Model

GPT-5.5 (High)

CLOSED

OpenAI · GPT-5.5 family · released Apr 23, 2026

Reasoning-effort sibling of the already-catalogued base 'GPT-5.5' entry. Same weights, same pricing/context as the default/xhigh siblings; distinguished only by the reasoning.effort=high API parameter (also selectable in the ChatGPT model picker's effort selector). Same-family, same-release-date, same-paramsB per the effort-tier convention.

ReasoningCodingVisionFunction callingTool useAgentic

2563.6

Elo · rank #13

Parameters

Undisclosed

Active params

—

Context

1.05M tokens

Architecture

Undisclosed architecture (presumed dense transformer, reasoning-tuned); codename "Spud"; 'high' reasoning-effort configuration

License

Proprietary (OpenAI API Terms)

Languages

—

API price (in/out)

$5 / $30

Modalities

text · vision

Benchmark results

Bar shows position within the tracked field; marker = field best

Agents' Last ExamAgents44.0%#5

best: GPT-5.6 · 52.7%

GDPval-AAAgents1472#17

best: Claude Fable 5 · 1932

GPQA DiamondReasoning93.2%#9

best: GPT-5.6 · 94.6%

Humanity's Last ExamReasoning43.0%#18

best: Claude Sonnet 5 · 57.4%

IFBenchReasoning71.6%#25

best: MiniMax M3 · 83.0%

MMMU-ProVision81.1%#6

best: Claude Opus 4.7 · 85.5%

Terminal-Bench 2.0Coding79.4%#9

best: GPT-5.6 · 88.8%

Run it locally

Closed weights — available via API only. No local deployment.

Input / M tok

Output / M tok

$30

GPT-5.5 family

Elo progression across releases

GPT-5.5Apr 20262680.9 GPT-5.5 (High)Apr 20262563.6 GPT-5.5 (xHigh)Apr 20262725.9

Resources

DOCShttps://developers.openai.com/api/docs/models/gpt-5.5 APIAvailable via OpenAI API

API price $5/$30 · each benchmark row carries its own source badge (see methodology)