GPT-5.3 Chat vs o3 Mini
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for GPT-5.3 Chat and o3 Mini.
GPT-5.3 Chat
GPT-5.3 Chat is an update to ChatGPT's most-used model that makes everyday conversations smoother, more useful, and more directly helpful. It delivers more accurate answers with better contextualization and significantly...
o3 Mini
OpenAI o3-mini is a cost-efficient language model optimized for STEM reasoning tasks, particularly excelling in science, mathematics, and coding. This model supports the `reasoning_effort` parameter, which can be set to...
Technical Specifications
| Specification | GPT-5.3 Chat | o3 Mini |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 128,000 tokens | 200,000 tokens |
| Agent Suitability | N/A | 91/100 |
| Time to First Token (TTFT) | N/A | 800 ms |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2026-03-03 | 2025-01-31 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.3 Chat
$1.75
o3 Mini
$1.10
Output Price per Million Tokens
GPT-5.3 Chat
$14.00
o3 Mini
$4.40
Want to test both models live?
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
GPT-5.3 Chat Quirks & Gotchas
No developer gotchas reported.
o3 Mini Quirks & Gotchas
- ▸Best cost/performance ratio for reasoning tasks in the OpenAI lineup
- ▸Still slower than GPT-5 for simple tool calls — route accordingly