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GPT-5.5 Instant

OpenAI · 2026-05-05

GPT-5.5 Instant is OpenAI's default ChatGPT conversational model released on May 5, 2026, replacing GPT-5.3 Instant as the standard model for all ChatGPT users. It delivers more concise, factual, and contextually personalized responses, with significantly fewer hallucinations compared to its predecessor and improved tone calibration for informal, practical conversation. It is also available via the API as the chat-latest alias.

Benchmark scores

BenchmarkScore
AA-LCR55.7
AA-Omniscience Index10.3
Artificial Analysis Intelligence Index33.5
Artificial Analysis Omniscience Accuracy45.5
Artificial Analysis Omniscience Hallucination Rate64.4
BullshitBench v2 Leaderboard34.0
Capability147.1
CritPt2.6
GPQA Diamond84.6
HealthBench (length-adjusted)51.4
HealthBench (updated implementation)50.9
HealthBench Hard (length-adjusted)22.9
HealthBench Hard (updated implementation)21.3
HealthBench Professional40.7
HealthBench Professional (Length-Adjusted)38.4
Humanity's Last Exam (Text-Only)20.3
IFBench (Artificial Analysis)71.5
SciCode (Artificial Analysis)50.3
SM Bench69.9
SM Bench — Adversarial (Hostile Logic)88.8
SM Bench — Ambiguous Interpretation88.1
SM Bench — Anti-hallucination95.8
SM Bench — Creative Writing (Mature Themes)96.0
SM Bench — EQ Boundaries62.4
SM Bench — NSFW (Explicit)0.0
SM Bench — NSFW (System Prompt)40.4
SM Bench — Overfit79.0
Terminal-Bench Hard42.4
τ²-bench (Telecom)49.4
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