Claude Fable 5.1 vs Claude Sonnet 5

rates, context and capabilities side by side on the impossibl api, and what the same workload costs on each.

the models at a glance: base rates, context window and modalities
specificationClaude Fable 5.1

anthropic/claude-fable-5-1

Claude Sonnet 5

anthropic/claude-sonnet-5

input · usd / 1m tok$10.00$2.00
output · usd / 1m tok$50.00$10.00
context window1mtokens1mtokens
modalities · in → out

takes text and image in, gives text out

takes text and image in, gives text out

pricing

base api rates by model
base api rates · usd per 1m tokensClaude Fable 5.1

anthropic/claude-fable-5-1

Claude Sonnet 5

anthropic/claude-sonnet-5

input$10.00$2.00
output$50.00$10.00
cache read$0.25$0.20
cache write · default ttl$12.50$2.50
cache write · 1h ttl$20.00$4.00

the estimate below prices one workload at these rates on every model.

specifications

published specifications by model
as publishedClaude Fable 5.1

anthropic/claude-fable-5-1

Claude Sonnet 5

anthropic/claude-sonnet-5

creatorAnthropicAnthropic
model typeText generationText generation
context window1,000,000tokens1,000,000tokens
input

takes text and image in, gives text out

takes text and image in, gives text out

outputtexttext
tool callingnot verifiednot verified
releasedsep 1, 2026jun 30, 2026
endpoint/v1/chat/completions/v1/chat/completions

unknown means the public catalog does not establish that fact. a model's documented capabilities can differ from what a particular api supports. see the model documentation for integration details.

benchmarks

benchmark scores by model, primary tested configuration
primary configurationClaude Fable 5.1

anthropic/claude-fable-5-1

Claude Sonnet 5

anthropic/claude-sonnet-5

max

intelligence index · gateway rank53.4#3 of 10838.2#33 of 108
coding index81.6#1 of 6471.5#19 of 64
agentic index57.9#1 of 5343.6#14 of 53
omnisciencenot measured16.4#17 of 84
gpqanot measured91.1%#20 of 80
humanity’s last examnot measured41.3%#21 of 87
aa-lcrnot measured82.0%
mmmu-pronot measured77.3%
multilingual lcrnot measured55.0%
scicodenot measured54.3%
analystagentnot measured46.3%
tau bankingnot measured37.3%
automationbench partialnot measured36.5%
critptnot measured16.9%
gdp.pdf all-passnot measured13.2%

Claude Fable 5.1 source ↗Claude Sonnet 5 source ↗

each column describes the tested configuration named under the model; performance and costs can differ on impossibl. a score one model was not measured on is left blank rather than scored zero. indices are ranked against every model on the gateway with one. last checked 2026-10-14.

estimate your cost

one token workload, priced on every model at the published rates, in usd. change the numbers to match yours.

token workload

total input, including cached tokens

include billable reasoning tokens

the same token usage in each request

a subset of total input, never additional tokens

Claude Fable 5.1

anthropic/claude-fable-5-1

estimated usage cost

$35.00

1,000 requests × (1,000 uncached input × $10.00 + 500 output × $50.00) / 1,000,000 = $35.00

base rates; no context pricing tiers are published.

Claude Sonnet 5

anthropic/claude-sonnet-5

estimated usage cost

$7.00

1,000 requests × (1,000 uncached input × $2.00 + 500 output × $10.00) / 1,000,000 = $7.00

base rates; no context pricing tiers are published.

estimates use published impossibl api usage rates. configured billing adjustments, funding fees, taxes, and custom workspace rates are excluded and may change the final amount.

image and audio usage, cache creation, and additional tool charges are excluded. reasoning tokens count as billable output, even when they are not visible in the response.

summary

Claude Fable 5.1 and Claude Sonnet 5 are available through the Impossibl API. they share the /v1/chat/completions endpoint; the model identifier selects the model for a request.

Claude Fable 5.1 is created by Anthropic. It has a 1,000,000-token context window. Base API pricing (USD): $10.00 per million input tokens; $50.00 per million output tokens.

Claude Sonnet 5 is created by Anthropic. It has a 1,000,000-token context window. Base API pricing (USD): $2.00 per million input tokens; $10.00 per million output tokens.

Claude Fable 5.1 →Claude Sonnet 5 →

this page compares Claude Fable 5.1 vs Claude Sonnet 5 as listed by the impossibl public api. prices and availability come from that catalog, refreshed here every five minutes. this is an impossibl offering, not a comparison of independent hosting-provider quotes.

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