GPT-5.5

GPT-5.5 is an OpenAI flagship model for the most complex professional work, positioned as a new class of intelligence for coding and knowledge work.

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input · usd / 1m tok

$5.00

output · usd / 1m tok

$30.00

context window

1.05mtokens

modalities · in → out

pricing

base api ratesusd per 1m tokens

input: $5.00over 272k · $10.00
output: $30.00over 272k · $45.00
cache read: $0.50over 272k · $1.00

brackets are by input tokens per request: a request over a threshold is billed at that bracket's rates for all of its tokens. cache creation can have a separate charge.

providers

Different companies host GPT-5.5. Impossibl routes your request intelligently and handles failover automatically when a provider is down.

Azure OpenAI
OpenAI

specifications

takes text and image in, gives text outopenai/gpt-5.5

creatorOpenAI
model typeText generation
context window1,050,000 tokens
maximum outputnot published
input
takes text and image in, gives text out
outputtext
tool callingnot verified
releasedapr 23, 2026
endpoint/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.

try it · your prompt, this model, live

# responses API
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["IMPOSSIBL_API_KEY"],
    base_url="https://api.impossibl.com/v1",
)

resp = client.responses.create(
    model="openai/gpt-5.5",
    input="▌",
)
print(resp.output_text)

edit the prompt, then run

# responses API
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["IMPOSSIBL_API_KEY"],
    base_url="https://api.impossibl.com/v1",
)

resp = client.responses.create(
    model="openai/gpt-5.5",
    input="▌",
)
print(resp.output_text)

edit the prompt, then run

benchmarks

intelligence index

38.4#32 of 108 models on the gateway

coding index74.9#13 of 64
agentic index36.4#26 of 53
omniscience20.5#15 of 84
gpqa93.5%#5 of 80
humanity’s last exam45.8%#12 of 87

Tau293.9%
GPQA93.5%
AA-LCR84.3%
MMMU-Pro79.9%
IFBench75.9%
Terminal-Bench Hard60.6%
SciCode55.8%
AnalystAgent50.0%
AutomationBench Partial47.3%
ITBench45.8%
Humanity’s Last Exam45.8%
Tau Banking39.0%
APEX-Agents37.7%
CritPt27.1%
GDP.pdf All-pass21.2%
Multilingual LCR17.8%

Intelligence Index38.36
Omniscience Index20.52
GDPval Elo1350.06
legal index (API)44.7
coding index (API)74.9
agentic index (API)36.4
economics index (API)47.8
engineering index (API)39.9
intelligence index (API)38.4
strategy and ops index (API)45.2
finance and accounting index (API)41.5
healthcare and medical index (API)38.5

view source ↗all source data and breakdowns (json) ↗

each configuration is listed separately; these evaluations describe the tested model configuration, and performance and costs can differ on impossibl. unmeasured scores are omitted and api values keep their source units. last checked 2026-10-14.

compare GPT-5.5 with other models

frontier labs and open weights, best-ranked firstusd / 1m tok · in / out

anthropic/claude-opus-5-5$4.00 / $20.00compare →
google/gemini-4-argon$2.00 / $10.00compare →
meta/muse-wonder$4.00 / $20.00compare →
xiaomi/mimo-v2.6-pro$0.435 / $0.87compare →

impossibl models --all →

frequently asked questions

What is GPT-5.5?

GPT-5.5 is an OpenAI flagship model for the most complex professional work, positioned as a new class of intelligence for coding and knowledge work. It builds on GPT-5.4 with stronger reasoning, higher reliability, and better token efficiency on hard tasks, with text and image input and tool use.

How much does GPT-5.5 cost?

GPT-5.5 costs $5.00 per million input tokens and $30.00 per million output tokens through the Impossibl API. Cache reads cost $0.50 per million tokens. These base rates apply through 272,000 total input tokens per request. Above 272,000 input tokens, the long-context rates in the pricing table apply to the whole request. All rates are in USD.

view the pricing table ↑

What is the context length of GPT-5.5?

GPT-5.5 has a 1,050,000-token context window through the Impossibl API.

What inputs and outputs does GPT-5.5 support?

GPT-5.5 accepts text and image as input. GPT-5.5 returns text.

How do I use GPT-5.5 through an API?

GPT-5.5 is available through the Impossibl API. Use openai/gpt-5.5 as the model identifier with /v1/chat/completions. The quickstart explains how to create an API key and send your first request.

follow the api quickstart →

When was GPT-5.5 released?

OpenAI released GPT-5.5 on April 23, 2026.

Creator release announcement ↗

this page describes GPT-5.5 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. model descriptions and release dates, where available, use the creator sources linked under the answers above.

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