Convert Watt-Hours to Kilojoules
Convert Watt-Hours (Wh) to Kilojoules (kJ) instantly and accurately.
Conversion Formula
kJ = Wh × 3.6
About Watt-Hours
A watt-hour (Wh) is the energy delivered by 1 watt for one hour - exactly 3,600 J. It is the practical unit for small-scale electrical energy: a 10,000 mAh 5 V power bank stores 50 Wh; a laptop battery holds 50-90 Wh; a smartphone battery holds 10-15 Wh; an AA alkaline cell stores ~3 Wh. LED lamps labelled 9 W save 51 Wh/h over a 60 W incandescent. IATA dangerous-goods rules use Wh as the threshold for lithium batteries in aircraft: cells >20 Wh and batteries >100 Wh need special approval. 1 Wh = 3,600 J = 3.412 BTU.
About Kilojoules
A kilojoule (kJ) is exactly 1,000 J and is the standard energy unit for food and physical chemistry. EU, Australian, and NZ food labels are mandatory in kJ: recommended adult intake is ~8,400 kJ/day. Bond dissociation energies: C-H bond 413 kJ/mol; C=C double bond 614 kJ/mol; N≡N triple bond 945 kJ/mol. Specific heat of water: 4.184 kJ/(kg·K). A cyclist riding at 150 W for one hour expends 540 kJ. Charpy and Izod impact toughness tests record results in J and kJ. 1 kJ = 1,000 J = 239.0 cal = 0.94782 BTU = 0.27778 Wh.
Quick Reference Table
| Watt-Hours (Wh) | Kilojoules (kJ) |
|---|---|
| 1 Wh | 3.6 kJ |
| 2 Wh | 7.2 kJ |
| 5 Wh | 18 kJ |
| 10 Wh | 36 kJ |
| 25 Wh | 90 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |