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How smart is Claude Opus 4.8?

132 SI-IQ · 90% interval 129–135
Rank 13 of 80 ranked models · Plausible rank range 9–28

Claude Opus 4.8 is a model from Anthropic, released on May 28, 2026. Its SI-IQ is 132 (90% interval 129–135), estimated from 8 benchmark results by 2 independent evaluators. Its strongest area is Math and its weakest is Knowledge.

Facts

Developer: Anthropic
Released: May 28, 2026
Access: API access
Benchmarks used: 8 results from 2 evaluators
API price: $5.00 input / $25 output per 1M tokens (developer's price list, Oct 18, 2026)
Context window: 1,000,000 tokens

Ability by area (SI-IQ, 90% interval)

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.

Benchmark	Area	Score	Implied SI-IQ	Evaluated by	As listed by the source	Retrieved	Source
Chess Puzzles	Reasoning	52.0%	135	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
Furniture Assembly not in index	Reasoning	42.5%	—	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
Mystery Game Puzzles	Reasoning	36.0%	128	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
FrontierMath Tier 4	Math	56.1%	132	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
FrontierMath Tiers 1–3	Math	80.0%	134	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
OTIS Mock AIME 2024–2025	Math	98.3%	132	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
GPQA Diamond	Knowledge	91.0%	127	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
GPQA Diamond (OpenRouter run)	Knowledge	89.6%	129	OpenRouter	`anthropic/claude-4.8-opus-20260528` Anthropic · first-party provider (1 of 5 rows)	Oct 18, 2026	OpenRouter benchmark datasets · data file
SimpleQA Verified	Knowledge	53.0%	132	Epoch AI	`claude-opus-4-8_max`	Oct 18, 2026	Epoch AI Benchmarking Hub · data file
τ²-bench Airline (OpenRouter run)	Agents	77.8%	134	OpenRouter	`anthropic/claude-4.8-opus-20260528` Anthropic · first-party provider (1 of 5 rows)	Oct 18, 2026	OpenRouter benchmark datasets · data file

Models with similar SI-IQ

Model	SI-IQ
Gemini 3.7 FlashGoogle DeepMind	131	Claude Opus 4.8 vs Gemini 3.7 Flash
GPT-5.4OpenAI	131	Claude Opus 4.8 vs GPT-5.4
GPT-5.6 LunaOpenAI	130	Claude Opus 4.8 vs GPT-5.6 Luna
GPT-5.6 TerraOpenAI	134	Claude Opus 4.8 vs GPT-5.6 Terra
GPT-6 LunaOpenAI	130	Claude Opus 4.8 vs GPT-6 Luna

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

Data sources: Epoch AI, ‘Capabilities & benchmarking’ (CC BY 4.0); API list prices via LiteLLM's price table (MIT); each price links to the developer's pricing page; Source: OpenRouter (openrouter.ai), licensed under CC BY 4.0: reuse and republish with attribution to OpenRouter..