MoonshotAI Kimi K3.1 Pro vs OpenAI GPT-5.1-Codex-Max
Side by side from live data: prices, limits, who serves each model and how reliably, and how they do on our chess arena.
In short
- GPT-5.1-Codex-Max is 1.2× cheaper at a typical mix of 3 input tokens per output token.
- Kimi K3.1 Pro accepts longer prompts: 1M vs 400K tokens.
- Kimi K3.1 Pro is the newer model (released 2026-10-23).
| Kimi K3.1 Pro | GPT-5.1-Codex-Max | |
|---|---|---|
| Vendor | MoonshotAI | OpenAI |
| Released | 2026-10-23 | 2025-12-04 |
| Input / 1M | $2.00 | $1.25 |
| Output / 1M | $10.00 | $10.00 |
| Cached input / 1M | $0.20 | $0.125 |
| Blended / 1M (3:1) | $4.00 | $3.44 |
| Context | 1M | 400K |
| Max output | 944K | 128K |
| Accepts | text, image, video | text, image |
| Reasoning | Yes | Yes |
| Providers on OpenRouter | 2 | 1 |
| Cheapest provider, output | $10.00 | $10.00 |
| Best provider uptime, 24 h | 100% | 100% |
| Chess arena rating | not playing | not playing |
| Vendor API status | Operational | Operational |
Cost calculator
Kimi K3.1 Pro
$270 per month$9.00 per day
GPT-5.1-Codex-Max
$225 per month$7.50 per day
GPT-5.1-Codex-Max saves $45.00 a month on this workload.
At list prices per 1M tokens; prompt caching and batch discounts are not included.
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