GPT-5.4 vs Mistral Large 3 675B Instruct
GPT-5.4 (2026) and Mistral Large 3 675B Instruct (2025) are frontier reasoning models from OpenAI and MistralAI. GPT-5.4 ships a 1.05m-token context window, while Mistral Large 3 675B Instruct ships a 128k-token context window. On MMLU PRO, GPT-5.4 leads by 2 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.4 fits 8x more tokens; pick it for long-context work and Mistral Large 3 675B Instruct for tighter calls.
Decision scorecard
Local evidence first| Signal | GPT-5.4 | Mistral Large 3 675B Instruct |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1.05m | 128k |
| Cheapest output | $15/1M tokens | $1.50/1M tokens |
| Provider routes | 4 tracked | 6 tracked |
| Shared benchmarks | MMLU PRO leader | 3 shared |
Decision tradeoffs
- GPT-5.4 holds a shared-benchmark lead on MMLU PRO, ahead by 2 points.
- GPT-5.4 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.4 uniquely exposes Reasoning, JSON / Tool use, and Code execution in local model data.
- Local decision data tags GPT-5.4 for Coding, RAG, and Agents.
- Mistral Large 3 675B Instruct has the lower cheapest tracked output price at $1.50/1M tokens.
- Mistral Large 3 675B Instruct has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Mistral Large 3 675B Instruct for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GPT-5.4
$5,750
Cheapest tracked route/tier: OpenAI API
Mistral Large 3 675B Instruct
$775
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $4,975. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter, AWS Bedrock, and Vercel AI Gateway; start route-level A/B tests there.
- Mistral Large 3 675B Instruct is $13.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, JSON / Tool use, and Code execution before moving production traffic.
- Provider overlap exists on OpenRouter, Vercel AI Gateway, and AWS Bedrock; start route-level A/B tests there.
- GPT-5.4 is $13.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.4 adds Reasoning, JSON / Tool use, and Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-05 | 2025-12-01 |
| Context window | 1.05m | 128k |
| Parameters | — | 675B |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Apache 2.0OSI-approved |
| Openness | Proprietary | Open source |
| Weights | Not released | Unknown |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2025-08 | 2024-11 |
Pricing and availability
| Pricing attribute | GPT-5.4 | Mistral Large 3 675B Instruct |
|---|---|---|
| Input price |
| $0.50/1M tokens |
| Output price |
| $1.50/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.4 | Mistral Large 3 675B Instruct |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| JSON / Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GPT-5.4 | Mistral Large 3 675B Instruct |
|---|---|---|
| MMLU PRO | 87.5 | 85.5 |
| Google-Proof Q&A | 92.0 | 43.9 |
| τ-bench | 78.3 | 70.2 |
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.