Claude Sonnet 5.5
No shutdown before this date. Claude Sonnet 5.5 stays on the Claude API until at least Sep 28, 2027.
≥ 11 mo- Earliest retirement
- ≥ 349 daysSep 28, 2027 · Claude API
- Arena Text
- 1,476#19 of 128 · Arena
- GPQA Diamond
- 95.6%#3 of 108 · Epoch AI
- List price · $ per 1M
- $2.00 in $10.00 outClaude API · cached input $0.10
- Context window
- 1MMax output 128K tokens
Dates on every platform
| Platform | Model ID and status | Deprecated | Shuts down | Replacement |
|---|---|---|---|---|
| Claude APIAnthropic: Model deprecations (opens in a new tab) · checked Oct 14, 2026 | claude-sonnet-5-5Active | – | ≥ 11 moNot sooner than | – |
| Azure AI FoundryMicrosoft: Claude models in Microsoft Foundry (opens in a new tab) · checked Oct 14, 2026 | claude-sonnet-5-5:1Active | – | None set | – |
| Azure AI FoundryMicrosoft: Claude models in Microsoft Foundry (opens in a new tab) · checked Oct 14, 2026 | claude-sonnet-5-5:2Active | – | None set | – |
| Amazon BedrockAmazon Web Services: Amazon Bedrock ListFoundationModels, us-east-1 (opens in a new tab) · checked Oct 14, 2026 | anthropic.claude-sonnet-5-5Active · also au.anthropic.claude-sonnet-5-5, eu.anthropic.claude-sonnet-5-5, global.anthropic.claude-sonnet-5-5, us.anthropic.claude-sonnet-5-5 | – | ≥ 11 moNot sooner than | – |
| Google Vertex AIGoogle Cloud: Claude Sonnet 5.5 on Google Cloud (opens in a new tab) · checked Oct 14, 2026 | claude-sonnet-5-5Active | – | ≥ 11 moNot sooner than | – |
Version 1 runs on Anthropic infrastructure.
Version 2 runs on Azure infrastructure.
In us-east-1, requests go through a cross-Region inference profile (listed in aliases).
What breaks when you move off Claude Sonnet 5.5
- Defaults
- Parameters
- Parameters
Intelligence
| Benchmark | Publisher | Score | Rank | Published |
|---|---|---|---|---|
| Arena Text | Arena | 1,476 ± 5 | #19 of 128 | Oct 8, 2026 |
| GPQA Diamond | Epoch AI | 95.6% ± 1.4% | #3 of 108 | Sep 29, 2026 |
| Arena WebDev | Arena | 1,774 ± 8 | #3 of 69 | Oct 8, 2026 |
| Arena Agent | Arena | 0 ± 0 | #7 of 35 | Oct 12, 2026 |
| FrontierMath Tier 4 | Epoch AI | 80.5% ± 6.3% | #8 of 58 | Sep 29, 2026 |
| FrontierMath Tiers 1-3 | Epoch AI | 88.8% ± 1.9% | #7 of 71 | Sep 29, 2026 |
| OTIS Mock AIME 2024-2025 | Epoch AI | 100.0% ± 0.0% | #4 of 105 | Sep 29, 2026 |
| SimpleQA Verified | Epoch AI | 46.5% ± 1.6% | #29 of 68 | Sep 29, 2026 |
Arena (arena.ai), https://arena.ai/leaderboard
Epoch AI, ‘Capabilities & benchmarking’. Published online at epoch.ai. Retrieved from ‘https://epoch.ai/benchmarks’ [online resource].
List prices
| Platform | Input | Cached | Output | In effect | Source |
|---|---|---|---|---|---|
Claude APIclaude-sonnet-5-5 | $2.00 | $0.10 | $10.00 | Sep 28, 2026Current | Anthropic: Pricing (opens in a new tab) |
Amazon Bedrockanthropic.claude-sonnet-5-5 | $2.20 | $0.11 | $11.00 | Oct 1, 2026Current · Standard tier, in-Region or geographic cross-Region inference, which Bedrock prices 10% above global cross-Region inference. | Amazon Web Services: AWS Price List API: AmazonBedrockFoundationModels, us-east-1 (opens in a new tab) |
Google Vertex AIclaude-sonnet-5-5 | $2.00 | $0.10 | $10.00 | Sep 28, 2026Current · Global endpoint price; regional and multi-region endpoints cost more. | Google Cloud: Agent Platform pricing (opens in a new tab) |
Change history
ShutdownClaude Sonnet 4.5 shuts down on the Claude APIClaude API6 breaks
Requests to claude-sonnet-4-5-20250929 fail after the shutdown date. Anthropic names Claude Sonnet 5.5 as the replacement.
- Platform
- Claude API
- Model
- Claude Sonnet 4.5
- Replacement
- Claude Sonnet 5.5
- Announced
- ParametersClaude 4.7 and later models return a 400 error when temperature, top_p or top_k is set to a non-default value. Remove them before switching.
- ParametersManual thinking budgets (thinking type "enabled" with budget_tokens) return a 400 error on Claude Sonnet 5.5. Use adaptive thinking and an effort level.
- ParametersA prefilled final assistant turn returns a 400 error. Claude Sonnet 4.5 accepted one.
- ParametersForced tool choice (tool_choice "any" or "tool") returns a 400 error on Claude Sonnet 5.5. Use "auto" with strict tools.
- DefaultsRequests without a thinking field run with adaptive thinking on Claude Sonnet 5.5, so responses can start with thinking blocks.
- TokenizerThe same text produces about 30% more tokens than on Claude Sonnet 4.5. Recount prompts and revisit max_tokens.
Source: Anthropic, Model deprecations (opens in a new tab); Anthropic, Claude Sonnet 5.5 migration guide (opens in a new tab)
ShutdownClaude Sonnet 4.5 retires on Azure AI FoundryAzure AI Foundry1 break
claude-sonnet-4-5 retires on Foundry. Microsoft lists claude-sonnet-5-5 as the replacement.
- Platform
- Azure AI Foundry
- Model
- Claude Sonnet 4.5
- Replacement
- Claude Sonnet 5.5
- AvailabilityInference requests to retired deployments return 410 Gone.
Source: Microsoft, Model retirement schedule - Microsoft Foundry (opens in a new tab); Microsoft, Microsoft Foundry Models lifecycle and support policy (opens in a new tab)
ReleaseClaude Sonnet 5.5 releasedClaude API, Google Vertex AI3 breaks
Anthropic released Claude Sonnet 5.5 at the Claude Sonnet 5 price, with cache reads at half the earlier rate. Google Cloud lists the same release date.
- Platform
- Claude API, Google Vertex AI
- Model
- Claude Sonnet 5.5
- DefaultsRequests without a thinking field now run with adaptive thinking.
- ParametersThinking type "disabled" returns a 400 error. Send thinking type "between_tools" to turn off up-front thinking.
- ParametersForced tool choice (tool_choice "any" or "tool") returns a 400 error.
Source: Anthropic, Claude Sonnet 5.5 (opens in a new tab); Anthropic, Claude Sonnet 5.5 migration guide (opens in a new tab); Google Cloud, Claude Sonnet 5.5 on Google Cloud (opens in a new tab); Google Cloud, Gemini Enterprise Agent Platform release notes (opens in a new tab)
ReleaseClaude Sonnet 5.5 available on Amazon BedrockAmazon Bedrock
Bedrock added Claude Sonnet 5.5 as anthropic.claude-sonnet-5-5.
- Platform
- Amazon Bedrock
- Model
- Claude Sonnet 5.5
Source: Amazon Web Services, Amazon Bedrock ListFoundationModels, us-east-1 (opens in a new tab)