Anthropic Expands Claude API Request Limit to 128 MB

The fourfold increase resolves payload capacity issues that previously forced developers to chunk large data inputs.

Updated on Oct. 30, 2026 in Artificial Intelligence

Isometric editorial illustration of a stack of server drive modules, symbolizing expanded data payload capacity for technical infrastructure. — Anthropic has quadrupled the maximum request size limit for its Claude Messages API to 128 MB, easing payload constraints for developers. AI Illustration. Upload story photo >

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Anthropic has increased the request size limit for its Claude Messages API and Token Counting endpoint to 128 MB. This update, which is now live, quadruples the previous limit of 32 MB to accommodate larger data payloads.

Why it matters

The change addresses technical bottlenecks for developers who previously encountered 413 errors when file attachments or image-heavy sessions exceeded the former 32 MB capacity. By expanding the limit, Anthropic aims to support more complex multi-turn sessions and document-heavy interactions.

The Claude API request limit has moved to 128 MB, a fourfold increase over the prior 32 MB standard. Users should note that base64 encoding typically inflates binary file sizes by roughly one third, which previously triggered HTTP 413 error responses during high-volume data transmissions.

The players

Anthropic

An AI research company that develops the Claude large language model family and provides API access to its models for developers.

The details

The update expands the maximum allowed data payload for HTTP requests directed at Claude. This modification is designed to prevent service interruptions during sessions that incorporate extensive image data or multi-turn computer-use sequences. While the Messages API limit is now 128 MB, the company maintains separate constraints for other tools, including 256 MB for the Message Batches API and 500 MB for the Files API.

October 27, 2026: Anthropic announced the API request limit increase.

The Tech Race

As AI models become more multimodal, managing the data overhead of high-resolution image inputs and long-form documents has become a primary engineering hurdle. By quadrupling the request limit, Anthropic moves closer to the higher-capacity thresholds offered by its specialized Message Batches and Files APIs.

Developers currently constrained by HTTP 413 errors during multi-turn computer-use sessions or image-heavy API requests can now leverage larger payloads immediately. This change simplifies workflows by reducing the need for manual data chunking and splitting that was previously required to stay under the 32 MB ceiling.

The takeaway

Anthropic's move reduces the friction of integrating high-bandwidth multimodal tasks into production workflows. Developers should monitor their API utilization metrics to see if these expanded limits eliminate remaining latency or truncation issues during heavy file-processing tasks.