GPT-6 Astra vs Claude Fable 5.1
GPT-6 Astra wins on Overall; Claude Fable 5.1 wins on Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose GPT-6 Astra if you…
- Best-in-class computer use
- Frontier research & reasoning
- Autonomous long-horizon tasks
- Strongest cybersecurity (gated)
- Best for: Computer use, Deep research, Cybersecurity
Choose Claude Fable 5.1 if you…
- Top agentic coding (Terminal-Bench 55.8)
- Highest AA Intelligence Index
- Reliable 1M long-running agents
- Cache reads 75% cheaper
- Best for: Agentic coding, Long-horizon tasks, Scientific research
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 26 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | GPT-6 Astra | Claude Fable 5.1 | Verdict |
|---|---|---|---|
| Vendor | OpenAI (US) | Anthropic (US) | Different vendors |
| Released | 2026.09 | 2026.09 | Claude Fable 5.1 is newer |
| Overall (rank) | 96 · #1 | 95 · #2 | GPT-6 Astra +1 |
| Coding | 97 · #3 | 99 · #1 | Claude Fable 5.1 +2 |
| Multimodal | 90 · #7 | 97 · #1 | Claude Fable 5.1 +7 |
| Context window | 1.05M | 1M | GPT-6 Astra larger |
| Max output | 128K | 128K | Tie |
| Effective-context | 96 | 99 | Claude Fable 5.1 more reliable |
| Input $/1M | $10 | $10 | Tie |
| Output $/1M | $50 | $50 | Tie |
| Cache discount | 50% off | 90% off | Claude Fable 5.1 deeper |
| Speed | ~35 tok/s | ~32 tok/s | GPT-6 Astra faster |
| TTFT | 1.1s | 1.1s | Tie |
| Function calling | 94 | 93 | GPT-6 Astra ahead |
| Refusal rate | ~13% | ~9% | Claude Fable 5.1 less restrictive |
| English | 99 | 99 | Tie |
| Chinese | 72 | 83 | Claude Fable 5.1 |
| Modalities | text, image | text, image | Same |
| Open weights | No | No | Both closed |
| Fine-tuning | No | No | |
| Free tier | No free API tier; Fast mode delivers up to ~2x throughput | No free tier; cache reads cut to a quarter of cost | |
| SOC2 / no-train | yes / yes | yes / yes | |
| Private deployment | No | No | Neither |
Fields drawn from vendor public documentation and the Modelspectra 26-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
GPT-6 Astra leads the overall aggregate by 1 points (96 vs 95). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while Claude Fable 5.1 remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a modest gap: Claude Fable 5.1 scores 99 against 97. On multi-file edits, SWE-style tickets and long-horizon agent loops Claude Fable 5.1 needs fewer correction turns; GPT-6 Astra is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
Claude Fable 5.1 leads multimodal 97 vs 90. Neither emits native video, so the comparison is about parsing images and documents, not generation.
Speed & latency
GPT-6 Astra is faster in interactive use: ~35 tok/s with 1.1s TTFT versus ~32 tok/s with 1.1s TTFT (about 1.1× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 1.05M for GPT-6 Astra and 1M for Claude Fable 5.1. Crucially, the larger nominal window does not win on usable recall: GPT-6 Astra advertises 1.05M but Claude Fable 5.1 scores higher on effective-context (99 vs 96), i.e. it actually retains more of what it was given.
Price & total cost
GPT-6 Astra is the cheaper API at $10/$50 versus Claude Fable 5.1 at $10/$50 per 1M input/output tokens — list input is about 1.0× lower. Cache discounts (GPT-6 Astra 50% vs Claude Fable 5.1 90%) shift the effective bill, worked out below.
Chinese vs English
English: GPT-6 Astra 99 vs Claude Fable 5.1 99. Chinese: 72 vs 83. Both are US-based models; for Chinese-first workloads also compare domestic models on the leaderboard.
Tool use & ecosystem
Function-calling score: GPT-6 Astra 94 vs Claude Fable 5.1 93, so GPT-6 Astra has the edge on structured tool use. Neither offers standard fine-tuning. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | GPT-6 Astra | Claude Fable 5.1 | Gap |
|---|---|---|---|
| List priceno cache applied | $2,500100M in × $10 + 30M out × $50 | $2,500100M in × $10 + 30M out × $50 | 1.00×even |
| With caching90% of inputs cache-hit | $2,05090M cached in × $5 + 10M in × $10 + 30M out × $50 | $1,69090M cached in × $1 + 10M in × $10 + 30M out × $50 | 1.21×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.