GPT-5.1-CodexvsKimi K2.5
Kimi K2.5 is cheaper than GPT-5.1-Codex at $0.6/M vs $1.25/M input tokens.
| Spec | GPT-5.1-Codex | Kimi K2.5 |
|---|---|---|
| Input price | $1.25/M tokens | $0.6/M tokens |
| Output price | $10/M tokens | $3/M tokens |
| Context window | 400K tokens | 262K tokens |
| Weights | Closed | Open |
| Free API (OpenRouter) | No | No |
| Released | Nov 2025 | Jan 2026 |
| SWE-bench Verified | 73.7% | 76.8% |
Our Verdict
GPT-5.1-Codex
Kimi K2.5Runner-up
Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, bigger context window, major provider backing.
Kimi K2.5 costs 3.3x less per token.
Too close to call
Reviewing agent-written code?See a Brief PR report
API pricing
Cost per 1M tokens
GPT-5.1-Codex
Input
$1.25
Output
$10.00
Kimi K2.5
Input
$0.60
2.1× cheaper
Output
$3.00
3.3× cheaper
Kimi K2.5 is cheaper on both: 2.1× input, 3.3× output.
Where to run it
7 hosts, cheapest first
GPT-5.1-Codex1 host
Per million tokens. Prices and uptime via OpenRouter, checked 11 Sep 2026.
Writing DNA
Style Comparison
Similarity
57%
GPT-5.1-Codex
Kimi K2.5
70%Vocabulary62%
17wSentence Length22w
0.39Hedging0.50
3.4Bold4.2
3.5Lists2.4
0.00Emoji0.01
0.50Headings0.51
0.38Transitions0.17
Based on 14 + 26 text responses
Research
What we learned reading every model
FAQ
Common questions
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