How much electricity does Bitcoin use?

Bitcoin uses a lot of electricity because of proof of work: computers around the world compete to solve a puzzle, and the winner adds the next block and earns new bitcoin. The more valuable bitcoin is, the more machines join the race and the more power they draw.

The best-known measure comes from the Cambridge Centre for Alternative Finance (CCAF) at Cambridge Judge Business School. Its Bitcoin Electricity Consumption Index estimates the network's demand from the machines in use and how efficient they are, and gives a range rather than one number.

In April 2025 the CCAF published a survey of mining companies covering almost half of global mining. It put Bitcoin's annual use at about 138 terawatt-hours, roughly 0.5 per cent of the world's electricity, and found that just over half of the energy came from sustainable sources, counting renewables and nuclear power.

The debate is not settled. Critics point to the emissions from the fossil-fuel share; miners argue they use spare power that would otherwise be wasted and can switch off when the grid is under strain. Ethereum avoided the question by switching to proof of stake in 2022, which cut its energy use by more than 99 per cent.