Grok 4.1 Fast vs Xiaomi MiMo-V2.5-TTS-Series
Grok 4.1 Fast (2025) and Xiaomi MiMo-V2.5-TTS-Series (2026) are frontier reasoning models from xAI and Xiaomi. Grok 4.1 Fast ships a 2m-token context window, while Xiaomi MiMo-V2.5-TTS-Series ships a not-yet-sourced context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
Xiaomi MiMo-V2.5-TTS-Series is safer overall; choose Grok 4.1 Fast when reasoning depth matters.
Decision scorecard
Local evidence first| Signal | Grok 4.1 Fast | Xiaomi MiMo-V2.5-TTS-Series |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps |
| Decision fit | RAG, Agents, and Long context | Vision |
| Context window | 2m | — |
| Cheapest output | $0.50/1M tokens | - |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Grok 4.1 Fast has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Grok 4.1 Fast has broader tracked provider coverage for fallback and procurement flexibility.
- Grok 4.1 Fast uniquely exposes Vision, Reasoning, and Function calling in local model data.
- Local decision data tags Grok 4.1 Fast for RAG, Agents, and Long context.
- Local decision data tags Xiaomi MiMo-V2.5-TTS-Series for Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Grok 4.1 Fast
$285
Cheapest tracked route/tier: OpenRouter
Xiaomi MiMo-V2.5-TTS-Series
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Grok 4.1 Fast and Xiaomi MiMo-V2.5-TTS-Series; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Reasoning, and Function calling before moving production traffic.
- No overlapping tracked provider route is sourced for Xiaomi MiMo-V2.5-TTS-Series and Grok 4.1 Fast; plan for SDK, billing, or endpoint changes.
- Grok 4.1 Fast adds Vision, Reasoning, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-19 | 2026-04-23 |
| Context window | 2m | — |
| Parameters | — | — |
| Architecture | - | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Grok 4.1 Fast | Xiaomi MiMo-V2.5-TTS-Series |
|---|---|---|
| Input price | $0.20/1M tokens | - |
| Output price | $0.50/1M tokens | - |
| Providers |
Capabilities
| Capability | Grok 4.1 Fast | Xiaomi MiMo-V2.5-TTS-Series |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | 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 4.1 Fast, reasoning mode: Grok 4.1 Fast, function calling: Grok 4.1 Fast, tool use: Grok 4.1 Fast, and structured outputs: Grok 4.1 Fast. Both models share 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.
Pricing coverage is uneven: Grok 4.1 Fast has $0.20/1M input tokens and Xiaomi MiMo-V2.5-TTS-Series has no token price sourced yet. Provider availability is 2 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Grok 4.1 Fast when reasoning depth and broader provider choice are central to the workload. Choose Xiaomi MiMo-V2.5-TTS-Series when provider fit 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. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Is Grok 4.1 Fast or Xiaomi MiMo-V2.5-TTS-Series open source?
Grok 4.1 Fast is listed under Proprietary. Xiaomi MiMo-V2.5-TTS-Series is listed under Proprietary. 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 4.1 Fast or Xiaomi MiMo-V2.5-TTS-Series?
Grok 4.1 Fast 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 4.1 Fast or Xiaomi MiMo-V2.5-TTS-Series?
Both Grok 4.1 Fast and Xiaomi MiMo-V2.5-TTS-Series expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Grok 4.1 Fast or Xiaomi MiMo-V2.5-TTS-Series?
Grok 4.1 Fast has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, Grok 4.1 Fast or Xiaomi MiMo-V2.5-TTS-Series?
Grok 4.1 Fast has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Grok 4.1 Fast and Xiaomi MiMo-V2.5-TTS-Series?
Grok 4.1 Fast is available on OpenRouter and xAI Console. Xiaomi MiMo-V2.5-TTS-Series is available on Xiaomi. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
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Last reviewed: 2026-05-26. Data sourced from public model cards and provider documentation.