Benchmark Almanac

METR Time Horizon 1.1

Claude Mythos Preview 17.4 h leads since Apr 2026 Not in model cards

Agents attempt 228 software and research tasks timed against skilled humans, run in Inspect. The score is the human task length at which the agent succeeds half the time.

It added 73 HCAST tasks, removed 15 and updated 53, and moved from Vivaria to Inspect. METR stopped updating the page on 2026-09-08 and calls results above 16 hours unreliable.

In the authors’ words

Despite rapid progress on AI benchmarks, the real-world meaning of benchmark performance remains unclear. To quantify the capabilities of AI systems in terms of human capabilities, we propose a new metric: 50%-task-completion time horizon. This is the time humans typically take to complete tasks that AI models can complete with 50% success rate. We first timed humans with relevant domain expertise on a combination of RE-Bench, HCAST, and 66 novel shorter tasks. On these tasks, current frontier AI models such as Claude 3.7 Sonnet have a 50% time horizon of around 50 minutes. Furthermore, frontier AI time horizon has been doubling approximately every seven months since 2019, though the trend may have accelerated in 2024. The increase in AI models' time horizons seems to be primarily driven by greater reliability and ability to adapt to mistakes, combined with better logical reasoning and tool use capabilities. We discuss the limitations of our results – including their degree of external validity – and the implications of increased autonomy for dangerous capabilities. If these results generalize to real-world software tasks, extrapolation of this trend predicts that within 5 years, AI systems will be capable of automating many software tasks that currently take humans a month.

Abstract of Measuring AI Ability to Complete Long Software Tasks (arXiv:2503.14499, CC0)
Made by METR Released Jan 2026 Task length Public tasks plus a private test set Last model added Apr 2026 Scores refreshed 2 Nov 2026
Level
Research frontier Researchers, on open problems or tasks that take days
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Agent task Many steps in a terminal, browser, desktop, app, game or robot.
26
Models scored on its own leaderboard

Claude Mythos Preview leads with 17.4 h among models released by Apr 2026

Best score per model from the benchmark's own leaderboard, read on 2 Nov 2026. Where a model ran with several settings or harnesses, we keep its best.

The newest model with a score here came out in Apr 2026, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:

  1. 1 Claude Mythos Preview 17.4 h
  2. 2 Claude Opus 4.6 12.0 h
  3. 3 Gemini 3.1 Pro 6.4 h
  4. 4 GPT-5.2 high 5.9 h
  5. 5 GPT-5.3 Codex high 5.8 h
  6. 6 GPT-5.4 xhigh 5.7 h
  7. 7 Claude Opus 4.5 4.9 h
  8. 8 Gemini 3 Pro 3.7 h
  9. 9 GPT-5.1-Codex-Max 3.7 h
  10. 10 GPT-5 3.4 h
  11. 11 o3 120 min
  12. 12 Claude Opus 4.1 100 min
  13. 13 Claude Opus 4 100 min
  14. 14 Claude 3.7 Sonnet 60 min
  15. 15 o1 39 min
  16. 16 Claude 3.5 Sonnet (October 2024) 21 min
  17. 17 o1-preview 20 min
  18. 18 Claude 3.5 Sonnet 11 min
  19. 19 GPT-4o May 2024 7.0 min
  20. 20 GPT-4 Turbo Nov 2023 4.0 min
  21. 21 GPT-4 Mar 2023 4.0 min
  22. 22 Claude 3 Opus 4.0 min
  23. 23 GPT-4 Turbo Apr 2024 3.7 min
  24. 24 GPT-3.5 Turbo Instruct 0.6 min
  25. 25 davinci-002 0.1 min
  26. 26 GPT-2 (1.5B) 0.1 min
#ModelScoreSettingDateSource
1 Claude Mythos Preview 17.4 h metr_agents/react Apr 2026 Official leaderboard
2 Claude Opus 4.6 12.0 h metr_agents/react Feb 2026 Official leaderboard
3 Gemini 3.1 Pro 6.4 h triframe_inspect/triframe_agent Feb 2026 Official leaderboard
4 GPT-5.2 5.9 h high, triframe_inspect/triframe_agent Dec 2025 Official leaderboard
5 GPT-5.3 Codex 5.8 h high, triframe_inspect/triframe_agent Feb 2026 Official leaderboard
6 GPT-5.4 5.7 h xhigh, metr_agents/react Mar 2026 Official leaderboard
7 Claude Opus 4.5 4.9 h metr_agents/react Nov 2025 Official leaderboard
8 Gemini 3 Pro 3.7 h metr_agents/react Nov 2025 Official leaderboard
9 GPT-5.1-Codex-Max 3.7 h triframe_inspect/triframe_agent Nov 2025 Official leaderboard
10 GPT-5 3.4 h triframe_inspect/triframe_agent Aug 2025 Official leaderboard
11 o3 120 min triframe_inspect/triframe_agent Apr 2025 Official leaderboard
12 Claude Opus 4.1 100 min metr_agents/react Aug 2025 Official leaderboard
13 Claude Opus 4 100 min metr_agents/react May 2025 Official leaderboard
14 Claude 3.7 Sonnet 60 min metr_agents/react Feb 2025 Official leaderboard
15 o1 39 min triframe_inspect/triframe_agent Dec 2024 Official leaderboard
16 Claude 3.5 Sonnet (October 2024) 21 min metr_agents/react Oct 2024 Official leaderboard
17 o1-preview 20 min Sep 2024 Official leaderboard
18 Claude 3.5 Sonnet 11 min metr_agents/react Jun 2024 Official leaderboard
19 GPT-4o May 2024 7.0 min metr_agents/react May 2024 Official leaderboard
20 GPT-4 Turbo Nov 2023 4.0 min metr_agents/react Nov 2023 Official leaderboard
21 GPT-4 Mar 2023 4.0 min Mar 2023 Official leaderboard
22 Claude 3 Opus 4.0 min metr_agents/react Feb 2024 Official leaderboard
23 GPT-4 Turbo Apr 2024 3.7 min metr_agents/react Apr 2024 Official leaderboard
24 GPT-3.5 Turbo Instruct 0.6 min Sep 2023 Official leaderboard
25 davinci-002 0.1 min Mar 2022 Official leaderboard
26 GPT-2 (1.5B) 0.1 min Nov 2019 Official leaderboard

3 models have held number one since its release in Jan 2026

Lab claims count from the day the card came out, independent runs from the model’s release.

OpenAI Anthropic
Own leaderboard Not tested since Apr 2026

Scores over time

All the scores we have, one dot each, so a model tested at several settings appears more than once.

On the benchmark’s own leaderboard
0.0 min 0.1 min 1.0 min 10 min 100 min 16.7 h 166.7 h 2020 2021 2022 2023 2024 2025 2026 0.0 min 0.1 min 1.0 min 10 min 100 min 16.7 h 166.7 h 2020 2022 2024 2026

No lab model card reports it yet

We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark.

Versions

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