GPT-5.3-Codex vs o1
Compare GPT-5.3-Codex and o1, both from OpenAI, context windows of 400K vs 128K, tested across 53 shared challenges. Updated April 2026.
Which is better, GPT-5.3-Codex or o1?
GPT-5.3-Codex and o1 are both competitive models. GPT-5.3-Codex costs $1.75/M input tokens vs $15/M for o1. Context windows: 400K vs 128K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-5.3-Codex and o1
GPT-5.3-Codex is made by openai while o1 is from openai. GPT-5.3-Codex has a 400K token context window compared to o1's 128K. On pricing, GPT-5.3-Codex costs $1.75/M input tokens vs $15/M for o1.
No community votes yet. On paper, GPT-5.3-Codex has the edge — bigger model tier, newer, bigger context window.
GPT-5.3-Codex is 4.3x cheaper per token — worth considering if cost matters.
Style Comparison
GPT-5.3-Codex uses 15.8x more emoji
vsAsk them anything yourself
Some models write identically. You are paying for the brand.
178 models fingerprinted across 32 writing dimensions. Free research.
185x
price gap between models that write identically
178
models
12
clone pairs
32
dimensions
279 AI models invented the same fake scientist.
We read every word. 250 models. 2.14 million words. This is what we found.
