units
One joule (J) is equal to:
| 1 Joule equals | Unit |
|---|---|
| 1 N·m | Newton-metre |
| 0.001 kJ | Kilojoule |
| 0.000001 MJ | Megajoule |
| 0.0002777778 Wh | Watt-hour |
| 0.0000002777778 kWh | Kilowatt-hour |
| 0.0000000002777778 MWh | Megawatt-hour |
| 0.7375621 ft·lbf | Foot-pound |
| 6,241,509,000,000 MeV | Megaelectronvolt |
| 0.2390057 cal | Calorie |
| 0.0002390057 kcal | Kilocalorie |
| 0.0009478171 BTU | British Thermal Unit |
Tips for converting Watt-hour to Joule
- To go from watt-hour to joule, multiply by 3,600; to go back, divide by 3,600 (or multiply by 0.0002777778).
- For a quick mental estimate, remember that 1 watt-hour ≈ 3,600 joule, so 10 watt-hour ≈ 36,000 joule.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Watt-hour to Joule converter
Type a number into the Watt-hour field and the equivalent in Joule appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Joule field to convert the other way (joule to watt-hour). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 Wh = 3,600 J), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for watt-hour-to-joule conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST — Definitions of the SI base units — the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
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Frequently asked questions
- How many joule are in 1 watt-hour?
- 1 watt-hour = 3,600 joule (J). To convert any number of watt-hour to joule, multiply by 3,600.
- How do I convert watt-hour to joule?
- Multiply the number of watt-hour by 3,600. For example, 10 watt-hour = 10 × 3,600 = 36,000 joule, and 25 watt-hour = 90,000 joule.
- How many watt-hour are in 1 joule?
- 1 joule = 0.0002777778 watt-hour. So to convert joule back to watt-hour, multiply by 0.0002777778.
- What is the formula to convert watt-hour to joule?
- joule = watt-hour × 3,600. The reverse formula is watt-hour = joule × 0.0002777778.
- How much is 100 watt-hour in joule?
- 100 watt-hour = 360,000 joule. (And 1000 watt-hour = 3,600,000 joule.)
- Which is bigger, a watt-hour or a joule?
- A watt-hour is larger: 1 watt-hour = 3,600 joule.
- Is this watt-hour to joule converter accurate?
- Yes — every value is computed from the exact 3,600 J per Wh factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert joule to watt-hour too?
- Yes. The converter works both ways — enter a value in either field. 1 joule = 0.0002777778 watt-hour.