Claude Sonnet 5 vs 5.5: Same Price, Specs and Whether to Switch
Sonnet 5.5 costs the same as Sonnet 5 ($2/$10 per million tokens, 1M context). Specs, Artificial Analysis scores and a cost example to help you decide.
Data checked: September 29, 2026. Specs and prices come from the BazaarLink public model catalog (/api/v1/models). Benchmark scores come from Artificial Analysis (AA below). Both were checked on the same day.
Claude Sonnet 5.5 (model ID claude-sonnet-5.5) is now available on BazaarLink.
The short version
- The price did not change. Sonnet 5.5 and Sonnet 5 both cost $2 per million input tokens and $10 per million output tokens, with a 1,000,000-token context at one flat price and no long-context surcharge. Switching does not raise your unit cost.
- The AA Intelligence Index gap is large. At maximum reasoning effort (Max), Sonnet 5.5 scores 56 and Sonnet 5 scores 38.2. At the default high effort it is 46.7 versus 31.7. This is one benchmark suite. It does not mean your own tasks will improve by the same amount.
- One behavior difference to note: the public catalog marks reasoning as mandatory for Sonnet 5.5 (
mandatory: true) and not mandatory for Sonnet 5. According to Anthropic's docs, sendingthinking: disabledto Sonnet 5.5 returns a 400, and up-front thinking is turned off withbetween_tools(high effort or below). If your workflow depends on switching reasoning off, rewrite and test before you switch. See what Anthropic officially says and which API changes to make. - Because the price is the same, the cost of switching is testing time, not your bill. Run a set of representative tasks side by side before switching everything.
Specs and pricing
| Item | Claude Sonnet 5 | Claude Sonnet 5.5 |
|---|---|---|
| Model ID | claude-sonnet-5 | claude-sonnet-5.5 |
| Input, per million tokens | US$2 | US$2 |
| Output, per million tokens | US$10 | US$10 |
| Context length | 1,000,000 tokens | 1,000,000 tokens |
| Input types | Text, image, file | Text, image, file |
| Output type | Text | Text |
| Reasoning effort options | max, xhigh, high, medium, low | max, xhigh, high, medium, low |
| Default reasoning effort | high | high |
| Reasoning mandatory | No | Yes |
Price and context are identical, so there is no "upgrade costs more" question. The BazaarLink catalog describes Sonnet 5.5 as a Sonnet-class model for well-scoped everyday work, succeeding Sonnet 5 as a direct upgrade. Live prices are in the BazaarLink model catalog.
Cost example
Unit prices per million tokens (identical for Sonnet 5 and 5.5; cache prices are for Sonnet 5.5):
| Item | USD |
|---|---|
| Input, per million tokens | $2 |
| Output, per million tokens | $10 |
| Cache read, per million tokens | $0.2 |
| Cache write, per million tokens | $2.5 |
| One request: 5,000 input + 2,000 output tokens | $0.03 |
A monthly customer-support bot example: 500 conversations a day, 3 turns each, 300 input + 150 output tokens per turn. That is about 13.5 million input and 6.75 million output tokens a month, or 13.5 x $2 + 6.75 x $10 = $94.5. The figure is the same on Sonnet 5 and 5.5. Your real monthly cost depends on your own usage records.
What Artificial Analysis says
AA is an independent model benchmarking site. As of September 29, 2026, the Intelligence Index for Sonnet 5.5 and Sonnet 5 is (scored separately per reasoning effort):
| Reasoning effort | Sonnet 5 | Sonnet 5.5 |
|---|---|---|
| Max | 38.2 | 56 |
| Xhigh | 34.4 | 51.9 |
| High | 31.7 | 46.7 |
| Medium | 28.1 | 40.7 |
| Low | 24.3 | 35.8 |
At Max effort, Sonnet 5.5 ranks 2nd of the 670 models AA tracks on the Intelligence Index (Sonnet 5 ranks 62nd). AA records a median output speed of 141.87 tokens per second, against 81.31 for Sonnet 5. Keep in mind:
- Scores are per model and effort combination, so different effort levels cannot be compared directly.
- The Intelligence Index is AA's own benchmark suite. It does not mean your tasks, languages or tool setups will improve by the same amount.
- These figures come from AA's Sonnet 5.5 page and Sonnet 5 page and may be updated.
Who should switch?
Worth trying Sonnet 5.5 first:
- You use Sonnet 5 for everyday coding, document work or support and want to try a higher benchmark score at the same unit price.
- New projects: at the same price there is no pricing reason to pick the older version.
Test before switching if:
- Your workflow depends on turning reasoning off or on very low latency.
- Your prompts and output formats are tuned and you need to confirm the new version's output style does not break downstream parsing.
Suggested process: pick 20 to 30 real tasks, fix the prompts, tools and reasoning effort, run both Sonnet 5 and 5.5, and record pass rate, manual fix time and input/output tokens. Switch everything once it checks out. If you are comparing a higher tier, see Claude Opus 5 vs Opus 5.5.
FAQ
Is Sonnet 5.5 more expensive than Sonnet 5?
No. Both cost $2 per million input tokens and $10 per million output tokens, with a 1,000,000-token context. The unit price is identical. Your total cost depends on your input and output volume.
How long is the Sonnet 5.5 context, and does price rise with length?
The context length is 1,000,000 tokens at one flat price, with no long-context tiers.
Can I keep using Sonnet 5?
Yes. Sonnet 5 is still in the BazaarLink model catalog. Since the price is the same, you can test side by side without rushing to switch everything.
Does Sonnet 5.5 accept images and files?
Yes. Input can be text, images and files, and output is text.
How often are the scores and prices in this article updated?
Prices and specs follow the BazaarLink public model catalog and scores follow the AA website. This article was checked on September 29, 2026. Use the live pages for later changes.
TWD billing · Taiwan invoices · leading AI models · OpenAI-compatible API