How much electricity does AI use?
One prompt costs a fraction of a watt-hour. A year of ordinary use costs a few kilowatt-hours. The scale only matters once you multiply by millions of people, and that multiplication is where every estimate diverges.
At the level of one person
Twenty messages a day, all ordinary text, comes to about 7.3 kWh a year. At the US residential average that is about $1.33. A refrigerator uses more.
At the level of a product
Multiply by daily active users and the same arithmetic produces gigawatt-hours. The uncertainty stops being about watt-hours per query and becomes about how many queries exist, what mix of models answers them, and how much of the capacity sits idle. Idle capacity is the part almost nobody counts: a data centre provisioned for peak load draws power whether or not a query arrives.
“A single short GPT-4o query consumes 0.43 Wh ... o3 and DeepSeek-R1 emerge as the most energy-intensive models, consuming over 33 Wh per long prompt, more than 70 times the consumption of GPT-4.1 nano.”
What the published ranges cover
| Kind of message | Low, Wh | Median, Wh | High, Wh |
|---|---|---|---|
| Short question | 0.16 | 0.31 | 0.70 |
| Ordinary text answer | 0.50 | 1.00 | 2.00 |
| Reasoning or thinking mode | 2.00 | 4.00 | 7.00 |
| Long or agentic task | 10.00 | 20.00 | 40.00 |
These are inference figures. Training runs are excluded because they are amortised over the lifetime of a model and reported as totals rather than per query, which makes them easy to quote impressively and hard to compare.
“The new Joule paper estimates 0.31 Wh median for standard frontier-model queries, with an interquartile range of 0.16-0.60 Wh.”
Converting to carbon and money
Carbon uses the US average of 0.37 kg CO2 per kWh. A cleaner grid produces a different answer for the same electricity, which is why a European query and a US query with identical energy can carry different emissions. Money uses the residential tariff, which is not what a data centre pays; commercial rates are lower, so the dollar figure in the calculator is what the same electricity would cost a household, not what it costs the operator.
“US net generation was about 4.18 trillion kWh and resulted in about 1.53 billion metric tons of CO2, which is roughly 0.37 kg CO2 per kWh.”
“US residential average price 18.17 cents per kWh, August 2026.”