Leanstral 1.5
Free Labs endpoint for Lean 4 formal proof engineering, autoformalization and automated theorem proving — genuinely $0 while Mistral gathers feedback, but it is a research preview with no availability guarantee, so don't build production on it.
Data checked 2026-09-06
Mistral AI
preview
open weights
labs-leanstral-1-5
- Context window
- 256K tokens in
- Max output
- 128K tokens out
- Input
- $0.00 per 1M tokens
- Output
- $0.00 per 1M tokens
- Cached input
- $0.00 per 1M tokens
- Blended
- $0.00 3:1 in:out
- Released
- 2026-06-30
- Parameters
- 119B-A6.5B MoE
- Licence
- Apache-2.0
A What it is for
(The older labs-leanstral-2603 still shown on the marketing pricing page was retired 30 Jun 2026.)
At a three-to-one input-to-output ratio, Leanstral 1.5 costs $0.00 per million tokens blended. A workload of one million input and 330,000 output tokens per day would run about $0.00 per month at list price, before caching or batch discounts.
B Capabilities
| Input modalities | text, image |
|---|---|
| Output modalities | text |
C Others from Mistral AI
| Model | Context | Max out | In $/M | Out $/M | Blended | Status |
|---|---|---|---|---|---|---|
Mistral Medium 3.5
mistral-medium-3-5
|
256K | — | $1.50 | $7.50 | $3.00 | ga open |
Mistral Large 3
mistral-large-2512
|
256K | — | $0.50 | $1.50 | $0.75 | ga open |
Mistral Small 4
mistral-small-2603
|
256K | — | $0.15 | $0.60 | $0.26 | ga open |
Ministral 3 14B
ministral-14b-2512
|
256K | — | $0.20 | $0.20 | $0.20 | ga open |
Ministral 3 8B
ministral-8b-2512
|
256K | — | $0.15 | $0.15 | $0.15 | ga open |
Ministral 3 3B
ministral-3b-2512
|
256K | — | $0.10 | $0.10 | $0.10 | ga open |
Z.ai GLM 5.2
zai-glm-5-2
|
1M | 128K | $1.40 | $4.40 | $2.15 | preview open |
Codestral
codestral-2508
|
128K | — | $0.30 | $0.90 | $0.45 | ga |
OCR 4.1
mistral-ocr-4-1
|
— | — | — | — | — | ga |
OCR 4.0
mistral-ocr-4-0
|
— | — | — | — | — | ga |
OCR 3
mistral-ocr-2512
|
— | — | — | — | — | ga |
Voxtral Small
voxtral-small-2507
|
32K | — | $0.10 | $0.40 | $0.18 | ga open |
D Verify before you commit
Model pricing changes without notice and this page is a snapshot. Confirm against the vendor's own page before you build a budget on it.
Source: docs.mistral.ai · checked 2026-09-06 · Mistral AI pricing · API docs