Hello meilinglam

When you upload an document via API, each document must be less than 25 MB, and the envelope total size including all documents cannot exceed 200 MB. Keep in mind that certain PDFs can increase the size when they are base64 encoded.
These rules and limits are valid for the SOAP and REST APIs, so if you need to add multiple files to the envelope whose combined size is greater than 25 MB, you can create a draft envelope and upload the files in batches of 25 MB or less.
You can also use the chuncked upload method (available only in REST) in order to upload documents in pieces of up to 52 MB. 
You can refer for more details regarding the limits and the chuncked upload method below:
Envelope Limits: https://support.docusign.com/s/articles/DocuSign-Document-and-Envelope-File-Size-Limitations?language=en_US
Chuncked Uploads:
https://www.docusign.com/blog/developers/the-trenches-chunked-uploads

Hello Thiago,

Thanks for your response.

The envelope sent (using REST) had only 1 document and it was 30 MB. Let’s assumed it’s increased to 41 MB with base64 encoded. If max size for envelope total is 200 MB, then POST request should not failed with message below. 

REQUEST_ENTITY_TOO_LARGE - The request size of 41625837 bytes exceeded the maximum size of 35651584 bytes