Leanstral 1.5
Leanstral 1.5 ranks first on 2 of the 2 benchmarks with five or more models scored.
6
Benchmarks with a score
2
Ranked first, out of five or more models
2
In the top three
Mistral AI Jul 2026 Leanstral 1.5
Open weights Mid-size
No Epoch Capabilities Index score yet
- PutnamBench 87.5% #1 /12
- miniF2F 100% #1 /5
Where it ranks
Its best score on each benchmark, and where that ranks among every model with a score there. We rank each model once, at its best setting.
Its lab's number next to a leaderboard
Where the benchmark's own leaderboard, or Epoch AI's run, also has this model. Gaps mostly come from different harnesses, effort levels and task subsets. Every pair.
| Benchmark | Lab says | Board says | Gap |
|---|---|---|---|
| PutnamBench | 87.4% PutnamBench 587/672 solved (pass@8, 4M tokens per attempt) | 87.5% Leaderboard, 4m tokens per problem | Same |
Its launch post
The benchmarks the lab chose to headline, with the scores it gave.
Its system card
Every result in the longer documents the lab published with it. 1 of them isn't in the launch post.
Leanstral Jul 2, 2026