GPT-5.5 Instant vs Mistral Large 3 675B Instruct
GPT-5.5 Instant (2026) and Mistral Large 3 675B Instruct (2025) are compact production models from OpenAI and MistralAI. GPT-5.5 Instant ships a 400K-token context window, while Mistral Large 3 675B Instruct ships a 128K-token context window. On pricing, Mistral Large 3 675B Instruct costs $0.5/1M input tokens versus $1.5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Mistral Large 3 675B Instruct is ~200% cheaper at $0.5/1M; pay for GPT-5.5 Instant only for coding workflow support.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-05 | 2025-12-01 |
| Context window | 400K | 128K |
| Parameters | — | 675B |
| Architecture | decoder only | decoder only |
| License | Proprietary | 1 |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| Pricing attribute | GPT-5.5 Instant | Mistral Large 3 675B Instruct |
|---|---|---|
| Input price | $1.5/1M tokens | $0.5/1M tokens |
| Output price | $6/1M tokens | $1.5/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.5 Instant | Mistral Large 3 675B Instruct |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: GPT-5.5 Instant, multimodal input: GPT-5.5 Instant, function calling: GPT-5.5 Instant, tool use: GPT-5.5 Instant, and code execution: GPT-5.5 Instant. Both models share structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, GPT-5.5 Instant lists $1.5/1M input and $6/1M output tokens, while Mistral Large 3 675B Instruct lists $0.5/1M input and $1.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Large 3 675B Instruct lower by about $2.05 per million blended tokens. Availability is 1 providers versus 3, so concentration risk also matters.
Choose GPT-5.5 Instant when coding workflow support and larger context windows are central to the workload. Choose Mistral Large 3 675B Instruct when provider fit, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, GPT-5.5 Instant or Mistral Large 3 675B Instruct?
GPT-5.5 Instant supports 400K tokens, while Mistral Large 3 675B Instruct supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, GPT-5.5 Instant or Mistral Large 3 675B Instruct?
Mistral Large 3 675B Instruct is cheaper on tracked token pricing. GPT-5.5 Instant costs $1.5/1M input and $6/1M output tokens. Mistral Large 3 675B Instruct costs $0.5/1M input and $1.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.5 Instant or Mistral Large 3 675B Instruct open source?
GPT-5.5 Instant is listed under Proprietary. Mistral Large 3 675B Instruct is listed under 1. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GPT-5.5 Instant or Mistral Large 3 675B Instruct?
GPT-5.5 Instant has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-5.5 Instant or Mistral Large 3 675B Instruct?
GPT-5.5 Instant has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GPT-5.5 Instant and Mistral Large 3 675B Instruct?
GPT-5.5 Instant is available on OpenAI API. Mistral Large 3 675B Instruct is available on AWS Bedrock, NVIDIA NIM, and Mistral AI Studio. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.