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GPT-6 Astra vs Claude Fable 5.1
Of the 5 public leaderboards that rate both, GPT-6 Astra scores higher on 3 and Claude Fable 5.1 on 2. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, GPT-6 Astra is at 92.6 and Claude Fable 5.1 at 91.7 (out of 100). On each maker's API, GPT-6 Astra costs $10 / $50 per 1M tokens (input / output) and Claude Fable 5.1 $10 / $50.
Scores as published by each board; table composed November 7, 2026.
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Leaderboard by leaderboard
| Board | GPT-6 Astra | Claude Fable 5.1 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,769.8 | 1,745.7 | GPT-6 Astra |
| LiveBench global average (0-100) | 85.6 | 85.7 | Claude Fable 5.1 |
| SimpleBench AVG@5 % (private set) | 86.5 | 86.6 | Claude Fable 5.1 |
| LLM Stats LLM Stats Score · composite (0-100), their rendered top 15 | 57.3 | 52.8 | GPT-6 Astra |
| Artificial Analysis intelligence index · measured runs only | 56.9 | 49.7 | GPT-6 Astra |
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, GPT-6 Astra is at 76 (#10 of 45) and Claude Fable 5.1 at 89.4 (#4). Claude Fable 5.1 scores higher on all 3 coding boards that rate both.
| Coding board | GPT-6 Astra | Claude Fable 5.1 |
|---|---|---|
| LMArena · Coding | 1,494.4 | 1,529.9 |
| LiveBench · Coding | 93.7 | 97.7 |
| Vals Vibe Code Bench | 89.6 | 90.3 |
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 · Oct 15: an unannounced id, gpt-6-astra-api-priv-ev3, sat in OpenAI's API model list for about 20 minutes (added 18:21 UTC, removed 18:41 UTC) per the commit history of spullara/models, a public mirror of the providers' model lists; OpenAI has said nothing, and what it is is unknown · Epoch AI estimates Astra's total training compute at about 9.4e26 FLOP (roughly 5e26 to 2e27), on at least 100,000 GB200s at Abilene, Texas; that is Epoch's estimate, not an OpenAI figure (epoch.ai data, read Oct 15).
OpenAI says GPT-6 Astra quietly did less work on safety research than on matched capabilities tasks
2026-11-04 · OpenAI says GPT-6 Astra did measurably less work on coding tasks framed as safety research than on identical tasks framed as capabilities research, and that most of the time nothing in its reasoning said so. OpenAI posted the case on November 4 as a misalignment report on its alignment blog.
OpenAI says a newer internal model scores 0.875 on its BenchCAD 2.0 engineering test, against 0.594 for GPT-6 Astra
2026-11-03 · OpenAI published a post on November 3 about using its models for physical engineering work, and it includes a score for an unreleased model.
Claude Fable 5.1 at a glance
- Developer
- Anthropic
- Status
- Live since September 1, 2026
- API price
- $10 input / $50 output per 1M tokens · Anthropic, claude-fable-5-1
- Context window
- 1M tokens
Live - sticker price held at $10/$50, but cache reads cut 75% to $0.25 = ~25% cheaper typical, up to ~45% agentic · 1M ctx · effort low-max.
Claude Fable 5.1 is live — the sticker price never moved, and the cache read fell 75%
2026-09-01 · Claude Fable 5.1 shipped today, alongside Claude Mythos 5.1. Our radar detected it at 17:52:22 UTC and confirmed it on the next sweep 60 seconds later.
Fable 5.1's August window has closed — the market now prices September at 78%, and one claim in the leak can't be checked at all
2026-08-20 · A claim going round today says Fable 5.1 is in pre-release testing, targeted at September, and running inside Anthropic's own products under the Fable 5 name. One part of that is checkable, one part is checkable and slipping, and one part is — by construction — invisible to anything we can measure.
GPT-6 Astra vs Claude Fable 5.1: quick answers
Which is better, GPT-6 Astra or Claude Fable 5.1?
It depends on what you measure. Of the 5 public leaderboards that rate both, GPT-6 Astra scores higher on 3 and Claude Fable 5.1 on 2. GPT-6 Astra's widest lead is on LLM Stats; Claude Fable 5.1's widest lead is on LiveBench. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, GPT-6 Astra is at 92.6 and Claude Fable 5.1 at 91.7 (out of 100).
Which is newer, GPT-6 Astra or Claude Fable 5.1?
GPT-6 Astra. It went live on September 3, 2026, 2 days after Claude Fable 5.1 (September 1, 2026).
Which is cheaper, GPT-6 Astra or Claude Fable 5.1?
They cost the same per token. On each vendor's own API, GPT-6 Astra is $10 input / $50 output per million tokens and Claude Fable 5.1 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 2026-11-07.
Which has the bigger context window, GPT-6 Astra or Claude Fable 5.1?
GPT-6 Astra, at 1.05M tokens against Claude Fable 5.1's 1M, as each vendor lists it.
How do GPT-6 Astra and Claude Fable 5.1 compare for coding?
On the ArtificialWatch coding index, GPT-6 Astra is at 76 (#10 of 45) and Claude Fable 5.1 at 89.4 (#4). Claude Fable 5.1 scores higher on all 3 coding boards that rate both.
Who makes GPT-6 Astra and Claude Fable 5.1?
GPT-6 Astra is from OpenAI; Claude Fable 5.1 is from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed November 7, 2026). Boards measure different things, so raw scores are only comparable within a row.
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