Benchmark Almanac

HLE Calibration

Muse Spark 1.1 23.4 leads since July 2026
o3 34.0 leads since April 2025
Muse Spark 1.1 23.4 leads since July 2026
Fading

Models give a confidence score with each HLE answer. The benchmark reports RMS calibration error and AUROC between confidence and correctness.

Calibration evaluation layered on the public Humanity's Last Exam. RMS error is on a 0-100 scale.

Released
January 2025
Kind
Hallucination rates
Level
Expert
Scored
Checked automatically
Answers
Short answer
Tasks
All public
Strongest model tested
Muse Spark 1.3 #26 on the capability index
Last in a launch post
March 2026, dropped before it saturated
Last model added
October 2026
Scores refreshed
November 12th, 2026

In the authors’ words

Benchmarks are important tools for tracking the rapid advancements in large language model (LLM) capabilities. However, benchmarks are not keeping pace in difficulty: LLMs now achieve over 90% accuracy on popular benchmarks like MMLU, limiting informed measurement of state-of-the-art LLM capabilities. In response, we introduce Humanity's Last Exam (HLE), a multi-modal benchmark at the frontier of human knowledge, designed to be the final closed-ended academic benchmark of its kind with broad subject coverage. HLE consists of 2,500 questions across dozens of subjects, including mathematics, humanities, and the natural sciences. HLE is developed globally by subject-matter experts and consists of multiple-choice and short-answer questions suitable for automated grading. Each question has a known solution that is unambiguous and easily verifiable, but cannot be quickly answered via internet retrieval. State-of-the-art LLMs demonstrate low accuracy and calibration on HLE, highlighting a significant gap between current LLM capabilities and the expert human frontier on closed-ended academic questions. To inform research and policymaking upon a clear understanding of model capabilities, we publicly release HLE at https://lastexam.ai.

Abstract of Humanity's Last Exam (arXiv:2501.14249, CC0)
3
Models scored in lab cards
1
Launch post lists it, from 1 lab
4
System cards report it, from 2 labs

Muse Spark 1.1 leads with 23.4 among models released by September 2026

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

o3 leads with 34.0 across all independent runs

Best score per model across the official leaderboard, Epoch AI’s own runs and any board Epoch AI copied. Each bar and row names its source.

Muse Spark 1.1 leads with 23.4, claims included

Best score per model from every source, including labs’ own numbers and claims Epoch AI collected from reports and papers. Labs pick their own settings, so a claim can beat an independent run of the same model.

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

  1. 1 Muse Spark 1.1 23.4
  2. 2 Muse Spark 1.3 35.3
  3. 3 Muse Spark 50.3

Source: Labs’ model cards

Source: Official HLE Calibration leaderboard

Sources: Labs’ model cards and official HLE Calibration leaderboard

#ModelScoreSettingDateSource
1 Muse Spark 1.1 23.4 Jul 2026 Lab model card
2 Muse Spark 1.3 35.3 Oct 2026 Lab model card
3 Muse Spark 50.3 Jun 2026 Lab model card
#ModelScoreSettingDateSource
1 o3 34.0 high Apr 2025 Official leaderboard
2 o4-mini 57.0 high Apr 2025 Official leaderboard
3 o3-mini 80.0 text only; high Jan 2025 Official leaderboard
4 o1 83.0 Dec 2024 Official leaderboard
#ModelScoreSettingDateSource
1 Muse Spark 1.1 23.4 Jul 2026 Lab model card
2 o3 34.0 high Apr 2025 Official leaderboard
3 Muse Spark 1.3 35.3 Oct 2026 Lab model card
4 Muse Spark 50.3 Jun 2026 Lab model card
5 o4-mini 57.0 high Apr 2025 Official leaderboard
6 o3-mini 80.0 text only; high Jan 2025 Official leaderboard
7 o1 83.0 Dec 2024 Official leaderboard

The benchmark's own leaderboard has 4 models. Switch the scores above to rank them together.

2 models have held number one in labs’ own numbers since its release in January 2025 3 models have held number one across all independent runs since its release in January 2025 4 models have held number one with claims included since its release in January 2025

Lab claims count from the day the card came out, independent runs from the model’s release. We draw one row each for the benchmark’s own leaderboard and what labs claim in their cards.

OpenAI Meta
Own leaderboard Not tested since Apr 2025
o3 34.0
Lab claims 2 leaders

Sources: Official HLE Calibration leaderboard and labs’ model cards

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 Reported by the lab in its model card
20.0 40.0 60.0 80.0 100.0 2025 2026 2027 20.0 40.0 60.0 80.0 100.0 2025 2026 2027

Sources: Official HLE Calibration leaderboard and labs’ model cards

Labs headline it less often now, last in March 2026

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

xAI
DateLaunch postScoreAs the post writes it
Mar 9, 2026 Grok 4.20 19 Humanity’s Last Exam, RMS calibration error 0.19, Grok 4.2 SA, Table 2

4 system cards report it, from 2 labs

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
Oct 23, 2026 Muse Spark 1.3 system card 35.3 Humanity's Last Exam calibration, RMS calibration error 0-100 with browser and search tools, Muse Spark 1.3 (API) (Table 2, Table 13). AUROC 72.22 Hallucination
Jul 9, 2026 Muse Spark 1.1 system card 23.4 Humanity's Last Exam RMS calibration error (Table 2, Table 11). AUROC 70.2 Hallucination
Jun 12, 2026 Muse Spark system card 50.3 HLE Calibration RMS calibration error (Table 2, Table 20) Hallucination
Apr 7, 2026 Grok 4.20 model card 19 Humanity’s Last Exam, RMS calibration error 0.19, Grok 4.2 SA, Table 2 Hallucination

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