Model comparison
GPT 5.5 vs Mistral Medium 3.1
GPT 5.5 (OpenAI) and Mistral Medium 3.1 (Mistral) side by side: what each costs per million tokens through Rapid Router, how much context each takes, what each supports, and where independent benchmarks place them. Same API, same key; switching is a one-string change.
| GPT 5.5 | Mistral Medium 3.1 | |
|---|---|---|
| Input price per 1M | $5.00 | $0.400 |
| Output price per 1M | $30.00 | $2.00 |
| Context window | 1.1M tokens | 262K tokens |
| Max output | 128K tokens | 262K tokens |
| Input types | text, image, pdf | text, image |
| Capabilities | tools, JSON, vision, reasoning | tools, vision |
| Author | OpenAI | Mistral |
| LMArena Overall | 1471 | 1424 |
| LMArena Coding | 1494 | 1433 |
| LMArena Math | 1487 | 1409 |
| LMArena Creative writing | 1455 | 1391 |
| LMArena Instruction following | 1479 | 1398 |
| LMArena Hard prompts | 1489 | 1426 |
| LMArena Vision | 1297 | 1172 |
| GPQA Diamond | 90.7% | — |
| OTIS Mock AIME | 84.4% | — |
| SimpleQA Verified | 63.0% | — |
Scores from LMArena and Epoch AI, as published; a blank cell means not measured there.
What a month costs on each
| Workload | GPT 5.5 | Mistral Medium 3.1 |
|---|---|---|
| Chatbot month (15M in, 4M out) | $195.00 | $14.00 |
| RAG month (40M in, 3M out) | $290.00 | $22.00 |
| Coding month (60M in, 10M out) | $600.00 | $44.00 |
On a typical 75/25 input-output mix, Mistral Medium 3.1 costs less (about 93% less than GPT 5.5). GPT 5.5 takes the longer prompt at 1.1M tokens. Try your own numbers in the cost calculator.
Call either one
curl https://rapidrouter.ai/api/v1/chat/completions \
-H "Authorization: Bearer $RAPIDROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "openai/gpt-5.5", "messages": [{"role": "user", "content": "Hello"}]}'
# the other one: change the model string
-d '{"model": "mistralai/mistral-medium-2508", ...}'Common questions
Which is cheaper, GPT 5.5 or Mistral Medium 3.1?
Mistral Medium 3.1 is cheaper on a typical mix of 75% input and 25% output tokens, by about 93%. Through Rapid Router both are billed at the provider list price per million tokens.
Which has the larger context window?
GPT 5.5, at 1.1M tokens. Mistral Medium 3.1 offers 262K tokens.
Can I switch between GPT 5.5 and Mistral Medium 3.1 without changing code?
Yes. Both are callable at https://rapidrouter.ai/api/v1 with the same OpenAI-compatible request; only the model string changes (openai/gpt-5.5 or mistralai/mistral-medium-2508).
How do I pay for GPT 5.5 or Mistral Medium 3.1?
Top up a Rapid Router balance by card in US dollars, and both models debit that balance per request.
More GPT models: OpenAI API pricing · More Mistral: Mistral API pricing