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GPT-5.5

OpenAI · released 23 Apr 2026 · proprietary API

Superseded as OpenAI's flagship by GPT-6 Astra on 2026-09-05; first OpenAI model with a 1M-token API context window.

Context window

1.05M

1,050,000 tokens

Input price

$5

per 1M tokens

Output price

$30

per 1M tokens

Blended

$11.25

3:1 in:out mix

Weights

Proprietary

API only

Released

23 Apr 2026

OpenAI

Long-context / tier pricing — >272K input billed 2x input / 1.5x output. Listed prices are the base rate for prompts up to ~200K tokens.

Where it ranks

Of 40 models tracked.

Cost to run

#36

of 40

Input price

#34(tied)

of 40

Context window

#1(tied)

of 40

See the full Frontier Index →

Compare with

The nearest models by blended cost to run.

Put it to work

Specs from BitByteCore's hand-verified Frontier Ledger (v2026-09-26), this row verified 5 Sep 2026 against OpenAI's official pricing ↗. Model pricing moves fast, so confirm with OpenAI before you rely on a figure.