Model Comparison
Claude Sonnet 5 vs GPT-5.3 CodexWhich is better in 2026?
Claude Sonnet 5 significantly outperforms across most benchmarks. GPT-5.3 Codex is 1.2x cheaper per token.
Verdict: Claude Sonnet 5 vs GPT-5.3 Codex — which is better?
Claude Sonnet 5 (by Anthropic) and GPT-5.3 Codex (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Claude Sonnet 5 outperforms in 3 benchmarks (OSWorld-Verified, SWE-Bench Pro, Terminal-Bench 2.0), while GPT-5.3 Codex is better at 0 benchmarks. Claude Sonnet 5 significantly outperforms across most benchmarks.
On price, GPT-5.3 Codex is roughly 1.2x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Sonnet 5 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Claude Sonnet 5 if…
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Jun 2026
Choose GPT-5.3 Codex if…
- cost matters — it's about 1.2x cheaper per token
Performance Benchmarks
Comparative analysis across standard metrics
Claude Sonnet 5 outperforms in 3 benchmarks (OSWorld-Verified, SWE-Bench Pro, Terminal-Bench 2.0), while GPT-5.3 Codex is better at 0 benchmarks.
Claude Sonnet 5 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Sonnet 5 ($3.00/1M tokens) is 1.7x more expensive than GPT-5.3 Codex ($1.75/1M tokens).
For output processing, Claude Sonnet 5 ($15.00/1M tokens) is 1.1x more expensive than GPT-5.3 Codex ($14.00/1M tokens).
In conclusion, Claude Sonnet 5 is more expensive than GPT-5.3 Codex.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Sonnet 5 accepts 1,000,000 input tokens compared to GPT-5.3 Codex's 400,000 tokens. GPT-5.3 Codex can generate longer responses up to 128,000 tokens, while Claude Sonnet 5 is limited to 64,000 tokens.
Input Capabilities
Supported data types and modalities
Both Claude Sonnet 5 and GPT-5.3 Codex support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Sonnet 5
GPT-5.3 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
Claude Sonnet 5 was released on 2026-06-30, while GPT-5.3 Codex was released on 2026-02-05.
Claude Sonnet 5 is 5 months newer than GPT-5.3 Codex.
Jun 30, 2026
3 weeks ago
4mo newerFeb 5, 2026
5 months ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
Claude Sonnet 5 is available from Anthropic. GPT-5.3 Codex is available from OpenAI.
Claude Sonnet 5
GPT-5.3 Codex
Outputs Comparison
Key Takeaways
Claude Sonnet 5
View detailsAnthropic
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Claude Sonnet 5 and GPT-5.3 Codex side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Claude Sonnet 5 vs GPT-5.3 Codex.