LIVE INTELLIGENCE · part of the Xentir AI Index

Claude Opus 4.8 vs GPT-5.6 Terra

Name: Claude Opus 4.8 vs GPT-5.6 Terra — benchmark results
Creator: Epoch AI
License: https://creativecommons.org/licenses/by/4.0/

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 2026-09-09 · Methodology · Data Sources

GPT-5.6 Terra leads on more of the 5 benchmarks where both are measured — Claude Opus 4.8 on 1, GPT-5.6 Terra on 4. The remaining 4 of 9 tracked benchmarks cannot be compared: 2 have a result for only one of the two models, 2 for neither. Nothing on this page is estimated to fill those in.

Head-to-head

Measured on 5 of 9 tracked benchmarks for both models — Claude Opus 4.8 leads on 1, GPT-5.6 Terra leads on 4.

Benchmark	Claude Opus 4.8	GPT-5.6 Terra	Leads
Epoch Capabilities Index (ECI)	158.3	159.2	GPT-5.6 Terra
SWE-bench Verified	Not measured	Not measured	Not measured on both
GPQA Diamond	0.910 (max)	0.933 (max)	GPT-5.6 Terra
MATH Level 5	Not measured	Not measured	Not measured on both
OTIS Mock AIME 2024-2025	0.983 (max)	0.997 (max)	GPT-5.6 Terra
FrontierMath	0.472 (max)	Not measured	Comparison unavailable — GPT-5.6 Terra has no published result
FrontierMath Tier 4	0.312 (max)	Not measured	Comparison unavailable — GPT-5.6 Terra has no published result
SimpleQA Verified	0.530 (max)	0.432 (max)	Claude Opus 4.8
Chess Puzzles	0.340 (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.

What remains uncertain

GPT-5.6 Terra has no published result on FrontierMath, FrontierMath Tier 4.
2 tracked benchmarks have no published result for either model.

A missing result means Xentir has not found one published by the source it cites, not that the model performs badly. See Data Sources.

Reference price

Per 1M tokens	Claude Opus 4.8	GPT-5.6 Terra
Output	$25.00 stale	$12.00

List price as published by the vendor. Xentir does not verify negotiated or enterprise rates, and price is not a measure of capability — see Data Sources.

Full profiles

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