GPT-5 vs GPT-5.1 Codex
GPT-5 and GPT-5.1 Codex are closely matched at 34.4 and 29.6 on the LLM Stats Score. GPT-5 and GPT-5.1 Codex cost the same.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-5 and GPT-5.1 Codex are closely matched on the overall LLM Stats Score at 34.4 and 29.6.
In the 1 individual benchmarks reported for both models, GPT-5 wins 1; this is a narrower head-to-head signal than the composite indexes.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
Choose GPT-5.1 Codex
- you want the most recent training data — it shipped Nov 2025
At a glance
The differences that matter most.
Individual benchmarks
34 reported for GPT-5 · 3 for GPT-5.1 Codex
GPT-5 outperforms in 1 benchmarks (SWE-Bench Verified), while GPT-5.1 Codex is better at 0 benchmarks.
GPT-5 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5 ($1.25/1M tokens) costs the same as GPT-5.1 Codex ($1.25/1M tokens).
For output processing, GPT-5 ($10.00/1M tokens) costs the same as GPT-5.1 Codex ($10.00/1M tokens).
In conclusion, GPT-5 and GPT-5.1 Codex cost the same.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Both models have the same input context window of 400,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both GPT-5 and GPT-5.1 Codex support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5
GPT-5.1 Codex
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-5 was released on 2025-08-07, while GPT-5.1 Codex was released on 2025-11-19.
GPT-5.1 Codex is 3 months newer than GPT-5.
Aug 7, 2025
1.1 years ago
Nov 19, 2025
9 months ago
3mo newerKnowledge Cutoff
When training data ends
Both models have the same knowledge cutoff date of 2024-09-30.
They should have similar awareness of historical events and information up to this date.
Sep 2024
Sep 2024
Provider Availability
GPT-5 is available from OpenAI. GPT-5.1 Codex is available from OpenAI.
GPT-5
GPT-5.1 Codex
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5 and GPT-5.1 Codex side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5 vs GPT-5.1 Codex.