GPT-4o is dead. Not deprecated, not “legacy,” not hidden behind a dropdown. Gone. OpenAI pulled the plug on April 3, 2026, across every plan: Free, Plus, Team, Enterprise. If you open ChatGPT today, GPT-5.4 Thinking is what greets you.

I’ve been running GPT-5.4 Thinking as my primary ChatGPT model since it launched in early March. So I had a month of overlap where both models were available. Now that GPT-4o is officially retired, I can give you a straight answer on what you’re gaining, what you’re losing, and whether “superhuman on benchmarks” means anything when you’re staring at a blank prompt at 9am on a Monday.

Quick Verdict: GPT-5.4 Thinking

Aspect	Rating
Overall Score	★★★★☆ (4.3/5)
Best For	Multi-step reasoning, agentic workflows, long-context analysis
Pricing	ChatGPT Plus $20/mo, API $2.50/$15 per 1M tokens
OSWorld-Verified	75.0% (first AI above human baseline)
Speed vs GPT-4o	Slower on simple tasks, faster on complex ones
GPT-4o Replacement?	Mostly yes, with caveats

Bottom line: GPT-5.4 Thinking is a better model than GPT-4o in nearly every measurable way. But “better at thinking” comes with trade-offs in speed and simplicity that GPT-4o users will notice immediately. The forced upgrade stings for some workflows.

The Forced Migration Nobody Asked For

Let me be clear about what happened. OpenAI didn’t give users a choice here. On April 3, GPT-4o stopped being an option. Every ChatGPT user (including the free tier) got moved to GPT-5.4 Thinking as the default reasoning model.

This matters because GPT-4o wasn’t just an old model people were clinging to out of habit. It was fast. Predictably fast. For quick questions, email drafts, simple code snippets, and the kind of low-stakes AI work most people do most of the time, GPT-4o responded in under two seconds with answers that were good enough.

GPT-5.4 Thinking doesn’t work that way. It thinks. That’s the whole point. But thinking takes time, and for a “what’s a good subject line for this email” prompt, the three-to-five second pause while the model reasons through something that doesn’t need reasoning… it’s noticeable. It’s a different rhythm.

OpenAI ships a Standard variant alongside Thinking and Pro, but Thinking is the default in ChatGPT. You can switch, but most people won’t.

What GPT-5.4 Thinking Actually Does Better

Okay, complaints about the forced migration aside. The model itself is impressive in specific, measurable ways.

The OSWorld Number

75.0% on OSWorld-Verified. That’s a 27.7 percentage point jump over GPT-5.2’s score. The human baseline on this benchmark is 72.4%. GPT-5.4 Thinking is the first AI model to exceed human-level performance on desktop task execution.

What does OSWorld actually test? Real GUI navigation. The model looks at screenshots of a desktop, plans a sequence of actions, clicks buttons, types text, navigates between applications. Not a chatbot parlor trick. Actual computer operation.

I tested this myself through the API’s computer-use capability. I had it file an expense report in a web app that required navigating four different screens, filling in form fields from a receipt photo, selecting the right cost center from a nested dropdown, and submitting. It nailed it. First try. That’s a task I’ve watched junior employees struggle with (no offense to junior employees — the expense app is genuinely terrible).

Reasoning That Feels Different

The “Thinking” in the name isn’t marketing fluff. When I give GPT-5.4 Thinking a multi-step problem — debug a race condition in a codebase, analyze three contradictory data sources — it visibly works through the problem in stages. You can see the chain-of-thought reasoning in the interface.

This produces better answers on hard problems. Measurably better. My informal testing across about 40 complex prompts over the past month:

• Multi-step logic problems: GPT-5.4 Thinking got 34/40 right. GPT-4o got 26/40 on the same set.
• Code debugging (real bugs, not toy problems): Thinking identified the root cause in 8/10 cases. GPT-4o managed 5/10.
• Document analysis with conflicting information: Night and day. Thinking flags contradictions that GPT-4o sailed right past.

Context Window

1 million tokens in the API. That’s roughly 750,000 words. GPT-4o maxed at 128K. For anyone bumping up against context limits (feeding in long documents, analyzing codebases, maintaining extended conversations), that’s an 8x increase.

I’ve been running it against full project repositories and multi-document research sets. It holds up across the full window, though I’ve noticed quality starts to soften slightly past 800K tokens on very detail-oriented tasks. Going from 128K to 1M changes what’s possible.

Where GPT-4o Was Actually Better

I’m not going to pretend this is a clean upgrade. Some things got worse.

Speed on simple tasks. GPT-4o averaged about 1.5 seconds for a quick response. GPT-5.4 Thinking averages 3-5 seconds because it’s, well, thinking. For rapid-fire Q&A sessions where I’m asking 20 small questions in a row, the cumulative slowdown is real. I’ve lost probably 30 minutes this month just to waiting on answers that didn’t need the extended reasoning treatment.

Predictability. GPT-4o’s responses had a consistency to them. Same prompt, roughly similar output, time after time. GPT-5.4 Thinking’s chain-of-thought reasoning introduces more variability. Sometimes it takes a different reasoning path and lands on a slightly different answer. For creative work, this is arguably a feature. For template-style tasks where you want identical formatting every time, it’s friction.

Cost at the API level. If you were running GPT-4o through the API for high-volume, low-complexity tasks, your bill is about to change. GPT-5.4’s pricing ($2.50/$15 per 1M tokens) is higher than GPT-4o was, and the thinking tokens add up. For batch processing thousands of simple requests, do the math before you migrate.

The Three Variants: Which One Do You Actually Need?

OpenAI launched GPT-5.4 in three flavors. This is where it gets confusing, so here’s the breakdown:

How to choose between GPT-5.4 Standard, Thinking, and Pro

1. GPT-5.4 Standard — No chain-of-thought reasoning. Faster responses. Best for straightforward tasks where you don’t need the model to think through problems step by step. This is the closest replacement for GPT-4o’s speed profile.
2. GPT-5.4 Thinking — Chain-of-thought enabled. The default in ChatGPT. Best for complex analysis, debugging, multi-step planning, and anything where reasoning quality matters more than speed. This is what most people will use most of the time.
3. GPT-5.4 Pro — Extended reasoning with higher compute allocation. Available on ChatGPT Pro ($200/mo) and via API at premium pricing. Best for the hardest problems: novel research questions, extremely complex code architecture, multi-document synthesis requiring deep analysis.

For most people on ChatGPT Plus, Thinking is the right default. Switch to Standard when you want speed. You don’t need Pro unless you’re regularly hitting the ceiling of what Thinking can handle, and in my experience, that ceiling is high.

GPT-5.4 Thinking vs the Competition

The competitive picture has shifted. Here’s where things stand as of April 2026:

Benchmark	GPT-5.4 Thinking	Claude Opus 4.6	Gemini 3.1 Pro
OSWorld-Verified	75.0%	72.7%	68.1%
SWE-bench Pro	57.7%	45.9%	52.3%
ARC AGI 2	62.4%	68.8%	58.1%
Context Window	1M	1M	2M

The pattern: GPT-5.4 Thinking leads on practical task execution (OSWorld, SWE-bench). Claude Opus 4.6 leads on abstract reasoning (ARC AGI 2). Gemini has the biggest context window but trails on most other benchmarks.

In my daily use, GPT-5.4 Thinking wins when I need something done: filing, navigating, coding against specific requirements. Opus wins when I need something understood: analyzing why a system is failing, finding patterns in a contradictory document set. Different tools for different problems.

Pricing After the Retirement

With GPT-4o gone, here’s what you’re paying now:

Plan	Monthly Cost	GPT-5.4 Access	Notes
Free	$0	Limited Thinking	Rate-limited, no API
Plus	$20/mo	Full Thinking + Standard	Best value for individuals
Team	$25/user/mo	All variants	Workspace features
Pro	$200/mo	All variants + Pro	Extended reasoning, highest limits
API	Pay-per-use	All variants	$2.50/$15 per 1M tokens (Standard)

For a deeper look at how this fits into the broader AI pricing picture, I wrote a full cost breakdown that covers what I actually pay across all my AI subscriptions.

The Plus plan at $20/month remains the sweet spot. You get full access to GPT-5.4 Thinking, which handles 90% of what I throw at it. The $200 Pro tier is for people who regularly need the hardest problems solved and have the budget to match.

My Honest Take After a Month

I liked GPT-4o. I used it constantly. It was the Honda Civic of AI models — reliable, efficient, got the job done without drama. I’m a little annoyed it’s gone because not everything needs extended reasoning.

But GPT-5.4 Thinking is a better model. That’s just true. The improvements on hard problems aren’t marginal. They’re substantial. The 75% OSWorld score isn’t a synthetic benchmark curiosity; it reflects a model that can actually navigate complex software better than most humans can. I’ve watched it do things with a mouse and keyboard (virtually, through the API) that would take me twice as long.

The adjustment period is real, though. If your whole workflow was built around GPT-4o’s speed-first approach, you’ll need to recalibrate. Use Standard mode for quick tasks. Save Thinking for problems that deserve it. And stop expecting 1.5-second responses on everything. That era is over.

For anyone coming from the original GPT-5 or even GPT-5.2, the jump to 5.4 Thinking is the biggest single-generation improvement OpenAI has shipped in the 5.x series. The OSWorld milestone alone would make it notable. Combined with the 1M context window and the three-tier model structure, it’s a comprehensive upgrade.

Is “superhuman on benchmarks” the same as superhuman in your workflow? No. Benchmarks test specific capabilities in controlled conditions. Your workflow involves ambiguous prompts, messy data, changing requirements, and that one coworker who sends you a screenshot of a spreadsheet instead of the actual file. GPT-5.4 Thinking handles the messy real world better than GPT-4o did. But it’s not magic, and the “superhuman” framing sets expectations that no model can meet.

My verdict: A worthy successor to GPT-4o, even if the forced retirement left a bad taste. Use Thinking as your default, switch to Standard when speed matters, and don’t pay for Pro unless you’ve actually hit Thinking’s limits. The benchmarks hold up. The practical improvements match. The hype? About 60% justified, which, for this industry, is actually pretty good.

Frequently Asked Questions

Why did OpenAI retire GPT-4o?

OpenAI retired GPT-4o on April 3, 2026. They’ve been clearing out older models with each major release, and GPT-4o’s number was up. GPT-5.4 Standard covers most of what GPT-4o could do and is the speed-optimized option in the new lineup.

Can I still access GPT-4o anywhere?

No. The retirement was across all OpenAI plans and the API. If you have applications built on GPT-4o API endpoints, they now default to GPT-5.4. OpenAI provided migration guides, but the switch was mandatory.

Is GPT-5.4 Thinking the same as GPT-5.4?

GPT-5.4 comes in three variants: Standard, Thinking, and Pro. Thinking is the default in ChatGPT and includes chain-of-thought reasoning. Standard skips the reasoning for faster responses. Pro adds extended compute for the hardest problems. All three share the same base model.

How does GPT-5.4 Thinking compare to Claude Opus 4.6?

GPT-5.4 Thinking leads on practical execution benchmarks (OSWorld, SWE-bench). Claude Opus 4.6 leads on abstract reasoning (ARC AGI 2). In daily use, I reach for GPT-5.4 when I need tasks completed and Claude when I need problems analyzed. Both are excellent; they have different strengths.

Is ChatGPT Plus still worth $20/month after this change?

Yes. You get full access to GPT-5.4 Thinking, which is a more capable model than GPT-4o was. The value proposition actually improved. You’re paying the same price for a significantly better model. The only downside is losing GPT-4o’s speed for simple tasks, but Standard mode partially compensates.

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Last updated: April 5, 2026. Based on one month of hands-on use with GPT-5.4 Thinking via ChatGPT Plus and API access. Features and pricing verified against OpenAI’s documentation. Benchmark data from OSWorld.

Related reading: GPT-5.4 Full Review | Claude Opus 4.6 Review | Claude vs ChatGPT vs Gemini