Joules (J) to Watt-Hours (Wh) Converter
Enter a value to instantly convert between energy units.
1 Joule = 0.0003 Watt-Hour
Key Formulas
Kilocalorie → Kilojoule
kJ = kcal × 4.184Kilojoule → Kilocalorie
kcal = kJ × 0.239006Kilowatt-Hour → Joule
J = kWh × 3600000Joule → Kilowatt-Hour
kWh = J × 2.77778e-7Formula
Wh = J ÷ 3600A watt-hour is the energy of one watt operating for one hour — that's 3600 joules since there are 3600 seconds in an hour. Watt-hours are the standard unit for electricity billing and battery capacity. Converting joules to watt-hours means dividing by 3600.
Source: NIST SP 811, Table B.8
Frequently Asked Questions
Real-World Examples
A student calculating 3600 J of energy consumption recognizes it as 1 Wh for the physics homework.
3600 J = 1 Wh
An electrician measuring 18,000 J used by a device over an hour reports 5 Wh for the energy audit.
18000 J = 5 Wh
A battery storing 7200 J of energy holds 2 Wh — a small coin cell capacity.
7200 J = 2 Wh
A solar panel generating 1000 J per hour produces 0.278 Wh — useful for the system design calculation.
1000 J = 0.278 Wh