Very long inputs
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 reads up to 1M tokens per request, against 200k for Claude Sonnet 3.5.
Claude Sonnet 3.5 vs Claude Sonnet 5.5: price, context and capabilities
Choose Claude Sonnet 5.5 for very long inputs and the latest release; on the other points the two are level or the data is missing.
In short
- Claude Sonnet 3.5 has been retired; Claude Sonnet 5.5 is the one you can still call.
- A price comparison is not possible: one of them has no comparable published price.
- Claude Sonnet 5.5 reads more per request: 1M tokens against 200k.
- Claude Sonnet 5.5 is the newer model (September 2026, against June 2024).
- Only Claude Sonnet 5.5 offers reasoning, prompt caching.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Latest release
Choose Claude Sonnet 5.5
Claude Sonnet 5.5 is the newer release (September 2026, against June 2024 for Claude Sonnet 3.5).
Specifications side by side
| Claude Sonnet 3.5 | Claude Sonnet 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Category | Language models | Language models |
| Status | Retired | Generally available |
| Headline price | $6.00 / 1M tokens | $4.00 / 1M tokens |
| Input | $3.00 / 1M tokens | $2.00 / 1M tokens |
| Output | $15.00 / 1M tokens | $10.00 / 1M tokens |
| Cached input | No data | $0.10 / 1M tokens |
| Context window | 200k | 1M |
| Max output | No data | 128k |
| Released | June 2024 | September 2026 |
| Knowledge cutoff | No data | June 2026 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Tool calling, Structured output, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-3-5-sonnet-20240620 | claude-sonnet-5-5 |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Sonnet 3.5 | Claude Sonnet 5.5 |
|---|---|---|
| Intelligence Index | No data | 56 |
| SciCode | No data | 61% |
| Humanity's Last Exam | No data | 55% |
| Long-context reasoning (AA-LCR) | No data | 82.7% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Sonnet 3.5 or Claude Sonnet 5.5?
Choose Claude Sonnet 5.5 for very long inputs and the latest release; on the other points the two are level or the data is missing.
Which is cheaper, Claude Sonnet 3.5 or Claude Sonnet 5.5?
A price comparison is not possible: one of them has no comparable published price.
Which has the larger context window, Claude Sonnet 3.5 or Claude Sonnet 5.5?
Claude Sonnet 5.5 reads more per request: 1M tokens against 200k.
What is the difference between Claude Sonnet 3.5 and Claude Sonnet 5.5?
Claude Sonnet 3.5 is made by Anthropic and Claude Sonnet 5.5 by Anthropic. Claude Sonnet 3.5 has been retired; Claude Sonnet 5.5 is the one you can still call. A price comparison is not possible: one of them has no comparable published price. Claude Sonnet 5.5 reads more per request: 1M tokens against 200k. Claude Sonnet 5.5 is the newer model (September 2026, against June 2024). Only Claude Sonnet 5.5 offers reasoning, prompt caching.
Which is newer, Claude Sonnet 3.5 or Claude Sonnet 5.5?
Claude Sonnet 5.5 was released on September 2026 and Claude Sonnet 3.5 on June 2024.