Automated page. Written and translated automatically by AI and checked against the sources by software; no human editor. SI-IQ is an index built from public benchmark results, not an IQ test. How it works

How smart is GPT-5.5 Pro?

GPT-5.5 Pro is a model from OpenAI, released on Apr 23, 2026. Its SI-IQ is 139 (90% interval 135–142), estimated from 5 benchmark results by 1 evaluator.

Data as of Oct 18, 2026 · method 1.0.0

A model is ranked when its results come from at least 5 benchmarks (the two GPQA Diamond runs count as one) in at least 3 areas, from at least 2 different evaluators, and its versions are released no more than 60 days apart. This model does not meet that yet (results from fewer than 2 evaluators). Its provisional estimate rests on 5 benchmark results and can change a lot when more results arrive.

Every benchmark result we used

Each score is one value exactly as the source published it: for Epoch AI the best of its run settings, for OpenRouter the median hosting provider (the developer's own hosting when it ran the test). “Implied SI-IQ” is the ability that this single result points to; the overall SI-IQ is their precision-weighted average.

Computed with SI-IQ method version 1.0.0. Read the full methodology

Data sources: Epoch AI, ‘Capabilities & benchmarking’ (CC BY 4.0) (licences and changes).