GPT-5.3-Codex vs OpenAI o3
Compare GPT-5.3-Codex and OpenAI o3, both from OpenAI, tested across 53 shared challenges.
Our Verdict
GPT-5.3-Codex
OpenAI o3
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Too close to call
API pricing
Cost per 1M tokens
GPT-5.3-Codex
Input
$1.75
5.7× cheaper
Output
$14.00
2.9× cheaper
OpenAI o3
Input
$10.00
Output
$40.00
GPT-5.3-Codex is cheaper on both — 5.7× input, 2.9× output
Writing DNA
Style Comparison
Similarity
55%
GPT-5.3-Codex uses 15.8x more emoji
GPT-5.3-Codex
OpenAI o3
65%Vocabulary68%
23wSentence Length14w
0.51Hedging0.26
6.5Bold0.7
6.2Lists3.0
0.16Emoji0.00
1.90Headings0.38
0.03Transitions0.12
Based on 23 + 16 text responses
Research
What we learned reading every model
FAQ
