The Model Index
Models/OpenAI

GPT-5.5

OpenAIReleased 23 Apr 2026Closed
177166–188Index score#11 of 229 modelsPro mode: 184 · $30 / $180
6/ 8Core tests taken5 of 6 areas · plus 24 anchor tests
FrontierVersus the frontier at releaseset or matched the recordReplaced by GPT-5.6 Sol
$5.0/ $30Price per million tokensinput / output, list price
1.05MContext windowtokens it reads at once

Where it sitson the frontier

Among the first models to reach this score.

Test resultsby area · tick = best by any model

Reasoning & knowledgeevidence
GPQA Diamond
94%
Humanity's Last Exam
no result
Mathsevidence
FrontierMath T1-3
85%
Codingevidence
SWE-bench Verified
81%
Terminal-Bench
85%
Agentsevidence
APEX-Agents
55%
Novel problemsevidence
ARC-AGI-2
85%
Long tasksno evidence yet
METR time horizon
no result

Independent results from the Epoch AI benchmarking hub, best reasoning setting. The core tests are shown here; anchor tests also inform the score and can be shown above.

What others sayrank on each leaderboard

Further left is better. Leaderboards measure different things: LMArena is people voting blind between two answers, the others are test scores. Click any row for the source.

Best attop three among current models

Where this model places in the top three of today's models, on category leaderboards and on our core tests.

Where to use itprices checked 1 Oct 2026

Provider prices come from OpenRouter's live listing; going direct to a provider can differ. Subscriptions are the lab's own apps.

Facts and sources

Released23 Apr 2026
Announcementnot linked yet
Release entry–
Scored asGPT-5.5
Artificial Analysis index–
Pro modeindex 184 · $30 / $180 per M
Output speed–
Hugging Faceclosed weights

OpenAI releasesaround this one