Choosing the Right Claude Model: Haiku, Sonnet, and Opus Explained Simply

Three Claude models in the picker and no idea which one to use? Picking wrong either burns your usage limit on a simple question or gets a shallow answer to a hard problem. The choice is simpler than it looks.

The bicycle, the sedan, the sports car

Haiku is the bicycle: fastest and lightest, for quick answers, summarizing short articles, pulling facts out of documents, sorting and categorizing. Sonnet is the sedan and the default for most work: writing, debugging code, analyzing data, multi-step problems that need some thinking. Opus is the sports car: built for deep research across long documents, multi-step reasoning where accuracy really matters, and problems Sonnet already failed to crack.

Why the choice costs money

Your account has a usage limit, like a monthly data plan. Every request uses some of it, and not all models use the same amount: Haiku uses very little, Sonnet a moderate amount, Opus the most, because it thinks harder and longer. Using Opus for a question Haiku could answer burns the plan for no benefit.

The trade-off

Model quality, speed, and usage cost move together; you only get to prioritize one per task. The safe default is the simplest model that can handle the job, then step up when the output is actually inadequate, not when you feel nervous. And re-test when new versions ship: each release is a fresh training run, so a task that needed Opus last year may be Sonnet work now.

Which models you get

Which models are available on which plans changes over time, and so do the limits. Check Anthropic's current pricing and plans page before assuming a model is out of reach.

What to do today

Default to Sonnet. Switch down to Haiku for lookups, up to Opus only after Sonnet fails.