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openaiopenai·Apr 24, 2026

OpenAI: GPT-5.5

openai/gpt-5.5
context
1.1M
Max Output
128K
Input / 1M
$5.00
Output / 1M
$30.00

About

GPT-5.5 is OpenAI's frontier model, a fully retrained base that builds on GPT-5.4 with stronger reasoning, higher reliability, and improved token efficiency on hard tasks. It exposes multiple reasoning effort levels (from non-reasoning to xhigh) and accepts text and image inputs within a 1M+ token context window (922K input, 128K output). Reported benchmarks include 82.7% on Terminal-Bench 2.0, 51.7% on FrontierMath Tier 1-3, 35.4% on FrontierMath Tier 4, and 84.9% on GDPval. It is aimed at complex professional, coding, and multimodal workflows that require large-scale reasoning in a single system.

Capabilities

Context Length
1.1M
Max Output
128K
Reasoning
Yes
In
file, image, text
Out
text

Benchmarks

View leaderboard
54.8#5 of 133
Intelligence Index
59.1#1 of 118
Coding Index

Reasoning & Knowledge

GPQA Diamond93.5%
HLE44.3%

Coding & Agentic

SciCode56.1%
Terminal-Bench Hard60.6%

Source: Artificial Analysis

Pricing

Full pricing
Type≤272K>272K
Input$5.00$10.00
Output$30.00$45.00
Cache Read$0.50$1.00
Web Search$0.01 / call

API

API reference

OpenAI-compatible · Model ID openai/gpt-5.5

curl https://api.elliotgate.com/v1/chat/completions \
  -H "Authorization: Bearer sk-omg-your-api-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.5",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

OFTEN COMPARED

GPT-5.5 comparisons

Decide which model wins on the dimensions that matter for your workload — context, benchmarks, pricing, or serving latency.