Benchmark Almanac

ECLeKTic

Claude Mythos Preview 56.3% leads since April 2026
o3 43.1% leads since April 2025
Claude Mythos Preview 56.3% leads since April 2026
Dropped

Models answer 384 closed-book questions, translated into 12 languages, about facts found in only one language's Wikipedia. Scoring checks transfer across languages.

Released
February 2025
Kind
Knowledge in many languages
Level
Everyday
Scored
Checked automatically
Answers
Short answer
Tasks
All public
Strongest model tested
o3 #83 on the capability index
Last in a launch post
June 2025, dropped before it saturated
Last model added
May 2026
Scores refreshed
November 12th, 2026

In the authors’ words

To achieve equitable performance across languages, large language models (LLMs) must be able to abstract knowledge beyond the language in which it was learnt. However, the current literature lacks reliable ways to measure LLMs' capability of such cross-lingual knowledge transfer. To that end, we present ECLeKTic, a multilingual closed-book QA dataset that Evaluates Cross-Lingual Knowledge Transfer in a simple, black-box manner. Concretely, we used the presence and absence of Wikipedia articles in 12 languages to detect pieces of information that were likely available during pre-training in one of the languages but not in the others. We curate ECLeKTic as a set of fact-seeking questions over this kind of information, in all the different languages. Therefore, in order to solve ECLeKTic the model is required to transfer knowledge between languages. We evaluated 8 LLMs and showed that current SOTA models struggle to effectively share knowledge across languages, even if they can predict the answer for questions in the language in which the knowledge was acquired.

Abstract of ECLeKTic: a Novel Challenge Set for Evaluation of Cross-Lingual Knowledge Transfer (arXiv:2502.21228, CC0)
7
Models scored in lab cards
2
Launch posts list it, from 1 lab
10
System cards report it, from 2 labs

Claude Mythos Preview leads with 56.3% among models released by April 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 43.1% 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.

Claude Mythos Preview leads with 56.3%, 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 April 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 Claude Mythos Preview 56.3%
  2. 2 Gemini 2.5 Pro Jun 2025 46.8%
  3. 3 Gemini 2.5 Flash Jun 2025 36.8%
  4. 4 Gemma 3 27B 16.7%
  5. 5 Gemma 3 12B 10.3%
  6. 6 Gemma 3 4B 4.60%
  7. 7 Gemma 3 1B 1.40%

Source: Labs’ model cards

Source: Official ECLeKTic leaderboard

Sources: Labs’ model cards and official ECLeKTic leaderboard

#ModelScoreSettingDateSource
1 Claude Mythos Preview 56.3% Apr 2026 Lab model card
2 Gemini 2.5 Pro Jun 2025 46.8% Jul 2025 Lab model card
3 Gemini 2.5 Flash Jun 2025 36.8% Jul 2025 Lab model card
4 Gemma 3 27B 16.7% Mar 2025 Lab model card
5 Gemma 3 12B 10.3% Mar 2025 Lab model card
6 Gemma 3 4B 4.60% Mar 2025 Lab model card
7 Gemma 3 1B 1.40% Mar 2025 Lab model card
#ModelScoreSettingDateSource
1 o3 43.1% Apr 2025 Official leaderboard
2 Gemini 2.5 Pro May 2025 40.1% May 2025 Official leaderboard
3 o1 38.7% Dec 2024 Official leaderboard
4 Gemini 2.5 Pro Jun 2025 36.9% Jun 2025 Official leaderboard
5 GPT-4.1 34.2% Apr 2025 Official leaderboard
6 Gemini 2.5 Flash Jun 2025 30.9% Jun 2025 Official leaderboard
7 GPT-4o Mar 2025 29.9% Mar 2025 Official leaderboard
8 Grok 3 29% Apr 2025 Official leaderboard
9 Gemini 2.0 Flash Feb 2025 24.6% Feb 2025 Official leaderboard
10 Claude Opus 4 24% May 2025 Official leaderboard
11 Claude 3.7 Sonnet 23.3% Feb 2025 Official leaderboard
12 o4-mini 22.6% Apr 2025 Official leaderboard
13 DeepSeek-V3 Mar 2025 22% Mar 2025 Official leaderboard
14 Gemini 1.5 Pro Sep 2024 20.2% Sep 2024 Official leaderboard
15 Claude 3.5 Sonnet 20% Jun 2024 Official leaderboard
16 DeepSeek-V3.1 19% Aug 2025 Official leaderboard
17 Claude Sonnet 4 18.5% May 2025 Official leaderboard
18 Grok-2 Dec 2024 18.4% Dec 2024 Official leaderboard
19 DeepSeek-R1 May 2025 17.5% May 2025 Official leaderboard
20 Grok-3 mini 17.1% Apr 2025 Official leaderboard
21 o3-mini 14.5% Jan 2025 Official leaderboard
22 Mistral Large 2 Nov 2024 13.4% Nov 2024 Official leaderboard
23 GPT-4o mini 12.4% Jul 2024 Official leaderboard
24 Gemini 1.5 Flash Sep 2024 11.6% Aug 2024 Official leaderboard
25 GPT-3.5 Turbo Jan 2024 10.3% Jan 2024 Official leaderboard
26 Claude 3.5 Haiku 10.1% Oct 2024 Official leaderboard
27 Gemini 1.5 Flash 8B 9.09% Oct 2024 Official leaderboard
28 o1-mini 8.69% Sep 2024 Official leaderboard
29 Mixtral 8x22B 8.52% Apr 2024 Official leaderboard
30 Gemma 3 27B 8.45% Mar 2025 Official leaderboard
31 Gemma 3 12B 6.20% Mar 2025 Official leaderboard
32 Ministral 8B 3.98% Oct 2024 Official leaderboard
33 Codestral 3.20% Jan 2025 Official leaderboard
34 Gemma 3 4B 2.25% Mar 2025 Official leaderboard
35 Ministral 3B 0.64% Oct 2024 Official leaderboard
#ModelScoreSettingDateSource
1 Claude Mythos Preview 56.3% Apr 2026 Lab model card
2 Gemini 2.5 Pro Jun 2025 46.8% Jul 2025 Lab model card
3 o3 43.1% Apr 2025 Official leaderboard
4 Gemini 2.5 Pro May 2025 40.1% May 2025 Official leaderboard
5 o1 38.7% Dec 2024 Official leaderboard
6 Gemini 2.5 Flash Jun 2025 36.8% Jul 2025 Lab model card
7 GPT-4.1 34.2% Apr 2025 Official leaderboard
8 GPT-4o Mar 2025 29.9% Mar 2025 Official leaderboard
9 Grok 3 29% Apr 2025 Official leaderboard
10 Gemini 2.0 Flash Feb 2025 24.6% Feb 2025 Official leaderboard
11 Claude Opus 4 24% May 2025 Official leaderboard
12 Claude 3.7 Sonnet 23.3% Feb 2025 Official leaderboard
13 o4-mini 22.6% Apr 2025 Official leaderboard
14 DeepSeek-V3 Mar 2025 22% Mar 2025 Official leaderboard
15 Gemini 1.5 Pro Sep 2024 20.2% Sep 2024 Official leaderboard
16 Claude 3.5 Sonnet 20% Jun 2024 Official leaderboard
17 DeepSeek-V3.1 19% Aug 2025 Official leaderboard
18 Claude Sonnet 4 18.5% May 2025 Official leaderboard
19 Grok-2 Dec 2024 18.4% Dec 2024 Official leaderboard
20 DeepSeek-R1 May 2025 17.5% May 2025 Official leaderboard
21 Grok-3 mini 17.1% Apr 2025 Official leaderboard
22 Gemma 3 27B 16.7% Mar 2025 Lab model card
23 o3-mini 14.5% Jan 2025 Official leaderboard
24 Mistral Large 2 Nov 2024 13.4% Nov 2024 Official leaderboard
25 GPT-4o mini 12.4% Jul 2024 Official leaderboard
26 Gemini 1.5 Flash Sep 2024 11.6% Aug 2024 Official leaderboard
27 GPT-3.5 Turbo Jan 2024 10.3% Jan 2024 Official leaderboard
28 Gemma 3 12B 10.3% Mar 2025 Lab model card
29 Claude 3.5 Haiku 10.1% Oct 2024 Official leaderboard
30 Gemini 1.5 Flash 8B 9.09% Oct 2024 Official leaderboard
31 o1-mini 8.69% Sep 2024 Official leaderboard
32 Mixtral 8x22B 8.52% Apr 2024 Official leaderboard
33 Gemma 3 4B 4.60% Mar 2025 Lab model card
34 Ministral 8B 3.98% Oct 2024 Official leaderboard
35 Codestral 3.20% Jan 2025 Official leaderboard
36 Gemma 3 1B 1.40% Mar 2025 Lab model card
37 Ministral 3B 0.64% Oct 2024 Official leaderboard

The benchmark's own leaderboard has 35 models. Switch the scores above to rank them together.

3 models have held number one in labs’ own numbers since its release in February 2025 2 models have held number one across all independent runs since its release in February 2025 4 models have held number one with claims included since its release in February 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 Google DeepMind Anthropic
Own leaderboard Not tested since Aug 2025
o3 43.1%
Lab claims Not tested since Apr 2026

Sources: Official ECLeKTic 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 Best so far
0% 20% 40% 60% 80% 100% 2024 2025 2026 Near the ceiling (85%) Claude Mythos Preview Gemini 2.5 Pro o1 Gemini 1.5 Pro GPT-3.5 Turbo 0% 20% 40% 60% 80% 100% 2024 2025 2026 Near the ceiling (85%) Claude Mythos Preview Gemini 2.5 Pro

Sources: Official ECLeKTic leaderboard and labs’ model cards

No launch post has listed it since June 2025

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.

Google DeepMind
DateLaunch postScoreAs the post writes it
Jun 26, 2025 Gemma 3n E4B 1.9 ECLeKTic score 0-shot (IT)
Mar 12, 2025 Gemma 3 27B ECLeKTic (PT); IT 0-shot = 16.7

10 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
May 28, 2026 Claude Opus 4.8 system card ECLeKTic full cross-lingual set (multilingual factual questions), net score 0.39 (correct minus incorrect), closed book, printed on chart (6.3.3.1, Figure 6.3.3.1.B) Hallucination
Apr 16, 2026 Claude Opus 4.7 system card ECLeKTic multilingual, full cross-lingual set, net score (correct minus incorrect), closed book, printed on chart. Correct 35.4, unsure 53.3, incorrect 11.3 (6.3.3.1, Figures 6.3.3.1.A and B) Hallucination
Apr 7, 2026 Claude Mythos Preview system card 56.3 Multilingual factual hallucinations, ECLeKTic full dataset including cross-lingual translations, correct rate, value printed on chart; unsure 31.5, incorrect 12.1 (4.3.3.2, Figure 4.3.3.2.A) Hallucination
Feb 5, 2026 Claude Opus 4.6 system card ECLeKTic subset in original languages, net score (correct minus incorrect), extended thinking, value printed on chart; correct rate 53.9, net 34.6 with thinking plus effort (Figure 4.3.A) Hallucination
Jul 7, 2025 Gemini 2.5 Pro technical report 46.8 ECLeKTic (Table 3) Capabilities
Jul 7, 2025 Gemini 2.5 Flash technical report 36.8 ECLeKTic (Table 3) Capabilities
Mar 25, 2025 Gemma 3 4B technical report 4.6 ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 11.0 Capabilities
Mar 25, 2025 Gemma 3 27B technical report 16.7 ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 24.4 Capabilities
Mar 25, 2025 Gemma 3 1B technical report 1.4 ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 4.69 Capabilities
Mar 25, 2025 Gemma 3 12B technical report 10.3 ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 17.2 Capabilities

The lab's number comes out ahead in 5 of 5 pairs that differ

Each score a lab reported for its own model, beside the same model's best score on the leaderboard. Gaps mostly come from different harnesses, effort levels and task subsets. Every benchmark.

Model Lab says Board says Gap
Gemini 2.5 Pro Jun 2025 46.8% ECLeKTic (Table 3) 36.9% Leaderboard +9.9 pts
Gemma 3 27B 16.7% ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 24.4 8.45% Leaderboard +8.2 pts
Gemini 2.5 Flash Jun 2025 36.8% ECLeKTic (Table 3) 30.9% Leaderboard +5.9 pts
Gemma 3 12B 10.3% ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 17.2 6.20% Leaderboard +4.1 pts
Gemma 3 4B 4.60% ECLeKTic score, IT, 0-shot (Table 18). PT 2-shot (Table 13): 11.0 2.25% Leaderboard +2.4 pts

More in Multilingual

All 120 in Multilingual
  • MMMLU In use MMLU professionally translated into 14 languages. Multiple-choice accuracy. Claude Mythos Preview 92.7%
  • WMT24++ In use English-to-55-language translation of WMT24 test data. Scored with automatic metrics such as MetricX or xCOMET. K-EXAONE 90.5%
  • MMLU-ProX In use MMLU-Pro translated into up to 29 languages with expert review. Multiple-choice accuracy per language. Qwen3.7-Max 87%
  • CLIcK In use Models answer 1,995 multiple-choice questions on Korean language and culture. Questions come from official Korean exams and textbooks in eleven categories. Solar Open 2 90.7%
  • Global MMLU Lite 3.0 In use Models answer 400 human-translated MMLU questions per language in 23 languages. Version 3.0 adds Czech, Hungarian, Oriya, Slovak and Tajik and updates Italian. Accuracy. Nemotron 3 Ultra 550B-A55B Base 90.1%
  • MMMB In use Models answer multiple-choice questions about images in six languages across 15 categories. The set has about 12,000 questions. LFM2.5-VL-3B 83%