Effort: max · Max, Default Fallback
anthropicReleased Sep 28, 2026
Anthropic: Claude Sonnet 5.5
Tuned for quick iteration on scoped fixes and documents; Anthropic favors Opus 5.5 for open-ended work needing sustained judgment.
Source description
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. It is especially strong at building features, fixing bugs, and producing...
Context window1M
Max output128K
Provider endpoints11
Benchmark results19
Agent runs1
Measured performance
All leaderboards ↗Benchmark results
Effort: max · Max, Default Fallback
GDPval-AA ↗2.1
1,837.82Effort: max · Max, Default Fallback
AutomationBench-AA ↗AA Index 4.3.2 collection
71.77%Effort: max · Max, Default Fallback
Effort: max · Max, Default Fallback · Harness unreported
SciCode ↗AA Index 4.3.2 collection
61%AA · Under reviewEffort: max · Max, Default Fallback
Humanity’s Last Exam ↗AA Index 4.3.2 collection
54.96%Effort: max · Max, Default Fallback
GDP.pdf ↗AA Index 4.3.2 collection
25.8%Effort: max · Max, Default Fallback
CritPt ↗AA Index 4.3.2 collection
31.43%AA · Under reviewEffort: max · Max, Default Fallback
AA-Omniscience ↗AA Index 4.3.2 collection
32.3Effort: max · Max, Default Fallback
AA-LCR ↗1.1
82.67%Effort: max · Max, Default Fallback
LiveBench Overall ↗2.0 · 2026-10-14 (dataset 2026-09-02)
82.46%Effort: max · single run · equal mean of 7 suites
LiveBench Design ↗2.0 · 2026-10-14 (dataset 2026-09-02)
85%Effort: max · single run
LiveBench Research ↗2.0 · 2026-10-14 (dataset 2026-09-02)
83.6%Effort: max · single run
LiveBench Browser Use ↗2.0 · 2026-10-14 (dataset 2026-09-02)
84%Effort: max · single run
LiveBench Coding ↗2.0 · 2026-10-14 (dataset 2026-09-02)
94.7%Effort: max · single run
LiveBench Agentic ↗2.0 · 2026-10-14 (dataset 2026-09-02)
78.8%Effort: max · single run
LiveBench Data Analysis ↗2.0 · 2026-10-14 (dataset 2026-09-02)
59.5%Effort: max · single run
LiveBench Reasoning ↗2.0 · 2026-10-14 (dataset 2026-09-02)
91.6%Effort: max · single run
Provider measurements
1 configurationSpeed
≈10K input tokens1 requestmedian / 72h
Artificial Analysis · first-party providers · serving endpoint not reported
Anthropic
Claude Sonnet 5.5 (Max, Default Fallback)
Reasoning max
- Output rate
- 141.375 tok/s
- Time to first chunk
- 471.377 s
Last checked Source ↗
Methodology 2.2.0 & measurement details
First chunk includes request processing and network time, and may include reasoning.
- Prompt
- long · ≈10,000 input tokens
- Parallel requests
- 1
- Minimum answer
- 1,500 tokens
- Aggregation
- median over 72 hours
- Token counting
- o200k_base
- Benchmark client
- Google Cloud us-central1-a
- Serving endpoint
- Not reported
- Serving region
- Not reported
- Sample size
- Not reported
- Window end
- Not reported
Model + harness
All agent results ↗Agent runs
Terminal-Bench 4.0
claude-code2.1.284
Reasoning effort max
Tested model identity
Sonnet 5.5anthropic/claude-sonnet-5-5Pass rate61.82%
95% CI 58.88%–64.76%
n = 330Checked
Access & cost
11 quotesPrices across providers
Your token mix
USD · listed token ratesOpenRouter
Catalog quote- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
- Input
- $2.00
- Output
- $10.00
Experiential
Standard list rate
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Catalog list rate. Plan allowances and temporary discounts are separate.
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Cache write $2.5/M tokens · 1h cache write $4/M tokens · Web search $0.01/search
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Cache write $2.5/M tokens · 1h cache write $4/M tokens · Web search $0.01/search
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Cache write $2.5/M tokens · 1h cache write $4/M tokens · Web search $0.01/search
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Cache write $2.5/M tokens · 1h cache write $4/M tokens · Web search $0.01/search
- Input
- $2.00
- Output
- $10.00
- Cached input
- $0.10
Cache write $2.5/M tokens · 1h cache write $4/M tokens · Web search $0.01/search
- Input
- $2.20
- Output
- $11.00
- Cached input
- $0.11
Cache write $2.75/M tokens · 1h cache write $4.4/M tokens · Web search $0.01/search
- Input
- $2.20
- Output
- $11.00
- Cached input
- $0.11
Cache write $2.75/M tokens · 1h cache write $4.4/M tokens · Web search $0.01/search
- Input
- $2.20
- Output
- $11.00
- Cached input
- $0.11
Cache write $2.75/M tokens · 1h cache write $4.4/M tokens · Web search $0.01/search
Model specifications
- Developer
- anthropic
- Modality
- Language
- Context
- 1,000,000 tokens
- Maximum output
- 128,000 tokens
- Weights
- Not reported
- Released
- Sep 28, 2026
- Provider listed
- Sep 28, 2026
- First discovered
- Oct 16, 2026
Exact identities
- openrouter
anthropic/claude-sonnet-5.5 - deepinfra
anthropic/claude-sonnet-5-5 - experiential
claude-sonnet-5.5 - artificial-analysis
b171d979-5ec1-45de-b8b9-db1ee65e77ec - livebench
claude-sonnet-5.5
Sources
Updated Oct 17, 2026
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