Claude Haiku 5.5 vs Claude Sonnet 5.5
| Benchmark | Haiku 5.5 | Sonnet 5.5 |
|---|---|---|
| Humanity's Last Exam | 33.8 | 45.8 |
| Terminal-Bench 4.0 | 15.2 | 43.9 |
| AutomationBench-AA | 28.6 | 59.4 |
Specs
| Spec | Haiku 5.5 | Sonnet 5.5 |
|---|---|---|
| Input, per 1M | $0.10 | $2 |
| Output, per 1M | $0.50 | $10 |
| Cost per task? | $0.047 | $0.88 |
| Speed, tok/s | 174 | 106 |
| Context | 1M | 1M |
| Weights | Closed | Closed |
| Released | Oct 2026 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | Partial | ✓ |
| Hear audio | — | — |
| Watch video | — | — |
| Call tools | ✓ | ✓ |
| Force a tool call | Partial | — |
| Return strict JSON | ✓ | ✓ |
| Search the web | ✓ | ✓ |
| Run code | ✓ | ✓ |
| Use a computer | ? | ✓ |
What breaks when you switch
No forced tool use›
Forced tool_choice any or tool returns HTTP 400; remove the forced choice.
Replace disabled thinking›
Disabled thinking returns HTTP 400; use between_tools for the lowest thinking setting.
No manual thinking budgets›
Manual thinking budgets and extra between_tools fields return HTTP 400; remove manual budgets and send between_tools without display, budget_tokens or block_binding.
Remove sampling parameters›
Non-default temperature, top_p or top_k returns HTTP 400; remove these parameters.
No assistant prefill›
A prefilled final assistant turn returns HTTP 400; remove that prefill.
Old computer tool rejected · Claude API / Google Cloud›
The computer_20251124 tool returns HTTP 400 on the Claude API and Google Cloud; use computer_toolset_20260801 there.
Remove sampling parameters›
Unsupported sampling values, any top_k or combined temperature and top_p return HTTP 400; omit all three and use prompting.
Replace manual thinking budgets›
Manual thinking with budget_tokens returns HTTP 400; replace the old thinking configuration.
No assistant prefill›
A final assistant prefill returns HTTP 400 even with thinking off; end messages with a user turn.
Replace old computer tool · Claude API / Google Cloud›
computer_20250124 returns HTTP 400 on the Claude API and Google Cloud; use computer_toolset_20260801 there.
Keep conversations append-only›
Replaying thinking after earlier history changes returns HTTP 400, with older accounts checked only when the binding field is set; keep history append-only.
Bedrock needs another computer version · Bedrock›
Bedrock does not accept computer_20250124; use computer_20251124 with the computer-use-2025-11-24 beta header.