Choosing the Right Claude Model

Claude comes in multiple model sizes. Choosing the right one saves money and often gets better results. Here's the practical guide.

The Three Models

Think of it like hiring: Opus is the senior consultant you bring in for the hard problems. Sonnet is the sharp full-time employee who handles most of the work. Haiku is the efficient assistant who knocks out straightforward tasks instantly.

When to Use Each

Opus: The Deep Thinker

Use Opus when quality matters most and you can wait a few extra seconds:

• Board presentations and investor communications — Where every word counts and nuance matters
• Complex strategic analysis — Multi-variable decisions with trade-offs
• Nuanced writing — Where tone, subtlety, and sophistication matter
• Difficult problems — Anything that requires careful, multi-step reasoning
• High-stakes decisions — When getting it right the first time is worth the extra time

Sonnet: The Daily Driver

Use Sonnet for 80% of your work. It's the sweet spot of speed, quality, and cost:

• Email drafting and editing — Fast enough for rapid iteration
• Content creation — Blog posts, social media, newsletters
• Data analysis — Summarizing trends, finding patterns
• Meeting prep and follow-ups — Agendas, talking points, recap emails
• General research and summarization — Distilling long documents into key points
• Creative brainstorming — Generating ideas, exploring angles

Most operators should default to Sonnet and only switch when they have a specific reason.

Haiku: The Quick Answer

Use Haiku when speed is everything and the task is simple:

• Yes/no questions — "Does this email sound professional?"
• Quick categorization — "Is this customer email a complaint, a question, or a feature request?"
• Simple reformatting — "Convert this paragraph into bullet points"
• Data extraction — "Pull the revenue numbers from this report"
• Grammar and spell-checking — Quick proofreading passes

Extended Thinking

Claude also has an "extended thinking" mode that gives the model more time to reason through complex problems before responding. Think of it as the difference between asking someone for a quick take versus asking them to sit down and really think it through.

Use extended thinking for:

• Multi-step analysis with many variables
• Problems with competing constraints
• Mathematical or logical reasoning
• Strategy with significant trade-offs
• Debugging complex issues

Skip extended thinking for:

• Simple writing tasks
• Quick questions with straightforward answers
• Reformatting or editing existing content
• Tasks where speed matters more than depth

Quick analysis: your pricing looks competitive, I'd suggest testing a higher tier.

Common Model Selection Mistakes

Mistake: Always using Opus "just in case"

Opus is slower and uses more of your token budget. For straightforward tasks, you're paying more for the same quality output. Sonnet handles 80% of work just as well.

Mistake: Using Haiku for complex writing

Haiku is great for speed but produces noticeably simpler output. If the writing needs to be persuasive, nuanced, or strategically framed, step up to Sonnet or Opus.

Mistake: Ignoring extended thinking for hard problems

If you find yourself asking Claude to "think harder" or "go deeper," you probably need extended thinking mode, not a better prompt. Turn it on, give Claude the space to reason, and the output quality jumps significantly.

The Decision Flowchart

When a task comes in, run through this quick check:

The Bottom Line

Start with Sonnet. It handles the vast majority of tasks well. Switch to Opus when you need extra quality for high-stakes work. Use Haiku when speed is the priority and the task is simple.

Here's the most important thing to remember: the difference in output quality between Sonnet and Opus is smaller than the difference between a vague prompt and a well-structured one. A great prompt with Sonnet will outperform a lazy prompt with Opus every time.

Get your prompting right first (see The Anatomy of a Great Prompt), then optimize model selection for the marginal gains.