Many users have a natural habit when using large language models:

To directly choose the newest, most expensive, and seemingly strongest model.

In most cases, this thought process isn’t entirely wrong. However, if you’re using Claude, you need to be a bit cautious.

This is because within the same generation of Claude models, there are typically three differently positioned versions:

• Haiku
• Sonnet
• Opus

In terms of pricing, it generally goes:

Opus > Sonnet > Haiku

Many people’s first reaction is:

Of course, I should use the most expensive Opus; it must be the best.

But in practice, my experience has been:

Not necessarily.

Especially for ordinary users who are just chatting, writing copy, summarizing, or asking questions, jumping straight to Opus often feels like using a sledgehammer to crack a nut.

This article aims to clearly explain the biggest differences between these three Claude models and how to choose the right one for different scenarios.

Starting with the Names: Haiku, Sonnet, and Opus Are Not Randomly Chosen

The names of Claude’s three models are not arbitrary. They all have literary meanings.

1. Haiku: A Short Poem

Haiku is a form of Japanese short poetry, typically consisting of seventeen syllables. Its characteristics include:

Short, small, light, and fast, emphasizing brevity.

In the context of Claude models, Haiku is clearly positioned as:

Inexpensive, lightweight, and responsive.

2. Sonnet: A Fourteen-Line Poem

Sonnet is a poetic form that originated in Italy and matured during the Renaissance. It is more complex than a haiku, with a more complete structure and deeper expression.

For Claude models, Sonnet is positioned as:

A balance between performance, speed, and cost.

3. Opus: A Work

Opus comes from Latin, typically referring to an author’s important work, or even understood as a “masterpiece.”

In the context of Claude models, Opus is positioned as:

Stronger reasoning capabilities, better performance on complex tasks, but at a higher cost and slower speed.

One-Sentence Conclusion: Ordinary Users Can Start with Sonnet

If I had to give one simple suggestion, I would say:

For the vast majority of users, starting with Sonnet is sufficient.

The reason is simple:

• Haiku is cheap and fast, but may lack detail for more complex tasks;
• Opus is powerful but too expensive and heavy for ordinary chatting and daily tasks;
• Sonnet strikes the best balance between effectiveness, speed, and cost.

If your usage mainly involves:

• Chatting with the model;
• Writing social media posts;
• Writing work reports;
• Editing articles;
• Summarizing materials;
• Performing simple analyses;
• Writing ordinary code scripts;

Then Sonnet is usually sufficient.

Test Explanation

As of the writing date April 29, 2026, the latest versions of the three Claude models are:

To ensure fairness, this test used the 4.5 version of each model for comparison.

I selected three common scenarios:

1. Generating copy;
2. Giving advice and making decisions;
3. Writing code.

Let’s look at the results directly.

Scenario 1: Generating Social Media Posts

The test prompt was as follows:

Please help me write a social media post. I just quit my job and plan to take a year off to travel the world while looking for new opportunities. The tone should be light, not too forced, and not motivational, around 100 words.

Haiku Output

Tokens used: 192 Tokens
Time taken: 3.8 seconds

I quit my job and plan to take a break. For the next year, I’ll be a wanderer, exploring while looking for inspiration for my next job. If you have good opportunities or suggestions, feel free to share. I’ll start by exploring the world map and then see what happens.

Haiku’s characteristics are clear:

Short, fast, and direct.

It understood the request and met the requirements of being “light, not motivational, around 100 words.”

However, the expression is slightly rough. Phrases like “wanderer” and “exploring the world map” feel a bit forced, lacking authenticity for social media.

Sonnet Output

Tokens used: 415 Tokens
Time taken: 3.8 seconds

Sonnet provided three versions:

Version 1:

Finally pressed the pause button on life.

For the next year, I want to see the scenery from the guides and figure out what I really want. Work is just a matter of fate; maybe I’ll encounter something interesting in a café or on a street corner. Just going for it, no rush.

Version 2:

I quit. Planning to wander for a year, playing while looking for my next stop.

No grand plans, just a sudden urge to be a little reckless. Feel free to recommend fun places or suitable opportunities.

Version 3:

Taking a long break to try a different way of living.

For this year, I’ll just travel around and see what happens with work. Life is about occasionally going off track, and that’s okay.

Sonnet’s advantages start to show.

It doesn’t just provide one answer but offers three stylistically similar yet tonally different versions. Version 1 is more literary, Version 2 is more conversational, and Version 3 is slightly reflective.

This is practical for ordinary users because often we don’t need the model to write the final draft at once; we want several directions to choose from.

In this type of task, Sonnet’s cost-effectiveness is high.

Opus Output

Tokens used: 238 Tokens
Time taken: 3.7 seconds

I submitted my resignation and decided to take a long break.

For the next year, I plan to travel around, exploring different cities and lifestyles. No grand plans, just wanting to make the most of this time.

Work will come naturally; if interesting opportunities arise, I’ll consider them; if not, I’ll keep wandering.

If you have recommendations for places or reliable opportunities, please let me know.

Opus’s output is stable.

The tone is natural, not overly formal, and avoids forced motivation.

However, in such a simple copywriting scenario, Opus’s advantages are not particularly evident.

It is indeed well-written, but Sonnet is also quite good. If the task is just to write a social media post, using Opus feels a bit extravagant considering the high cost.

Scenario 1 Summary

If you are just writing social media posts, notifications, or short copy, I recommend:

Prioritize Sonnet; use Haiku for simple tasks, and there’s no need to jump straight to Opus.

Scenario 2: Giving Advice and Making Decisions

The test prompt was as follows:

I currently have 100,000 yuan in savings, I’m 25 years old, and I work in a first-tier city with a monthly salary of 15,000 yuan. Some suggest I buy gold, others suggest index funds, and some suggest saving in fixed deposits. What should I do? Just give me the conclusion.

Disclaimer: The following content is for model testing only and does not constitute any investment advice!

Haiku Output

Tokens used: 414 Tokens
Time taken: 3.8 seconds

Haiku’s suggested plan is roughly:

Keep 3-6 months of living expenses as an emergency fund;

Use the remaining funds mainly to buy index funds;

Allocate a small amount to gold;

Fixed deposits should only be used as a backup;

Lastly, it reminds not to invest all at once but to consider a systematic investment over 3-6 months.

This response appears structured and provides a direct plan.

However, there is a clear issue: it states that “gold can hedge against risks and will not lose money.”

Gold can serve as a hedge asset, but it does not mean it will not lose money. Gold prices can fluctuate and may decline in certain periods.

This is the risk of using a lightweight model for decision-making tasks:

It may give you a seemingly complete answer, but it might contain imprecise judgments.

Sonnet Output

Tokens used: 422 Tokens
Time taken: 4.9 seconds

Sonnet’s suggested plan is:

Suggested allocation:

60% (60,000) in broad-based index funds, such as the CSI 300 or the CSI 500;

30% (30,000) in liquid/money market funds as an emergency reserve;

10% (10,000) in gold for risk hedging.

It is not recommended to keep the main funds in fixed deposits, as being 25 gives you a time advantage.

It also adds several reasons:

Young, with stable cash flow;

Index funds are suitable for long-term holding;

Living costs in first-tier cities are high, so an emergency fund is necessary;

Gold is more of an insurance, not a primary investment tool;

Continuing to invest monthly is more important than this 100,000 principal.

This response is more stable than Haiku.

Especially since it prioritizes the emergency fund and does not mischaracterize gold as a guaranteed investment.

Its risk expression is more restrained, and the structure is also more suitable for ordinary readers.

Opus Output

Tokens used: 451 Tokens
Time taken: 3.9 seconds

Opus’s conclusion is:

60,000 in index fund investments + 20,000 in gold + 20,000 in liquid/money market funds.

Its explanation is also quite complete:

Index funds are the main focus because of youth and time advantage;

A small allocation to gold for risk hedging, not as a primary investment tool;

Retain liquid funds to cope with uncertainties in first-tier city living;

Fixed deposits are not a primary choice.

Opus’s response is similar to Sonnet but has a more decisive tone, sounding more like someone who is making a conclusion.

Scenario 2 Summary

In decision-making tasks, the differences among the three models become more pronounced, so my suggestion is:

For general advice questions, use Sonnet.

For complex decisions, multi-faceted considerations, and high-risk judgments, consider Opus.

Haiku is more suitable for low-risk, low-complexity simple Q&A.

Scenario 3: Writing Code

The test prompt was as follows:

Write a Python script that reads a CSV file, counts the number of empty values in each column, and outputs a summary table.

Haiku Output

Tokens used: 1935 Tokens
Time taken: 3.9 seconds

Haiku provided a very complete script directly. It not only wrote a basic version but also included an “advanced version,” which covers:

Reading CSV;

Counting the number of empty values in each column;

Calculating the proportion of empty values;