Which ChatGPT model should you be using?

ChatGPT is an incredibly powerful tool when used right - but it can also be frustrating when it’s not doing what you want it to do (like hallucinating, or over-simplifying).

If you are looking to use ChatGPT for anything more than the most basic applications, the paid version might be a good option - for $20 a month, you can upgrade to higher usage limits and are given the choice of which model to use. But what does that mean? And how do you choose?

I’ll break it all down here today.

(Note that if you are on the free tier, you will be defaulted to using Model GPT-4o, and there will be usage limits imposed - if you’ve never come up across the usage limits, and don’t use it for anything complex, you likely don’t need to worry about this info).

Let’s clarify some terms:

If you’re using a paid version of ChatGPT and look at the top left side of your screen, you’ll see a little drop-down called “models.” But what is it? And which one should you be using?

Some key definitions:

• Model: In ChatGPT, a model is the underlying AI system—a large neural network trained on vast amounts of text—that predicts the next words in a conversation. (For a recap of LLMs, check out this post here). Each named model (e.g., GPT‑3.5, GPT‑4o) is a specific version of that system with its own training data, size, and capabilities, which determines how well it understands prompts, reasons through problems, and generates responses. That means they are specialized for specific use cases - and you’ll get better results by using the right one for the job.

• Cost: ChatGPT usage on a standard $20/month paid plan is set up a bit like a phone plan. The more “expensive” models (i.e. the ones that use more “tokens” and have higher complexity of processing) will hit your messaging limits much faster than the “cheaper” ones. Basically - don’t use a more complex model than you need for a given task, and you probably won’t have to worry about running into any limits.

• Context Window: A context window is simply the amount of recent “memory” the model can keep in view. Pick the smallest board that still fits your task; upgrade to a larger one only when you’re squeezing big documents or very long chats into a single session. A bigger context window is important if you’re doing multi-step problem-solving and don’t want to re-explain earlier steps to ChatGPT.

• Hallucination: When an LLM doesn’t know and answer to a question but confidently answers it anyway, giving you misinformation. More common in some models than others.

Each model is trained a little differently with a different task in mind - so here’s your quick guide to picking a model based on your task:

Model: GPT-4o (aka “omni”)

What it’s best at:

• Fastest high-end model

• Strong reasoning and creativity

• Handles text and images natively (to describe, analyze, generalize)

What to use it for:

• Everyday conversations where you want quick, detailed answers 

• Image‑based questions (“What’s in this photo?” “Turn this sketch into marketing copy.”) 

• Brainstorming, code help, summarizing long docs. 

Prompt tip: be direct; you usually don’t need elaborate chains‑of‑thought.

Drawbacks: A bit more expensive than GPT-3.5

Model: GPT-4 (and GPT-4 Turbo)

What it’s best at:  

• Top-tier reasoning and depth

• Large context window

What to use it for:

• Long, nuanced tasks - like large and technical analysis, multi-step code, large document Q&A

• When you care more about accuracy than speed

Prompt tip: break big jobs into explicit steps so the model can plan before writing.

Drawbacks: Slower and costlier than GPT-4o, no native image input (text only)

Model: GPT-3.5

What it’s best at:

• Very fast and inexpensive responses

• Solid everyday language ability

What to use it for:

• Casual chats

• Quick drafts

• Simple code snippets 

• High-volume workflows

Prompt tip: Shorter prompts can work reasonably well, but for any sort of deeper research you might need to be more specific.

Drawbacks: Weaker on complex logic, more hallucinations, smaller context window.

Model: o3

What it’s best at:

• Specialized for step‑by‑step reasoning before answering  

• Good at explaining thought processes clearly

What to use it for: 

• Teaching 

• troubleshooting 

• “think it through” problems 

• detailed decision making

Prompt tip: Ask for structured breakdowns (“walk me through” or “explain step-by-step”) - this will be the best use of its complex reasoning style.

Drawbacks: Relatively slow, expensive

Model: DALL E 3 - image generator

What it does: 

• Turns text descriptions into images or edits existing images

What to use it for:

• Concept art

• Social posts

• Marketing visuals

• Storyboards

Prompt tips: describe the subject, style, lighting, and mood in separate clauses for best control.

Drawbacks: Purely visual—no long‑form text output; each generation costs credits

Cheat Sheet: How to choose quickly

• Need speed & visuals? → GPT‑4o
  

• Need maximum depth or 100‑page analysis? → GPT‑4 Turbo
  

• Need cheap, decent drafts at scale? → GPT‑3.5
  

• Need meticulous reasoning with transparency? → o3‑powered chats
  

• Need images? → DALL·E 3
  

And if you find yourself running up against usage limits, try the following workflow:

1. Draft or explore in GPT‑3.5 or 4o mini (unlimited).

2. Upgrade to GPT‑4o or 4 Turbo only for the specific prompts that need deeper reasoning, vision, or giant context.

And there you have it! A quick breakdown of the models, how/when to use them, and how best to structure your workflows.

Hopefully this helps you get a bit more out of ChatGPT. Have you experimented with any of these?