Comparison · prices as of 2026-07-04 · re-verified 2026-08-18
GPT-5.1 vs Mistral Medium 3.5
On price alone, Mistral Medium 3.5 (Mistral) runs about 10% cheaper than GPT-5.1 for a typical chat workload (2K input + 500 output tokens, 1,000 requests/day). Whether that's the right trade depends on the capability gap — the breakdown below shows where each one wins.
Price per million tokens
| Spec | GPT-5.1 | Mistral Medium 3.5 |
|---|---|---|
| Input / MTok | $1.25 | $1.50 |
| Output / MTok | $10 | $7.50 |
| Context window | 400K | 128K |
| Max output | 128K | 32K |
| Class | frontier | workhorse |
Estimated monthly cost by workload
Same models, three realistic usage levels. The gap between them scales with volume, so the right pick can change as you grow.
| Workload | GPT-5.1 | Mistral Medium 3.5 | Cheaper |
|---|---|---|---|
| Light — chatbot 0.5K in / 0.2K out · 200 req/day | $15.75 | $13.50 | Mistral Medium 3.5 |
| Typical — assistant 2K in / 0.5K out · 1K req/day | $225 | $203 | Mistral Medium 3.5 |
| Heavy — RAG / agent 8K in / 2K out · 5K req/day | $4,500 | $4,050 | Mistral Medium 3.5 |
Which should you pick?
- Cheapest overall: Mistral Medium 3.5 — about 10% less per month on a typical assistant workload.
- Input-heavy work (long-context RAG, summarization): GPT-5.1 wins on input at $1.25/MTok. Output-heavy work (drafting, code generation): Mistral Medium 3.5 wins on output at $7.50/MTok.
- Largest context window: GPT-5.1 at 400K tokens vs 128K — the one to pick if you feed in whole documents or codebases.
- Different classes: GPT-5.1 is a frontier model, Mistral Medium 3.5 is a workhorse model — expect GPT-5.1 to be stronger on hard reasoning and Mistral Medium 3.5 to be faster and cheaper to run.
Frequently asked questions
Is GPT-5.1 or Mistral Medium 3.5 cheaper?
Mistral Medium 3.5 is cheaper — roughly 10% less per month on a typical assistant workload (2K input + 500 output tokens, 1,000 requests/day).
What do GPT-5.1 and Mistral Medium 3.5 cost per million tokens?
GPT-5.1 is $1.25 per million input tokens and $10 per million output. Mistral Medium 3.5 is $1.50 input and $7.50 output. Prices are first-party API list rates as of 2026-07-04.
Which has the larger context window, GPT-5.1 or Mistral Medium 3.5?
GPT-5.1 does, at 400K tokens versus 128K for Mistral Medium 3.5.
When should I choose GPT-5.1 over Mistral Medium 3.5?
Choose GPT-5.1 when you need the extra capability of its frontier class; drop to Mistral Medium 3.5 when speed and cost matter more than peak quality.
Related comparisons
Sources: OpenAI pricing · Mistral pricing. Run your own numbers in the cost calculator.