OpenAI's New 4.1 Series - Read This Before You Try It

The Complete Guide to ChatGPT Models in 2025

May 16, 2025

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ChatGPT's Model Lineup Gets a Major Upgrade

OpenAI has just launched two powerful new models that are reshaping how we use AI assistants. GPT-4.1 and GPT-4.1 Mini hit the market in April-May 2025, bringing significant improvements in reasoning, context handling, and speed.

If you're feeling overwhelmed by all the different ChatGPT models available now, you're not alone. Most people are overwhelmed with how many models are available and don't actually know when to use them.

This guide will help you navigate the new landscape, understand which models have been replaced, and know exactly which ChatGPT model to use for different tasks.

In addition, for businesses already implementing different AI models in their organization, I’ve prepared a special checklist for you!

At the bottom of this post you will find a step-by-step checklist that will help you asses your current use of GPT models and which adjustments you have to make.

Let’s dive in.

The 4.1 Series Revolution

GPT-4.1: The New Flagship

Released on April 14, 2025 (was available via AI but rolled out to ChatGPT earlier this week), GPT-4.1 is OpenAI's most advanced general-purpose AI model available to ChatGPT Plus, Pro, and Team subscribers (sorry, this one isn’t FREE…yet).

The standout feature is its massive 1-million token context window – allowing it to process approximately 750,000 words of text at once.

GPT-4.1 is going to be amazing for anything that is very logic-based.

Think about coding or any type of analysis. This model excels at technical reasoning tasks and can handle extremely complex problems, including multi-step coding challenges and detailed document analysis.

GPT-4.1 Mini: The New Default

Launched on May 15, 2025, GPT-4.1 Mini is now the default model for free ChatGPT users and serves as a fallback for paid tiers. This model replaces GPT-4o Mini and is incredibly fast for everyday tasks.

The Mini variant delivers near GPT-4o quality performance but at GPT-3.5 pricing and speed (that’s 83% cheaper than 4o mini), making it an exceptional value proposition for both casual and professional users.

The O-Series: OpenAI's Reasoning-Focused Models

In addition to the 4.1 series, OpenAI has been developing specialized "o-series" models optimized for deeper reasoning:

OpenAI o3

Released April 16, 2025, this model is available as a "High reasoning" toggle for Plus, Pro and Team users. O3 excels at deep chain-of-thought reasoning, particularly for mathematical and data science applications.

O3 is incredible. It was my main go-to model for brainstorming and strategy sessions.

In fact, it might be one of the most powerful models because this is the thinking model. If you need to plan something out, if you want to go back and forth and you don't want to give it very clear instructions on exactly what to do, this is the model you should use!

OpenAI o4-mini

Also released on April 16, 2025, this model offers a "Fast reasoning" toggle for Plus and Pro customers. It's designed for cost-efficiency and high throughput while outperforming GPT-3.5 Turbo on most benchmarks.

What Got Replaced?

The introduction of these new models has led to a significant reorganization of ChatGPT's lineup:

GPT-4.1 Mini has replaced GPT-4o Mini, which has been retired from the model picker (though it's still temporarily available for older chats)
GPT-4.1 has supplanted GPT-4 Turbo as the "best" option in ChatGPT (Turbo remains in the API but is no longer the flagship)
O4-mini has replaced o3-mini (2024), though the latter is kept for backward compatibility but hidden by default
The entire GPT-4-series has replaced GPT-4 (legacy March 2023), which was fully deprecated in both the web app and API in January 2025

GPT-4o Mini and GPT-4o Mini High are quite frankly useless now that you have 4.1, because 4.1 and 4.1 mini are going to completely replace these things and they just do a better job.

The Complete ChatGPT Model Ranking Guide

Here's a comprehensive ranking of all current ChatGPT models across key use cases.

First, let’s look at Huggingface comparison table and see what’s changed:

To make it more interesting I also asked the different AI models (Gemini, Claude, Perplexity…and ChatGPT to rank the new models and how they function in various tasks.

Rankings are on a scale of 1-10, with 10 being the highest performance.

Here are the answers:

ChatGPT’s rankings (using o3):

Claude’s rankings (3.7 Sonnet)

Perplexity AI rankings:

Gemini 2.5 Pro rankings:

Considerations for the ranking:

Brainstorming: Involves creativity, idea generation, and flexibility.
Coding: Focuses on accuracy, understanding complex logic, and generating functional code.
Content Creation: Involves writing quality, coherence, style adaptation, and creativity.
Research: Involves accessing, synthesizing, and summarizing information.
Logic & Reasoning: For heavy math problems and complex strategies.
Human-like Conversations: Measures the naturalness, empathy ("EQ"), and flow of dialogue.

When to Use Each Model

GPT-4.1: The Logic Powerhouse

Best for: Complex coding projects, technical analysis, massive document processing
Key strength: The 1-million token context allows it to process entire codebases or lengthy documents
Special note: You need to be hyper-literal with GPT-4.1. It's way more precise than older versions, so you need to say exactly what you want.

GPT-4.1 Mini: The Everyday Assistant

Best for: Daily AI tasks where you need good quality without premium costs
Key strength: Near-GPT-4o quality at GPT-3.5 pricing and speed
Special note: While it's missing the Canvas feature available in GPT-4.1, it retains all other tools

OpenAI o3: The Deep Thinker

Best for: Advanced planning, complex problem-solving, data science
Key strength: Exceptional reasoning capabilities that work through problems step-by-step
Special note: O3 is amazing for planning. You can upload different searches, CSV files, PDFs, and various data. You can provide all the information for your business or life and get it to actually do the planning phase.

GPT-4.5: The Creative Director

Best for: Writing and creative ideation
Key strength: Most human-like writing style with high creativity
Special note: GPT-4.5 has the creativity turned up on it. It's going to be good at writing, but you might find that it hallucinates a little bit more than other models.
Future status: Currently in research preview and planned to sunset July 14, 2025, as GPT-4.1 can now achieve similar quality at lower cost

How to Get the Most from GPT-4.1

The new GPT-4.1 models require a different approach to prompting. You have to completely change how you're actually prompting these things. Here's how to maximize your results:

13 Essential GPT-4.1 Prompting Tips

Be hyper-literal: GPT-4.1 is way more precise than older versions. Say exactly what you want.
Repeat key instructions: For long requests, put important instructions at both the beginning and end.
Use clear separators: Use markdown headers or XML tags. Avoid formats like JSON for long text as it breaks.
Activate thinking mode: If you don't tell it to think step by step, it won't do that. This simple instruction boosts accuracy dramatically.
Enable agent mode: This is "beast mode" for GPT-4.1. Give reminders like "don't stop until the task is 100% done," "use tools," "don't guess," and "plan every step before action."
Respect the context window: The context window is 1 million tokens. Try to use the whole thing, but if you go past it, quality drops.
Be clear about knowledge sources: Mix base knowledge with custom context or tell it to use only one.
Structure your prompts: Give the role, goal, instructions, reasoning steps, output format, and examples for better responses.
Guide information finding: Tell it to scan documents and filter for relevant parts before taking action.
Avoid confusing patterns: This model is hyper-intelligent but needs clear direction – like a brilliant professor who might struggle with simple tasks.
Correct efficiently: When giving corrections, use one clean line with clear fixes.
Use code frameworks: Provide clear structures for coding tasks.
Trigger logic mode: GPT-4.1 is not automatically a logic machine. It excels at logic but won't use that superpower unless you tell it to.

Prompt Example - Comprehensive study on strategic innovation in 2025

ROLE: You are a senior innovation analyst.
GOAL: Deliver a 2 000-word, citation-backed study on corporate and startup innovation strategies used between 1 Jan 2025 and TODAY.
SOURCES: Only 2025 material from reputable business/tech outlets, peer-review papers, or official company releases; cite inline (Harvard style).
MANDATORY SECTIONS: Executive Summary (150 w), Methodology, Strategy Themes, Case Studies, Risks, C-suite Recommendations, Conclusion, References.
RULES: Think step-by-step, be precise, no guesses. State “data unavailable” if needed. Keep each paragraph ≤ 120 words.
OUTPUT: Start with “EXECUTIVE SUMMARY” and follow the section order above.

How Businesses Should Adapt

The recent launch of GPT-4.1 and GPT-4.1 Mini doesn't just give businesses new AI toys, it fundamentally changes the enterprise AI landscape.

For companies already implementing AI, these updates require strategic pivots to maintain competitive advantage and maximize ROI on AI investments.

Immediate Actions for Business Leaders

1. Audit Your Current AI Implementation

Model Usage Assessment

Identify all instances where GPT-4o Mini or legacy GPT-4 models are being used
Document which departments/teams are using which models
Catalog current API integration points and usage volumes
Review automation workflows built on potentially deprecated models
Assess current monthly spend on different OpenAI models

Use Case Mapping

Map current AI use cases to the new model capabilities
Identify high-value applications that could benefit from GPT-4.1's 1M token context
Flag resource-intensive tasks that could be handled by GPT-4.1 Mini instead of premium models
Identify planning and strategic applications suited for o3's reasoning capabilities
Document cases where human-like conversation (4o) vs. logic-driven responses (4.1) are more appropriate

Technical Integration

Check if current API implementation requires updates
Verify that prompts follow the new GPT-4.1 best practices
Identify breaking changes in model responses that might affect downstream systems
Review token usage efficiency across applications

Cost & Performance

Benchmark current AI task completion times
Calculate current cost-per-task across different operations
Project potential cost savings from model substitution
Identify high-compute tasks that could benefit from more efficient model routing

First, understand what you're working with.

Most businesses need to perform a comprehensive audit of their AI implementations to identify which models are currently in use and where they should migrate. Use the audit checklist I've created to guide this process.

2. Revise Your Enterprise Prompt Strategy

The new GPT-4.1 models require a fundamentally different prompting approach. Businesses that don't update their prompts will see diminished performance despite paying for better models.

Action required: Train your AI teams on the new hyper-literal prompting paradigm
Key change: Implement prompt templates that include explicit thinking instructions, agent mode activation, and clear structural elements
Quick win: Add "Think step by step" to your existing prompts for an immediate performance boost

Choosing the Right Model for Your Needs

To sum things up, the new ChatGPT model lineup gives users unprecedented options for different AI tasks:

GPT-4.1 for complex coding and technical analysis (when you can provide very specific instructions)
GPT-4.1 Mini for everyday tasks with excellent speed-to-quality ratio
OpenAI o3 for planning and step-by-step reasoning
GPT-4.5 for creative writing and ideation (while it's still available)
GPT-4o for natural-sounding conversations

By understanding the strengths of each model and applying the right prompting techniques, you can dramatically improve your AI productivity in 2025 and beyond.

The key is not just choosing the right model, but knowing how to communicate with it effectively.

As AI capabilities continue to evolve at breakneck speed, staying updated on these changes will give you a significant advantage in leveraging ChatGPT's full potential for your personal and professional needs.