GPT-5.3 Chat

by OpenAI

GPT-5.3 Chat is a model from OpenAI, released on March 4, 2026. It has a 128K-token context window and can generate up to 16K output tokens. API pricing is $1.75 per 1M input tokens and $14 per 1M output tokens. It ranks #85 of 220 models by Intelligence Score with a score of 29.4.

GPT-5.3 Chat is the instant model used in ChatGPT. It features high intelligence with medium speed, supporting text and image inputs with a 128k context window. It supports streaming, function calling, and structured outputs, priced at $1.75/1M input and $14.00/1M output tokens.

Key specs

ProviderOpenAI
Release date2026-03-04
Licenseproprietary
Context window128K tokens
Max output16K tokens
Input price$1.75 / 1M tokens
Output price$14 / 1M tokens
Intelligence Score29.4

Quick answers

What is the context window of GPT-5.3 Chat?

GPT-5.3 Chat has a context window of 128K tokens, with a maximum output of 16K tokens per response.

How much does GPT-5.3 Chat cost?

GPT-5.3 Chat costs $1.75 per 1M input tokens and $14 per 1M output tokens through the API.

Is GPT-5.3 Chat open source?

No. GPT-5.3 Chat is a proprietary model from OpenAI (proprietary license).

When was GPT-5.3 Chat released?

OpenAI released GPT-5.3 Chat on March 4, 2026.

How does GPT-5.3 Chat compare to Claude Opus 5.5 (Reasoning)?

GPT-5.3 Chat scores 29.4 on the Intelligence Score versus 60.5 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $1.75 vs $4 per 1M tokens.

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