GPT-5.1 Codex Max vs Kimi K2 Thinking Turbo
GPT-5.1 Codex Max (2025) and Kimi K2 Thinking Turbo (2025) compare a coding-specialized model against a standalone API model. GPT-5.1 Codex Max ships a not-yet-sourced context window, while Kimi K2 Thinking Turbo ships a 262k-token context window. On pricing, Kimi K2 Thinking Turbo costs $1.15/1M input tokens versus $1.25/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: GPT-5.1 Codex Max is coding-specialized model, while Kimi K2 Thinking Turbo is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | GPT-5.1 Codex Max | Kimi K2 Thinking Turbo |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | general production evaluation |
| Decision fit | Coding, Agents, and Vision | Long context |
| Context window | — | 262k |
| Cheapest output | $10/1M tokens | $8/1M tokens |
| Provider routes | 1 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- GPT-5.1 Codex Max uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags GPT-5.1 Codex Max for Coding, Agents, and Vision.
- Kimi K2 Thinking Turbo has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Kimi K2 Thinking Turbo has the lower cheapest tracked output price at $8/1M tokens.
- Local decision data tags Kimi K2 Thinking Turbo for Long context.
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 Thinking Turbo
$2,920
Cheapest tracked route/tier: Vercel AI Gateway
Estimated monthly gap: $580. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- Kimi K2 Thinking Turbo is $2/1M 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.
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.1 Codex Max is $2/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.1 Codex Max adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-19 | 2025-11-06 |
| Context window | — | 262k |
| Parameters | — | 1T (32B active) |
| Architecture | - | - |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Weights | Not released | Unknown |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2024-09 | - |
Pricing and availability
| Pricing attribute | GPT-5.1 Codex Max | Kimi K2 Thinking Turbo |
|---|---|---|
| Input price | $1.25/1M tokens | $1.15/1M tokens |
| Output price | $10/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.1 Codex Max | Kimi K2 Thinking Turbo |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| JSON / 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 scores are currently available for this pair.
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.