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HEAD TO HEAD · UPDATED NOV 6, 2026
Claude Sonnet 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 Sonnet 5.5 | GPT-6 Astra | |
|---|---|---|
| Arena Elo | 1477 source ↗ | 1476 source ↗ |
| GPQA Diamond | 95.6% source ↗ | 96.0% source ↗ |
| $ per 1M in / out | $2 / $10 source ↗ | $10 / $50 source ↗ |
| Blended $ per 1M (3:1) | $4.00 source ↗ | $20.00 source ↗ |
| Context window | 1M source ↗ | 1.05M source ↗ |
| Output speed | 155 tok/s source ↗ | not published |
| Released | Sep 28, 2026 source ↗ | Sep 3, 2026 source ↗ |
| Open weights | No source ↗ | No source ↗ |
| Reasoning effort tiers | low · medium · high · xhigh · max (default: high) | 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 | SWE-bench Pro: 81.3% source ↗ AA Intelligence Index v5.0.1: 55 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) | Fast (155 tok/s, Artificial Analysis) and strong on science: 95.6% GPQA Diamond at max effort (Epoch AI), above Opus 5.5's 90.6%. 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 Sonnet 5.5 is about 5.0 times cheaper per token. 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 Sonnet 5.5 is the cheaper option: $4.00 vs $20.00 per 1M tokens at a 3:1 input-to-output mix (about 5.0 times less).
- On the Arena text leaderboard they are close (1477 vs 1476): a gap under 20 points is within the leaderboard's margin of error.
- On GPQA Diamond they are close (95.6% vs 96.0%).
- Claude Sonnet 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 Sonnet 5.5 or GPT-6 Astra better?
Claude Sonnet 5.5 is the cheaper option: $4.00 vs $20.00 per 1M tokens at a 3:1 input-to-output mix (about 5.0 times less). On the Arena text leaderboard they are close (1477 vs 1476): a gap under 20 points is within the leaderboard's margin of error. On GPQA Diamond they are close (95.6% vs 96.0%). Claude Sonnet 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 Sonnet 5.5 or GPT-6 Astra?
For high-volume work where cost matters most, Claude Sonnet 5.5 is about 5.0 times cheaper per token. 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 Sonnet 5.5 cost compared with GPT-6 Astra?
Claude Sonnet 5.5 lists at $2 / $10 per 1M input/output tokens ($4.00/1M 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].