Grok 4 Fast Reasoning vs Mistral Large 3 675B Instruct
Grok 4 Fast Reasoning (2025) and Mistral Large 3 675B Instruct (2025) are frontier reasoning models from xAI and MistralAI. Grok 4 Fast Reasoning ships a 2m-token context window, while Mistral Large 3 675B Instruct ships a 128k-token context window. On pricing, Mistral Large 3 675B Instruct costs $0.50/1M input tokens versus $1.25/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Mistral Large 3 675B Instruct is ~150% cheaper at $0.50/1M; pay for Grok 4 Fast Reasoning only for reasoning depth.
Decision scorecard
Local evidence first| Signal | Grok 4 Fast Reasoning | Mistral Large 3 675B Instruct |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and long-context analysis | multimodal apps and provider-routed production |
| Decision fit | Long context and Vision | Coding, RAG, and Agents |
| Context window | 2m | 128k |
| Cheapest output | $2.50/1M tokens | $1.50/1M tokens |
| Provider routes | 2 tracked | 5 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Grok 4 Fast Reasoning has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Grok 4 Fast Reasoning uniquely exposes Reasoning in local model data.
- Local decision data tags Grok 4 Fast Reasoning for Long context and Vision.
- 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 procurement flexibility.
- Mistral Large 3 675B Instruct uniquely exposes Structured outputs in local model data.
- 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.
Grok 4 Fast Reasoning
$1,625
Cheapest tracked route/tier: xAI Console
Mistral Large 3 675B Instruct
$775
Cheapest tracked route/tier: AWS Bedrock
Estimated monthly gap: $850. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Microsoft Foundry; start route-level A/B tests there.
- Mistral Large 3 675B Instruct is $1/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Mistral Large 3 675B Instruct adds Structured outputs in local capability data.
- Provider overlap exists on Microsoft Foundry; start route-level A/B tests there.
- Grok 4 Fast Reasoning is $1/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Structured outputs before moving production traffic.
- Grok 4 Fast Reasoning adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-01 | 2025-12-01 |
| Context window | 2m | 128k |
| Parameters | — | 675B |
| Architecture | decoder only | decoder only |
| License | Proprietary | Mistral License |
| Openness | Proprietary | Open weights |
| Commercial use | Commercial use with conditions | Non-commercial only |
| Knowledge cutoff | - | 2024-11 |
Pricing and availability
| Pricing attribute | Grok 4 Fast Reasoning | Mistral Large 3 675B Instruct |
|---|---|---|
| Input price | $1.25/1M tokens | $0.50/1M tokens |
| Output price | $2.50/1M tokens | $1.50/1M tokens |
| Providers |
Capabilities
| Capability | Grok 4 Fast Reasoning | Mistral Large 3 675B Instruct |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | No | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Grok 4 Fast Reasoning and structured outputs: Mistral Large 3 675B Instruct. Both models share vision and multimodal input, 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, Grok 4 Fast Reasoning lists $1.25/1M input and $2.50/1M output tokens on the cheapest tracked provider, while Mistral Large 3 675B Instruct lists $0.50/1M input and $1.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Large 3 675B Instruct lower by about $0.83 per million blended tokens. Availability is 2 providers versus 5, so concentration risk also matters.
Choose Grok 4 Fast Reasoning when reasoning depth and larger context windows are central to the workload. Choose Mistral Large 3 675B Instruct when vision-heavy evaluation, 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, Grok 4 Fast Reasoning or Mistral Large 3 675B Instruct?
Grok 4 Fast Reasoning supports 2m 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, Grok 4 Fast Reasoning or Mistral Large 3 675B Instruct?
Mistral Large 3 675B Instruct is cheaper on tracked token pricing. Grok 4 Fast Reasoning costs $1.25/1M input and $2.50/1M output tokens. Mistral Large 3 675B Instruct costs $0.50/1M input and $1.50/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Grok 4 Fast Reasoning or Mistral Large 3 675B Instruct open source?
Grok 4 Fast Reasoning is listed under Proprietary. Mistral Large 3 675B Instruct is listed under Mistral License. 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, Grok 4 Fast Reasoning or Mistral Large 3 675B Instruct?
Both Grok 4 Fast Reasoning and Mistral Large 3 675B Instruct expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Grok 4 Fast Reasoning or Mistral Large 3 675B Instruct?
Both Grok 4 Fast Reasoning and Mistral Large 3 675B Instruct expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Grok 4 Fast Reasoning and Mistral Large 3 675B Instruct?
Grok 4 Fast Reasoning is available on Microsoft Foundry and xAI Console. Mistral Large 3 675B Instruct is available on AWS Bedrock, NVIDIA NIM, Mistral AI Studio, Microsoft Foundry, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-04. Data sourced from public model cards and provider documentation.