HLE Calibration
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.
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.
- Level
- Expert Specialists with years of training, often over hours of work
- Scored
- Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
- Answers
- Short answer A number, word or short string matched to a key.
Muse Spark 1.1 leads with 23.4 among models released by Sep 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.
The newest model with a score here came out in Sep 2026, and nobody has reported a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:
- GPT-6 Astra
- Claude Opus 5.5
- GPT-6.1 Terra
- GPT-6.1 Sol
- and 16 more
- 1
Muse Spark 1.1 23.4
- 2
Muse Spark 1.3 35.3
- 3
Muse Spark 50.3
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | | 23.4 | Jul 2026 | Model card | |
| 2 | | 35.3 | Oct 2026 | Model card | |
| 3 | | 50.3 | Jun 2026 | Model card |
2 models have held number one since its release in Jan 2025
Lab claims count from the day the card came out, independent runs from the model’s release.
Scores over time
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Labs report it only in system cards
We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark. Some system cards do, below.
3 system cards report it, from 1 lab
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.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| 23 Oct 2026 | | 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 |
| 9 Jul 2026 | | 23.4 | Humanity's Last Exam RMS calibration error (Table 2, Table 11). AUROC 70.2 | Hallucination |
| 12 Jun 2026 | | 50.3 | HLE Calibration RMS calibration error (Table 2, Table 20) | Hallucination |
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