FaithJudge
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).
- Made by
- University of Waterloo and Vectara (Tamber et al.)
- 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.
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:
- Claude Fable 5.2
-
Gemini 4 Carbon
- GPT-6 Astra
- Claude Opus 5.5
- and 16 more
- 1
Gemini 2.5 Flash Jun 2025 6.26%
- 2
Gemini 2.5 Pro Jun 2025 6.65%
- 3
Gemini 2.5 Pro Mar 2025 7.63%
- 4
DeepSeek-R1 May 2025 9.78%
- 5
Gemini 2.0 Flash Feb 2025 10.2%
- 6 o3-mini medium 11.6%
- 7 GPT-4.5 11.9%
- 8 GPT-4.1 11.9%
- 9 Claude Opus 4 thinking 14.1%
- 10 GPT-3.5 Turbo Jan 2024 14.9%
- 11 Grok 3 15.3%
- 12 GPT-4.1 mini 15.7%
- 13 GPT-4o Nov 2024 15.8%
- 14 Claude 3.7 Sonnet 16.1%
- 15
Llama 3.3 70B Instruct 16.4%
- 16
Phi-4 17%
- 17
Mistral Small 3 17%
- 18 o3 medium 17.8%
- 19 Claude Sonnet 4 thinking 18.2%
- 20 GPT-4o mini 18.6%
- 21
Qwen2.5-32B 19.2%
- 22
Llama 4 Maverick 20.6%
- 23
Qwen2.5-72B 20.7%
- 24
QwQ-32B 24.7%
- 25 GLM-4-9B-Chat 25.4%
- 26 o4-mini medium 25.8%
- 27
Llama 3.1-8B 28.4%
- 28
Qwen2.5-14B 29%
- 29
Ministral 8B 30.9%
- 30
Phi-4 Mini 38.4%
- 31
Qwen2.5-7B 38.5%
- 32 Jamba 1.6 Mini 39.1%
- 33
Llama 3.2 3B 46.2%
- 34
Qwen2.5-3B 56%
- 35
Qwen2.5-1.5B 66.7%
- 36
Llama 3.2 1B 67.7%
- 37
Qwen2.5-0.5B 76.3%
Source: Official FaithJudge leaderboard
- 1
Gemini 2.5 Flash Jun 2025 6.26%
- 2
Gemini 2.5 Pro Jun 2025 6.65%
- 3 Kimi K2 Jul 2025 7.40%
- 4
Gemini 2.5 Pro Mar 2025 7.63%
- 5
DeepSeek-R1 May 2025 9.78%
- 6
Gemini 2.0 Flash Feb 2025 10.2%
- 7 o3-mini medium 11.6%
- 8 GPT-4.5 11.9%
- 9 GPT-4.1 11.9%
- 10 Claude Opus 4 thinking 14.1%
- 11 GPT-3.5 Turbo Jan 2024 14.9%
- 12 Grok 3 15.3%
- 13 GPT-4.1 mini 15.7%
- 14 GPT-4o Nov 2024 15.8%
- 15 Claude 3.7 Sonnet 16.1%
- 16
Llama 3.3 70B Instruct 16.4%
- 17
Phi-4 17%
- 18
Mistral Small 3 17%
- 19 o3 medium 17.8%
- 20 Claude Sonnet 4 thinking 18.2%
- 21 GPT-4o mini 18.6%
- 22
Qwen2.5-32B 19.2%
- 23
Llama 4 Maverick 20.6%
- 24
Qwen2.5-72B 20.7%
- 25
QwQ-32B 24.7%
- 26 GLM-4-9B-Chat 25.4%
- 27 o4-mini medium 25.8%
- 28
Llama 3.1-8B 28.4%
- 29
Qwen2.5-14B 29%
- 30
Ministral 8B 30.9%
- 31
Phi-4 Mini 38.4%
- 32
Qwen2.5-7B 38.5%
- 33 Jamba 1.6 Mini 39.1%
- 34
Llama 3.2 3B 46.2%
- 35
Qwen2.5-3B 56%
- 36
Qwen2.5-1.5B 66.7%
- 37
Llama 3.2 1B 67.7%
- 38
Qwen2.5-0.5B 76.3%
Sources: Official FaithJudge leaderboard and labs’ model cards
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | | 6.26% | Jun 2025 | Official leaderboard | |
| 2 | | 6.65% | Jun 2025 | Official leaderboard | |
| 3 | | 7.63% | Mar 2025 | Official leaderboard | |
| 4 | | 9.78% | May 2025 | Official leaderboard | |
| 5 | | 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 | | 16.4% | Dec 2024 | Official leaderboard | |
| 16 | | 17% | Dec 2024 | Official leaderboard | |
| 17 | | 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 | | 19.2% | Sep 2024 | Official leaderboard | |
| 22 | | 20.6% | Apr 2025 | Official leaderboard | |
| 23 | | 20.7% | Sep 2024 | Official leaderboard | |
| 24 | | 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 | | 28.4% | Jul 2024 | Official leaderboard | |
| 28 | | 29% | Sep 2024 | Official leaderboard | |
| 29 | | 30.9% | Oct 2024 | Official leaderboard | |
| 30 | | 38.4% | Feb 2025 | Official leaderboard | |
| 31 | | 38.5% | Sep 2024 | Official leaderboard | |
| 32 | Jamba 1.6 Mini | 39.1% | Mar 2025 | Official leaderboard | |
| 33 | | 46.2% | Sep 2024 | Official leaderboard | |
| 34 | | 56% | Sep 2024 | Official leaderboard | |
| 35 | | 66.7% | Sep 2024 | Official leaderboard | |
| 36 | | 67.7% | Sep 2024 | Official leaderboard | |
| 37 | | 76.3% | Sep 2024 | Official leaderboard |
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | | 6.26% | Jun 2025 | Official leaderboard | |
| 2 | | 6.65% | Jun 2025 | Official leaderboard | |
| 3 | Kimi K2 Jul 2025 | 7.40% | Jul 2025 | Lab model card | |
| 4 | | 7.63% | Mar 2025 | Official leaderboard | |
| 5 | | 9.78% | May 2025 | Official leaderboard | |
| 6 | | 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 | | 16.4% | Dec 2024 | Official leaderboard | |
| 17 | | 17% | Dec 2024 | Official leaderboard | |
| 18 | | 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 | | 19.2% | Sep 2024 | Official leaderboard | |
| 23 | | 20.6% | Apr 2025 | Official leaderboard | |
| 24 | | 20.7% | Sep 2024 | Official leaderboard | |
| 25 | | 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 | | 28.4% | Jul 2024 | Official leaderboard | |
| 29 | | 29% | Sep 2024 | Official leaderboard | |
| 30 | | 30.9% | Oct 2024 | Official leaderboard | |
| 31 | | 38.4% | Feb 2025 | Official leaderboard | |
| 32 | | 38.5% | Sep 2024 | Official leaderboard | |
| 33 | Jamba 1.6 Mini | 39.1% | Mar 2025 | Official leaderboard | |
| 34 | | 46.2% | Sep 2024 | Official leaderboard | |
| 35 | | 56% | Sep 2024 | Official leaderboard | |
| 36 | | 66.7% | Sep 2024 | Official leaderboard | |
| 37 | | 67.7% | Sep 2024 | Official leaderboard | |
| 38 | | 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.
Source: Official FaithJudge leaderboard
| Model | Effort | Harness | Score | Cost per task | Output tokens |
|---|---|---|---|---|---|
| | 76.3% | ||||
| | 67.7% | ||||
| | 66.7% | ||||
| | 56% | ||||
| | 46.2% | ||||
| Jamba 1.6 Mini | 39.1% | ||||
| | 38.5% | ||||
| | 38.4% | ||||
| | 30.9% | ||||
| o4-mini | high | 29.9% | |||
| | 29% | ||||
| | 28.4% | ||||
| o4-mini | low | 28% | |||
| o4-mini | medium | 25.8% | |||
| GLM-4-9B-Chat | 25.4% | ||||
| | 24.7% | ||||
| | 20.7% | ||||
| | 20.6% | ||||
| o3 | low | 20.6% | |||
| Claude Opus 4 | 19.6% | ||||
| | 19.2% | ||||
| GPT-4o mini | 18.6% | ||||
| o3 | high | 18.6% | |||
| Claude Sonnet 4 | 18.6% | ||||
| Claude Sonnet 4 | thinking | 18.2% | |||
| o3 | medium | 17.8% | |||
| | 17% | ||||
| | 17% | ||||
| | 16.4% | ||||
| Claude 3.7 Sonnet | thinking | 16.2% | |||
| Claude 3.7 Sonnet | 16.1% | ||||
| GPT-4o Nov 2024 | 15.8% | ||||
| GPT-4.1 mini | 15.7% | ||||
| Grok 3 | 15.3% | ||||
| GPT-3.5 Turbo Jan 2024 | 14.9% | ||||
| Claude Opus 4 | thinking | 14.1% | |||
| o3-mini | high | 12.5% | |||
| o3-mini | low | 11.9% | |||
| GPT-4.5 | 11.9% | ||||
| GPT-4.1 | 11.9% | ||||
| o3-mini | medium | 11.6% | |||
| | 10.2% | ||||
| | 9.78% | ||||
| | 7.63% | ||||
| | 6.65% | ||||
| | 6.26% |
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.
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.
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.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| Jul 21, 2025 | Kimi K2 technical report | 7.4 | FaithJudge (1-Hallu.), o3-mini judge, hallucination rate 7.4% (Table 3) | Hallucination |
More in Factuality
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Qwen3.7-Plus 81.7%
- HallusionBench In use Models answer 1,129 yes or no questions about 346 images, built in pairs to expose language hallucination and visual illusion. Scored by accuracy.
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- SimpleQA Verified In use 1,000 human-verified, de-duplicated short-answer factual questions measuring parametric knowledge.
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- Kimi Hallu Bench In use Models answer hard prompts drawn from practical work tasks. Fact-checking agents score the share of claims that are hallucinated. GPT-6 Astra 4.20%
- Internal adversarially-designed factuality evaluations In use Models answer adversarial questions in nine categories such as history, math and code. Scored on agreement with human ideal responses. GPT-6 Luna 7.60%
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