GPT-5.3-Codex vs GPT-5 Nano
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
- ✓Choose GPT-5 Nano if you need maximum output speed at 170 t/s for responsive interactions.
- ✓Choose GPT-5 Nano if you need the lowest cost at $0.4 per million tokens for high-volume use.
- ✓Choose GPT-5 Nano if you need efficient handling of very large document contexts with text, image, and file inputs.
- ✓Choose GPT-5 Nano if you need a lightweight model for extended but non-complex multimodal tasks.
Choose GPT-5 Nano if you need
- ✓Choose GPT-5.3-Codex if you need higher intelligence (53.6 index) for complex reasoning or workflows.
- ✓Choose GPT-5.3-Codex if you need a model specialized for programming and coding tasks.
- ✓Choose GPT-5.3-Codex if you need extensive 400k context optimized for diverse input quality in development.
- ✓Choose GPT-5.3-Codex if you need stronger performance depth despite higher cost and slower speed.
Verdict
GPT-5.3-Codex leads decisively on intelligence (53.6 vs 26.8) and coding specialization, while GPT-5 Nano dominates on speed (170 t/s vs 101 t/s) and price ($0.4 vs $14 per million tokens). Both share identical 400k context and multimodal input support from OpenAI, creating a clear split between lightweight efficiency and high-capability depth.
GPT-5.3-Codex vs GPT-5 Nano: side by side
| Spec | GPT-5.3-Codex | GPT-5 Nano | Winner |
|---|---|---|---|
| Intelligence | 53.6 | 26.8 | GPT-5.3-Codex |
| Output speed | 101 t/s | 170 t/s | GPT-5 Nano |
| Output price | $14.00/1M | $0.40/1M | GPT-5 Nano |
| Context | 400K | 400K | Tie |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | OpenAI | OpenAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5.3-CodexGPT-5.3-Codex scores 53.6 on the intelligence index compared to GPT-5 Nano's 26.8. This gap indicates stronger capability for complex tasks. GPT-5 Nano's lower score aligns with its noted limitations in advanced reasoning depth.
Speed
Winner: GPT-5 NanoGPT-5 Nano delivers 170.06 tokens per second versus GPT-5.3-Codex at 101.39 t/s. The faster output supports its lightweight design for responsive applications. Both maintain the same 400k context length without speed trade-offs mentioned for context size.
Pricing
Winner: GPT-5 NanoGPT-5 Nano costs $0.4 per million tokens while GPT-5.3-Codex costs $14 per million tokens. The 35x price difference favors Nano for budget-sensitive or high-volume scenarios. No other cost factors are provided in the data.
Specialization
Winner: GPT-5.3-CodexGPT-5.3-Codex is explicitly positioned as a coding model with strengths in programming workflows. GPT-5 Nano focuses on general multimodal document handling with text, image, and file support. Both are proprietary OpenAI models with identical context sizes.
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 Nano
Pros
- +Handles very large contexts efficiently
- +Supports text, image, and file inputs
- +Lightweight design for faster responses
- +Practical for extended document tasks
Cons
- –Lower capability depth than full-scale models
- –May struggle with highly complex reasoning
- –Trade-off in advanced task performance
Summary: GPT-5.3-Codex vs GPT-5 Nano
Select GPT-5 Nano for speed-critical, cost-sensitive multimodal document work. Select GPT-5.3-Codex when maximum intelligence and coding focus justify the higher price and slower speed. The models complement rather than overlap in primary use cases.
Frequently asked questions
GPT-5.3-Codex is better for intelligence and coding tasks; GPT-5 Nano is better for speed and cost in general multimodal use.