---
id: "openai/gpt-5.5-pro"
also: ["openai/gpt-5.5-pro-20260423", "requesty/openai/gpt-5.5-pro", "vercel/openai/gpt-5.5-pro"]
card_usd_per_m: "30.0 in, 180.0 out, at openai"
cheapest_list_usd_per_m: "15.0 in, 90.0 out, at openai/flex on openrouter"
cheapest_effective_usd_per_m: "15.0 in, 90.0 out, at openai/flex on openrouter"
context: 1050000
max_output: 128000
input: ["file", "image", "text"]
output: ["text"]
released: "2026-04-24"
reasoning: ["xhigh", "high", "medium"]
api: ["/api/v1/chat/completions", "/api/v1/completions", "/api/v1/messages", "/api/v1/responses"]
params: ["include_reasoning", "max_tokens", "reasoning", "reasoning_effort", "response_format", "seed", "stop", "structured_outputs", "temperature", "tool_choice", "tools", "verbosity"]
endpoints: 5
gateways: "openrouter (2), requesty (2), vercel (1)"
no_training: 5
trains: 0
retains_prompts: 4
---
# OpenAI: GPT-5.5 Pro

GPT-5.5 Pro is OpenAI's high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for text and image inputs, and is designed for long-horizon problem solving, agentic coding, and precise execution across multi-step workflows.