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Model comparison · Updated 10 Oct 2026

Claude Fable 5.1 vs Claude Opus 4.1

Claude Fable 5.1 is about 1.5× cheaper on input ($10.00 against $15.00 per 1M tokens) and on output. Claude Fable 5.1 has the larger context window (1M against 200K tokens). For a support chatbot at 10,000 chats a day, the standard-tier bill is about $9,000 a month for Claude Fable 5.1 and $13,500 for Claude Opus 4.1.

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ModelsAtlas. “Claude Fable 5.1 vs Claude Opus 4.1”. Retrieved 10 Oct 2026. https://modelsatlas.com/compare/anthropic/claude-fable-5-1/vs/anthropic/claude-opus-4-1

Model A

Claude Fable 5.1

by Anthropic · weights not marked open · GRIDG5

Input / 1M
$10.00
observed We measured
Source
Our catalogue
Retrieved
10 Oct 2026
Output / 1M$50.00
Context1M
vs

Model B

Claude Opus 4.1

by Anthropic · weights not marked open · GRIDG3

Input / 1M
$15.00
asserted Vendor states
Source
docs.anthropic.com/en/docs/about-claude/pricing
Retrieved
17 Aug 2026
Output / 1M$75.00
Context200K

Key numbers

Standard tier · highlighted = better

Claude Fable 5.1
Claude Opus 4.1
Input / 1M tokens
$10.00
$15.00
Output / 1M tokens
$50.00
$75.00
Batch input / output
$5.00 / $25.00
$7.50 / $37.50
Context window
1,000,000
200,000
Input types
Not disclosed
Not disclosed
Weights
Not marked open
Not marked open
Tiers listed
batch, standard
batch, standard
Prices checked
2026-10-10
2026-08-17

What it costs for real workloads

Monthly, standard tier, 30 days

Support chatbot10k chats/day · 1.5k in, 300 out
$9,000/mo
$13,500/mo
RAG over documents2k queries/day · 12k in, 500 out
$8,700/mo
$13,050/mo
Coding agent300 tasks/day · 60k in, 8k out
$9,000/mo
$13,500/mo

Claude Fable 5.1   Claude Opus 4.1 · Derived from the standard-tier prices above, input and output tokens per request as stated, 30 days. Excludes caching discounts and batch. Try your own numbers.

On the atlas

Price band (A–H) × context band (1–6)

2 squares apart. Claude Opus 4.1 (G3) sits 2 context bands smaller than Claude Fable 5.1 (G5).

Same square as Claude Fable 5.1: Claude Fable 5 ($10.00). Same square as Claude Opus 4.1: Claude Opus 4 ($15.00). Open G5 · Open G3

AFreeB<$0.10C$0.10–0.30D$0.30–1E$1–3F$3–10G$10–30H$30+1<32K232–128K3128–256K4256K–1M51M6>1MINPUT PRICE PER 1M TOKENS →CONTEXT WINDOW ↑ · position within a square follows the real valueClaude Fable 5 · G5GPT-5 Image · G4GPT-6 Astra · G6Claude Opus 4.6 · F5Claude Opus 4.7 · F5Claude Opus 4.8 · F5Claude Opus 4 · G3Claude Opus 4.5 · F3Claude Sonnet 4 · F3Claude Fable 5.1Claude Fable 5.1Claude Opus 4.1Claude Opus 4.1
Claude Fable 5.1Claude Opus 4.1Nearest neighboursOpen weights
View the map as a table (6 squares)
SquarePrice bandContext bandModels
GRIDF3$3–10128–256KClaude Opus 4.5, Claude Sonnet 4
GRIDF5$3–101MClaude Opus 4.6, Claude Opus 4.7, Claude Opus 4.8
GRIDG3$10–30128–256KClaude Opus 4.1, Claude Opus 4
GRIDG4$10–30256K–1MGPT-5 Image
GRIDG5$10–301MClaude Fable 5.1, Claude Fable 5
GRIDG6$10–30>1MGPT-6 Astra

Capabilities side by side

Only what our records list

Claude Fable 5.1
Claude Opus 4.1
Vision input
Not disclosed
Not disclosed
Audio input
Not disclosed
Not disclosed
Open weights
Not marked open
Not marked open
Batch tier
Supported
Supported
Free tier
Not listed
Not listed
Thinking tier
Not listed
Not listed

Neither record lists input types, so we do not claim any.

Which should you choose?

Editorial

Choose Claude Fable 5.1 if…

  • you pay by the token: it costs $10.00 per 1M input against $15.00
  • output dominates your bill: $50.00 per 1M output against $75.00
  • your prompts are long: it takes 1,000,000 tokens against 200,000

Choose Claude Opus 4.1 if…

Nothing in the recorded numbers favours Claude Opus 4.1 over Claude Fable 5.1. Pick it for what our records do not cover — your own tests, or an account you already have with Anthropic.

Each reason is a fact from the tables above. Picking between them is our judgement, and we do not benchmark quality: price and context are what we can measure, so test both on your own prompts before you commit.

Questions

Is Claude Fable 5.1 better than Claude Opus 4.1?
We do not benchmark quality, so we cannot say. On the recorded numbers: Claude Fable 5.1 is about 1.5× cheaper on input ($10.00 against $15.00 per 1M tokens) and on output. Claude Fable 5.1 has the larger context window (1M against 200K tokens). For a support chatbot at 10,000 chats a day, the standard-tier bill is about $9,000 a month for Claude Fable 5.1 and $13,500 for Claude Opus 4.1. Which is better for you depends on your task; test both on your own prompts.
Which is cheaper, Claude Fable 5.1 or Claude Opus 4.1?
Claude Fable 5.1: $10.00 against $15.00 per 1M input tokens, and $50.00 against $75.00 per 1M output, on standard pricing.
How much does each cost per 1M tokens?
Claude Fable 5.1: $10.00 input and $50.00 output. Claude Opus 4.1: $15.00 input and $75.00 output. Standard tier, USD.
Which has the larger context window?
Claude Fable 5.1, with 1,000,000 tokens. Claude Opus 4.1 has 200,000 tokens.
Do both offer batch pricing?
Claude Fable 5.1 lists a batch tier, at 50% of its standard price. Claude Opus 4.1 lists a batch tier, at 50% of its standard price.
Can both read images or audio?
Input types recorded for Claude Fable 5.1: none recorded. For Claude Opus 4.1: none recorded. Where a record lists none we say so rather than guess; check each vendor's documentation before relying on a capability.
Is either model open-weight?
Claude Fable 5.1: not marked open-weight in our records. Claude Opus 4.1: not marked open-weight in our records.
What would each cost for a support chatbot?
At 10,000 chats a day, 1,500 input and 300 output tokens each, 30 days, standard tier: about $9,000 a month for Claude Fable 5.1 and $13,500 for Claude Opus 4.1. This is our calculation from the listed prices, not a quote.

About the two models

Claude Fable 5.1

By Anthropic. $10.00 input and $50.00 output per 1M tokens, 1M context, atlas square G5. Tiers listed: batch, standard.

Full specs & pricing →

Claude Opus 4.1

By Anthropic. $15.00 input and $75.00 output per 1M tokens, 200K context, atlas square G3. Tiers listed: batch, standard.

Full specs & pricing →

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Compare Claude Opus 4.1 with…

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