GPT-5.1-Codex vs Kimi K3
GPT-5.1-Codex (OpenAI) and Kimi K3 (Moonshot) compared on benchmarks, pricing, context window, and use-case rankings.
- GPT-5.1-Codex is cheaper on input tokens — $1.25 vs $2.10 per 1M.
- Kimi K3 has a larger context window (1M vs 400K tokens).
- Kimi K3 ranks higher for coding (97th vs 43th percentile).
| Attribute | GPT-5.1-Codex | Kimi K3 |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | — | 158 |
| Coding | 43 | 97 |
| Math | 76 | 80 |
| Reasoning & Knowledge | 56 | 73 |
| Agentic & Tools | 42 | 80 |
| Specifications | ||
| Developer | OpenAI | Moonshot |
| Family | GPT | Kimi |
| Released | Nov 12, 2025 | Jul 16, 2026 |
| Parameters | — | 2.8T |
| Availability | API access | Open weights (non-commercial) |
| Context window | 400K | 1M |
| Price — $/M input | $1.25 | $2.10 |
| Price — $/M output | $10.00 | $10.95 |
| Inputs | text, image | text, image, video |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 96% | 97% |
| APEX | 21% | 39% |
| GPQA Diamond | 86% | 93% |
| Humanity's Last Exam | 26% | 47% |
| LiveCodeBench | 85% | — |
| MMLU-Pro | 86% | — |
| SciCode | 40% | 60% |
| Terminal-Bench | 58% | — |
| WebDev Arena | 1336 | 1674 |
| τ²-bench | 83% | — |
| ARC-AGI | — | 95% |
| ARC-AGI-2 | — | 60% |
| SimpleBench | — | 61% |
| SimpleQA Verified | — | 51% |
| WeirdML | — | 83% |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
Frequently asked questions
Which is cheaper, GPT-5.1-Codex or Kimi K3?
GPT-5.1-Codex is cheaper on input tokens at $1.25 per million, versus $2.10 (representative OpenRouter pricing).
Which has a larger context window, GPT-5.1-Codex or Kimi K3?
Kimi K3 supports up to 1M tokens, compared with 400K for the other.
Which is better for coding, GPT-5.1-Codex or Kimi K3?
Across coding benchmarks like SWE-bench Verified and Terminal-Bench, Kimi K3 ranks higher — 97th vs 43th percentile among the models tracked on Model Beat.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.