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
Benchmarks
Performance scores for Leanstral 1.5 across standard benchmarks.
miniF2Fmistral · Jul 2026
100%
PutnamBenchmistral · Jul 2026
587%
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
Pricing Calculator
Input cost$0.00
Output cost$0.00
Estimated monthly cost$0.00
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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