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Epoch AI's Capabilities Index scores language models on one aggregate scale, and nothing since has held first place as long as GPT-4 did after its March 2023 release — roughly a year. The second-longest lead, by OpenAI's o1, lasted a little over three months, less than a third of GPT-4's run at the top
Verified 2026-08-12
More on Models
- Epoch AI fits a trend through the models whose context windows ranked among the ten longest on their release date, and finds that since mid-2023 the frontier context window has been getting about 30× longer every year
- Of the notable AI models released in 2025, Stanford's AI Index counts over 90% as coming from industry
- Across 42 notable language models, Epoch AI estimates frontier training costs have risen from roughly $2 million for GPT-3 to up to nearly $390 million per run