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Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 scores higher than GPT-6 Astra on all 6 public leaderboards that rate both. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Opus 5.5 is at 100 and GPT-6 Astra at 91.2 (out of 100).
Scores as published by each board; table composed October 8, 2026.
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Leaderboard by leaderboard
| Board | Claude Opus 5.5 | GPT-6 Astra | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,813 | 1,786.1 | Claude Opus 5.5 |
| LiveBench global average (0-100) | 83.2 | 82.2 | Claude Opus 5.5 |
| SimpleBench AVG@5 % (private set) | 88.4 | 86.5 | Claude Opus 5.5 |
| LLM Stats LLM Stats Score · composite (0-100), their rendered top 15 | 60.4 | 58.3 | Claude Opus 5.5 |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 67 | 63.1 | Claude Opus 5.5 |
| Artificial Analysis intelligence index · measured runs only | 57.6 | 52.7 | Claude Opus 5.5 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Claude Opus 5.5 is at 96.9 (#1 of 35) and GPT-6 Astra at 85.3 (#5). Claude Opus 5.5 scores higher on all 3 coding boards that rate both.
| Coding board | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| LMArena · Coding | 1,549.5 | 1,541.6 |
| LiveBench · Coding | 80.5 | 68.8 |
| Vals Vibe Code Bench | 90.3 | 89.6 |
Claude Opus 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since September 22, 2026
- API price
- $4 input / $20 output per 1M tokens · Anthropic, claude-opus-5-5
- Context window
- 1M tokens
Live — Sep 22 · $4/$20 per MTok, down from Opus 5 at $5/$25 · 1M ctx / 128K out · adaptive thinking always on, default effort medium · cache reads 5% of base input · Anthropic now says start here for most workloads, and Opus 5 is legacy.
Claude Opus 5.5 ships at $4/$20 - and that is LESS than the Opus 5 it replaces
2026-09-22 · Claude Opus 5.5 is live. Our sweep read the id claude-opus-5-5 at 16:24:44 UTC on September 22 and the alert went out at 16:25:45 - 61 seconds later, to 307 inboxes and one phone. The hunt that caught it was armed the previous day, before the model had a confirmed name, on the version range rather than on the rumour.
Markets put the next Claude Opus at 83% by Thursday — the name going around is 5.5
2026-09-21 · Polymarket's "Next Claude Opus released by...?" book, read directly at 06:49 UTC, September 21: 83% by September 24, 91% by September 27, 95% by September 30. Polymarket's own post about nine hours earlier had Thursday at 72%, so the number has been climbing through the day.
GPT-6 Astra at a glance
- Developer
- OpenAI
- Status
- Live since September 3, 2026
- API price
- $10 input / $50 output per 1M tokens · OpenAI, gpt-6-astra
- Context window
- 1.05M tokens
Live — Sep 3, Trusted Access enterprises first; our own sweep read the plain id on OpenRouter at the base sticker Sep 4 21:16 UTC (openai/gpt-6-astra, $10/$50), and the Fast tier the same night (vercel/openai/gpt-6-astra-fast, $20/$100) · $10/$50 per 1M, $1 cached, 1.05M ctx / 128K out · AA Coding Agent Index 67 (≈ Opus 5, Fable 5), Intelligence Index 61 (= GPT-5.6 Sol, 5 below Fable 5.1) · DevDay Sep 29: an Ultrafast tier (up to 8x faster, ~300 tokens/s in Codex) is in the API and, in ChatGPT Work and Codex, on Pro 500 and Enterprise.
GPT-6 Astra and GPT-6.1 Sol now run about 50% faster on ChatGPT subscriptions
2026-10-05 · GPT-6 Astra and GPT-6.1 Sol now run about 50% faster by default for ChatGPT subscribers, OpenAI's Tibo Sottiaux said today. He puts it at about 50 tokens per second, up from 30.
GPT-6 Astra is out — Fable 5.1's sticker, trusted access first, public API within days
2026-09-03 · OpenAI shipped GPT-6 Astra today. Its own words, from the model documentation: "Our most capable model, built for the hardest end-to-end work" — complex reasoning, coding, computer use, research and document creation.
Claude Opus 5.5 vs GPT-6 Astra: quick answers
Which is better, Claude Opus 5.5 or GPT-6 Astra?
It depends on what you measure. Claude Opus 5.5 scores higher than GPT-6 Astra on all 6 public leaderboards that rate both. Claude Opus 5.5's widest lead is on LLM Stats. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Opus 5.5 is at 100 and GPT-6 Astra at 91.2 (out of 100).
Which is newer, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5. It went live on September 22, 2026, 19 days after GPT-6 Astra (September 3, 2026).
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 is cheaper on both input and output. On each vendor's own API, Claude Opus 5.5 is $4 input / $20 output per million tokens and GPT-6 Astra is $10 input / $50 output per million tokens. GPT-6 Astra's rate rises for prompts over 272K tokens. Prices as published in the models.dev catalog, as of 2026-10-08.
Which has the bigger context window, Claude Opus 5.5 or GPT-6 Astra?
GPT-6 Astra, at 1.05M tokens against Claude Opus 5.5's 1M, as each vendor lists it.
How do Claude Opus 5.5 and GPT-6 Astra compare for coding?
On the ArtificialWatch coding index, Claude Opus 5.5 is at 96.9 (#1 of 35) and GPT-6 Astra at 85.3 (#5). Claude Opus 5.5 scores higher on all 3 coding boards that rate both.
Who makes Claude Opus 5.5 and GPT-6 Astra?
Claude Opus 5.5 is from Anthropic; GPT-6 Astra is from OpenAI.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed October 8, 2026). Boards measure different things, so raw scores are only comparable within a row.
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