Anthropic's Claude models come in three sizes. They all understand the same questions; they differ in how deeply they think, how fast they answer and how much they cost. Picking the right one for each task is the easiest way to get better answers for less money.
The short version
| Model | Best for | Speed | Cost |
|---|---|---|---|
| Haiku | Quick questions, translation, summaries, short emails | Fastest | Lowest |
| Sonnet | Writing, coding, analysis, long files | Fast | Middle |
| Opus | Hard reasoning, careful long documents, research, tricky code | Slower | Highest |
On Duplibot an Opus reply costs roughly five times a Haiku reply. You can see the exact estimate for each model before you send a message, on the models page and in the app.
When Haiku is enough
Use Haiku when the task is short and clear:
- "Translate this paragraph into Bangla."
- "Summarise this article in five points."
- "Write a polite reply saying I will join the meeting."
- "What does this error message mean?"
Haiku answers in seconds and costs very little, so it is perfect for everyday use.
When to use Sonnet
Use Sonnet for work you will keep or hand in:
- a report, proposal or CV;
- an assignment outline with clear sections;
- working code, or finding a bug;
- analysing a spreadsheet or a long PDF.
For most people, Sonnet is the best value. If you only remember one thing from this guide: when in doubt, use Sonnet.
When Opus is worth it
Use Opus when the problem is genuinely hard:
- many steps of reasoning, such as a complex business or legal question;
- a long document that must be careful and consistent;
- deep research that compares many sources;
- a difficult bug that smaller models keep getting wrong.
A simple routine
- Start with the cheapest model that might work.
- If the answer is not good enough, switch to a bigger model and regenerate. Your chat keeps its history.
- Use the effort setting: Low for quick answers, High or Max only for hard problems.
Models change
New Claude versions come out regularly, and they usually keep these three sizes. The names on Duplibot show the exact version (for example Sonnet 5). See Anthropic's model overview for official details.
