GPT-5.1 Codex Max vs Kimi K2.6
GPT-5.1 Codex Max (2025) and Kimi K2.6 (2026) are agentic coding models from OpenAI and Moonshot AI. GPT-5.1 Codex Max ships a not-yet-sourced context window, while Kimi K2.6 ships a 262K-token context window. On pricing, Kimi K2.6 costs $0.75/1M input tokens versus $1.25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Kimi K2.6 is ~67% cheaper at $0.75/1M; pay for GPT-5.1 Codex Max only for coding workflow support.
Decision scorecard
Local evidence first| Signal | GPT-5.1 Codex Max | Kimi K2.6 |
|---|---|---|
| Decision fit | Coding, Agents, and Vision | Coding, RAG, and Agents |
| Context window | — | 262K |
| Cheapest output | $10/1M tokens | $3.5/1M tokens |
| Provider routes | 1 tracked | 4 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.1 Codex Max uniquely exposes Structured outputs in local model data.
- Local decision data tags GPT-5.1 Codex Max for Coding, Agents, and Vision.
- Kimi K2.6 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Kimi K2.6 has the lower cheapest tracked output price at $3.5/1M tokens.
- Kimi K2.6 has broader tracked provider coverage for fallback and procurement flexibility.
- Kimi K2.6 uniquely exposes Vision in local model data.
- Local decision data tags Kimi K2.6 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
GPT-5.1 Codex Max
$3,500
Cheapest tracked route: OpenRouter
Kimi K2.6
$1,475
Cheapest tracked route: OpenRouter
Estimated monthly gap: $2,025. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Kimi K2.6 is $6.5/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Structured outputs before moving production traffic.
- Kimi K2.6 adds Vision in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- GPT-5.1 Codex Max is $6.5/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Vision before moving production traffic.
- GPT-5.1 Codex Max adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-19 | 2026-04-20 |
| Context window | — | 262K |
| Parameters | — | 1T |
| Architecture | - | Mixture of Experts (MoE) |
| License | Proprietary | Open Source |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | GPT-5.1 Codex Max | Kimi K2.6 |
|---|---|---|
| Input price | $1.25/1M tokens | $0.75/1M tokens |
| Output price | $10/1M tokens | $3.5/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.1 Codex Max | Kimi K2.6 |
|---|---|---|
| Vision | No | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Kimi K2.6 and structured outputs: GPT-5.1 Codex Max. Both models share multimodal input, reasoning mode, function calling, and tool use, 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-5.1 Codex Max lists $1.25/1M input and $10/1M output tokens, while Kimi K2.6 lists $0.75/1M input and $3.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Kimi K2.6 lower by about $2.3 per million blended tokens. Availability is 1 providers versus 4, so concentration risk also matters.
Choose GPT-5.1 Codex Max when coding workflow support are central to the workload. Choose Kimi K2.6 when coding workflow support, 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. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which is cheaper, GPT-5.1 Codex Max or Kimi K2.6?
Kimi K2.6 is cheaper on tracked token pricing. GPT-5.1 Codex Max costs $1.25/1M input and $10/1M output tokens. Kimi K2.6 costs $0.75/1M input and $3.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.1 Codex Max or Kimi K2.6 open source?
GPT-5.1 Codex Max is listed under Proprietary. Kimi K2.6 is listed under Open Source. 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-5.1 Codex Max or Kimi K2.6?
Kimi K2.6 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-5.1 Codex Max or Kimi K2.6?
Both GPT-5.1 Codex Max and Kimi K2.6 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, GPT-5.1 Codex Max or Kimi K2.6?
Both GPT-5.1 Codex Max and Kimi K2.6 expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run GPT-5.1 Codex Max and Kimi K2.6?
GPT-5.1 Codex Max is available on OpenRouter. Kimi K2.6 is available on NVIDIA NIM, Moonshot AI Kimi, Fireworks AI, and OpenRouter. 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.