LIVE INTELLIGENCE · part of the Xentir AI Index

Claude Opus 4.6 vs GPT-5.3 Codex

Name: Claude Opus 4.6 vs GPT-5.3 Codex — benchmark results
Creator: Epoch AI
License: https://creativecommons.org/licenses/by/4.0/

Claude Opus 4.6 · Anthropic, released 2026-02-05
GPT-5.3 Codex · OpenAI, released 2026-02-05

“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

Neither model leads on more of the 2 benchmarks where both are measured — Claude Opus 4.6 on 1, GPT-5.3 Codex on 1. The remaining 7 of 9 tracked benchmarks cannot be compared: 6 have a result for only one of the two models, 1 for neither. Nothing on this page is estimated to fill those in.

Head-to-head

Measured on 2 of 9 tracked benchmarks for both models — Claude Opus 4.6 leads on 1, GPT-5.3 Codex leads on 1.

Benchmark	Claude Opus 4.6	GPT-5.3 Codex	Leads
Epoch Capabilities Index (ECI)	155.3	156.6	GPT-5.3 Codex
SWE-bench Verified	0.772	0.748 (high)	Claude Opus 4.6
GPQA Diamond	0.905 (32k)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result
MATH Level 5	Not measured	Not measured	Not measured on both
OTIS Mock AIME 2024-2025	0.944 (64k)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result
FrontierMath	0.407 (max)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result
FrontierMath Tier 4	0.229 (max)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result
SimpleQA Verified	0.470 (max)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result
Chess Puzzles	0.170 (32k)	Not measured	Comparison unavailable — GPT-5.3 Codex has no published result

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-5.3 Codex has no published result on Chess Puzzles, FrontierMath, FrontierMath Tier 4, GPQA Diamond, OTIS Mock AIME 2024-2025, SimpleQA Verified.
1 tracked benchmark has 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 4.6	GPT-5.3 Codex
Output	$25.00 stale	—

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 4.6 → · GPT-5.3 Codex → · the full AI Model Rankings table