Benchmark Almanac

FaithJudge

Gemini 2.5 Flash Jun 2025 6.26% leads since June 2025
Gemini 2.5 Flash Jun 2025 6.26% leads since June 2025
Only in system cards

Models answer retrieval-augmented tasks from given passages. An LLM judge guided by human-annotated examples flags unfaithful answers, giving a hallucination rate.

The board reports the hallucination rate. Kimi K2 reported one minus the rate (92.6), stored here as the rate it also prints (7.4).

Released
May 2025
Kind
Faithful to sources
Level
Everyday
Scored
Graded by a model
Answers
Open-ended
Tasks
All public
Strongest model tested
o3 #83 on the capability index
Last in a system card
July 2025
Last model added
July 2025
Scores refreshed
November 12th, 2026

In the authors’ words

Retrieval-augmented generation (RAG) aims to reduce hallucinations by grounding responses in external context, yet large language models (LLMs) still frequently introduce unsupported information or contradictions even when provided with relevant context. This paper presents two complementary efforts at Vectara to measure and benchmark LLM faithfulness in RAG. First, we describe our original hallucination leaderboard, which has tracked hallucination rates for LLMs since 2023 using our HHEM hallucination detection model. Motivated by limitations observed in current hallucination detection methods, we introduce FaithJudge, an LLM-as-a-judge framework that leverages a pool of diverse human-annotated hallucination examples to substantially improve the automated hallucination evaluation of LLMs. We introduce an enhanced hallucination leaderboard centered on FaithJudge that benchmarks LLMs on RAG faithfulness in summarization, question-answering, and data-to-text generation tasks. FaithJudge enables a more reliable benchmarking of LLM hallucinations in RAG and supports the development of more trustworthy generative AI systems: https://github.com/vectara/FaithJudge.

Abstract of Benchmarking LLM Faithfulness in RAG with Evolving Leaderboards (arXiv:2505.04847, CC0)
37
Models scored on its own leaderboard
1
System card reports it, from 1 lab

Gemini 2.5 Flash leads with 6.26% among models released by June 2025

Best score per model from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Every run is in the next chart.

Gemini 2.5 Flash leads with 6.26%, 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 June 2025, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:

  1. 1 Gemini 2.5 Flash Jun 2025 6.26%
  2. 2 Gemini 2.5 Pro Jun 2025 6.65%
  3. 3 Gemini 2.5 Pro Mar 2025 7.63%
  4. 4 DeepSeek-R1 May 2025 9.78%
  5. 5 Gemini 2.0 Flash Feb 2025 10.2%
  6. 6 o3-mini medium 11.6%
  7. 7 GPT-4.5 11.9%
  8. 8 GPT-4.1 11.9%
  9. 9 Claude Opus 4 thinking 14.1%
  10. 10 GPT-3.5 Turbo Jan 2024 14.9%
  11. 11 Grok 3 15.3%
  12. 12 GPT-4.1 mini 15.7%
  13. 13 GPT-4o Nov 2024 15.8%
  14. 14 Claude 3.7 Sonnet 16.1%
  15. 15 Llama 3.3 70B Instruct 16.4%
  16. 16 Phi-4 17%
  17. 17 Mistral Small 3 17%
  18. 18 o3 medium 17.8%
  19. 19 Claude Sonnet 4 thinking 18.2%
  20. 20 GPT-4o mini 18.6%
  21. 21 Qwen2.5-32B 19.2%
  22. 22 Llama 4 Maverick 20.6%
  23. 23 Qwen2.5-72B 20.7%
  24. 24 QwQ-32B 24.7%
  25. 25 GLM-4-9B-Chat 25.4%
  26. 26 o4-mini medium 25.8%
  27. 27 Llama 3.1-8B 28.4%
  28. 28 Qwen2.5-14B 29%
  29. 29 Ministral 8B 30.9%
  30. 30 Phi-4 Mini 38.4%
  31. 31 Qwen2.5-7B 38.5%
  32. 32 Jamba 1.6 Mini 39.1%
  33. 33 Llama 3.2 3B 46.2%
  34. 34 Qwen2.5-3B 56%
  35. 35 Qwen2.5-1.5B 66.7%
  36. 36 Llama 3.2 1B 67.7%
  37. 37 Qwen2.5-0.5B 76.3%

Source: Official FaithJudge leaderboard

#ModelScoreSettingDateSource
1 Gemini 2.5 Flash Jun 2025 6.26% Jun 2025 Official leaderboard
2 Gemini 2.5 Pro Jun 2025 6.65% Jun 2025 Official leaderboard
3 Gemini 2.5 Pro Mar 2025 7.63% Mar 2025 Official leaderboard
4 DeepSeek-R1 May 2025 9.78% May 2025 Official leaderboard
5 Gemini 2.0 Flash Feb 2025 10.2% Feb 2025 Official leaderboard
6 o3-mini 11.6% medium Jan 2025 Official leaderboard
7 GPT-4.5 11.9% Feb 2025 Official leaderboard
8 GPT-4.1 11.9% Apr 2025 Official leaderboard
9 Claude Opus 4 14.1% thinking May 2025 Official leaderboard
10 GPT-3.5 Turbo Jan 2024 14.9% Jan 2024 Official leaderboard
11 Grok 3 15.3% Apr 2025 Official leaderboard
12 GPT-4.1 mini 15.7% Apr 2025 Official leaderboard
13 GPT-4o Nov 2024 15.8% Nov 2024 Official leaderboard
14 Claude 3.7 Sonnet 16.1% Feb 2025 Official leaderboard
15 Llama 3.3 70B Instruct 16.4% Dec 2024 Official leaderboard
16 Phi-4 17% Dec 2024 Official leaderboard
17 Mistral Small 3 17% Jan 2025 Official leaderboard
18 o3 17.8% medium Apr 2025 Official leaderboard
19 Claude Sonnet 4 18.2% thinking May 2025 Official leaderboard
20 GPT-4o mini 18.6% Jul 2024 Official leaderboard
21 Qwen2.5-32B 19.2% Sep 2024 Official leaderboard
22 Llama 4 Maverick 20.6% Apr 2025 Official leaderboard
23 Qwen2.5-72B 20.7% Sep 2024 Official leaderboard
24 QwQ-32B 24.7% Mar 2025 Official leaderboard
25 GLM-4-9B-Chat 25.4% Jun 2024 Official leaderboard
26 o4-mini 25.8% medium Apr 2025 Official leaderboard
27 Llama 3.1-8B 28.4% Jul 2024 Official leaderboard
28 Qwen2.5-14B 29% Sep 2024 Official leaderboard
29 Ministral 8B 30.9% Oct 2024 Official leaderboard
30 Phi-4 Mini 38.4% Feb 2025 Official leaderboard
31 Qwen2.5-7B 38.5% Sep 2024 Official leaderboard
32 Jamba 1.6 Mini 39.1% Mar 2025 Official leaderboard
33 Llama 3.2 3B 46.2% Sep 2024 Official leaderboard
34 Qwen2.5-3B 56% Sep 2024 Official leaderboard
35 Qwen2.5-1.5B 66.7% Sep 2024 Official leaderboard
36 Llama 3.2 1B 67.7% Sep 2024 Official leaderboard
37 Qwen2.5-0.5B 76.3% Sep 2024 Official leaderboard
#ModelScoreSettingDateSource
1 Gemini 2.5 Flash Jun 2025 6.26% Jun 2025 Official leaderboard
2 Gemini 2.5 Pro Jun 2025 6.65% Jun 2025 Official leaderboard
3 Kimi K2 Jul 2025 7.40% Jul 2025 Lab model card
4 Gemini 2.5 Pro Mar 2025 7.63% Mar 2025 Official leaderboard
5 DeepSeek-R1 May 2025 9.78% May 2025 Official leaderboard
6 Gemini 2.0 Flash Feb 2025 10.2% Feb 2025 Official leaderboard
7 o3-mini 11.6% medium Jan 2025 Official leaderboard
8 GPT-4.5 11.9% Feb 2025 Official leaderboard
9 GPT-4.1 11.9% Apr 2025 Official leaderboard
10 Claude Opus 4 14.1% thinking May 2025 Official leaderboard
11 GPT-3.5 Turbo Jan 2024 14.9% Jan 2024 Official leaderboard
12 Grok 3 15.3% Apr 2025 Official leaderboard
13 GPT-4.1 mini 15.7% Apr 2025 Official leaderboard
14 GPT-4o Nov 2024 15.8% Nov 2024 Official leaderboard
15 Claude 3.7 Sonnet 16.1% Feb 2025 Official leaderboard
16 Llama 3.3 70B Instruct 16.4% Dec 2024 Official leaderboard
17 Phi-4 17% Dec 2024 Official leaderboard
18 Mistral Small 3 17% Jan 2025 Official leaderboard
19 o3 17.8% medium Apr 2025 Official leaderboard
20 Claude Sonnet 4 18.2% thinking May 2025 Official leaderboard
21 GPT-4o mini 18.6% Jul 2024 Official leaderboard
22 Qwen2.5-32B 19.2% Sep 2024 Official leaderboard
23 Llama 4 Maverick 20.6% Apr 2025 Official leaderboard
24 Qwen2.5-72B 20.7% Sep 2024 Official leaderboard
25 QwQ-32B 24.7% Mar 2025 Official leaderboard
26 GLM-4-9B-Chat 25.4% Jun 2024 Official leaderboard
27 o4-mini 25.8% medium Apr 2025 Official leaderboard
28 Llama 3.1-8B 28.4% Jul 2024 Official leaderboard
29 Qwen2.5-14B 29% Sep 2024 Official leaderboard
30 Ministral 8B 30.9% Oct 2024 Official leaderboard
31 Phi-4 Mini 38.4% Feb 2025 Official leaderboard
32 Qwen2.5-7B 38.5% Sep 2024 Official leaderboard
33 Jamba 1.6 Mini 39.1% Mar 2025 Official leaderboard
34 Llama 3.2 3B 46.2% Sep 2024 Official leaderboard
35 Qwen2.5-3B 56% Sep 2024 Official leaderboard
36 Qwen2.5-1.5B 66.7% Sep 2024 Official leaderboard
37 Llama 3.2 1B 67.7% Sep 2024 Official leaderboard
38 Qwen2.5-0.5B 76.3% Sep 2024 Official leaderboard

Labs report scores for 1 model in their cards. Switch the scores above to rank them together.

Scores at each effort level

Models the leaderboard ran at two or more effort levels. We don’t have enough cost data here to say what the extra effort costs.

Lowest effort to highest, light to dark
o4-mini
low medium high
29.9%
Claude Sonnet 4
thinking
18.6%
o3
low medium
20.6%
Claude 3.7 Sonnet
thinking
16.2%
Claude Opus 4
thinking
19.6%
o3-mini
low
12.5%

Source: Official FaithJudge leaderboard

3 models have held number one on the official leaderboard since its release in May 2025 3 models have held number one with claims included since its release in May 2025

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

Google DeepMind
Own leaderboard Not tested since Jun 2025

Source: Official FaithJudge leaderboard

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 Best so far
0% 20% 40% 60% 80% 100% 2024 2025 Gemini 2.5 Flash Gemini 2.0 Flash GPT-3.5 Turbo 0% 20% 40% 60% 80% 100% 2024 2025 Gemini 2.5 Flash o3-mini

Sources: Official FaithJudge leaderboard and labs’ model cards

Labs report it only in system cards

We read the headline results of 522 launch posts from 52 labs, and none of them list this benchmark. Some system cards do, below.

One system card reports it

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
Jul 21, 2025 Kimi K2 technical report 7.4 FaithJudge (1-Hallu.), o3-mini judge, hallucination rate 7.4% (Table 3) Hallucination

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