Convert joule to watt-hour

What is a joule?

Joule is a metric that is utilized for the evaluation of work, heat and energetic levels and has international recognition. Its definition tells us that it corresponds to the work done by a 1-newton force, which moves mass for 1 meter in the force’s direction. Therefore, one J equals one N per m or one kg x m² x s-².

It is also applied in electrical area and means the work of the force of an electric field done for 1 second at a 1-volt voltage to keep the stability of a 1-ampere current.

The term was introduced at the Second International Congress of Electricians, held in the year of Joule's death and was recognized internationally nine years after this event. From that time, one international joule equals 1.00020 absolute units. Later, this unit was also applied as the standard and belongs to the metrics applicable worldwide.

What is a watt hour?

The watt belongs to the common metrics and is defined as a joule per second. It reveals the power of a battery or a device. Thus, before purchasing them, it is recommended to check their watt-hours.

First and foremost, the higher this value, the longer the battery will work. For instance, a 100 watt hour one will put out exactly 100 watts during one hour of operation.

This option is also referred to as W*h for short and evaluates power in W over time, namely hours. If your battery is rated at 100 W, it will consume exactly such power per hour and 300 W for three hours.

To find out this value from amp hours, the following calculation is used:

W*h = Amp hours * Volts

For instance, a 3-volt battery that produces 2 amperes during one hour has a power of 6 W*h.