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HEAD TO HEAD · UPDATED NOV 6, 2026
Claude Opus 5.5 vs GPT-6 Astra
Anthropic against OpenAI, on sourced numbers only. Green marks the higher (or cheaper) value on each row; the text below only calls a lead when the gap is bigger than measurement noise.
| Claude Opus 5.5 | GPT-6 Astra | |
|---|---|---|
| Arena Elo | 1509 source ↗ | 1476 source ↗ |
| GPQA Diamond | 90.6% source ↗ | 96.0% source ↗ |
| $ per 1M in / out | $4 / $20 source ↗ | $10 / $50 source ↗ |
| Blended $ per 1M (3:1) | $8.00 source ↗ | $20.00 source ↗ |
| Context window | 1M source ↗ | 1.05M source ↗ |
| Output speed | 110 tok/s source ↗ | not published |
| Released | Sep 22, 2026 source ↗ | Sep 3, 2026 source ↗ |
| Open weights | No source ↗ | No source ↗ |
| Reasoning effort tiers | low · medium · high · xhigh · max (default: medium) | low · medium · high · xhigh · max (default: not stated) |
| API effort control | output_config={"effort": "low" | "medium" | "high" | "xhigh" | "max"} source ↗ | reasoning={"effort": "low" | "medium" | "high" | "xhigh" | "max"} source ↗ |
| Additional benchmarks | Arena WebDev: 1810 (#1) source ↗ SWE-bench Pro: 89.9% source ↗ Terminal-Bench 4.0: 66.4% (xhigh) source ↗ GDPval-AA v2.1: 1846 source ↗ CursorBench 4.0: 57.8% at max effort, 52.5% at default source ↗ AA Intelligence Index v5.0.1: 59 source ↗ | DeepSWE v1.1: 74.1% source ↗ Terminal-Bench 4.0: 57.9% source ↗ AA Intelligence Index v5.0.1: 57 (Max) source ↗ |
| Best for (workload) | Anthropic suggests starting with Opus 5.5 for most workloads. #1 on Arena WebDev (1810); 66.4% on Terminal-Bench 4.0 at xhigh effort (Anthropic). source ↗ | OpenAI's most capable model: 96.0% GPQA Diamond, 74.1% DeepSWE v1.1 and 57.9% Terminal-Bench 4.0 (OpenAI). source ↗ |
Arena Elo from the arena.ai text leaderboard as of Oct 27, 2026 source ↗. Speed measured by Artificial Analysis and varies by provider.
Which one should I use?
For high-volume work where cost matters most, Claude Opus 5.5 is about 2.5 times cheaper per token. For overall answer quality as rated by people in blind tests, Claude Opus 5.5 leads clearly (1509 vs 1476 Arena Elo). For hard science and analysis questions, GPT-6 Astra scores higher on GPQA Diamond (96.0% vs 90.6%). On release timing, Anthropic is at day 30 of a typical ~15-day gap (PAST TYPICAL GAP), and OpenAI is at day 11 of a typical ~23-day gap (ADOPT NOW · FRESH RELEASE).
Key differences from the sourced numbers
- Claude Opus 5.5 is the cheaper option: $8.00 vs $20.00 per 1M tokens at a 3:1 input-to-output mix (about 2.5 times less).
- Claude Opus 5.5 scores 33 Elo points higher (1509 vs 1476) on the Arena text leaderboard, where people vote on blind side-by-side answers.
- On GPQA Diamond, graduate-level science questions, GPT-6 Astra leads 96.0% to 90.6%.
- Claude Opus 5.5 pricing note: Same rate across the full 1M context window.
- GPT-6 Astra pricing note: Prompts up to 272K tokens; $20 / $75 above 272K. Batch and Flex: $5 / $25.
Frequently asked questions
Is Claude Opus 5.5 or GPT-6 Astra better?
Claude Opus 5.5 is the cheaper option: $8.00 vs $20.00 per 1M tokens at a 3:1 input-to-output mix (about 2.5 times less). Claude Opus 5.5 scores 33 Elo points higher (1509 vs 1476) on the Arena text leaderboard, where people vote on blind side-by-side answers. On GPQA Diamond, graduate-level science questions, GPT-6 Astra leads 96.0% to 90.6%. Claude Opus 5.5 pricing note: Same rate across the full 1M context window. GPT-6 Astra pricing note: Prompts up to 272K tokens; $20 / $75 above 272K. Batch and Flex: $5 / $25.
Which one should I use: Claude Opus 5.5 or GPT-6 Astra?
For high-volume work where cost matters most, Claude Opus 5.5 is about 2.5 times cheaper per token. For overall answer quality as rated by people in blind tests, Claude Opus 5.5 leads clearly (1509 vs 1476 Arena Elo). For hard science and analysis questions, GPT-6 Astra scores higher on GPQA Diamond (96.0% vs 90.6%). On release timing, Anthropic is at day 30 of a typical ~15-day gap (PAST TYPICAL GAP), and OpenAI is at day 11 of a typical ~23-day gap (ADOPT NOW · FRESH RELEASE).
How much does Claude Opus 5.5 cost compared with GPT-6 Astra?
Claude Opus 5.5 lists at $4 / $20 per 1M input/output tokens ($8.00/1M blended at 3:1). GPT-6 Astra lists at $10 / $50 per 1M input/output tokens ($20.00/1M blended at 3:1).
Facts checked Nov 5, 2026 against official sources. Every number links to its source. Spotted an error? Email [email protected].