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Anthropic · Official-source model record

Claude Sonnet 4.5

Claude Sonnet · Version claude-sonnet-4-5-20250929

DeprecatedChecked Oct 23, 2026
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Publisher-sourced inventory. Specifications come from official documentation and model cards. “Not documented” means we have no verified value. This inventory is separate from our editorial reviews.

Coverage & sources ↗

Current catalog answers

What to know about Claude Sonnet 4.5

AI-compiled from linked model documentation. This is a catalog reference, not an independent performance review. Catalog checked October 23, 2026.

What are Claude Sonnet 4.5's context and output limits?

The documented context window is 200,000 tokens. Source

The documented maximum output is 64,000 tokens. Source

Context, input and output limits describe different constraints. Do not add the figures together to infer a larger window. Check the endpoint's accounting for conversation history, system instructions, tools, media and generated tokens; a documented maximum is not a guarantee of answer quality or a measured usable capacity.

Which Claude Sonnet 4.5 does this page describe?

Claude Sonnet 4.5 is a model record from Anthropic in the Claude Sonnet family. Source

The recorded model identifier or checkpoint is claude-sonnet-4-5-20250929. Use that exact identifier when checking documentation or a provider listing. Source

How can you access Claude Sonnet 4.5?

The catalog documents API access for Claude Sonnet 4.5. Source

As of the catalog check, this version was marked deprecated. Source Check the linked lifecycle information before starting a new integration.

For API use, confirm the exact model identifier, your account and region, and the endpoint's current limits in the linked documentation. An API listing does not establish access through a consumer subscription.

What dates are documented for Claude Sonnet 4.5?

Knowledge cutoff: January 2025. Source This labels the documented knowledge boundary; it is not a promise that every earlier fact is known or correct. The source labels this “Reliable knowledge cutoff.”

Training-data cutoff: July 2025. Source This describes the reported data boundary, not the day training finished. The source labels this “Training data cutoff.”

Release date: September 29, 2025. Source This is a release milestone, not a knowledge or training cutoff. The source labels this “Released.”

Retrieval or web tools can supply newer information at run time. That does not change the model's recorded training or knowledge dates, and this record does not establish that a particular endpoint includes those tools.

What can Claude Sonnet 4.5 receive and generate?

Documented inputs: text and image. Source

Documented outputs: text. Source

Input support and output generation are separate capabilities. Reading an image does not establish image generation; a text output listing does not establish speech output. File sizes, formats and media limits depend on the documented implementation.

Keep the exact version in view

Other Claude Sonnet models from Anthropic.

These are separate records in the same publisher family. A shared family name does not establish equal capabilities or interchangeable licenses.

Claude Sonnet 5

API · 1,000,000 context tokens

The documented record

Specifications, with their sources.

A missing value remains unknown. Input limits, output limits and the total context window are separate measurements.

Publisher
AnthropicSource ↗
Family
Claude SonnetSource ↗
Version
claude-sonnet-4-5-20250929Source ↗
Availability
DeprecatedSource ↗
Access
APISource ↗
Inputs
Text · ImageSource ↗
Outputs
TextSource ↗
Context window
200,000 tokensSource ↗
Maximum input
Not documented
Maximum output
64,000 tokensSource ↗
Knowledge cutoff
Jan 2025Reliable knowledge cutoff · month precisionSource ↗
Training-data cutoff
Jul 2025Training data cutoff · month precisionSource ↗
Training completed
Not documented
Release date
Sep 29, 2025Released · day precisionSource ↗
License
Not documented
Input price / 1M tokens
Not documented
Output price / 1M tokens
Not documented
Model identifiers and aliases 1
  • claude-sonnet-4-5

Follow the evidence

Official sources.

  1. model deprecations — official Anthropic documentation ↗platform.claude.com
  2. Claude Sonnet 4.5 official reference ↗platform.claude.com

From the Headless Thrones newsroom

Editorial about Claude Sonnet 4.5

No published articles are linked to this exact model yet. New coverage will appear here as it is published.

Your starting point

Claude Sonnet 4.5

Anthropic · API

Browse all models ↗
Inputs
Text · ImageSource ↗
Outputs
TextSource ↗
Context window
200,000 tokensSource ↗
Knowledge cutoff
Jan 2025Reliable knowledge cutoff · month precisionSource ↗

A place to begin comparing

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Matches must share an access route, support every documented input type of your starting model, and return text. When both publish a context limit in the same field, the candidate must fall between half and twice that limit. Unknown or differently defined limits remain as broader matches, after verified near-context matches. Within each group, recent documented releases appear first. These criteria do not establish equal quality. The full current inventory is considered.

Anthropic

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Cohere

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OpenAI

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A record you can follow

The source belongs beside the fact.

Official sources

Model records cite the developer’s documentation, release notes and model cards. A listing alone is not a tested service or a recommendation.

Dates mean different things

Knowledge cutoff, training-data cutoff, training completion and release date are separate fields. A model’s name or repository upload date does not establish any of them.

Limits need context

Some publishers use rounded K/M token figures. Deployment, reasoning settings and regional access can change usable limits. Read the source before choosing.

Coverage and last check

Independent editorial model library assembled from primary vendor documentation and official publisher model cards. This is a dated, auditable inventory of the sources reviewed, not a claim to every model worldwide. First-party language-model inventory for OpenAI, Anthropic, Google Gemini/Gemma, xAI, Meta and Reflection. Includes vendor-listed legacy/retired identities with explicit statuses; official pretrained and instruction-tuned checkpoints remain distinct. Excludes embeddings, moderation/guard models, image/audio/video-only generation, community fine-tunes, speculative draft helpers, format/runtime/quantization duplicates, and PaliGemma dataset-specific benchmark fine-tunes. Availability means documented vendor API or downloadable official weights, not guaranteed account eligibility. Unknown specifications and dates remain null. Rounded K/M limits preserve vendor granularity; exact integers are used only where documented. No OpenRouter facts are used. Primary-source inventory of language-capable models from Alibaba/Qwen, DeepSeek, Moonshot, MiniMax, Z.ai, ByteDance Seed, Tencent, Baidu, Xiaomi, StepFun, 01.AI, Shanghai AI Laboratory, Baichuan and OpenBMB. Includes full reachable official public weight inventories plus documented hosted API models and explicit retirements. Embeddings, reward/classifier/router/tokenizer/draft-head components, standalone OCR/document converters and image/video/audio-only generators are excluded; multimodal language models retained. Official packaging variants are folded into aliases where a canonical listing was identifiable; remaining research/base/SFT variants retain exact identities. Not a guarantee every historical/private/regional model is available. Unknown specifications remain null; K/M API display quantities use decimal normalization where explicitly noted, rather than implying verified exact serving ceilings. Model-name dates and repository creation timestamps are never used as release/training dates. Open weights does not mean unrestricted or OSI-open-source licensing. Some model-card bodies were unreachable; their public inventory metadata is retained and disclosed. Official Mistral, Cohere, AI21, NVIDIA Nemotron, Microsoft Phi/MAI, Amazon Nova, IBM Granite, AllenAI OLMo/Molmo, TII Falcon, Nous Research, Arcee and Essential AI model inventory checked 2026-10-23. Includes base, instruction, reasoning, coding and text-producing multimodal models, including legacy API versions. Excludes embeddings/rerankers/reward and safety classifiers, image/audio/video-only generation, robotics-only models, duplicate quantization/runtime packages, adapters, intermediate checkpoint experiments, and third-party mirrors. Arcee coverage focuses on its named product families rather than exploratory merge repositories. Repository listing means listed, not independently verified API availability. K/M figures are nominal decimal normalizations when the source supplies shorthand; deployment-specific exact token limits may differ. Unverified values remain null. This is a source-backed inventory, not a complete claim-level independent editorial review. Supplemental official Liquid AI, Reka and Inception generative language catalog. Excludes media-only generators and decision/classification-only models. No assumed training dates.

Catalog edition updated . Source links are provided on each model record.

View the full coverage report and discovery sources ↗