GPT-5.5 Pro
OpenAI · released 23 Apr 2026 · proprietary API
- Largest context window (8-way tie)
The extra-compute tier of GPT-5.5: it spends more tokens thinking before answering, and OpenAI warns a request may take several minutes and should use background mode.
Context window
1.05M
1,050,000 tokens
Input price
$30
per 1M tokens
Output price
$180
per 1M tokens
Blended
$67.50
3:1 in:out mix
Weights
Proprietary
API only
Released
23 Apr 2026
OpenAI
Long-context / tier pricing — Responses and Batch APIs only; reasoning effort medium/high/xhigh. OpenAI publishes no cached-input rate for this model. Listed prices are the base rate for prompts up to ~200K tokens.
Where it ranks
Of 40 models tracked.
Cost to run
#40
of 40
Input price
#40
of 40
Context window
#1(tied)
of 40
Compare with
The nearest models by blended cost to run.
Put it to work
Specs from BitByteCore's hand-verified Frontier Ledger (v2026-09-23), this row verified 22 Sep 2026 against OpenAI's official pricing ↗. Model pricing moves fast, so confirm with OpenAI before you rely on a figure.