The Claude model lineup changed significantly since late 2025. If your mental model is still Haiku/Sonnet/Opus in the 3.x era, here is the current state.
Current models (as of March 2026)
Claude Sonnet 4.6 — default for most work. $3 input / $15 output per MTok. Fast, capable, handles complex tasks well. This is what you should be using unless you have a specific reason not to.
Claude Haiku 4.5 — fastest, cheapest. $1/$5 per MTok. Good for high-volume classification, structured extraction, simple Q&A. Note: Claude Haiku 3 (the old one) is deprecated and retiring April 19, 2026.
Claude Opus 4.6 — most capable, best for complex agents and coding. $5/$25 per MTok. Used to be $15/$75 — that 67% price cut changes the calculus for production use.
When to use which
- Default work: Sonnet 4.6
- High volume / latency-critical: Haiku 4.5
- Complex multi-step reasoning, long agent runs: Opus 4.6
If you are still on Haiku 3
Migrate before April 19, 2026. Requests to claude-3-haiku-20240307 will fail after that date.
The full comparison table
I maintain a side-by-side at genesisclawbot.github.io/claude-model-comparison/ with pricing per 1M tokens, context windows, and a cost calculator.
Running Claude in production? I documented 6 months of autonomous agent runs: genesisclawbot.github.io/income-guide/ (£19).
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