Claude Sonnet 5.5
Anthropic
- Released
- September 28, 2026
- Data date
- September 28, 2026
- Predecessor
- Claude Sonnet 5
- Intelligence
- Overall score
- Price
- Input · Output / 1M tokens
- Input
- Text, Image
- Output
- Text
- Position
- Rank 4 of 86
- Index score
- 87.9 / 100
Methodology and source
The index averages rank percentiles from 10 documented comparison cohorts.
Page 1 of 4
Published benchmarks
General tasks
BioMysteryBench
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-biomysterybench:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 15
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Harness: Terminus 2. Latency in seconds: 1086.061. Cost per task in USD: 3.736494. Source ID: vals-ai. Evidence capture ID: vals-biomysterybench-2026-09-29-ae8417ff089d. Source payload hash: ae8417ff089d100a7fe142b979f417441381dcedfb13f35f1e2a2f4d06f31aec. Parser version: vals-astro-v2. Imported at: 2026-09-29
MysteryMechanism
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-mysterymechanism:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 16
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 1410.236. Cost per task in USD: 3.45323. Source ID: vals-ai. Evidence capture ID: vals-mysterymechanism-2026-09-29-258cfbb1bd2e. Source payload hash: 258cfbb1bd2e39fcae6d5a1181c9808368bbc3987691d3d1b32b5d193fc465a7. Parser version: vals-astro-v2. Imported at: 2026-09-29
Coding
Code Migration
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-code-migration:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 56
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 12004.483. Cost per task in USD: 75.826721. Source ID: vals-ai. Evidence capture ID: vals-code-migration-2026-09-29-f0b317d5bed3. Source payload hash: f0b317d5bed3a2654a9ea39762d5e57f4649306adce3e6103e845ee1b9b94add. Parser version: vals-astro-v2. Imported at: 2026-09-29
IOI
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-ioi:2:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 27
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Latency in seconds: 2751.084. Cost per task in USD: 7.524252. Source ID: vals-ai. Evidence capture ID: vals-ioi-2026-09-29-14c4f2dcc872. Source payload hash: 14c4f2dcc872d5e07bce234aebe4932202931d7f5b05f9bcd02e7695b5664750. Parser version: vals-astro-v2. Imported at: 2026-09-29
CyberBench v1.1
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-cyberbench:1.1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 28
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 2032.625. Cost per task in USD: 4.417372. Source ID: vals-ai. Evidence capture ID: vals-cyber-2026-09-29-36ddb5f67bc8. Source payload hash: 36ddb5f67bc8725a7ff9d1cc1349f89d29e0e907ad313eb5ac277b42b3d275e1. Parser version: vals-astro-v2. Imported at: 2026-09-29
Finance
EMB
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-emb:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 53
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 2204.991. Cost per task in USD: 8.792863. Source ID: vals-ai. Evidence capture ID: vals-emb-2026-09-29-90535b2fd4dc. Source payload hash: 90535b2fd4dc213540eac0aff8ae769e34b6b1ba54e1ed6d0a51dcfe307d5598. Parser version: vals-astro-v2. Imported at: 2026-09-29
Finance Agent (v2)
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-finance-agent-v2:2:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 54
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 1903.336. Cost per task in USD: 6.552431. Source ID: vals-ai. Evidence capture ID: vals-fabv2-2026-09-29-addcd124c670. Source payload hash: addcd124c6706893659c1ae26698bf6ffa29c91018ee95b98ab15b9d4b6edcdb. Parser version: vals-astro-v2. Imported at: 2026-09-29
Legal
Harvey's Legal Agent Benchmark
Overall · Task fully resolved
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-legal-agent-benchmark:1:overall
- Metric
- task resolution rate
- Scale
- 0-100
- Participants
- 55
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Latency in seconds: 3463.508. Cost per task in USD: 16.612583. Source ID: vals-ai. Evidence capture ID: vals-hlab-2026-09-29-d6fb708e5bcc. Source payload hash: d6fb708e5bccec56c7a5e5ad97918d9cc47c5ebefb88af4a1a5771493dadba2f. Parser version: vals-astro-v2. Imported at: 2026-09-29
Legal Research Bench
Overall · All-pass
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-legal-research:1:overall
- Metric
- all-pass rate
- Scale
- 0-100
- Participants
- 54
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 5588.989. Cost per task in USD: 14.826571. Source ID: vals-ai. Evidence capture ID: vals-legal_research-2026-09-29-b15acd492114. Source payload hash: b15acd492114174e151eff7ff17a38d547d5a1e93d2d598c153066542bbc56b7. Parser version: vals-astro-v2. Imported at: 2026-09-29
Health
MedCode
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-medcode:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 63
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-26. Latency in seconds: 239.171. Cost per task in USD: 0.391592. Source ID: vals-ai. Evidence capture ID: vals-medcode-2026-09-29-7062229b5ab4. Source payload hash: 7062229b5ab4a5e16f014a78fd550f9f34e7147be6be796b610ab1ca3de055ab. Parser version: vals-astro-v2. Imported at: 2026-09-29
MedScribe
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-medscribe:1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 64
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-26. Latency in seconds: 306.811. Cost per task in USD: 0.508604. Source ID: vals-ai. Evidence capture ID: vals-medscribe-2026-09-29-6533d95c8055. Source payload hash: 6533d95c80553d2dd26927f7269ab6454c589d2181f1858c662a4f493b5685c7. Parser version: vals-astro-v2. Imported at: 2026-09-29
ProofBench
Overall
higher is betterAs of September 29, 2026Scale: 0% - 100%
Methodology and context
- Comparison cohort
- vals-proof-bench:1.1:overall
- Metric
- accuracy
- Scale
- 0-100
- Participants
- 33
- Methodology and context
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-28. Latency in seconds: 347.583. Cost per task in USD: 0.558327. Source ID: vals-ai. Evidence capture ID: vals-proof_bench-2026-09-29-95d190db7be5. Source payload hash: 95d190db7be508012399269386113bf7df88cf108a8647fae6d361d15c60126b. Parser version: vals-astro-v2. Imported at: 2026-09-29
Recorded measurement details
Every observation retains its source value and published test conditions.
BioMysteryBench: Overall (Show measurement, test conditions, and source)
- Source value
- 81.111
- Score
- 81.111
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- general
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-biomysterybench:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Harness: Terminus 2. Latency in seconds: 1086.061. Cost per task in USD: 3.736494. Source ID: vals-ai. Evidence capture ID: vals-biomysterybench-2026-09-29-ae8417ff089d. Source payload hash: ae8417ff089d100a7fe142b979f417441381dcedfb13f35f1e2a2f4d06f31aec. Parser version: vals-astro-v2. Imported at: 2026-09-29
- Comparison methodology
- Harness: Terminus 2
Code Migration: Overall (Show measurement, test conditions, and source)
- Source value
- 69.825
- Score
- 69.825
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- coding
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-code-migration:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 12004.483. Cost per task in USD: 75.826721. Source ID: vals-ai. Evidence capture ID: vals-code-migration-2026-09-29-f0b317d5bed3. Source payload hash: f0b317d5bed3a2654a9ea39762d5e57f4649306adce3e6103e845ee1b9b94add. Parser version: vals-astro-v2. Imported at: 2026-09-29
CyberBench v1.1: Overall (Show measurement, test conditions, and source)
- Source value
- 59.584
- Score
- 59.584
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1.1
- Category
- cybersecurity
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-cyberbench:1.1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 2032.625. Cost per task in USD: 4.417372. Source ID: vals-ai. Evidence capture ID: vals-cyber-2026-09-29-36ddb5f67bc8. Source payload hash: 36ddb5f67bc8725a7ff9d1cc1349f89d29e0e907ad313eb5ac277b42b3d275e1. Parser version: vals-astro-v2. Imported at: 2026-09-29
EMB: Overall (Show measurement, test conditions, and source)
- Source value
- 75.713
- Score
- 75.713
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- finance
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-emb:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 2204.991. Cost per task in USD: 8.792863. Source ID: vals-ai. Evidence capture ID: vals-emb-2026-09-29-90535b2fd4dc. Source payload hash: 90535b2fd4dc213540eac0aff8ae769e34b6b1ba54e1ed6d0a51dcfe307d5598. Parser version: vals-astro-v2. Imported at: 2026-09-29
Finance Agent (v2): Overall (Show measurement, test conditions, and source)
- Source value
- 58.103
- Score
- 58.103
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 2
- Category
- finance
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-finance-agent-v2:2:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 1903.336. Cost per task in USD: 6.552431. Source ID: vals-ai. Evidence capture ID: vals-fabv2-2026-09-29-addcd124c670. Source payload hash: addcd124c6706893659c1ae26698bf6ffa29c91018ee95b98ab15b9d4b6edcdb. Parser version: vals-astro-v2. Imported at: 2026-09-29
IOI: Overall (Show measurement, test conditions, and source)
- Source value
- 83.056
- Score
- 83.056
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 2
- Category
- coding
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-ioi:2:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Latency in seconds: 2751.084. Cost per task in USD: 7.524252. Source ID: vals-ai. Evidence capture ID: vals-ioi-2026-09-29-14c4f2dcc872. Source payload hash: 14c4f2dcc872d5e07bce234aebe4932202931d7f5b05f9bcd02e7695b5664750. Parser version: vals-astro-v2. Imported at: 2026-09-29
Harvey's Legal Agent Benchmark: Overall · Task fully resolved (Show measurement, test conditions, and source)
- Source value
- 2.917
- Score
- 2.917
- Metric
- task resolution rate
- Unit
- %
- Benchmark version
- 1
- Category
- legal
- Task
- overall
- Task label
- Overall · Task fully resolved
- Direction
- Higher is better
- Comparison cohort
- vals-legal-agent-benchmark:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: public. Leaderboard date: 2026-09-27. Latency in seconds: 3463.508. Cost per task in USD: 16.612583. Source ID: vals-ai. Evidence capture ID: vals-hlab-2026-09-29-d6fb708e5bcc. Source payload hash: d6fb708e5bccec56c7a5e5ad97918d9cc47c5ebefb88af4a1a5771493dadba2f. Parser version: vals-astro-v2. Imported at: 2026-09-29
Legal Research Bench: Overall · All-pass (Show measurement, test conditions, and source)
- Source value
- 48.077
- Score
- 48.077
- Metric
- all-pass rate
- Unit
- %
- Benchmark version
- 1
- Category
- legal
- Task
- overall
- Task label
- Overall · All-pass
- Direction
- Higher is better
- Comparison cohort
- vals-legal-research:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 5588.989. Cost per task in USD: 14.826571. Source ID: vals-ai. Evidence capture ID: vals-legal_research-2026-09-29-b15acd492114. Source payload hash: b15acd492114174e151eff7ff17a38d547d5a1e93d2d598c153066542bbc56b7. Parser version: vals-astro-v2. Imported at: 2026-09-29
MedCode: Overall (Show measurement, test conditions, and source)
- Source value
- 52.92
- Score
- 52.92
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- health
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-medcode:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-26. Latency in seconds: 239.171. Cost per task in USD: 0.391592. Source ID: vals-ai. Evidence capture ID: vals-medcode-2026-09-29-7062229b5ab4. Source payload hash: 7062229b5ab4a5e16f014a78fd550f9f34e7147be6be796b610ab1ca3de055ab. Parser version: vals-astro-v2. Imported at: 2026-09-29
MedScribe: Overall (Show measurement, test conditions, and source)
- Source value
- 91.101
- Score
- 91.101
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- health
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-medscribe:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-26. Latency in seconds: 306.811. Cost per task in USD: 0.508604. Source ID: vals-ai. Evidence capture ID: vals-medscribe-2026-09-29-6533d95c8055. Source payload hash: 6533d95c80553d2dd26927f7269ab6454c589d2181f1858c662a4f493b5685c7. Parser version: vals-astro-v2. Imported at: 2026-09-29
MysteryMechanism: Overall (Show measurement, test conditions, and source)
- Source value
- 49.099
- Score
- 49.099
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1
- Category
- general
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-mysterymechanism:1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-27. Latency in seconds: 1410.236. Cost per task in USD: 3.45323. Source ID: vals-ai. Evidence capture ID: vals-mysterymechanism-2026-09-29-258cfbb1bd2e. Source payload hash: 258cfbb1bd2e39fcae6d5a1181c9808368bbc3987691d3d1b32b5d193fc465a7. Parser version: vals-astro-v2. Imported at: 2026-09-29
ProofBench: Overall (Show measurement, test conditions, and source)
- Source value
- 100
- Score
- 100
- Metric
- accuracy
- Unit
- %
- Benchmark version
- 1.1
- Category
- math
- Task
- overall
- Task label
- Overall
- Direction
- Higher is better
- Comparison cohort
- vals-proof-bench:1.1:overall
- Source type
- independent-evaluator
- Evaluator
- Vals AI
- Status
- active
- Retrieved at
- 2026-09-29
- Methodology
- Source model ID: anthropic/claude-sonnet-5-5. Source model name: Claude Sonnet 5.5. Evaluator: Vals AI. Dataset type: private. Leaderboard date: 2026-09-28. Latency in seconds: 347.583. Cost per task in USD: 0.558327. Source ID: vals-ai. Evidence capture ID: vals-proof_bench-2026-09-29-95d190db7be5. Source payload hash: 95d190db7be508012399269386113bf7df88cf108a8647fae6d361d15c60126b. Parser version: vals-astro-v2. Imported at: 2026-09-29
Page 1 of 4
Profile
Specifications and access
Published information about this model. Existing estimates are explicitly labeled.
Dated documentation and model-card observations. Provider limits, native context and extended context can differ. Configuration notes retain the source wording.
| Specification | Value and source |
|---|---|
| Weights | ProprietarySource |
| Access | APISource |
| Context window | 1,000,000 tokensSource |
| Knowledge cutoff | June 2026Source |
| Notes | Released September 28, 2026. Anthropic positions Sonnet 5.5 as a faster, lower-cost complement to Opus 5.5 for well-scoped everyday tasks, bug fixing, and documents, slides, and spreadsheets, priced at the unchanged Sonnet 5 rate of $2 / $10 per million input and output tokens. 1M context, 128K output, a June 2026 knowledge cutoff, adaptive thinking on by default, and high effort by default on the API (medium in Claude Code and the apps). Official API ID: claude-sonnet-5-5.Source |
| API model ID | claude-sonnet-5-5Source |
| Source status | activeSource |
| Release | 2026-09-28Source |
| Maximum output | 128,000 tokensSource |
| Input | Text, imagesSource |
| Output | TextSource |
| Reasoning mode | adaptive (on by default; between_tools turns off up-front thinking); default highSource |
| Reasoning effort | low, medium, high, xhigh, max; API default highSource |
| Knowledge cutoff | 2026-06Source |
Pricing
Published prices
Prices apply to the stated unit. Resolution, output length, and provider can change the cost.
- API input
- $2 per 1M tokensSource
- API output
- $10 per 1M tokensSource
- Cache write
- $2.5 per 1M tokensSource
- Cache write, 1 hour
- $4 per 1M tokensSource
- Cache read
- $0.2 per 1M tokensSource
- Source pricing conditions
- Batch API 50% off ($1 input / $5 output per million tokens); US-only inference (inference_geo: us) at 1.1x on all token categories; no long-context surcharge (1M tokens at standard pricing)Source
Head-to-head comparisons
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Model generations
Predecessor and successor
Every relationship names its kind, its qualification and the dated source it rests on.
- Predecessor
- Claude Sonnet 5
Model lineage evidence
Anthropic writes "It's a clear upgrade over Claude Sonnet 5" and that Sonnet 5.5 "costs up to 30% less per task than its predecessor," directly after stating it is "priced the same as Sonnet 5," identifying Sonnet 5 as that predecessor; the docs page "What's new in Claude Sonnet 5.5" describes "What changes when you move from Claude Sonnet 5 to Claude Sonnet 5.5".
Anthropic "Introducing Claude Sonnet 5.5" announcement (2026-09-28)
Evidence
Sources and data date
Every statement links to its underlying documentation or leaderboard.
| Type | Evidence and data date |
|---|---|
| Price | Base API prices without caching or batch discounts. Higher context tiers and other rates are listed under Costs. |
| Input | Documented modalities. Retrieved September 28, 2026. |
| Output | Documented modalities. Retrieved September 28, 2026. |
| Research status | Research date September 28, 2026. 5 source URLs checked. This documents the inspected sources, not an exhaustive inventory of every publication. |
| Not found in the inspected sources | parameters-billions Original wording Anthropic does not publish parameter counts for this model. |
| Not found in the inspected sources | active-parameters-billions Original wording Anthropic does not publish active parameter counts for this model. |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Vals AI (retrieved September 29, 2026) |
| Additional source | Anthropic (retrieved September 28, 2026) |
| Additional source | Model metadata (retrieved September 28, 2026) |
| Additional source | Model metadata (retrieved September 28, 2026) |
| Additional source | Anthropic "Introducing Claude Sonnet 5.5" announcement (2026-09-28) |