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GPT-5.1-Codex-Max vs Kimi K2 Thinking

How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for GPT-5.1-Codex-Max and Kimi K2 Thinking.

OpenAI

GPT-5.1-Codex-Max

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...

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Moonshot AI

Kimi K2 Thinking

Kimi K2 Thinking is Moonshot AI’s most advanced open reasoning model to date, extending the K2 series into agentic, long-horizon reasoning. Built on the trillion-parameter Mixture-of-Experts (MoE) architecture introduced in...

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Technical Specifications

SpecificationGPT-5.1-Codex-MaxKimi K2 Thinking
ProviderOpenAIMoonshot AI
Context Window400,000 tokens262,144 tokens
Agent SuitabilityN/AN/A
Time to First Token (TTFT)N/AN/A
Deployment Modelmanaged apimanaged api
Production Stabilitystablestable
API AvailableYesYes
Released Date2025-12-042025-11-06

API Pricing Comparison

Input Price per Million Tokens

GPT-5.1-Codex-Max

$1.25

Kimi K2 Thinking

$0.60

Output Price per Million Tokens

GPT-5.1-Codex-Max

$10.00

Kimi K2 Thinking

$2.50

Want to test both models live?

Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.

Benchmark Performance Metrics

Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.

MMLUGeneral knowledge & multi-task understanding
N/Avs8850.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking
HumanEvalPython coding & logic synthesis
N/Avs9100.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking
MATHComplex mathematical problem solving
N/Avs8540.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking
GPQAGraduate-level expert reasoning
N/Avs5450.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking
HellaSwagCommonsense reasoning and inference
N/Avs8880.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking
MT-BenchMulti-turn conversation flow quality
N/Avs922.0%
GPT-5.1-Codex-Max
Kimi K2 Thinking

GPT-5.1-Codex-Max Quirks & Gotchas

No developer gotchas reported.

Kimi K2 Thinking Quirks & Gotchas

No developer gotchas reported.