Grok 4 Fast Reasoning vs Mixtral 8x22B Instruct v0.3
Grok 4 Fast Reasoning (2025) and Mixtral 8x22B Instruct v0.3 (2024) are frontier reasoning models from xAI and MistralAI. Grok 4 Fast Reasoning ships a 2m-token context window, while Mixtral 8x22B Instruct v0.3 ships a 64k-token context window. On pricing, Grok 4 Fast Reasoning costs $1.25/1M input tokens versus $2/1M 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.
Grok 4 Fast Reasoning is ~60% cheaper at $1.25/1M; pay for Mixtral 8x22B Instruct v0.3 only for provider fit.
Decision scorecard
Local evidence first| Signal | Grok 4 Fast Reasoning | Mixtral 8x22B Instruct v0.3 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and long-context analysis | tool-calling agents |
| Decision fit | Long context and Vision | Agents and JSON / Tool use |
| Context window | 2m | 64k |
| Cheapest output | $2.50/1M tokens | $2/1M tokens |
| Provider routes | 2 tracked | 1 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 has broader tracked provider coverage for fallback and procurement flexibility.
- Grok 4 Fast Reasoning uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags Grok 4 Fast Reasoning for Long context and Vision.
- Mixtral 8x22B Instruct v0.3 has the lower cheapest tracked output price at $2/1M tokens.
- Mixtral 8x22B Instruct v0.3 uniquely exposes Function calling in local model data.
- Local decision data tags Mixtral 8x22B Instruct v0.3 for Agents and JSON / Tool use.
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
Mixtral 8x22B Instruct v0.3
$2,100
Cheapest tracked route/tier: Replicate API
Estimated monthly gap: $475. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Grok 4 Fast Reasoning and Mixtral 8x22B Instruct v0.3; plan for SDK, billing, or endpoint changes.
- Mixtral 8x22B Instruct v0.3 is $0.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- Mixtral 8x22B Instruct v0.3 adds Function calling in local capability data.
- No overlapping tracked provider route is sourced for Mixtral 8x22B Instruct v0.3 and Grok 4 Fast Reasoning; plan for SDK, billing, or endpoint changes.
- Grok 4 Fast Reasoning is $0.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Function calling before moving production traffic.
- Grok 4 Fast Reasoning adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-01 | 2024-07-01 |
| Context window | 2m | 64k |
| Parameters | — | 8x22B |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | Apache 2.0(OSI) |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use with conditions | Commercial use allowed |
| Knowledge cutoff | - | 2024-01 |
Pricing and availability
| Pricing attribute | Grok 4 Fast Reasoning | Mixtral 8x22B Instruct v0.3 |
|---|---|---|
| Input price | $1.25/1M tokens | $2/1M tokens |
| Output price | $2.50/1M tokens | $2/1M tokens |
| Providers |
Capabilities
| Capability | Grok 4 Fast Reasoning | Mixtral 8x22B Instruct v0.3 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| Function calling | No | Yes |
| Tool use | No | No |
| Structured outputs | No | No |
| 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 vision: Grok 4 Fast Reasoning, multimodal input: Grok 4 Fast Reasoning, reasoning mode: Grok 4 Fast Reasoning, and function calling: Mixtral 8x22B Instruct v0.3. Both models share the core language-model surface, 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 Mixtral 8x22B Instruct v0.3 lists $2/1M input and $2/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok 4 Fast Reasoning lower by about $0.38 per million blended tokens. Availability is 2 providers versus 1, so concentration risk also matters.
Choose Grok 4 Fast Reasoning when reasoning depth, larger context windows, and lower input-token cost are central to the workload. Choose Mixtral 8x22B Instruct v0.3 when provider fit are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Grok 4 Fast Reasoning or Mixtral 8x22B Instruct v0.3?
Grok 4 Fast Reasoning supports 2m tokens, while Mixtral 8x22B Instruct v0.3 supports 64k 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 Mixtral 8x22B Instruct v0.3?
Grok 4 Fast Reasoning is cheaper on tracked token pricing. Grok 4 Fast Reasoning costs $1.25/1M input and $2.50/1M output tokens. Mixtral 8x22B Instruct v0.3 costs $2/1M input and $2/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Grok 4 Fast Reasoning or Mixtral 8x22B Instruct v0.3 open source?
Grok 4 Fast Reasoning is listed under Proprietary. Mixtral 8x22B Instruct v0.3 is listed under Apache 2.0. 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 Mixtral 8x22B Instruct v0.3?
Grok 4 Fast Reasoning 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.
Which is better for multimodal input, Grok 4 Fast Reasoning or Mixtral 8x22B Instruct v0.3?
Grok 4 Fast Reasoning 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 Grok 4 Fast Reasoning and Mixtral 8x22B Instruct v0.3?
Grok 4 Fast Reasoning is available on Microsoft Foundry and xAI Console. Mixtral 8x22B Instruct v0.3 is available on Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-20. Data sourced from public model cards and provider documentation.