IQ of SI
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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

Claude Opus 5.5 vs GPT-5.6 Sol: which is smarter?

Claude Opus 5.5 has an SI-IQ of 144 and GPT-5.6 Sol has 140. The table compares them area by area using only independent benchmark results.

Data as of Oct 18, 2026 · method 1.0.0

MetricClaude Opus 5.5GPT-5.6 Sol
SI-IQ144141–148140137–143
Reasoning146140
Math145141
Knowledge137139
DeveloperAnthropicOpenAI
ReleasedSep 22, 2026Jul 9, 2026
AccessAPI accessAPI access
Price in / out (USD per 1M tokens)$4.00 / $20$4.00 / $20
Benchmarks used99
Claude Opus 5.5GPT-5.6 Sol
130140150SI-IQReasoningMathKnowledge

Benchmarks every compared model was tested on

Raw scores as published by the evaluators.

BenchmarkClaude Opus 5.5GPT-5.6 Sol
Chess Puzzles67.0%59.0%
FrontierMath Tier 495.0%82.9%
FrontierMath Tiers 1–391.2%89.1%
Furniture Assembly83.3%56.7%
GPQA Diamond90.6%93.5%
GPQA Diamond (OpenRouter run)90.2%92.3%
Mystery Game Puzzles71.0%58.0%
OTIS Mock AIME 2024–2025100.0%100.0%
SimpleQA Verified72.2%69.7%
τ²-bench Airline (OpenRouter run)75.6%73.3%

The difference of 4 points is within the statistical uncertainty: the two models are roughly on par.

Data sources: Arena leaderboard dataset on Hugging Face (CC BY 4.0); Epoch AI, ‘Capabilities & benchmarking’ (CC BY 4.0); LiteLLM, model_prices_and_context_window.json (MIT); Source: OpenRouter (openrouter.ai), licensed under CC BY 4.0: reuse and republish with attribution to OpenRouter (licences and changes).