GPT-5 vs GPT-5.1 Codex
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5 by OpenAI wins on 7 of 15 benchmarks against GPT-5.1 Codex by OpenAI, which leads on 5. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, GPT-5.1 Codex scores 1395 on Chatbot Arena ELO compared to GPT-5's 1390, while GPT-5 scores 86.0% 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 GPT-5's 92.0%, while GPT-5.1 Codex scores 78.0% on SWE-bench Verified compared to GPT-5's 74.9%, while GPT-5.1 Codex scores 85.0% on LiveCodeBench compared to GPT-5's 78.0%.
Math: In math, GPT-5 scores 94.6% on MATH compared to GPT-5.1 Codex's 85.0%, while GPT-5 scores 98.0% on GSM8K compared to GPT-5.1 Codex's 95.0%.
Reasoning: In reasoning, GPT-5 scores 87.3% 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 GPT-5's 50.0%.
Context: In context, both score 400K on Context Length.
Pricing Comparison
GPT-5 costs $1.3/1M input tokens and $10.0/1M output tokens, while GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output. Both models are priced identically for input tokens.
Speed Comparison
GPT-5 generates output at 100 tok/s compared to GPT-5.1 Codex's 85 tok/s, and the time to first token is 320 ms for GPT-5 versus 400 ms for GPT-5.1 Codex. GPT-5 delivers faster throughput.
Verdict
For developers prioritizing math and speed, GPT-5 has the edge. For those who value coding and general intelligence, GPT-5.1 Codex is the stronger choice.
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GPT-5 vs GPT-5.1 Codex — FAQ
Which is better, GPT-5 or GPT-5.1 Codex?
GPT-5 wins on more benchmarks overall (7 vs 5). However, the best choice depends on your specific needs — each model excels in different areas.
How does GPT-5 compare to GPT-5.1 Codex for coding?
GPT-5.1 Codex is better for coding, scoring 78.0% on SWE-bench Verified compared to 74.9%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is GPT-5 cheaper than GPT-5.1 Codex?
Both models are priced the same at $1.3/1M input tokens. GPT-5 output costs $10.0/1M and GPT-5.1 Codex output costs $10.0/1M.
Which is faster, GPT-5 or GPT-5.1 Codex?
GPT-5 is faster, generating output at 100 tok/s compared to 85 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the GPT-5 vs GPT-5.1 Codex comparison cover?
This comparison covers 15 benchmarks including Chatbot Arena ELO, MMLU-Pro, HumanEval+, MATH, GPQA Diamond, SWE-bench Verified, Output Speed, LiveCodeBench, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.