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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-LCR v1.166.3
AA-Omniscience Index11.2
Artificial Analysis Omniscience Accuracy46.3
Artificial Analysis Omniscience Hallucination Rate65.3
Artificial Analysis Progress Index v1267
BullshitBench v2 Leaderboard34.0
Capability146.5
Chess Puzzles12.0
CritPt (avg@5)2.6
Epoch Capabilities Index (ECI)142
FrontierMath Tier 4 (v2) - Private2.4
FrontierMath Tiers 1-3 (v2) - Private26.3
GPQA Diamond82.5
GPQA Diamond (Artificial Analysis avg@5)84.6
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)21.6
IFBench (Artificial Analysis avg@5)71.5
OTIS Mock AIME 2024-202568.1
SciCode (Artificial Analysis avg@3)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
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