Claude Opus 4.5: What’s New. Is It Better? What You Need to Know.

I tested Claude Opus 4.5 this week on something real: organizing 200+ pieces of my own content into a Notion database to find new article opportunities.

This is work I normally do with Sonnet. Usually it takes 3-4 rounds. I explain what I want. It does something close. I say “not quite.” It adjusts. Rinse and repeat.

With Opus 4.5? First try. The database structure made sense. The tags were useful. I could actually use it without reworking anything.

That’s the difference that matters to me.

What Makes Opus 4.5 Different.

There’s a lot of marketing noise around this release. Most of it won’t affect you. But three real things changed:

The price actually dropped. Opus 4.5 costs $5 per million input tokens and $25 per million output tokens. The old Opus was $15/$75. That’s about two-thirds cheaper. This means you’re not saving Opus for emergencies anymore. You can actually use it for real work.

It understands what you’re asking better. When I dumped all my content into Claude and said “organize this so I can find new article opportunities,” it got what I meant without me having to explain it five different ways. Sonnet would’ve needed multiple rounds of clarification. Opus just understood the context and built something useful.

You can control how hard it thinks. There’s a new “effort parameter” that lets you tell Claude how much reasoning to spend on a problem. Low effort is fast and cheap. Medium is balanced. High means Claude spends more tokens thinking deeply. I tested high effort on organizing my content and it was noticeably better at catching edge cases. On simpler stuff, medium effort worked fine and used fewer tokens.

Why This Matters For Your Work.

If you use Claude casually, this probably doesn’t change much. You’re fine with what you have.

But if you’re doing actual knowledge work with Claude, Opus is worth paying attention to now.

I’d use it for content organization. Like what I just did. I had 200+ pieces scattered across posts, guides, and guest articles. Opus understood that I wanted to find patterns and spot new content opportunities. It built a database structure I could actually use. Sonnet would’ve needed me to break this into smaller tasks and iterate multiple times.

Complex problem-solving. When there’s no obvious right answer and you need to think through tradeoffs. Opus is better at this.

Long-form analysis. You can throw entire documents, research papers, or transcripts at Opus (it has a 200K token context window—that’s huge) and have it reason across all of it. Sonnet has 200K too, but Opus reasons through it better.

Coding. It scores 80.9% on SWE-bench, which is a real software engineering benchmark. Not marketing speak. Actual coding tasks. It’s good at it.

Anything where you’ve been iterating with Sonnet. If you’re currently spending 30 minutes reexplaining yourself to Claude, Opus saves that time.

Here’s What You DON’T Need Opus For.

Simple writing (Sonnet is fine and costs way less). Quick questions (Haiku is faster and cheaper). Casual brainstorming (Sonnet is adequate). Anything you’ve already figured out how to get right with good prompting (switching models won’t help if your workflow is the problem).

I’m being honest here because Opus costs more per token. It’s not worth using it for everything. But it’s worth using it for the stuff that currently frustrates you.

The Effort Parameter, How it Works.

I was skeptical about this when I heard about it. Spending more tokens to “think harder”? Seemed like marketing.

But I tested it.

High effort on the content organization task took longer (Claude was visibly taking more time to respond) but produced something noticeably better. It caught edge cases I hadn’t mentioned. It organized the content in a way that actually helped me spot new article ideas.

Medium effort on a simpler task—just organizing a list of tools—got me 90% of the way there in half the time using fewer tokens.

Low effort was too simple for complex work.

Here’s the honest part: high effort uses roughly twice the tokens of low effort on the same task. So it’s not magic. But if high effort means you don’t have to iterate, that saves you money overall. You’re paying more per token but using fewer total tokens because you get it right the first time.

One Thing I don’t like about Opus 4.5.

Opus 4.5 is slower than Sonnet. You’ll notice this. It takes longer to generate responses because it’s doing more reasoning.

For work where speed doesn’t matter—content organization, complex analysis, problem-solving—it’s worth the wait. You’re willing to wait 10 seconds longer if the answer is better.

For rapid back-and-forth iteration—like debugging code in real-time or drafting something where you want quick feedback—Sonnet is still better. The latency is noticeable.

It’s a real tradeoff. You need to decide if better output is worth waiting longer.

Should You Use it?

If you have a Claude Pro subscription: Test it on your hardest problem. The kind of task where Sonnet usually needs you to rephrase or iterate. If Opus saves you one round of back-and-forth, it pays for itself.

If you’re on the free tier: Probably doesn’t matter. Haiku is fast and works for most people.

If you do complex knowledge work: Worth trying. The pricing makes it feasible to use regularly now, which is new.

If you code: The improvements are real. Try it on your next non-trivial problem.

If you just ask quick questions and write simple stuff: Stick with Sonnet. You won’t notice a difference and you’ll pay more.

When to Use Which Model.

Use Haiku when: You need a fast answer and don’t care much about depth. Quick questions, simple summaries, high-volume automation.

Use Sonnet when: You’re writing, brainstorming, doing iterative work, or fine with asking follow-up questions to refine the answer. It’s the “good enough for most things” model.

Use Opus when: You’re solving something complex, working with lots of information, doing knowledge work where reworking would take hours, or tired of reexplaining yourself to Claude. The work is worth the extra tokens.

How Opus 4.5 Helps Me.

The real insight from testing Opus: I was underestimating how much time I spend iterating. I’d ask Sonnet something, get close, say “not quite,” ask again. Usually takes 3-4 rounds for complex tasks.

Opus cuts that to one round.

One round. That saves time. And time is money.

The cheaper pricing matters because it means I can use Opus regularly instead of just for emergencies. I can stop treating it like “nuclear option, only use if desperate.”

FAQ

Q: Is Opus worth paying more for vs Sonnet?

A: Only if you’re currently spending 30+ minutes iterating with Sonnet. If Opus saves you one round of reworking, it pays for itself.

Q: Does the effort parameter actually save money?

A: Sometimes. High effort costs more tokens upfront but might save you from iterating. Medium effort is a good sweet spot for a lot of tasks.

Q: Should I use Opus for everything now?

A: No. Use Sonnet for straightforward work. Use Opus when you’re doing something complex or when Sonnet keeps making you rephrase things.

Q: How does it compare to GPT-4o?

A: Opus has a way bigger context window (200K vs 128K tokens) and is better at abstract reasoning. GPT-4o is cheaper for straightforward tasks. If you’re doing complex thinking and need to work with lots of information, Opus wins.

Q: Is it actually available now?

A: Yeah. If you have Pro or Max on Claude.ai, it’s in the model selector dropdown.

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Thinking about switching from ChatGPT? We tested both and wrote what we found in our Claude review.

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