Compact microwaves use between 750 and 900 watts during heating. An average modern microwave will use around 800 watts.
See the energy consumption of a microwave oven using 800 Watts for 30 minutes a day @ £0.19 per kWh.
Cost Per Hour: £0.1520
Cost Per Day: £0.0760
Cost Per Month: £2.31
Cost Per Year: £27.74
kWh Per Day: 0.40
Tip:In addition to using energy while cooking or heating, a microwave will also use 2 to 7 watts of power while in standby mode. This energy is used to display the clock and to wait for a user command. In a single year a microwave using 4 watts in 24/7 standby mode will use 35 kWh, this is not a significant amount of electricity but if you are away for a considerable amount of time you may consider unplugging your microwave to conserve energy.