GPT-5.3-Codex vs GPT-5.5
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose GPT-5.3-Codex if you need
- ✓Extremely large 1.05M-token context for document-heavy tasks
- ✓Native support for files and images in flexible multimodal workflows
- ✓General-purpose multimodal use where context size outweighs speed
Choose GPT-5.5 if you need
- ✓Higher intelligence (44.3) and specialized programming workflows
- ✓Faster output at 91.14 t/s and lower cost of $14 per 1M tokens
- ✓Extensive 400k-token context with support for diverse input types
Verdict
GPT-5.3-Codex leads with higher intelligence (44.3 vs 43.5), more than 50% faster output (91.14 t/s vs 58.13 t/s), and less than half the price ($14 vs $30 per 1M tokens). GPT-5.5 counters with a 2.6x larger context window (1.05M vs 400k tokens) and explicit native file/image support for document-heavy multimodal tasks. GPT-5.3-Codex is the stronger all-around performer for coding-focused users while GPT-5.5 suits maximum-context general workflows.
GPT-5.3-Codex vs GPT-5.5: side by side
| Spec | GPT-5.3-Codex | GPT-5.5 | Winner |
|---|---|---|---|
| Intelligence | 44.3 | 43.5 | GPT-5.3-Codex |
| Output speed | 91 t/s | 58 t/s | GPT-5.3-Codex |
| Output price | $14.00/1M | $30.00/1M | GPT-5.3-Codex |
| Context | 400K | 1050K | GPT-5.5 |
| Params | — | — | Tie |
| Provider | OpenAI | OpenAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5.3-CodexGPT-5.3-Codex scores 44.3 on the intelligence index compared to 43.5 for GPT-5.5. This edge aligns with its specialization for coding tasks. Both models remain close overall.
Speed & Pricing
Winner: GPT-5.3-CodexGPT-5.3-Codex delivers 91.14 tokens per second at $14 per million tokens. GPT-5.5 runs at 58.13 t/s and costs $30 per million tokens. The gap favors GPT-5.3-Codex for high-volume use.
Context Window
Winner: GPT-5.5GPT-5.5 provides a 1,050,000-token context versus 400,000 tokens for GPT-5.3-Codex. This makes GPT-5.5 preferable for very long multimodal documents. GPT-5.3-Codex still offers substantial context for most coding needs.
Multimodal Strengths
Winner: GPT-5.5GPT-5.5 explicitly supports native files and images for flexible document workflows. GPT-5.3-Codex emphasizes diverse inputs within programming specialization. Neither lists native audio or video support.
GPT-5.3-Codex
Pros
- +Specialized for programming workflows
- +Extensive context handling
- +Support for diverse input types
Cons
- –Narrower focus than general-purpose models
- –Performance tied to input quality
GPT-5.5
Pros
- +Extremely large context window
- +Native support for files and images
- +Flexible multimodal workflows
Cons
- –No native audio or video support
- –Large context may increase latency
- –Performance depends on input quality across modalities
Summary: GPT-5.3-Codex vs GPT-5.5
Choose GPT-5.3-Codex for superior speed, price, and intelligence in coding-oriented multimodal work. Select GPT-5.5 when the largest context window and native file/image handling are the priority. The decision hinges on whether coding specialization or maximum context matters more.
Frequently asked questions
GPT-5.3-Codex is better for most users due to higher intelligence, faster speed, and lower price, while GPT-5.5 wins only on raw context size and file/image focus.