GPT-6 Astra vs Claude Fable 5.1
Official OpenAI and Anthropic API prices and LMArena scores, checked 2026-10-18. Add up to 2 more models to compare 4.
Same bill; Claude Fable 5.1 wins more LMArena tasks.
GPT-6 Astra and Claude Fable 5.1 have the same list price per token ($10 in, $50 out per 1M). Claude Fable 5.1 scores 69 points higher for reasoning and math; GPT-6 Astra scores 12 points higher for coding. Across 8 shared LMArena tasks, Claude Fable 5.1 leads 6 to 2. A medium month (20M input + 5M output tokens) costs $450 on GPT-6 Astra and $450 on Claude Fable 5.1.
- Pick GPT-6 Astra if you care most about coding (+12).
- Pick Claude Fable 5.1 if you care most about reasoning and math (+69), creative writing (+47) and chat (+44) or you reuse long prompts (cached input $0.25 vs $1).
Medium: 20M input + 5M output tokens a month at list price (short-context rate, no caching or batch discounts).
Marked side is better: lower for prices, higher for context and scores. Bars are scaled to the larger of the two.
| Spec | GPT-6 Astra | Claude Fable 5.1 |
|---|---|---|
| Price per 1M tokens | ||
| Input | $10 | $10 |
| Cached input | $1 | $0.25 |
| Output | $50 | $50 |
| Blend 3:1 | $20 | $20 |
| Sample month, medium | $450 | $450 |
| Context | ||
| Context window | 1.05M tokens | 1M tokens |
| Quality (LMArena, out of 100) | ||
| Coding | 89/100 #2 of 23 | 77/100 #5 of 23 |
| Chat | 18/100 #13 of 25 | 62/100 #4 of 25 |
| Creative writing | 7/100 #14 of 25 | 54/100 #5 of 25 |
| Roleplay and characters | 15/100 #13 of 25 | 16/100 #10 of 25 |
| Reasoning and math | 25/100 #14 of 24 | 94/100 #2 of 24 |
| Vision | 67/100 #9 of 21 | 68/100 #8 of 21 |
| Long documents | 78/100 #6 of 9 | 100/100 #1 of 9 |
| Cheap bulk and agents | 86/100 #2 of 23 | 85/100 #3 of 23 |
| Details | ||
| Provider | OpenAI | Anthropic |
| API model id | gpt-6-astra | claude-fable-5.1 |
| Notes | Prompts up to 272K. Longer prompts cost $20 in, $75 out. | Cache reads $0.25, 5-minute cache writes $12.50. |
| Sources | ||
| Last checked | 2026-10-18 | 2026-10-18 |
| Official pricing | OpenAI pricing | Anthropic pricing |
Plans from data checked hourly against each vendor's official pricing page. Vendors state limits in different units, so we quote them as published. Team and enterprise plans are per seat.
API prices in USD per 1M tokens from each provider's official pricing page. Blend 3:1 = (3 x input + output) / 4. Sample month = stated input and output tokens at the list price, no caching. Quality: relative score out of 100 on each LMArena leaderboard (100 = top model we price on that board, n/a = not ranked there), data licensed CC BY 4.0. See how we pick.
Where each one ranks on LMArena
Relative score out of 100 on each leaderboard (100 = the top model we price there), with the rank among the models from our API price table that appear on that board.
- Coding (Code Arena): GPT-6 Astra #2 of 23 (89/100), Claude Fable 5.1 #5 of 23 (77/100)
- Chat (Text Arena): GPT-6 Astra #13 of 25 (18/100), Claude Fable 5.1 #4 of 25 (62/100)
- Creative writing (Text Arena creative writing): GPT-6 Astra #14 of 25 (7/100), Claude Fable 5.1 #5 of 25 (54/100)
- Roleplay and characters (Text Arena multi-turn): GPT-6 Astra #13 of 25 (15/100), Claude Fable 5.1 #10 of 25 (16/100)
- Reasoning and math (Text Arena math): GPT-6 Astra #14 of 24 (25/100), Claude Fable 5.1 #2 of 24 (94/100)
- Vision (Vision Arena): GPT-6 Astra #9 of 21 (67/100), Claude Fable 5.1 #8 of 21 (68/100)
- Long documents (Document Arena): GPT-6 Astra #6 of 9 (78/100), Claude Fable 5.1 #1 of 9 (100/100)
- Cheap bulk and agents (Agent Arena): GPT-6 Astra #2 of 23 (86/100), Claude Fable 5.1 #3 of 23 (85/100)
Pricing details from the official pages
GPT-6 Astra lists $10 input, $50 output, $1 cached input per 1M tokens on OpenAI pricing. Claude Fable 5.1 lists $10 input, $50 output, $0.25 cached input per 1M tokens on Anthropic pricing. Prices checked 2026-10-18.
- GPT-6 Astra: Prompts up to 272K. Longer prompts cost $20 in, $75 out.
- Claude Fable 5.1: Cache reads $0.25, 5-minute cache writes $12.50.
Sample monthly bill at list price, no caching: Light (2M input + 0.5M output tokens): $45 vs $45. Medium (20M input + 5M output tokens): $450 vs $450. Heavy (200M input + 50M output tokens): $4,500 vs $4,500.
FAQ
Is GPT-6 Astra cheaper than Claude Fable 5.1?
They have the same list price: $10 input and $50 output per 1M tokens.
Which is better for coding, GPT-6 Astra or Claude Fable 5.1?
On LMArena's Code Arena GPT-6 Astra scores 89/100 (#2 of 23) and Claude Fable 5.1 77/100 (#5 of 23), so GPT-6 Astra is ahead by 12 points.
Which has the bigger context window?
GPT-6 Astra: 1.05M tokens. Claude Fable 5.1: 1M tokens. Long prompts can cost more; see the pricing notes above.
How much do GPT-6 Astra and Claude Fable 5.1 cost per month?
Light (2M input + 0.5M output tokens): $45 vs $45. Medium (20M input + 5M output tokens): $450 vs $450. Heavy (200M input + 50M output tokens): $4,500 vs $4,500. Pick your own token counts in the plan vs API calculator.
Where do these numbers come from?
Prices come from each provider's official pricing page, checked daily. Quality is the relative score on the LMArena leaderboard dataset, licensed CC BY 4.0. Where a model is not ranked we show n/a.