GPT-5.3 Instant
Parameters
Undisclosed
Context Length
Undisclosed
Modality
Multimodal
Architecture
Undisclosed
License
Proprietary
Release Date
3 Mar 2026
Knowledge Cutoff
-
API Pricing (per 1M)
Input: $1.75 · Output: $14.00
Evaluation Benchmarks
Rank
#59
| Benchmark | Score | Rank |
|---|---|---|
General Text | 1449 | 56 |
Rankings
Overall Rank
#59
Coding Rank
-
About GPT-5.3 Instant
GPT-5.3 Instant is OpenAI's update to ChatGPT's most-used model, delivering smoother and more helpful everyday conversations. Key improvements over GPT-5.2 Instant include significantly reduced unnecessary refusals and disclaimers, better-synthesized web search answers, a more natural and focused conversational tone, and improved factual accuracy (26.8% fewer hallucinations with web use, 19.7% without). It is also a stronger creative writing partner. Available via API as gpt-5.3-chat-latest. Released March 3, 2026.
Technical Specifications
Architecture specifications are undisclosed for proprietary models.
Attention
Attention Structure
Multi-Head Attention
Attention Heads
Undisclosed
Key-Value Heads
Undisclosed
Attention Head Dimension
Undisclosed
Position Embedding
Absolute Position Embedding
RoPE Theta
Undisclosed
Sliding Window Attention
Undisclosed
Sliding Window Size
Undisclosed
Sliding Window Ratio
Undisclosed
Linear Attention
Undisclosed
Linear Attention Ratio
Undisclosed
Normalization
Undisclosed
Activation Function
Undisclosed
Dimensions
Hidden Dimension Size
Undisclosed
Number of Layers
Undisclosed
FFN Intermediate Size (Dense)
Undisclosed
Multi-Token Prediction Heads
Undisclosed
Tokenizer
Vocabulary Size
Undisclosed
Resources
About GPT-5.3
OpenAI's GPT-5.3 series represents specialized frontier models with a focus on coding excellence. The Codex variants feature enhanced programming capabilities, deeper understanding of software architecture, and superior performance on coding benchmarks. Designed for professional software development with advanced code generation, debugging, and refactoring abilities.