Convert Watt-hours (Wh) to Joules (J)
1 watt-hour equals 3600 Joules.
Watt-hour to Joule Converter
How to Convert Watt-hour to Joule
1 watt-hour = 3600 Joules exact
Joule = Watt-hour × 3600
Example: 1 Wh × 3600 = 3600 J
Reverse Conversion
To convert Joules back to watt-hours:
- Remember, 1 joule equals 0.000277778 watt-hours.
- To convert 3600 J to Wh, multiply
3600 x 0.000277778, resulting in1 Wh.
exact This conversion factor is exact by international definition.
Common Watt-hour to Joule Conversions
| Watt-hour | Joule | Actions |
|---|---|---|
| 1 watt-hour | 3600 Joules | |
| 5 watt-hours | 18000 Joules | |
| 10 watt-hours | 36000 Joules | |
| 50 watt-hours | 180000 Joules |
| Watt-hour | Joule | Actions |
|---|---|---|
| 100 watt-hours | 360000 Joules | |
| 500 watt-hours | 1800000 Joules | |
| 1000 watt-hours | 3600000 Joules |
Watt-hours to Joules Conversion Table
Reference table with common watt-hours to joules conversions. All values calculated with high precision.
Watt-hours to Joules Table
1 to 100000
Joules to Watt-hours Table
10000 to 1 × 109
Definition of Watt-hour
- Definition
- Energy equal to one watt of power sustained for one hour.
- Exact factor
- 1 Wh = 3600 J
- Sources
- NIST SP 811
Definition of Joule
- Definition
- SI unit of energy: 1 J = 1 N·m = 1 kg·m²·s⁻².
- Notes
- Used universally in physics, chemistry, and engineering.
- Sources
- BIPM — SI Brochure
About the Watt-hour
Facts & Uses
- Convenient battery energy unit for laptops, drones, UPS, and tools: 1 Wh = 3600 J (exact).
- Relates to amp-hours via voltage: Wh = V × Ah (use nominal/average V for accurate estimates).
- Used for device-level energy budgeting, IoT power profiling, and portable electronics specs.
- Scales naturally across mWh, Wh, and kWh for clear capacity comparisons and runtime planning.
Curiosities
- Airline rules commonly cap spare lithium batteries at around 100 Wh in carry-on (check current regulations).
- Users often confuse Ah (charge) with Wh (energy); Wh accounts for voltage, making it better for runtime comparisons.
- Energy meters and PMICs integrate instantaneous power over time to accumulate Wh/kWh with high accuracy.
- Quick mental math: 3.6 kJ per Wh, so 50 Wh ≈ 180 kJ — handy for physics and engineering estimates.
Sources
About the Joule
Facts & Uses
- SI unit of energy: 1 J = 1 N·m = 1 W·s = 1 C·V = 1 Pa·m³; ubiquitous in mechanics, thermodynamics, electromagnetism, and chemistry.
- Common engineering scales: kJ, MJ, GJ for fuels, heating/cooling loads, and process energy.
- Everyday intuition: lifting ~1 N through 1 m ≈ 1 J; a 10 Wh battery stores ≈ 36,000 J for devices/IoT.
- Key links: 1 kWh = 3.6 × 10⁶ J; 1 eV = 1.602176634×10⁻¹⁹ J (exact) via the fixed elementary charge.
Curiosities
- Joule heating (I²R) connects electrical losses to thermal energy in conductors and electronics.
- Although both use N·m, torque (vector, moment) and energy (scalar, work) are physically distinct.
- Compression/expansion work in gases is often expressed as Pa·m³ (= J), linking pressure–volume integrals to energy.
- Named for James P. Joule, who quantified the mechanical equivalent of heat, bridging thermal and mechanical domains.
Sources
Frequently Asked Questions
How many Joules are in one watt-hour?
One watt-hour equals 3600 Joules. To convert, multiply the watt-hour value by 3600. For the reverse, divide the joule value by 3600 (or multiply by 0.000277778).
What is 0.4 watt-hours in Joules?
0.4 watt-hours = 1440 Joules. This is one of the most commonly searched conversions for this pair.
Is the watt-hour-to-joule conversion exact?
Yes. The factor 3600 is exact by international definition, not an approximation. Any imprecision comes only from the original measurement, not the conversion.
Looking for the reverse? Convert Joule to Watt-hour
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- Watts to Kilowatts — kW measures power; kWh measures energy (power × time)
