But there’s a lot more to unpack—including how much better it is than GPT-4.5, what it costs, and the not-so-great and great news for ChatGPT users.
What Is GPT-4.1?
GPT-4.1 is OpenAI’s latest series of models, available only via the API. It includes:
- GPT-4.1
- GPT-4.1 Mini
- GPT-4.1 Nano
Each version is designed for different use cases—from high-performance tasks to lightweight, real-time applications.
A Context Window So Big It Changes Everything
What is a 1M context window?
With a 1 million token context window, GPT-4.1 can handle:
- Entire books
- Large codebases
- Long conversations
- Legal and financial documents
- Multi-hour transcripts
For perspective, GPT-4 (the ChatGPT version) maxes out at 128k tokens. This upgrade is nearly 8x larger, and miles ahead of what GPT-4.5 could do.
How Much Better Is GPT-4.1 Compared to GPT-4.5?
Instruction Following
- GPT-4.1 is 10.5% better at following instructions than GPT-4o.
- Compared to GPT-4.5, it’s noticeably more accurate, especially in multi-step reasoning and user alignment.
Coding Abilities
- 21% better than GPT-4o at solving code problems
- 27% better than GPT-4.5 in coding evaluations
- Works better with long, complex code thanks to the extended context
Speed & Cost
- Faster than GPT-4.5, making it more viable for real-time apps
- Cheaper to run—with pricing as low as:
- $2 / 1M input tokens (GPT-4.1)
- $0.40 / 1M input tokens (Mini)
- $0.10 / 1M input tokens (Nano)
GPT-4.1 also supports token caching, bringing costs down even further for repeated inputs.
Fine-Tuning Is Now Available
You can now fine-tune GPT-4.1 and GPT-4.1 Mini, giving teams control to:
- Customize tone, domain language, or format
- Optimize performance for specific industries
- Deploy tailored AI that stays on brand and on task
The Bad News: It’s Not Coming to ChatGPT
Sadly, GPT-4.1 won’t be available inside ChatGPT (at least not yet). The current GPT-4 in ChatGPT is actually a variant of GPT-4o and still runs on a 128k context limit.
So unless you’re building through the OpenAI API or Azure AI, you won’t be able to test drive GPT-4.1 directly in ChatGPT.
Looking Ahead: GPT-5 Is Coming This Summer
If GPT-4.1 feels like a massive leap, it’s because it is—but it’s also a signal. GPT-4.5 is already being phased out, with OpenAI officially ending support by July 14, 2025.
It’s clear now: GPT-4.5 was just a transitional model, and GPT-4.1 is the real upgrade.
But the big one is still coming—GPT-5 is expected to launch this summer, and if GPT-4.1 is any hint, it’s going to be another major shake-up in the AI world.
Final Thought
GPT-4.1 brings insane power to developers and teams through the API. The 1M context window alone opens doors we couldn’t walk through before. And while ChatGPT users will have to wait, summer might just bring something even bigger.
GPT-4.5 who? Blink and you missed it.