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Claude Fable 5.1 vs GPT-6 Astra

At 10,000 requests a month of 5,000 input and 500 output tokens, GPT-6 Astra costs about $750 a month and Claude Fable 5.1 about $975, so GPT-6 Astra is 23% cheaper. Claude Fable 5.1 has a context window of 1,000,000 tokens and GPT-6 Astra has 1,050,000 tokens. Claude Fable 5.1 has no announced retirement. Anthropic says it will not retire it before Sep 1, 2027. GPT-6 Astra has no announced retirement. Prices checked 2026-10-21.

Prices are USD per 1M tokens, standard tier, checked 2026-10-21. Monthly cost uses the workload below.

  • Claude Fable 5.1 Anthropic

    Input per 1M
    $10
    Output per 1M
    $50
    Monthly cost
    $975
    $98 per 1,000 requests
    Context
    1M
    Retirement
    Active
    Anthropic says not retired before Sep 1, 2027
    API ID:
    claude-fable-5-1
    Max output:
    128K
    Inputs:
    Text, Images
    Released:
    Sep 1, 2026
    Knowledge cutoff:
    Jun 2026

  • GPT-6 Astra OpenAI

    Input per 1M
    $10
    Output per 1M
    $50
    Monthly cost
    $750Cheapest
    $75 per 1,000 requests
    Context
    1.05M
    Retirement
    Active
    No retirement date listed
    API ID:
    gpt-6-astra
    Max output:
    128K
    Inputs:
    Text, Images
    Released:
    Not published
    Knowledge cutoff:
    Apr 30, 2026
Compare with other models

Monthly cost estimate

Example sizes are our round numbers. Set your own below.

  • Claude Fable 5.1 $975 a month

    $98 per 1,000 requests

  • GPT-6 Astra Cheapest $750 a month

    $75 per 1,000 requests

List prices checked 2026-10-21, standard tier, no caching, no batch discount. Claude 4.7 and later count about 30% more tokens for the same text, so their rows include that. Long-prompt prices apply where the vendor sets them.

The facts side by side

Each model page lists every fact with its source: Claude Fable 5.1 and GPT-6 Astra.

Prices are USD per 1M tokens, standard tier. Monthly cost is 10,000 requests of 5,000 input and 500 output tokens. Checked 2026-10-21 on each vendor's own pages.

  • Claude Fable 5.1 Anthropic

    Input per 1M
    $10
    Output per 1M
    $50
    Monthly cost
    $975
    $98 per 1,000 requests
    Context
    1M
    Retirement
    Active
    Anthropic says not retired before Sep 1, 2027
    API ID:
    claude-fable-5-1
    Max output:
    128K
    Inputs:
    Text, Images
    Released:
    Sep 1, 2026
    Knowledge cutoff:
    Jun 2026

  • GPT-6 Astra OpenAI

    Input per 1M
    $10
    Output per 1M
    $50
    Monthly cost
    $750Cheapest
    $75 per 1,000 requests
    Context
    1.05M
    Retirement
    Active
    No retirement date listed
    API ID:
    gpt-6-astra
    Max output:
    128K
    Inputs:
    Text, Images
    Released:
    Not published
    Knowledge cutoff:
    Apr 30, 2026

Benchmark scores side by side

Independent scores from Epoch AI, which scores every vendor's models the same way. Ranks compare each model with the others on our AI models page.

Benchmark Claude Fable 5.1GPT-6 Astra
Epoch Capabilities Index One score that combines many benchmarks, such as math, science, and coding tests, into a single scale. Epoch sets Claude 3.5 Sonnet at 130 and GPT-5 at 150. 166.49 Rank 4 of 17 models here 168.81 Rank 2 of 17 models here
GPQA Diamond 198 hard multiple-choice questions in biology, chemistry, and physics, written by PhD-level experts. Guessing scores 25%. We show the highest score for each model across the reasoning settings Epoch ran. No score listed 95.8% Rank 2 of 16 models here

Scores are Epoch AI's, not ours. Source: Epoch AI, Capabilities and benchmarking, from its public data download, checked 2026-10-21. Used under CC BY 4.0. We drew the charts. A benchmark is one test, so run your own inputs before you choose.

What each vendor says

"For demanding reasoning and long-horizon agentic work"
"Our most capable model for the most demanding work."

Want a different pair? Use the AI model compare tool, or get a shortlist for your job from the AI model picker. For older models with shutdown dates, see our AI model retirement dates calendar.

Questions clients ask

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Which is cheaper, Claude Fable 5.1 or GPT-6 Astra?

They have the same list price: $10 in and $50 out per 1M tokens. At 10,000 requests a month of 5,000 input and 500 output tokens, Claude Fable 5.1 costs about $975 a month and GPT-6 Astra about $750. The monthly figures add about 30% to Claude 4.7 and later rows, because Anthropic says they count more tokens for the same text. Checked 2026-10-21.

Which has the larger context window?

Claude Fable 5.1: 1,000,000 tokens. GPT-6 Astra: 1,050,000 tokens.

Is either model being retired?

Claude Fable 5.1 has no announced retirement. Anthropic says it will not retire it before Sep 1, 2027. GPT-6 Astra has no announced retirement.

Which should I use?

Run 20 to 50 of your real inputs through both and compare the answers and the token counts. Price per token is only half of the cost. The other half is how many tokens each model uses for your task.

Want both tested on your data?

Send us 20 real inputs. An engineer runs them through both models and replies with the results. We bill hourly or by milestone.

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