How much electricity does one ChatGPT question use?
About 2% of a phone charge. OpenAI says an average question uses 0.34 Wh. Other published figures are 0.24 Wh (Google, for Gemini) and 1.86 Wh (one large open model, estimated by MIT Technology Review). They measure different things, so they can’t be ranked. Pasting in a long document can use about 7 to 120 times more (Epoch AI), and thinking modes about 30 times more on average (Hugging Face, open models).
The bigger pictureIt adds up because there are so many: ChatGPT alone handled 18 billion messages a week by July 2025. At 0.34 Wh each, that’s about 0.32 TWh a year by Hum’s sums. All the world’s data centres together used about 485 TWh in 2025.
- 0.24 Wh Google, median Gemini prompt: counts idle machines and cooling (company figure)
- 0.34 Wh OpenAI, average ChatGPT question: method not published (company figure)
- 1.86 Wh One large open model, MIT Technology Review: one model, estimated by the magazine
Hollow dots are the companies’ own figures. Unit: Wh per short text question.
How big is that?
- One short AI question0.34 WhOpenAI says 0.34 Wh; other published figures differ
- Charging a phone once19 WhUS EPA, about 19 Whabout 56× the line above
- One short AI video clip90 Whabout 90 Wh, measured by Hugging Faceabout 4.7× the line above
- Boiling a litre of water99 Whabout 99 Wh from 15 °C, by Hum’s sums from physicsabout the same as the line above
- A US home for a day28 kWhabout 28 kWh, Epoch AI from US dataabout 283× the line above
- A US home for a year11 MWhabout 10,500 kWh, Epoch AI from US dataabout 375× the line above
- AI in the world’s data centres for a year156 TWhabout 156 TWh by Hum’s sums: the middle of the US share of AI, 26.5 to 38%, used as a world estimateabout 14.9 million times the line above
- All the world’s data centres for a year485 TWhabout 485 TWh in 2025, IEAabout 3.1× the line above
The dots sit on a log scale: each step to the right is ten times bigger. It’s the only way a phone charge and all the world’s data centres fit on one line.
What nobody knows yet
- OpenAI hasn’t published how its 0.34 Wh is measured or what it includes.
- No company publishes figures for its newest models or for long, document-heavy chats.
Sources (9)
- OpenAI (Sam Altman; average query, method not published) Company says so
“the average query uses about 0.34 watt-hours, about what an oven would use in a little over one second”
Quote checked on the page, 2 Oct 2026 - Google Cloud (median Gemini text prompt, includes idle machines and data-centre cooling) Company says so
“we estimate the median Gemini Apps text prompt uses 0.24 watt-hours (Wh) of energy”
Quote checked on the page, 2 Oct 2026 - MIT Technology Review (one large open model, Llama 3.1 405B) Estimated
“an estimated 6,706 joules total, for each response”
Quote checked on the page, 2 Oct 2026 - US EPA Estimated
“[28.446 Wh – (22 hours x 0.411 Watts)] x 1 kWh/1,000 Wh = 0.019 kWh/smartphone charged”
Quote checked on the page, 18 Oct 2026 - Epoch AI (input of about 10,000 tokens, a long report) Estimated
“would substantially increase the cost per query to around 2.5 watt-hours”
Quote checked on the page, 18 Oct 2026 - Epoch AI (input of about 100,000 tokens) Estimated
“would require almost 40 watt-hours of energy”
Quote checked on the page, 18 Oct 2026 - Hugging Face, AI Energy Score v2 (open models, measured) Measured
“reasoning models use, on average, 30 times more energy”
Quote checked on the page, 18 Oct 2026 - NBER Working Paper 34255 (OpenAI and Harvard), How People Use ChatGPT Measured
“By July 2025, 18 billion messages were being sent each week by 700 million users, representing around 10% of the global adult population.”
Quote checked on the page, 18 Oct 2026 - IEA, Key Questions on Energy and AI (2026) Estimated
“electricity consumption from data centres roughly doubling from 485 TWh in 2025 to 950 TWh in 2030”
Quote checked on the page, 3 Oct 2026
Hum’s sums
- 6,706 J ÷ 3,600 ≈ 1.86 Wh
- 0.019 kWh = 19 Wh
- 0.34 Wh ÷ 19 Wh ≈ 0.018, about 2% of a phone charge
- 19 Wh ÷ 1.86 Wh ≈ 10 questions per charge
- 19 Wh ÷ 0.24 Wh ≈ 80 questions per charge
- 2.5 Wh ÷ 0.34 Wh ≈ 7
- 40 Wh ÷ 0.34 Wh ≈ 120
- 18 billion × 52 weeks × 0.34 Wh ≈ 0.32 TWh a year
Cite this
OpenAI (Sam Altman; average query, method not published), as quoted in Hum, “How much electricity does one ChatGPT question use?”, https://humearth.org/q/one-question (quote checked 2 Oct 2026).
Cite the original source first; Hum is where you found it.
What do Wh, kWh and TWh mean?
Wh is a watt-hour: a 1-watt light left on for an hour. 1 kWh = 1,000 Wh, and 1 TWh = 1 billion kWh. Hum compares each number with something everyday so you don’t need the units.
Send this answer
One ChatGPT question uses about 2% of a phone charge (0.34 Wh, OpenAI’s figure). Billions of them add up: data centres used about 485 TWh in 2025.