Claude 3 Opus vs GPT-5.1 Codex Comparison

Comparing Claude 3 Opus and GPT-5.1 Codex across benchmarks, pricing, and capabilities.

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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude 3 Opus and GPT-5.1 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-5.1 Codex costs less

For input processing, Claude 3 Opus ($15.00/1M tokens) is 12.0x more expensive than GPT-5.1 Codex ($1.25/1M tokens).

For output processing, Claude 3 Opus ($75.00/1M tokens) is 7.5x more expensive than GPT-5.1 Codex ($10.00/1M tokens).

In conclusion, Claude 3 Opus is more expensive than GPT-5.1 Codex.*

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

Lowest available price from all providers

Sun Mar 15 2026 • llm-stats.com

Claude 3 Opus

Input tokens$15.00

Output tokens$75.00

Best providerAnthropic

GPT-5.1 Codex

Input tokens$1.25

Output tokens$10.00

Best providerOpenAI

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Context Window

Maximum input and output token capacity

GPT-5.1 Codex accepts 400,000 input tokens compared to Claude 3 Opus's 200,000 tokens. Claude 3 Opus can generate longer responses up to 200,000 tokens, while GPT-5.1 Codex is limited to 128,000 tokens.

Claude 3 Opus

Input200,000 tokens

Output200,000 tokens

GPT-5.1 Codex

Input400,000 tokens

Output128,000 tokens

Sun Mar 15 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude 3 Opus and GPT-5.1 Codex support multimodal inputs.

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

Claude 3 Opus

Text

Images

Audio

Video

GPT-5.1 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 3 Opus

Proprietary

Closed source

GPT-5.1 Codex

Proprietary

Closed source

Release Timeline

When each model was launched

Claude 3 Opus was released on 2024-02-29, while GPT-5.1 Codex was released on 2025-11-19.

GPT-5.1 Codex is 21 months newer than Claude 3 Opus.

Claude 3 Opus

Feb 29, 2024

2.0 years ago

GPT-5.1 Codex

Nov 19, 2025

3 months ago

1.7yr newer

Knowledge Cutoff

When training data ends

GPT-5.1 Codex has a documented knowledge cutoff of 2024-09-30, while Claude 3 Opus's cutoff date is not specified.

We can confirm GPT-5.1 Codex's training data extends to 2024-09-30, but cannot make a direct comparison without Claude 3 Opus's cutoff date.

Claude 3 Opus

—

GPT-5.1 Codex

Sep 2024

Provider Availability

Claude 3 Opus is available from Anthropic, Bedrock, Google. GPT-5.1 Codex is available from OpenAI. The availability of providers can affect quality of the model and reliability.