GPT-5.3 Codex vs o3-pro
Comparing GPT-5.3 Codex and o3-pro across benchmarks, pricing, and capabilities.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-5.3 Codex and o3-pro trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, GPT-5.3 Codex is roughly 7.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.3 Codex also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.3 Codex
- cost matters — it's about 7.3x cheaper per token
- you process long inputs — it offers a 400,000 token context window
- you want the most recent training data — it shipped Feb 2026
Choose o3-pro
- you want predictable pricing at $20.00/M input and $80.00/M output
At a glance
The differences that matter most.
Individual benchmarks
6 reported for GPT-5.3 Codex · 0 for o3-pro
GPT-5.3 Codex and o3-prodon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.3 Codex ($1.75/1M tokens) is 11.4x cheaper than o3-pro ($20.00/1M tokens).
For output processing, GPT-5.3 Codex ($14.00/1M tokens) is 5.7x cheaper than o3-pro ($80.00/1M tokens).
In conclusion, o3-pro 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
GPT-5.3 Codex accepts 400,000 input tokens compared to o3-pro's 200,000 tokens. GPT-5.3 Codex can generate longer responses up to 128,000 tokens, while o3-pro is limited to 100,000 tokens.
Input capabilities
Documented input modalities across available providers
Both GPT-5.3 Codex and o3-pro support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.3 Codex
o3-pro
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-5.3 Codex was released on 2026-02-05, while o3-pro was released on 2025-06-10.
GPT-5.3 Codex is 8 months newer than o3-pro.
Feb 5, 2026
7 months ago
8mo newerJun 10, 2025
1.3 years ago
Knowledge Cutoff
When training data ends
o3-pro has a documented knowledge cutoff of 2024-05-31, while GPT-5.3 Codex's cutoff date is not specified.
We can confirm o3-pro's training data extends to 2024-05-31, but cannot make a direct comparison without GPT-5.3 Codex's cutoff date.
—
May 2024
Provider Availability
GPT-5.3 Codex is available from OpenAI. o3-pro is available from OpenAI.
GPT-5.3 Codex
o3-pro
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.3 Codex and o3-pro side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.3 Codex vs o3-pro.