GPT-4.5

GPT-4.5

Quick answer: GPT-4.5 (API: gpt-4-5-preview) is OpenAI's February 2025 large-scale GPT-4 model, scoring 88% on HumanEval and 5.44% on Humanity's Last Exam. It was OpenAI's largest dense model at launch, trained with a focus on world knowledge and emotional intelligence. Priced at $75 input / $150 output per 1M tokens — extremely expensive relative to performance; most workloads are better served by GPT-4.1 or GPT-5.x.

At a Glance

Where GPT-4.5 leads

• 88.0% HumanEval — strong function-level coding completion
• OpenAI's largest dense model at launch — designed for breadth of world knowledge
• Strong conversational naturalness and emotional intelligence
• 128K-token context window with vision support

Where it lags

• $75/$150 per 1M tokens — among the most expensive models ever offered by OpenAI
• 5.44% Humanity's Last Exam — below o3 (20.32%) and Gemini 2.5 Pro (21.64%)
• SHADE-Arena 0.0 — low agentic sabotage-detection (expected for safe model, but indicates limited agentic reasoning)
• Superseded by GPT-5 and GPT-5.6 for nearly every use case
• No reasoning/chain-of-thought mode

Best for: Research contexts requiring GPT-4.5-specific outputs; teams that require the specific model version for reproducibility.

What GPT-4.5 Is

GPT-4.5 (gpt-4-5-preview) was OpenAI's last major GPT-4-series model before the GPT-5 launch. Released February 27, 2025, it was OpenAI's largest dense language model — trained at greater scale than GPT-4o with an emphasis on world knowledge depth and more natural, human-like conversation rather than raw reasoning scores.

OpenAI positioned GPT-4.5 as a research preview of large-scale dense training, in contrast to the o-series reasoning models and later GPT-5. Its pricing ($75/$150 per 1M) reflected its experimental and large-scale nature rather than production economics — at that price, almost every workload is more cost-effectively served by GPT-4o, GPT-4.1, or a GPT-5 family model.

For teams not explicitly requiring the gpt-4-5-preview model ID, there is no practical reason to use GPT-4.5 over GPT-5 mini or GPT-4.1, both of which offer better benchmark performance at a fraction of the cost.

Specifications

Pricing

Pricing per OpenAI pricing page. This is one of the highest per-token rates OpenAI has offered — verify current pricing and consider GPT-4.1 ($2/$8) or GPT-5 mini as alternatives.

Context Window

GPT-4.5 has a 128,000-token context window — roughly 90 pages of text in a single request.

Public Benchmark Scores

GPT-4.5 vs Alternatives

GPT-4.5's HumanEval score (88%) is competitive, but GPT-4.1 achieves a similar HLE score at $2/$8 — a 97% cost saving. For almost all production use cases, migrating away from GPT-4.5 is strongly recommended.

Related Models & Benchmarks

• Compare: GPT-4.1 · GPT-4o · GPT-5 mini
• Benchmarks: HumanEval · Humanity's Last Exam

Frequently Asked Questions

Specs and scores sourced from OpenAI's official GPT-4.5 announcement (February 2025) and Benchgen evaluations. Pricing cited to the OpenAI pricing page. Last updated 2026-07-24.