Claude Sonnet vs Opus vs Haiku: Which Model Should You Use (and When)?

Anthropic offers three Claude models at very different price points. Here is a simple guide to which one you actually need — most people are overpaying by using the most expensive model for everything.

If you use Claude (Anthropic's AI assistant), you may have noticed that there are three different models to choose from: Haiku, Sonnet, and Opus. They range from fast and cheap to slow and powerful, and choosing the right one for each task can save you significant money — or get you significantly better results.

Think of it like choosing between economy, business, and first class on a flight. They all get you to the same destination, but the experience (and price) is very different. And just like flying, sometimes economy is the smart choice.

The Three Claude Models, Explained Simply

Claude Haiku 4.5 is the fast, affordable model. It responds almost instantly and costs very little to use through the Application Programming Interface (API). Haiku is best for quick, simple tasks: answering factual questions, summarising short texts, categorising information, or generating simple content. Think of Haiku as your quick-answer assistant.

Claude Sonnet 4.6 is the balanced, everyday model. This is the default model for most Claude users and the one the free version of Claude uses. It is significantly more capable than Haiku — better at writing, coding, analysis, and nuanced tasks — while still being reasonably fast and affordable. Sonnet is what you should use for most of your work.

Claude Opus 4.6 is the most powerful model. It produces the highest-quality output, especially for complex tasks that require deep reasoning, sophisticated analysis, or expert-level coding. Opus takes longer to respond and costs more, but for truly difficult tasks, the difference in quality is noticeable. Think of Opus as your senior consultant — you bring them in for the hard problems.

How Much Each Model Costs

If you use Claude through the website or mobile app with a Pro subscription ($20 per month), you have access to all three models. The subscription gives you a fixed amount of usage per month — you are not charged per message.

If you use Claude through the API (the technical method for building AI into applications), pricing is per token (a chunk of text, roughly three-quarters of a word):

Haiku 4.5: $1 per million input tokens, $5 per million output tokens — the most affordable option.

Sonnet 4.6: $3 per million input tokens, $15 per million output tokens — good balance of cost and quality.

Opus 4.6: $5 per million input tokens, $25 per million output tokens — premium pricing for premium quality.

To put this in perspective: processing a 10-page document through Sonnet costs roughly $0.05. Through Opus, it costs roughly $0.08. Through Haiku, it costs roughly $0.02. These are very small amounts per individual request, but they add up at scale.

Source: Pricing from platform.claude.com/docs/en/about-claude/pricing as of March 2026.

When to Use Each Model: A Decision Guide

Here is a simple rule of thumb:

Use Haiku when: you need a quick answer to a simple question, you are processing large volumes of text (like categorising hundreds of customer support tickets), or speed matters more than perfection.

Use Sonnet when: you are writing content, helping with code, analysing documents, or doing any everyday knowledge work. This should be your default choice 80 percent of the time.

Use Opus when: you are working on something genuinely difficult — a complex architecture decision in software, a nuanced legal analysis, a research paper that requires deep reasoning, or a creative project where quality is paramount.

The most common mistake we see is people using Opus for everything. Most tasks do not need the most powerful model. Using Sonnet for your daily work and switching to Opus only for genuinely complex tasks is both smarter and more cost-effective.

If you use Claude through the website (rather than the API), Sonnet is the default model. You can switch to Opus in the model selector dropdown — but do this selectively, because it uses your monthly usage allowance faster.

The Bottom Line

For most people, here is our recommendation:

If you use Claude casually (a few times per week): The free plan with Sonnet is all you need.

If you use Claude daily for work: Claude Pro at $20 per month with Sonnet as your default, switching to Opus for complex tasks.

If you build applications with Claude's API: Use Haiku for high-volume, simple tasks. Use Sonnet for most application features. Use Opus only for the tasks that genuinely require the highest quality.

And remember — Anthropic regularly improves all three models. Sonnet today is more capable than Opus was just six months ago. So do not assume you need the most expensive model. Try Sonnet first and see if the quality meets your needs.

Want help figuring out which AI tools and plans make the most sense for you? Take our free 60-second AI Match quiz: aitoolsmentor.com/wizard