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Models · gpt-4

GPT-4.5

Proprietary OpenAI · 2025-02-27 · Proprietary

Released February 27, 2025 as a research preview of OpenAI's largest pretrained chat model, internally referred to as Orion. Sam Altman characterized it as a giant, expensive model; pricing came in at $75 input and $150 output per million tokens, roughly 30x GPT-4o's input rate at launch.

Cost

$0.00 / Mtok input
$0.00 / Mtok output

OpenAI API · as of 2026-05-21

source ↗

Speed

0 tok/sec output
0 ms TTFT

· as of 2026-05-21

source ↗

Architecture

tokens in Embedding vocab not disclosed × N layers Architecture not disclosed (proprietary or undocumented) Output projection tokens out
Schema-generated from data/models.yaml. Every label is auditable against the model's sources.

Specs

Architecture
unknown
Total params
not disclosed
Active params
not disclosed
Context window
128K tokens
Attention
unknown
Position encoding
unknown
Post-training
rlhf
OSI-approved
no
Data released
no
Training code
not released

Available quantizations

None. The weights are not distributed, so there are no public quantizations.

Notable innovations

  • · Largest publicly accessible OpenAI non-reasoning model at release
  • · Multilingual MMLU coverage across 15 languages

Sources