OpenAI Models

OpenAI maintains a variety of foundational AI models that power its ChatGPT product, the OpenAI API, and other tools. These models serve different purposes — some are optimized for reasoning, others for speed, some for multimodal tasks (handling images, audio), and others for long context. Below are some of the major model families and what they’re used for.

GPT-4.1 Series

GPT-4.1 is a powerful model optimized for instruction-following and coding. According to OpenAI’s release notes, it supports up to 1 million tokens of context, making it great for long documents and complex, multi-step tasks.

There are smaller variants like GPT-4.1 mini and GPT-4.1 nano that trade off some capacity for lower latency and cost, but retain high performance on coding and reasoning.

GPT-4o (“o” means Omni)

GPT-4o is OpenAI’s multimodal “omni” model: it accepts text, images, audio, and video inputs, and can output multiple modalities too.

This model is becoming OpenAI’s default in ChatGPT (as of April 2025, GPT-4 is being retired in ChatGPT in favor of GPT-4o).

There are also reasoning-specific “o-series” variants like o3 and o4-mini, which are designed for tasks such as deep research, math, science, or coding, with lower cost or faster inference.

GPT-4.5 (Research Preview)

OpenAI has released a research preview of GPT-4.5. According to their model release notes, it improves in “EQ,” reasoning, and pattern recognition.

This model is not yet fully production-stable, but available in certain paid plans.

✅ Key Strengths of These Models

Multimodal Reasoning: With GPT-4o, you can feed in images, audio, and text — great for complex use cases.

Long Context Handling: GPT-4.1 supports very long-context inputs, useful for large documents, codebases, or multi-turn tasks.

Cost/Performance Trade-offs: Smaller variants (mini/nano) let you optimize for speed or cost without losing too much power.

Newer Research-Grade Models: GPT-4.5 is pushing improvements in creativity, understanding, and “EQ”-style reasoning.

⚠️ Things to Consider / Limitations

Advanced models like GPT-4.1 and GPT-4.5 may be more expensive per token than smaller or older models.

Using multimodal input (e.g., images + text) requires appropriate prompt design — not all tasks will benefit from their full capacity.

The “o-series” (like o3, o4-mini) are great for reasoning, but may be less capable on highly creative or very large generation tasks compared to bigger models.

Research preview models (like GPT-4.5) may have evolving behavior and may not be as stable.

🎯 Recommendation: When to Use Which Model

Use GPT-4o if you need multimodal capabilities (images, audio) or want a “one model to rule them all” experience.

Use GPT-4.1 (or its mini/nano variants) if you’re building tools that require deep understanding, long context, or precise code generation.

Try GPT-4.5 (preview) if you’re experimenting, need better pattern recognition or creativity, and don’t mind early-stage behavior.