Claude Sonnet 5.5
AnthropicProprietaryReleased Sep 28, 2026
Claude Sonnet 5.5 ranks #28 on LMArena (1471.2); official output price $10.00 per 1M tokens.
Key metrics
Rank history
LMArena rank, last 7 days#34 on Oct 3, #28 now; best #28 in this period.
Reasoning effort comparison
Artificial Analysis measurements per reasoning effort of the same model| Effort | Intelligence | Coding | tok/s | TTFT (s) | First answer (s) |
|---|---|---|---|---|---|
| maxUsed in table | 56.0 | – | 137 | 271 | 271 |
| xhigh | 51.9 | – | 98 | 18 | 18 |
| high | 46.8 | – | 101 | 7.6 | 7.6 |
| medium | 40.8 | – | 94 | 0.8 | 0.8 |
| low | 35.9 | – | 91 | 1.0 | 1.0 |
Models ranked nearby
Sorted by Arena score| # | Model | Arena | Intel. | Output $ | tok/s |
|---|---|---|---|---|---|
| 21 |  Muse Spark | 1473.9 | 31.3 | – | – |
| 22 |  GPT-5.5 | 1471.5 | 38.4 | $30.00 | – |
| 23 |  GLM-5.3 | 1471.2 | 44.8 | $4.40 | 65 |
| 24 | Claude Sonnet 5.5This page | 1471.2 | 56.0 | $10.00 | 137 |
| 25 | GLM-5.3 Flash | 1471.1 | 41.8 | $0.50 | 53 |
| 26 | GLM-5.2 | 1469.8 | 33.7 | $4.40 | – |
| 27 | GPT-5.4 | 1469.0 | 39.0 | $15.00 | – |
More from Anthropic
| # | Model | Arena | Intel. | Output $ | tok/s |
|---|---|---|---|---|---|
| 2 | Claude Opus 5.5 | 1514.8 | 57.6 | $20.00 | 98 |
| 3 | Claude Fable 5.1 | 1510.0 | 53.4 | $50.00 | 72 |
| 4 | Claude Opus 5 | 1507.0 | 50.8 | $25.00 | – |
| 5 | Claude Opus 4.6 | 1502.9 | 31.9 | $25.00 | – |
| 8 | Claude Fable 5 | 1491.2 | 49.6 | $50.00 | – |
| 9 | Claude Opus 4.7 | 1489.6 | 40.7 | $25.00 | – |
Pricing
- Official API list price: $2.00 input and $10.00 output per 1M tokens (USD).
- At a typical 3:1 input-to-output ratio, the blended cost is about $4.00 per 1M tokens.
- Among 78 models with an output price, it is the #50 cheapest.
- The cheapest OpenRouter route charges $2.00 input / $10.00 output.
Sources & methodology
Claude Sonnet 5.5 (Anthropic): Arena 1471.2 (#28), Intelligence Index 56.0, $2.00 in / $10.00 out per 1M tokens, 1M context. Data updated Oct 9, 2026.
- LMArena — Arena score, 95% confidence interval, votes and rank.
- Artificial Analysis — Intelligence / Coding Index, output speed and latency (medians).
- OpenRouter — Route prices, context length and listing date.
Arena scores use the Bradley-Terry model (not Elo); ± is the half-width of the 95% confidence interval. Latency figures are Artificial Analysis medians; for reasoning models, time to first token and to first answer include the thinking phase. Data syncs daily at 14:20 (UTC+8).
FAQ
What rank is Claude Sonnet 5.5 right now?
Claude Sonnet 5.5 is #24 on our leaderboard of 68 scored models (Arena score 1471.2); its raw LMArena rank is #28.
What does Claude Sonnet 5.5 cost via API?
Input $2.00 / output $10.00 per 1M tokens (official API list price; the OpenRouter quote when no official price is available). At a typical 3:1 input-to-output ratio, the blended cost is about $4.00 per 1M tokens.
How fast is Claude Sonnet 5.5?
Artificial Analysis measures about 137 output tokens per second, 271 s to the first token and 271 s to the first answer token; it is a reasoning model, so latency includes thinking time.
How close is Claude Sonnet 5.5 to the models ranked next to it?
It is 0.0 points behind GLM-5.3 (1471.2) and 0.1 points ahead of GLM-5.3 Flash (1471.1); gaps smaller than the confidence interval (±8.8) are not significant.
Is Claude Sonnet 5.5 open source? Can it be self-hosted?
Claude Sonnet 5.5 is a closed model, available only via official APIs or hosted services.
What is the context length of Claude Sonnet 5.5?
1M (1,000,000 tokens, as listed on OpenRouter).