OpenAI GPT-4.5 vs. GPT Models: Which One Should You Use?

Key Takeaways

OpenAI’s GPT-4.5, released in February 2025, represents a refinement of its predecessors, focusing on conversational fluency, emotional intelligence, and factual accuracy. However, it is not optimized for step-by-step reasoning or logic-heavy tasks, which remain the strengths of OpenAI’s o-series models. Choosing between GPT-4.5 and other GPT models depends on specific use cases, budget constraints, and performance requirements.

Understanding GPT-4.5: A General-Purpose Model

GPT-4.5 was introduced on February 27, 2025, as part of OpenAI’s research preview phase. Unlike reasoning-focused models such as o1 or o3-mini, GPT-4.5 prioritizes natural interactions and pattern recognition over structured problem-solving^1,2. It is designed to feel more humanlike in conversations, with OpenAI CEO Sam Altman describing it as “the first model that feels like talking to a thoughtful person”¹.

Training and Development

GPT-4.5 builds upon the foundation of GPT-4o with expanded pretraining datasets and advanced techniques such as supervised fine-tuning (SFT) and reinforcement learning from human feedback (RLHF)^1,3. These methods enhance its conversational abilities while reducing exposure to harmful content during training¹.

Key Strengths of GPT-4.5

Conversational Fluency and Emotional Intelligence

GPT-4.5 excels in natural language processing and emotional intelligence. It adapts its tone based on user input, making interactions feel intuitive and engaging^1,4. For example:

• It recognizes emotional cues in text and adjusts its responses accordingly.

• It delivers concise yet comprehensive answers to queries, improving overall user experience³.

Human evaluations show that GPT-4.5 is preferred over GPT-4o for professional and casual conversations due to its clarity and tone³.

Improved Factual Accuracy

GPT-4.5 demonstrates significant improvements in factual accuracy compared to earlier models. Benchmarks reveal that it achieves a 62.5% accuracy rate on SimpleQA tasks, outperforming GPT-4o (38.2%) and other o-series models³. However, it still produces hallucinations at a rate of 37.1%, which is lower than GPT-4o’s 61.8% but far from perfect³.

Multilingual Proficiency

The model performs exceptionally well across 14 languages, including Arabic, Chinese, French, Hindi, Japanese, and Spanish^1,3. This makes GPT-4.5 a valuable tool for global applications requiring multilingual support.

Content Creation and Summarization

GPT-4.5 is adept at generating creative content and summarizing large volumes of information with clarity^1,3. These capabilities make it ideal for tasks such as:

• Writing articles or stories

• Summarizing research papers or documents

• Assisting with professional communication

Limitations of GPT-4.5

Reasoning Capabilities

Unlike the o-series models (e.g., o1 or o3-mini), GPT-4.5 does not excel in chain-of-thought (CoT) reasoning tasks that require step-by-step logic or detailed problem-solving^2,3. For instance:

• It struggles with advanced math problems or scientific reasoning.

• It relies on intuition rather than structured logic for generating responses.

This limitation makes it less suitable for applications requiring rigorous logical analysis or complex programming assistance².

Hallucination Rates

While GPT-4.5 reduces hallucinations compared to earlier models like GPT-4o, its hallucination rate remains significant at 37.1%³. OpenAI has also stopped reporting hallucination metrics for open-ended queries, raising concerns about reliability in real-world scenarios².

Cost Considerations

GPT-4.5 is significantly more expensive than other models in OpenAI’s lineup:

• Input cost: $75 per million tokens

• Output cost: $150 per million tokens
  In contrast, GPT-4o costs $2.50 per million input tokens and $10 per million output tokens^1,3. This high cost may deter smaller organizations or individual developers from adopting GPT-4.5.

Comparing GPT Models: When to Choose Each

Feature	GPT-4o	GPT-4.5
Release Date	May 13, 2024	February 27, 2025
Primary Focus	Multimodal integration	Conversational fluency
Reasoning Ability	Strong	Moderate
Factual Accuracy	Moderate	High
Hallucination Rate	61.8%	37.1%
Cost (per million tokens)	$2.50 input / $10 output	$75 input / $150 output

Use Cases for GPT Models

When to Choose GPT-4.5

GPT-4.5 is ideal for applications that prioritize conversational fluency, emotional intelligence, and factual accuracy:

• Customer service chatbots requiring nuanced interactions

• Content creation for blogs or marketing materials

• Multilingual support in global applications

• Summarization of complex documents

• When to Choose Other Models

For tasks requiring detailed reasoning or cost-effective solutions:

1. GPT-o Series (e.g., o1, o3-mini):

• Complex problem-solving in math or science

• Logical reasoning tasks requiring step-by-step explanations

• Applications where cost efficiency is critical

2. GPT-4o:

• General-purpose tasks with moderate accuracy needs

• Multimodal capabilities (e.g., text-to-image integration)

Conclusion

GPT-4.5 represents a significant advancement in OpenAI’s model lineup by improving conversational fluency and factual accuracy while maintaining versatility across diverse applications. However, its limitations in logical reasoning and high computational costs highlight the importance of matching the model to specific use cases.

For users seeking a general-purpose AI with enhanced conversational abilities, GPT-4.5 is an excellent choice despite its cost premium. On the other hand, users requiring advanced reasoning capabilities or budget-friendly options may find better value in the o-series models or earlier iterations like GPT-4o.

By understanding these distinctions, developers can make informed decisions about which model best suits their needs.

Citations:

1. “GPT‑4.5 Explained: Everything You Need to Know.” TechTarget, 04 Mar. 2025.

2. Wood, Michael. “GPT‑4.5 Train Wreck: OpenAI Fails to Solve Hallucinations… Again.” LinkedIn, 28 Feb. 2025.

3. ” ChatGPT 4.5: Features, Access, GPT-4o Comparison, and More”, DataCamp Blog, 27 Feb. 2025.

4. Mahale, Niyati  ” GPT-4.5 vs GPT-4o: Testing The AI Models Using Seven Prompts,” WriteSonic Blog, 03 Mar. 2025.