GPT-5.1 Codex vs Grok 4
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.1 Codex by OpenAI wins on 9 of 15 benchmarks against Grok 4 by xAI, which leads on 6. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from the AI Value Index.
Category-by-Category Breakdown
General Intelligence: In general intelligence, Grok 4 scores 1430 on Chatbot Arena ELO compared to GPT-5.1 Codex's 1395, while Grok 4 scores 87.0% on MMLU-Pro compared to GPT-5.1 Codex's 82.0%.
Coding: In coding, GPT-5.1 Codex scores 96.0% on HumanEval+ compared to Grok 4's 90.0%, while GPT-5.1 Codex scores 78.0% on SWE-bench Verified compared to Grok 4's 72.0%, while GPT-5.1 Codex scores 85.0% on LiveCodeBench compared to Grok 4's 65.0%, while Grok 4 scores 79.6% on Aider Polyglot compared to GPT-5.1 Codex's 76.0%.
Math: In math, Grok 4 scores 91.0% on MATH compared to GPT-5.1 Codex's 85.0%, while Grok 4 scores 97.0% on GSM8K compared to GPT-5.1 Codex's 95.0%.
Reasoning: In reasoning, Grok 4 scores 87.0% on GPQA Diamond compared to GPT-5.1 Codex's 65.0%, while GPT-5.1 Codex scores 52.0% on ARC-AGI compared to Grok 4's 50.0%.
Context: In context, GPT-5.1 Codex scores 400K on Context Length compared to Grok 4's 256K.
Pricing Comparison
GPT-5.1 Codex costs $1.3/1M input tokens and $10.0/1M output tokens, while Grok 4 costs $3.0/1M input and $15.0/1M output. GPT-5.1 Codex is the more affordable option for API usage.
Speed Comparison
GPT-5.1 Codex generates output at 85 tok/s compared to Grok 4's 55 tok/s, and the time to first token is 400 ms for GPT-5.1 Codex versus 500 ms for Grok 4. GPT-5.1 Codex delivers faster throughput.
Verdict
For developers prioritizing coding and affordability and speed, GPT-5.1 Codex has the edge. For those who value general intelligence and math, Grok 4 is the stronger choice.
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GPT-5.1 Codex vs Grok 4 — FAQ
Which is better, GPT-5.1 Codex or Grok 4?
GPT-5.1 Codex wins on more benchmarks overall (9 vs 6). However, the best choice depends on your specific needs — each model excels in different areas.
How does GPT-5.1 Codex compare to Grok 4 for coding?
GPT-5.1 Codex is better for coding, scoring 78.0% on SWE-bench Verified compared to 72.0%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is GPT-5.1 Codex cheaper than Grok 4?
Yes, GPT-5.1 Codex is cheaper. GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output tokens. Grok 4 costs $3.0/1M input and $15.0/1M output tokens.
Which is faster, GPT-5.1 Codex or Grok 4?
GPT-5.1 Codex is faster, generating output at 85 tok/s compared to 55 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the GPT-5.1 Codex vs Grok 4 comparison cover?
This comparison covers 15 benchmarks including Chatbot Arena ELO, MMLU-Pro, HumanEval+, MATH, SWE-bench Verified, GPQA Diamond, Output Speed, Time to First Token, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.