Question: how much electricity does a computer use if left on uk?
Answer: How much electricity does a PC use in the UK? A desktop PC typically uses around 100 watts of electricity, the equivalent of 0.1 kWh. This means that if a PC is on for eight hours a day, it will cost 10p a day to run the laptop (based on an average energy unit cost of 12.5 p/kWh).