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 $0.73/1M 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.
Kimi K2.6 is ~71% cheaper at $0.73/1M; 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 |
|---|---|---|
| Best for | custom coding agents, code generation, and tool loops | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, Agents, and Vision | Coding, RAG, and Agents |
| Context window | — | 262k |
| Cheapest output | $10/1M tokens | $3.49/1M tokens |
| Provider routes | 3 tracked | 9 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- 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 $3.49/1M tokens.
- Kimi K2.6 has broader tracked provider coverage for fallback and route flexibility.
- 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 route or tier on this page.
GPT-5.1 Codex Max
$3,500
Cheapest tracked route/tier: Vercel AI Gateway
Kimi K2.6
$1,457
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $2,044. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Kimi K2.6 is $6.51/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Provider overlap exists on Vercel AI Gateway and OpenRouter; start route-level A/B tests there.
- GPT-5.1 Codex Max is $6.51/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-19 | 2026-04-20 |
| Context window | — | 262k |
| Parameters | — | 1T |
| Architecture | - | Mixture of Experts |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Weights | Not released | Available·Moonshot Modified MIT License |
| Code | Unknown | Available·Moonshot Modified MIT License |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2024-09 | 2025-04 |
Pricing and availability
| Pricing attribute | GPT-5.1 Codex Max | Kimi K2.6 |
|---|---|---|
| Input price | $1.25/1M tokens | $0.73/1M tokens |
| Output price | $10/1M tokens | $3.49/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.1 Codex Max | Kimi K2.6 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
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Last reviewed: 2026-06-30. Data sourced from public model cards and provider documentation.