Opus: deep reasoning
The most capable family. Use it for hard problems: multi-step analysis, tricky code, strategy, long documents where nuance matters. It is slower and costs more per message.
Lesson 2
Claude Models
Three model families, three trade-offs between depth, speed and cost. Pick the model to fit the job.
Sonnet: everyday work
The balanced default. Strong enough for most writing, coding, analysis and research, fast enough to feel interactive. If you are unsure, start here.
Haiku: fast simple tasks
The quickest and cheapest. Ideal for classification, extraction, short rewrites, high-volume jobs and anything where speed beats depth.
How to choose
Start with Sonnet. If the answer is shallow or misses steps, move up to Opus. If you are running the same simple task hundreds of times, move down to Haiku. Extended thinking (when available) gives any model more room to reason before answering.
Names change, roles don't
Version numbers move forward regularly. The pattern of a deep, a balanced and a fast tier has stayed stable, so learn the roles rather than the version numbers.
Try this prompt
Before answering, tell me whether this task needs deep reasoning or is a quick lookup, and why: [paste your task]
Avoid
- Using the biggest model for trivial tasks
- Blaming the model when the prompt was vague
- Never trying a different tier when results disappoint