All models
Anthropic · launched 28 Sept 2026
Claude Sonnet 5.5
The second model in the Claude 5.5 family. Priced the same as Sonnet 5, it runs more than 30% faster and needs fewer tokens per task.
Read the official announcementModel details
- Vendor
- Anthropic
- Launch date
- 28 Sept 2026
- Input price
- $2.00 / 1M tokens
- Output price
- $10 / 1M tokens
- Cached input
- $0.20 / 1M tokens
- Batch discount
- 50%
- Context window
- 1M tokens
- Max output
- 128K tokens
- Input types
- Text, Image, File
- API model ID
- claude-sonnet-5-5
- OpenRouter ID
- anthropic/claude-sonnet-5.5
Compared with Claude Sonnet 5
Input price
$2.00
was $2.00 · Same price
Output price
$10
was $10 · Same price
Blended price
$4.00
was $4.00 · Same price
Best published results
- Terminal-Bench 4.0max effort · $12.5 per attempt · reported by Anthropic70.6%
- FrontierCode v1.1xhigh effort · $1.59 per task · reported by Anthropic52.1%
- CursorBench 4.0max effort · $9.67 per task · reported by Anthropic55.5%
- AA-Briefcase v1.1max effort · $29.2 per task · reported by Anthropic1811 Elo
Price compared with other models
| Model | Launched | Input / 1M | Output / 1M | Cached / 1M | Blended / 1M | vs Claude Sonnet 5.5 |
|---|---|---|---|---|---|---|
| GPT-6 LunaOpenAI | 22 Sept 2026 | $0.10 | $0.50 | $0.01 | $0.20 | 95% cheaper |
| GPT-5.6 LunaOpenAI | 9 Jul 2026 | $0.20 | $1.20 | $0.02 | $0.45 | 89% cheaper |
| Claude Sonnet 5Anthropic · previous generation | 30 Jun 2026 | $2.00 | $10 | $0.20 | $4.00 | Same price |
| Claude Sonnet 5.5Anthropic | 28 Sept 2026 | $2.00 | $10 | $0.20 | $4.00 | Baseline |
| GPT-6 SolOpenAI | 22 Sept 2026 | $2.00 | $10 | $0.20 | $4.00 | Same price |
| Claude Opus 5.5Anthropic | 22 Sept 2026 | $4.00 | $20 | $0.20 | $8.00 | 2× the price |
| GPT-5.6 SolOpenAIPrice before the GPT-6 launch, from OpenAI's announcement. OpenRouter now lists $2 / $10. | 9 Jul 2026 | $4.00 | $20 | – | $8.00 | 2× the price |
| Claude Opus 5Anthropic | 24 Jul 2026 | $5.00 | $25 | $0.50 | $10 | 2.5× the price |
| Claude Fable 5Anthropic | 9 Jun 2026 | $10 | $50 | $1.00 | $20 | 5× the price |
| Claude Fable 5.1Anthropic | 1 Sept 2026 | $10 | $50 | $0.25 | $20 | 5× the price |
| GPT-6 AstraOpenAI | 4 Sept 2026 | $10 | $50 | $1.00 | $20 | 5× the price |
USD per million tokens, checked 2 Oct 2026 via OpenRouter. Comparison uses the blended price (3 input tokens for every output token).
Official benchmark results
Claude Sonnet 5.5 launch results
Reported by Anthropic on 28 Sept 2026 · exact values
| Benchmark | Claude Sonnet 5.5 | Claude Sonnet 5 | Claude Opus 5.5 | GPT-6 Sol |
|---|---|---|---|---|
| Terminal-Bench 4.0Agentic coding | 70.6% | 10.3% | 66.4% | – |
| FrontierCode 1.1 (main)Agentic coding · Sonnet 5.5 at max effort, 52.1% at xhigh | 46.2% | 42.4% | 54.4% | 49.3% |
| CursorBench 4.0Agentic coding | 55.5% | 34.1% | 57.8% | – |
| GDPval-AA v2.1Knowledge work | 1844 Elo | 1449 Elo | 1846 Elo | 1487 Elo |
| AA-Briefcase v1.1Knowledge work | 1811 Elo | 1359 Elo | 1822 Elo | 1483 Elo |
| Humanity's Last ExamMultidisciplinary reasoning · with tools | 64.5% | 54.9% | 67.7% | – |
| OSWorld 2.1Computer use · partial | 80.1% | 57% | 81.8% | – |
| ChartographyVisual chart recognition · no tools | 61.6% | 15.6% | 64.4% | 53.6% |
- Bold marks the best reported score in each row.
- Claude Opus 5.5's Terminal-Bench 4.0 score is at xhigh effort, its highest.
- OpenAI recently fixed a bug affecting GPT-6 Sol's image understanding; its GDPval-AA, AA-Briefcase and Chartography scores may predate the fix.
- A dash means the lab did not report a result for that model.
Terminal-Bench 4.0
Accuracy against cost · reported by Anthropic on 28 Sept 2026 · exact values
Measures how well a model completes complex, multi-step professional tasks within a command-line interface.
- Claude Sonnet 5.5
- Claude Opus 5.5
- Claude Sonnet 5
- GPT-5.6 Sol
Show data table
| Model | Effort | Score | Cost per task |
|---|---|---|---|
| Claude Sonnet 5.5 | low | 20% | $0.76 |
| Claude Sonnet 5.5 | medium | 28.8% | $0.83 |
| Claude Sonnet 5.5 | high | 43% | $1.94 |
| Claude Sonnet 5.5 | xhigh | 61.5% | $5.30 |
| Claude Sonnet 5.5 | max | 70.6% | $12.5 |
| Claude Opus 5.5 | low | 38.5% | $1.29 |
| Claude Opus 5.5 | medium | 57.6% | $2.94 |
| Claude Opus 5.5 | high | 64.2% | $3.88 |
| Claude Opus 5.5 | xhigh | 66.4% | $7.35 |
| Claude Opus 5.5 | max | 64.8% | $11.2 |
| Claude Sonnet 5 | low | 3.2% | $3.78 |
| Claude Sonnet 5 | medium | 4.4% | $4.83 |
| Claude Sonnet 5 | high | 4.5% | $8.20 |
| Claude Sonnet 5 | xhigh | 7% | $9.95 |
| Claude Sonnet 5 | max | 10.3% | $11.6 |
| GPT-5.6 Sol | low | 7.9% | $1.46 |
| GPT-5.6 Sol | medium | 20.9% | $2.69 |
| GPT-5.6 Sol | high | 26.1% | $4.12 |
| GPT-5.6 Sol | xhigh | 28.5% | $5.39 |
| GPT-5.6 Sol | max | 37.3% | $7.89 |
- Exact values from the data published with Anthropic's announcement.
- OpenAI did not report GPT-6 Sol on this benchmark, so Anthropic shows GPT-5.6 Sol.
FrontierCode v1.1, main set
Accuracy against cost · reported by Anthropic on 28 Sept 2026 · exact values
Measures whether an agent's code changes would be merged.
- Claude Sonnet 5.5
- Claude Opus 5.5
- Claude Sonnet 5
- GPT-6 Sol
Show data table
| Model | Effort | Score | Cost per task |
|---|---|---|---|
| Claude Sonnet 5.5 | low | 29.3% | $0.19 |
| Claude Sonnet 5.5 | medium | 36.5% | $0.24 |
| Claude Sonnet 5.5 | high | 49.4% | $0.42 |
| Claude Sonnet 5.5 | xhigh | 52.1% | $1.59 |
| Claude Sonnet 5.5 | max | 46.2% | $20.8 |
| Claude Opus 5.5 | low | 47.3% | $0.40 |
| Claude Opus 5.5 | medium | 54.6% | $0.80 |
| Claude Opus 5.5 | high | 54% | $1.09 |
| Claude Opus 5.5 | xhigh | 51.4% | $2.25 |
| Claude Opus 5.5 | max | 54.4% | $6.19 |
| Claude Sonnet 5 | low | 28.7% | $2.39 |
| Claude Sonnet 5 | medium | 35.2% | $3.81 |
| Claude Sonnet 5 | high | 39.4% | $6.10 |
| Claude Sonnet 5 | xhigh | 42.7% | $10.1 |
| Claude Sonnet 5 | max | 42.4% | $17.1 |
| GPT-6 Sol | low | 37.3% | $0.43 |
| GPT-6 Sol | medium | 45.9% | $0.77 |
| GPT-6 Sol | high | 47.7% | $1.04 |
| GPT-6 Sol | xhigh | 48.4% | $1.32 |
| GPT-6 Sol | max | 49.3% | $2.07 |
- Exact values from the data published with Anthropic's announcement.
CursorBench 4.0
Accuracy against cost · reported by Anthropic on 28 Sept 2026 · exact values
Evaluates coding agents on ambiguous, multi-file tasks taken from real Cursor sessions.
- Claude Sonnet 5.5
- Claude Opus 5.5
- Claude Sonnet 5
- GPT-5.6 Sol
Show data table
| Model | Effort | Score | Cost per task |
|---|---|---|---|
| Claude Sonnet 5.5 | low | 35.8% | $0.50 |
| Claude Sonnet 5.5 | medium | 39.2% | $0.70 |
| Claude Sonnet 5.5 | high | 47.8% | $1.67 |
| Claude Sonnet 5.5 | xhigh | 53.1% | $3.88 |
| Claude Sonnet 5.5 | max | 55.5% | $9.67 |
| Claude Opus 5.5 | low | 43.7% | $1.17 |
| Claude Opus 5.5 | medium | 52.5% | $2.91 |
| Claude Opus 5.5 | high | 56% | $3.97 |
| Claude Opus 5.5 | xhigh | 56% | $6.98 |
| Claude Opus 5.5 | max | 57.8% | $13.4 |
| Claude Sonnet 5 | low | 24.1% | $1.39 |
| Claude Sonnet 5 | medium | 28% | $2.31 |
| Claude Sonnet 5 | high | 30.8% | $3.48 |
| Claude Sonnet 5 | xhigh | 32% | $4.55 |
| Claude Sonnet 5 | max | 34.1% | $7.17 |
| GPT-5.6 Sol | low | 24.6% | $0.87 |
| GPT-5.6 Sol | medium | 31.1% | $1.77 |
| GPT-5.6 Sol | high | 35.7% | $2.85 |
| GPT-5.6 Sol | xhigh | 37.7% | $4.40 |
| GPT-5.6 Sol | max | 41.7% | $8.23 |
- Exact values from the data published with Anthropic's announcement.
- CursorBench does not report GPT-6 Sol publicly, so Anthropic shows GPT-5.6 Sol.
AA-Briefcase v1.1
Elo against cost · reported by Anthropic on 28 Sept 2026 · exact values
Artificial Analysis's benchmark of long-horizon knowledge work.
- Claude Sonnet 5.5
- Claude Opus 5.5
- Claude Sonnet 5
- GPT-6 Sol
Show data table
| Model | Effort | Elo | Cost per task |
|---|---|---|---|
| Claude Sonnet 5.5 | low | 1264 Elo | $0.87 |
| Claude Sonnet 5.5 | medium | 1461 Elo | $1.64 |
| Claude Sonnet 5.5 | high | 1634 Elo | $3.95 |
| Claude Sonnet 5.5 | xhigh | 1746 Elo | $9.63 |
| Claude Sonnet 5.5 | max | 1811 Elo | $29.2 |
| Claude Opus 5.5 | low | 1285 Elo | $1.15 |
| Claude Opus 5.5 | medium | 1642 Elo | $4.40 |
| Claude Opus 5.5 | high | 1705 Elo | $6.27 |
| Claude Opus 5.5 | xhigh | 1780 Elo | $12.3 |
| Claude Opus 5.5 | max | 1822 Elo | $21 |
| Claude Sonnet 5 | low | 923 Elo | $0.82 |
| Claude Sonnet 5 | medium | 1056 Elo | $1.73 |
| Claude Sonnet 5 | high | 1177 Elo | $3.76 |
| Claude Sonnet 5 | xhigh | 1274 Elo | $7.56 |
| Claude Sonnet 5 | max | 1359 Elo | $14.4 |
| GPT-6 Sol | low | 905 Elo | $0.12 |
| GPT-6 Sol | medium | 1142 Elo | $0.34 |
| GPT-6 Sol | high | 1289 Elo | $0.63 |
| GPT-6 Sol | xhigh | 1364 Elo | $1.19 |
| GPT-6 Sol | max | 1483 Elo | $2.67 |
- Exact values from the data published with Anthropic's announcement.
- Artificial Analysis ran Sonnet 5.5 on a pre-release deployment with a since-fixed structured output bug, which may slightly understate its score.