All tasks / Comparisons

Claude Opus 5.5 vs GPT-6 Astra

Compared only on public benchmark results, across the 9 tasks where both are listed: Claude Opus 5.5 is a tier higher in 2 of 9 shared tasks, GPT-6 Astra in 2, they share a tier in 3.

Claude Opus 5.5

Anthropic's Opus-tier Claude model for long-running agentic coding and knowledge work.

Vendor: Anthropic
Weights: Closed: API and apps only
Released: 22 Sep 2026
API price: $4 in / $20 out per 1M tokens
License: proprietary
Last verified: 18 Oct 2026

Alternatives to Claude Opus 5.5

GPT-6 Astra

OpenAI's most capable GPT tier, introduced with GPT-6, aimed at complex reasoning and coding.

Vendor: OpenAI
Weights: Closed: API and apps only
Released: 3 Sep 2026
API price: $10 in / $50 out per 1M tokens
License: proprietary
Last verified: 18 Oct 2026

Alternatives to GPT-6 Astra

Task by task

Task	Claude Opus 5.5	GPT-6 Astra	Higher tier
Chat & assistants Models	S1,508 on LMArena Text Arena (overall, style control) · Cloud	A1,477 on LMArena Text Arena (overall, style control) · Cloud	Claude Opus 5.5
Search & research Models	A1,211 on LMArena Search Arena (style control) · Cloud	S1,246 on LMArena Search Arena (style control) · Cloud	GPT-6 Astra
Writing Models	S1,519 on LMArena Text Arena: Creative Writing (style control) · Cloud	A1,450 on LMArena Text Arena: Creative Writing (style control) · Cloud	Claude Opus 5.5
Documents & OCR Models	–No public result yet · Cloud	–No public result yet · Cloud	—
Coding Models	S1,806 on LMArena WebDev / Code Arena (overall) · Cloud	S1,776 on LMArena WebDev / Code Arena (overall) · Cloud	Same tier
Image understanding Models	S1,293 on LMArena Vision Arena (overall, style control) · Cloud	S1,286 on LMArena Vision Arena (overall, style control) · Cloud	Same tier
Vector graphics & logos Models	C1,332 on Design Arena SVG · Cloud	B1,431 on Design Arena SVG · Cloud	GPT-6 Astra
Browser & computer agents Models	–No public result yet · Cloud	–No public result yet · Cloud	—
Workflow automation Models	A69.5% on AutomationBench-AA (Artificial Analysis) · Cloud	A68.5% on AutomationBench-AA (Artificial Analysis) · Cloud	Same tier

A tier spans a range of scores, and small gaps on a leaderboard are often within its margin of error, so only a different tier counts as ahead. How we rank.

Same benchmark, both results

Benchmark	Claude Opus 5.5	GPT-6 Astra	Snapshot
Artificial Analysis Intelligence Index Composite index over Artificial Analysis' own evaluation suite, higher is better	58 Claude Opus 5.5 (Max, Default Fallback)	53 GPT-6 Astra (Max)	18 Oct 2026
Artificial Analysis MMMU-Pro (independent evaluation) Accuracy on MMMU-Pro (multi-discipline multimodal questions over images), as run by Artificial Analysis, higher is better	87.7% Claude Opus 5.5 (Max, Default Fallback)	86.9% GPT-6 Astra (Max)	19 Oct 2026
AutomationBench-AA (Artificial Analysis) Score: average share of each task's objectives completed across 657 business-workflow tasks in 40 simulated SaaS apps via REST APIs; a task with any guardrail (business-rule) violation scores zero, higher is better	69.5% Claude Opus 5.5 (Max, Default Fallback)	68.5% GPT-6 Astra (Max)	19 Oct 2026
Design Arena SVG Elo rating from crowdsourced blind pairwise votes on SVG markup that models generate from a prompt (icons, illustrations, diagrams, artistic compositions), higher is better	1,332 Claude Opus 5.5	1,431 GPT-6 Astra (xhigh)	19 Oct 2026
EQ-Bench Creative Writing v3 Elo score from LLM-judged pairwise comparisons of creative-writing outputs (rubric score shown alongside), higher is better	2,050 claude-opus-5-5	2,173 gpt-6-astra	24 Sep 2026
LMArena Search Arena (style control) Arena score (Bradley-Terry rating from pairwise human votes on search-grounded answers, style-controlled view), higher is better	1,211 claude-opus-5.5-medium	1,246 gpt-6-astra-max	13 Oct 2026
LMArena Text Arena (overall, style control) Arena score (Bradley-Terry rating from pairwise human votes, style-controlled default view), higher is better	1,508 Claude Opus 5.5 (High)	1,477 gpt-6-astra-max	15 Oct 2026
LMArena Text Arena: Creative Writing (style control) Arena score (Bradley-Terry rating from pairwise human votes, creative-writing prompts only, style-controlled view), higher is better	1,519 Claude Opus 5.5 (High)	1,450 gpt-6-astra-max	15 Oct 2026
LMArena Vision Arena (overall, style control) Arena score (Bradley-Terry rating from pairwise human votes on image + text prompts, style-controlled view), higher is better	1,293 claude-opus-5.5-high	1,286 gpt-6-astra-max	9 Oct 2026
LMArena WebDev / Code Arena (overall) Arena score (Bradley-Terry rating from pairwise human votes on web-app generation), higher is better	1,806 Claude Opus 5.5 (Max)	1,776 GPT-6 Astra (Max)	18 Oct 2026
ParseBench (models) Overall: mean of five rule-based dimension scores (tables, charts, content faithfulness, semantic formatting, visual grounding) on ~2,000 human-verified enterprise pages, higher is better	79.8% Anthropic Opus 5.5 (Effort High)	70.7% OpenAI GPT-6 Astra (Reasoning Low)	9 Oct 2026