By the toolist.ai editors. Researched from public sources, not hands-on tested by toolist.ai. Updated October 27, 2026; prices checked October 21, 2026.

GPT-6 Astra vs Claude Fable 5.1

Verdict

GPT-6 Astra is the stronger model at the same token price. Both cost $10 per million input tokens and $50 per million output tokens, and Astra leads Fable 5.1 on all four Artificial Analysis scores both have at max effort: 57 against 49 on the Intelligence Index, 59% against 52% on Terminal-Bench 4.0, 64% against 60% on HLE-Diamond and 63% against 43% on Terminal-Bench-Science. Fable 5.1 is cheaper to repeat: its cached input costs $0.25 per million tokens against Astra's $1, and it adds no long-context surcharge.

Verdict based on published prices, limits and benchmarks, not on our own tests.

Choose GPT-6 Astra if

  • Your agents do long terminal work: 59% against 52% on Terminal-Bench 4.0, and 63% against 43% on Terminal-Bench-Science
  • You need a paid speed tier, since OpenAI offers Fast and Ultrafast modes for Astra and Fable 5.1 has no fast mode

Choose Claude Fable 5.1 if

  • Your prompts repeat: cached input costs $0.25 per million tokens against Astra's $1
  • Your prompts run past 272,000 tokens, where OpenAI doubles Astra's input price and Anthropic adds no surcharge

Price

Input costs the same on both. Output costs the same on both.

Per million tokensGPT-6 AstraClaude Fable 5.1
Input$10 source$10 source
Cached input$1 source$0.25 source
Output$50 source$50 source

GPT-6 Astra: Prompts over 272,000 input tokens are billed at twice the input rate and 1.5 times the output rate for the whole request. Batch and Flex cost half; Fast mode costs double and Ultrafast six times.

Claude Fable 5.1: Cache writes cost $12.50 per million tokens (5-minute cache) or $20 (1-hour cache). The Batch API costs half. There is no long-context surcharge and no fast mode.

Worked example: what a month costs

We priced three monthly workloads at the standard rates. The provider does not publish these figures.

WorkloadGPT-6 AstraClaude Fable 5.1
Support chatbot
100,000 replies, each 3,000 input and 400 output tokens, no caching (300M in, 40M out)		 $5,000$5,000
Document Q&A
5,000 questions over the same 60,000-token document set (90% cache hits), 800 output tokens each (300M in, 4M out)		 $770$568
Coding agent
200 tasks, each 1.5 million input tokens (90% cache hits) and 50,000 output tokens (300M in, 10M out)		 $1,070$868

Price your own workload

ModelCost a month
GPT-6 Astra $750
Claude Fable 5.1 $750

Standard API prices, no batch or priority discounts. Cached input is billed at the cache-read price; cache-write charges are not included. Reasoning models bill their thinking as output tokens.

Limits and release dates

GPT-6 AstraClaude Fable 5.1
ReleasedSeptember 3, 2026 sourceSeptember 1, 2026 source
Context window1,050,000 tokens source1,000,000 tokens source
Maximum output128,000 tokens source128,000 tokens source
Knowledge cutoffApril 30, 2026 sourceJune 2026 source
Input and outputText and images in; text out sourceText and images in; text out source
API model namegpt-6-astraclaude-fable-5-1

Benchmarks

Scores as published by the provider or measured by Artificial Analysis; higher is better. A dash means no score was published.

BenchmarkGPT-6 AstraClaude Fable 5.1
Artificial Analysis Intelligence Index
max effort		 57.0 source49.0 source
Intelligence Index at everyday effort 51.0 (medium effort; OpenAI publishes no default) source47.0 (high effort, the API default) source
Terminal-Bench 4.0
max effort		 59.0% source52.0% source
HLE-Diamond
max effort		 64.0% source60.0% source
Terminal-Bench-Science 0.1
max effort		 63.0% source43.0% source
Output speed 59 tokens/s (medium effort, Artificial Analysis) source59.8 tokens/s (high effort, Artificial Analysis) source

Benchmark and speed data from Artificial Analysis where linked.

Read more

Sources