LLM Comparison
Leanstral 1.5 vs Solar Pro 3
Side-by-side specs, pricing & capabilities · Updated September 2026
Add to comparison
2/6 modelsSame tier:
| Organization | ||
| OpenTools Score | 9 24.0 | |
| Family | Leanstral | Solar |
| Status | Current | Current |
| Release Date | Jun 2026 | Jan 2026 |
| Context Window | 256K tokens | 128K tokens |
| Input Price | Free | $0.15/M tokens |
| Output Price | Free | $0.60/M tokens |
| Pricing Notes | Mistral model card lists Leanstral 1.5 price as $0. Changelog says the Labs endpoint is scheduled to retire on 2026-09-30. | Cache read: $0.0150/M tokens |
| Capabilities | textreasoningcodingformal-verificationtool-usestructured-output | textcode |
| Max Output | 128K tokens | — |
| API Identifier | labs-leanstral-1-5 | upstage/solar-pro-3 |
| Benchmarks | ||
| miniF2F | 100mistral | — |
| PutnamBench | 587mistral | — |
| FLTEval pass@8 | 43.2mistral | — |
| Artificial Analysis Intelligence Index v4.3 | — | 7.8155artificial-analysis |
| GPQA Diamond | — | 72.4242artificial-analysis |
| SciCode | — | 25.463artificial-analysis |
| Terminal-Bench 2.1 | — | 11.985artificial-analysis |
| View Leanstral 1.5 | View Solar Pro 3 | |
Cost Calculator
Enter your expected monthly token usage to compare costs.
| Model | Input | Output | Total / mo | vs Best |
|---|---|---|---|---|
| Leanstral 1.5Cheapest | $0.00 | $0.00 | $0.00 | — |
| Solar Pro 3 | $0.15 | $0.30 | $0.45 | +0% |
Mistral AI
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.
Upstage
Solar Pro 3
Solar Pro 3 is a large language model from Upstage. Supports up to 128,000 token context window. Available from $0.15/M input tokens.
More Comparisons
Looking for more AI models?
Browse All LLMs