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Claude Opus 4.5 vs GPT-5 Codex (Comparative Analysis)

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Comparative Analysis: Claude Opus 4.5 vs. GPT-5 Codex
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Overview

GPT-5 Codex was released 2 months before Claude Opus 4.5.
Claude Opus 4.5Claude Opus 4.5
GPT-5 CodexGPT-5 Codex
Model Provider
The organization behind this AI's development
Anthropic logoAnthropic
OpenAI logoOpenAI
Input Context Window
Maximum input tokens this model can process at once
200K
tokens
400K
tokens
Output Token Limit
Maximum output tokens this model can generate at once
64K
tokens
128K
tokens
Release Date
When this model first became publicly available
November 24th, 2025
September 23rd, 2025
Knowledge Cutoff
Latest training-data date reported by the provider
Not reported
September 30, 2024

Capabilities & Features

Compare supported features, modalities, and advanced capabilities
Claude Opus 4.5
GPT-5 Codex
Input Types
Supported input formats
📁File🖼️Image📝Text
📝Text🖼️Image
Reasoning Controls
Defaults and configurable reasoning effort
Optional
Always enabled
Output Types
Supported output formats
📝Text
📝Text
Tokenizer
Text encoding system
ClaudeGPT
Key Features
Advanced capabilities
Function CallingStructured OutputReasoning ModeContent Moderation
Function CallingStructured OutputReasoning ModeContent Moderation

Pricing

Claude Opus 4.5 is roughly 4.0x more expensive compared to GPT-5 Codex for input tokens and roughly 2.5x more expensive for output tokens.
Claude Opus 4.5Claude Opus 4.5
GPT-5 CodexGPT-5 Codex
Input Token Cost
Cost per million input tokens
$5.00
per million tokens
$1.25
per million tokens
Output Token Cost
Cost per million output tokens
$25.00
per million tokens
$10.00
per million tokens
Web Search Cost
Additional cost for each web search operation
$0.01
per search
$0.01
per search
Cache Read Cost
Cost to reuse cached input tokens
$0.50
per million tokens
$0.13
per million tokens
Cache Write Cost
Cost to write input tokens to the cache
$6.25
per million tokens
Not specified
1-Hour Cache Write Cost
Cost to cache input tokens for one hour
$10.00
per million tokens
Not specified

Benchmarks

Compare relevant benchmarks between Claude Opus 4.5 and GPT-5 Codex.
Claude Opus 4.5Claude Opus 4.5
GPT-5 CodexGPT-5 Codex
Best Design Arena Score
Highest human-preference Elo score across design arenas
1,288 Elo
(#20 in Game Dev (59.4% win rate))
1,138 Elo
(#26 in Webapps (52.4% win rate))

At a Glance

Quick overview of what makes Claude Opus 4.5 and GPT-5 Codex unique.
Anthropic logoClaude Opus 4.5 by Anthropic understands both text and images, can use external tools and APIs, offers advanced reasoning, generates structured data. It can handle standard conversations with its 200K token context window. Premium pricing at $5.00/M input and $25.00/M output tokens. Includes built-in content moderation for safer outputs. Released November 24th, 2025.
OpenAI logoGPT-5 Codex by OpenAI understands both text and images, can use external tools and APIs, offers advanced reasoning, generates structured data. It can handle standard conversations with its 400K token context window. Reasonably priced at $1.25/M input and $10.00/M output tokens. Includes built-in content moderation for safer outputs. Released September 23rd, 2025.

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