If you’re searching “haiku 4.5 vs sonnet 4.6,” you’re trying to answer one question: which Claude model should I point my coding agent at? Here’s the honest version.
Use Sonnet 4.6 as your default. Drop to Haiku 4.5 when the task is simple, latency matters, or you’re running high volume and the bill is climbing. The two models aren’t really competitors. They’re the two ends of a sensible coding stack, and the best setups use both.
The 30-second version
| Claude Haiku 4.5 | Claude Sonnet 4.6 | |
|---|---|---|
| Tier | Fast / budget | Default workhorse |
| Cost (input / output) | $1 / $5 per 1M | $3 / $15 per 1M |
| Context window | 200K | 1M |
| SWE-bench Verified | 73.3% | 79.6% |
| Speed | ~80-120 tok/s (4-5x faster) | Standard |
| Best for | Quick edits, scaffolding, routing, high volume | Multi-file refactors, architecture, hard debugging |
Pick Haiku 4.5 if the work is shallow and frequent (boilerplate, commit messages, file summaries, IDE-style completions, quick fixes), or if you’re firing thousands of agent calls a day and want the bill to stay sane.
Pick Sonnet 4.6 if the work is deep: refactoring across files, reasoning about an architecture, debugging something that’s wrong in a non-obvious way, or anything where a confidently-wrong answer costs you more than the extra tokens.
The price gap is the whole story (mostly)
The headline difference is cost. Haiku 4.5 lands at roughly a third of Sonnet 4.6’s per-token price. That ratio is what makes the model-choice decision real rather than academic.
A concrete frame: for a workload of 50K daily agent interactions averaging ~2,000 tokens each, Haiku 4.5 runs around $15/day where Sonnet would run closer to $75/day. At that volume, routing the easy 80% of calls to Haiku and reserving Sonnet for the hard 20% is the single biggest lever on your coding-agent bill.
Two caveats keep the gap from being a slam dunk:
- Prompt caching (up to 90% savings) and batch processing (50% savings) apply to both models, so disciplined caching narrows the absolute dollar difference.
- A wrong answer from the cheaper model isn’t free. If Haiku takes three tries to land a refactor that Sonnet gets in one, you’ve spent more tokens and more of your own time. Cheap-but-wrong is the most expensive outcome.
Speed: where Haiku earns its keep
Haiku 4.5 runs 4-5x faster than the previous Sonnet generation, in the neighborhood of 80-120 tokens per second. For anything interactive (inline completions, a chat-style assistant, a tool that has to feel instant), that latency difference is the feature. Sonnet’s extra quality doesn’t help if the user is staring at a spinner.
This is also why Haiku makes a great router and first-pass triager in agent systems: it can classify an incoming task and knock out the simple ones directly in a fraction of the time, handing only the genuinely hard work up to Sonnet.
Coding quality: Sonnet’s lead is real but narrow
On SWE-bench Verified, Sonnet 4.6 scores 79.6% to Haiku 4.5’s 73.3%, a meaningful but not enormous gap. For context, that puts Sonnet 4.6 within a point of Opus-class performance on that benchmark, while Haiku 4.5 still lands among the better coding models available at any price.
The difference doesn’t show up in single-function generation; both are strong there. It shows up in the long-horizon work: multi-step tasks, multi-file edits, and reliability. Sonnet 4.6 is more consistent, makes fewer false “I’m done” claims, and follows through on multi-step instructions more dependably. For agentic coding where the model is driving for many turns, that consistency compounds.
Context window: 1M vs 200K
Sonnet 4.6’s 1M-token context window is 5x Haiku 4.5’s 200K. If your workflow involves dropping a substantial codebase into context and asking the model to reason across all of it, Sonnet is the only one of the two that fits the job. For focused, file-at-a-time work, which is most day-to-day coding-agent activity, 200K is plenty, and Haiku’s window won’t be the bottleneck.
The real answer: run both
The most cost-effective 2026 coding setups don’t choose one model; they layer them:
- Haiku 4.5 as the fast front line: routing, classification, simple edits, boilerplate, summaries, the high-frequency shallow stuff.
- Sonnet 4.6 as the workhorse: the bulk of real code generation, refactoring, and debugging.
- Opus 4.6 or 4.8 held in reserve for the problems Sonnet gets wrong twice in a row.
You get most of Sonnet’s quality on the work that needs it and most of Haiku’s savings on the work that doesn’t.
How to use Haiku 4.5 and Sonnet 4.6
- haimaker.ai — access Haiku 4.5, Sonnet 4.6, and hundreds of other models through one OpenAI-compatible endpoint, with unified pricing and benchmarks so you can route between them without juggling provider accounts.
- Anthropic’s API — both models are first-party; export
ANTHROPIC_API_KEYand call them directly. - In a coding agent — both are drop-in choices for OpenClaw. See best Claude models for OpenClaw for the full setup, or the individual guides for Haiku 4.5 and Sonnet 4.6.
The bottom line
Sonnet 4.6 is the better coder and the right default. Haiku 4.5 is dramatically faster and cheaper, and it’s good enough that you should hand it everything that doesn’t need Sonnet. The decision isn’t really “which one”; it’s “where’s the line in my workload,” and the savings live in drawing that line well.