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Claude Opus 4.8 vs GPT-5.6 Terra

Claude Opus 4.8 · Anthropic, released 2026-05-28
GPT-5.6 Terra · OpenAI, released 2026-07-09

“Epoch AI, 'AI Benchmarking Hub'. Published online at epoch.ai. Retrieved from 'https://epoch.ai/benchmarks' [online resource].” · epoch.ai/benchmarks · Licensed CC BY 4.0 · data last verified 2026-07-26 · Methodology · Data Sources

Head-to-head

Measured on 5 of 9 tracked benchmarks for both models — GPT-5.6 Terra leads on 5.

BenchmarkClaude Opus 4.8 GPT-5.6 TerraLeads
Epoch Capabilities Index (ECI)158.0158.2GPT-5.6 Terra
SWE-bench VerifiedNot measuredNot measuredNot measured on both
GPQA Diamond0.910 (max)0.933 (max)GPT-5.6 Terra
MATH Level 5Not measuredNot measuredNot measured on both
OTIS Mock AIME 2024-20250.983 (max)0.997 (max)GPT-5.6 Terra
FrontierMath0.472 (max)Not measuredNot measured on both
FrontierMath Tier 40.312 (max)Not measuredNot measured on both
SimpleQA Verified0.395 (max)0.431 (max)GPT-5.6 Terra
Chess Puzzles0.340 (max)0.540 (max)GPT-5.6 Terra
Benchmark results measure specific tasks and should not be treated as a universal measure of model quality. A model with no row here for a benchmark has not been measured on it — that is left blank, never estimated.

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Claude Opus 4.8 → · GPT-5.6 Terra → · the full AI Model Rankings table