Model Comparison

Claude Sonnet 4.5 vs GPT-5.3 Codex

Comparing Claude Sonnet 4.5 and GPT-5.3 Codex across benchmarks, pricing, and capabilities.

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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Sonnet 4.5 and GPT-5.3 Codex don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.3 Codex costs less

For input processing, Claude Sonnet 4.5 ($3.00/1M tokens) is 1.7x more expensive than GPT-5.3 Codex ($1.75/1M tokens).

For output processing, Claude Sonnet 4.5 ($15.00/1M tokens) is 1.1x more expensive than GPT-5.3 Codex ($14.00/1M tokens).

In conclusion, Claude Sonnet 4.5 is more expensive than GPT-5.3 Codex.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Wed Apr 15 2026 • llm-stats.com
Anthropic
Claude Sonnet 4.5
Input tokens$3.00
Output tokens$15.00
Best providerAnthropic
OpenAI
GPT-5.3 Codex
Input tokens$1.75
Output tokens$14.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.3 Codex accepts 400,000 input tokens compared to Claude Sonnet 4.5's 200,000 tokens. GPT-5.3 Codex can generate longer responses up to 128,000 tokens, while Claude Sonnet 4.5 is limited to 64,000 tokens.

Anthropic
Claude Sonnet 4.5
Input200,000 tokens
Output64,000 tokens
OpenAI
GPT-5.3 Codex
Input400,000 tokens
Output128,000 tokens
Wed Apr 15 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Sonnet 4.5 and GPT-5.3 Codex support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 4.5

Text
Images
Audio
Video

GPT-5.3 Codex

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Sonnet 4.5

Proprietary

Closed source

GPT-5.3 Codex

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 4.5 was released on 2025-09-29, while GPT-5.3 Codex was released on 2026-02-05.

GPT-5.3 Codex is 4 months newer than Claude Sonnet 4.5.

Claude Sonnet 4.5

Sep 29, 2025

6 months ago

GPT-5.3 Codex

Feb 5, 2026

2 months ago

4mo newer

Knowledge Cutoff

When training data ends

Claude Sonnet 4.5 has a documented knowledge cutoff of 2025-01-31, while GPT-5.3 Codex's cutoff date is not specified.

We can confirm Claude Sonnet 4.5's training data extends to 2025-01-31, but cannot make a direct comparison without GPT-5.3 Codex's cutoff date.

Claude Sonnet 4.5

Jan 2025

GPT-5.3 Codex

—

Provider Availability

Claude Sonnet 4.5 is available from Anthropic. GPT-5.3 Codex is available from OpenAI.

Claude Sonnet 4.5

anthropic logo
Anthropic
Input Price:Input: $3.00/1MOutput Price:Output: $15.00/1M

GPT-5.3 Codex

openai logo
OpenAI
Input Price:Input: $1.75/1MOutput Price:Output: $14.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
OpenAI
Larger context window (400,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

AI Model Comparison Table
Feature
Anthropic
Claude Sonnet 4.5
OpenAI
GPT-5.3 Codex

FAQ

Common questions about Claude Sonnet 4.5 vs GPT-5.3 Codex

Claude Sonnet 4.5 (Anthropic) and GPT-5.3 Codex (OpenAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.
Claude Sonnet 4.5 scores MMMLU: 89.1%, AIME 2025: 87.0%, TAU-bench Retail: 86.2%, GPQA: 83.4%, MMMUval: 77.8%. GPT-5.3 Codex scores SWE-Lancer (IC-Diamond subset): 81.4%, Cybersecurity CTFs: 77.6%, Terminal-Bench 2.0: 77.3%, OSWorld-Verified: 64.7%, SWE-Bench Pro: 56.8%.
GPT-5.3 Codex is 1.7x cheaper for input tokens. Claude Sonnet 4.5 costs $3.00/M input and $15.00/M output via anthropic. GPT-5.3 Codex costs $1.75/M input and $14.00/M output via openai.
Claude Sonnet 4.5 supports 200K tokens and GPT-5.3 Codex supports 400K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.
Key differences include context window (200K vs 400K), input pricing ($3.00 vs $1.75/M). See the full comparison above for benchmark-by-benchmark results.
Claude Sonnet 4.5 is developed by Anthropic and GPT-5.3 Codex is developed by OpenAI.