Claude Sonnet 5.5 vs GPT-4o

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 Sonnet 5.5

anthropic/claude-sonnet-5-5

GPT-4o

openai/gpt-4o

input · usd / 1m tok$2.00$2.50
output · usd / 1m tok$10.00$10.00
context window1mtokens128ktokens
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 Sonnet 5.5

anthropic/claude-sonnet-5-5

GPT-4o

openai/gpt-4o

input$2.00$2.50
output$10.00$10.00
cache read$0.20$1.25
cache write · default ttl$2.50not published
cache write · 1h ttl$4.00not published

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

specifications

published specifications by model
as publishedClaude Sonnet 5.5

anthropic/claude-sonnet-5-5

GPT-4o

openai/gpt-4o

creatorAnthropicOpenAI
model typeText generationText generation
context window1,000,000tokens128,000tokens
input

takes text and image in, gives text out

takes text and image in, gives text out

outputtexttext
tool callingnot verifiednot verified
releasedsep 28, 2026may 13, 2024
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 Sonnet 5.5

anthropic/claude-sonnet-5-5

GPT-4o

openai/gpt-4o

nov '24

intelligence index · gateway rank56.0#2 of 1058.4#98 of 105
omnisciencenot measured-10.5#50 of 81
gpqanot measured54.3%#74 of 79
humanity’s last examnot measured2.4%#84 of 84
aa-lcrnot measured49.3%
ifbenchnot measured34.3%
livecodebenchnot measured30.9%
tau2not measured25.1%
terminal-bench hardnot measured8.3%
aime 2025not measured6.0%
critptnot measured0.0%

Claude Sonnet 5.5 source ↗GPT-4o 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 Sonnet 5.5

anthropic/claude-sonnet-5-5

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.

GPT-4o

openai/gpt-4o

estimated usage cost

$7.50

1,000 requests × (1,000 uncached input × $2.50 + 500 output × $10.00) / 1,000,000 = $7.50

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 Sonnet 5.5 and GPT-4o are available through the Impossibl API. they share the /v1/chat/completions endpoint; the model identifier selects the model for a request.

Claude Sonnet 5.5 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.

GPT-4o is created by OpenAI. It has a 128,000-token context window. Base API pricing (USD): $2.50 per million input tokens; $10.00 per million output tokens.

Claude Sonnet 5.5 →GPT-4o →

this page compares Claude Sonnet 5.5 vs GPT-4o 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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