GPT-5.5
Default frontier GPT for coding, computer use, research, and knowledge work
ECI STANDING#8 of 266
SCORE159.12156.91–161.95 CI
FRONTIER LAGLaunched in the leadNothing released before it had scored higher.
SCORES LIKE THESE MODELSGPT-5.6 TerraOpenAI · Jul 2026159.14GPT-5.4 ProOpenAI · Mar 2026158.95Claude Opus 4.8Anthropic · May 2026158.3Kimi K3Moonshot · Jul 2026157.63
Full Epoch Capabilities Index ranking ↗From the lab
Launch announcement · Apr 23, 2026Introducing GPT-5.5RELEASE DATEApr 23, 2026
WEIGHTSClosed weights
CONTEXT WINDOW1.05M
MAX OUTPUT128K
REASONINGYes
TOOL CALLINGYes
INPUTStext, image, pdf
OUTPUTStext
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