How much energy does GPT-5.1 use?

OpenAI · released 2025-11-13

GPT-5.1 uses about 0.252 Wh of electricity to answer a typical question. A long, complex answer costs about 23× more, at 5.87 Wh. That places it 197 of 277 among the models we can measure, and every figure here is calculated the same way as every other model.

A typical question

0.252 Wh

0.12 g CO₂·under a metre of driving

A long, complex answer

5.87 Wh

2.7 g CO₂·≈ 11 metres (36 feet) of driving

Capability

149.8

Energy rank

197 of 277

Human votes

1443

How capable is it, really?

The capability figure of 149.76 is a composite over 58 benchmarks, Epoch AI's Capabilities Index, which folds in software engineering, agentic tool use, long-context comprehension and creative writing as well as science reasoning. It is one number standing for a lot of separate tests, so treat a small gap between two models as noise rather than a ranking.

41,651 people have voted on it in blind head-to-head comparisons on LMArena, giving it a rating of 1443. This is the only figure here that measures whether anyone actually prefers the answers, rather than how the model scores on a test. Broken down, people rate it 1453 on coding, 1427 on creative writing, 1443 on following instructions.

What this figure is

Day-one estimate Calculated from an estimated parameter count, the maker hasn't published one. Every model on this site is calculated the same way, so the comparison holds even where the absolute value carries uncertainty. Our figures are good to roughly a factor of two to three, which is why we only ever state a difference of 5× or more.

The figure above is an understatement. GPT-5.1 generates reasoning text you never see, and that text costs energy to produce. Our calculation counts a fixed answer length, so the real figure is higher, we cannot say by how much, because the amount is not published.

Is there a better choice?

A lighter model that does the job

Claude Haiku 5.5

Anthropic · capability 159.0. It scores higher than GPT-5.1 on Epoch's Capabilities Index (158.98 against 149.76), the composite over 58 benchmarks that the capability figure above comes from, and uses about 11× less energy per answer: 0.515 Wh against 5.87 Wh. It has not faced human head-to-head voting, where GPT-5.1 carries 41,651 votes, worth weighing.

What OpenAI publishes

Energy cannot be worked out without knowing how big a model is. Of the 39 models from OpenAI that we track, 34 can be assessed at all, the rest publish too little for anyone outside the company to calculate anything.

Where these figures come from

Capability and the roster come from Epoch AI, whose Capabilities Index is the 58-benchmark composite quoted above. Energy is calculated with EcoLogits and calibrated against laboratory measurements from ML.ENERGY. Human preference comes from LMArena. All four are public and free; the full method is here.

These figures are published under CC BY 4.0, use them anywhere, including commercially, with credit to The AI Footprint.

Compare it with something

Compare GPT-5.1 with another model

Or work out what a year of using it adds up to, for you or for a whole organisation.

Figure calculated 2026-10-17 · how these numbers are made · the full comparison of 277 models