# How to calculate watt hours

I have a really basic question:

How does one calculate watt-hours? :blush:

e.g. I have a machine that consumes 400 watts, how many watt-hours of power do I need to run it for 1 hour?

TIA

Pokey: I have a really basic question:

How does one calculate watt-hours? :blush:

e.g. I have a machine that consumes 400 watts, how many watt-hours of power do I need to run it for 1 hour?

TIA

If it consumes a steady 400 watts for an hour then it will also consume 400 watt-hours. Where watt hours can very from device current consumtion is if the device is turned off for some time in that hour window, or if the devices current consumption changes with load or if it's current draw changes. Watthours is a integrated value of total power consumed over time.

Lefty

Thank you Lefty!

That is actually pretty straightforward.

My apologies for asking such basic questions.

For completeness a watt-hour is also 3.6kJ (kilojoules). A Joule is a watt-second and there are 3600 seconds in an hour...