Leanstral 1.5
Leanstralv1.5CurrentReleased June 30, 2026
Context256K tokens
Price (In / Out)Free / Free
CategoryLarge Language Model
Max Output128K tokens
About Leanstral 1.5
Leanstral 1.5 is Mistral AI free Lean 4 formal proof-engineering model for automated theorem proving, autoformalization, and real-world code verification. Official Mistral docs list it as a Labs model with 119B total parameters, 6.5B active parameters, a 256k context window, 128k max output, $0 pricing, and the labs-leanstral-1-5 API identifier.
Capabilities
textreasoningcodingformal verificationtool usestructured output
Technical Details
- API Identifier
- labs-leanstral-1-5
- Category
- Large Language Model
- Context Window
- 256,000 tokens
- Max Output Tokens
- 128,000 tokens
Tags
formal-verificationlean-4theorem-provingopen-weightscoding
Run this model yourself
Local and cloud setup for Leanstral 1.5, with exact configurations, sources and clear evidence limits.
No reviewed setup guide is available for this model yet. Explore configurations with documented support in the hardware finder.
Benchmarks
Performance scores for Leanstral 1.5 across standard benchmarks.
miniF2Fmistral · Jul 2026
100%
PutnamBenchmistral · Jul 2026
587 problems solved
FLTEval pass@8mistral · Jul 2026
43.2%
Pricing
Token pricing for Leanstral 1.5 API usage.
Input Tokens
Free
per million tokens
Output Tokens
Free
per million tokens
Mistral model card lists Leanstral 1.5 price as $0. Changelog says the Labs endpoint is scheduled to retire on 2026-09-30.
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