measuring the amount of file uploaded

There isn't a way to check the progress of an in-process upload remotely via the API. Depending on what, if any, SDK or library you're using though, there may be a local progress callback available though. (For example, here's a sample of using that in the Objective-C SDK.) Check the documentation for whatever SDK/library, if any, you're using for more information.

Note that for files larger than 150 MB though, you should be using "upload sessions", which do have you upload files in pieces:

https://www.dropbox.com/developers/documentation/http/documentation#files-upload_session-start
https://www.dropbox.com/developers/documentation/http/documentation#files-upload_session-append_v2
https://www.dropbox.com/developers/documentation/http/documentation#files-upload_session-finish

In that way, you can track (again, from the API client side) how much you've uploaded, in between calls. 

Yes, I actually found out about the upload session recently, but it's giving me errors. For example, I'm using this core logic for upload sessions, but I'm getting a connection timeout error or something like API error.

test_files = ['testfile.iso']
file_path = os.path.join(os.path.dirname(os.path.abspath('__file__')),test_files[0])
file_size =os.path.getsize(file_path)
chunk_size = 4*1024*1024 # 4mb chunks
dest_path = '/upload_filetest.iso'


dbx = dropbox.Dropbox("{}".format(dropbox_id))#dropbox_id is my api key
f = open(file_path, 'rb')

if file_size <= chunk_size:
    dbx.files_upload(f.read(), dest_path)
    f.close()
    print("file has been uploaded")
else:
    upload_session_info = dbx.files_upload_session_start(f.read(chunk_size), close=False)
    print("Chunk uploaded from start: ", f.tell()/(1024*1024))
    #session_id = upload_session_info.session_id
    print("The session_id is: ", upload_session_info.session_id)
    cursor = dropbox.files.UploadSessionCursor(session_id=upload_session_info.session_id,  
                offset=f.tell())                                     
    
    commit = dropbox.files.CommitInfo(dest_path)

    while f.tell() < file_size:
        if (file_size - f.tell()) <= chunk_size:
            dbx.files_upload_session_finish(f.read(chunk_size), cursor, commit)
            print("chunk uploaded in finish: ", f.tell()/(1024*1024))
            time.sleep(1)
        
        else:
            dbx.files_upload_session_append_v2(f.read(chunk_size), cursor)
            cursor = dropbox.files.UploadSessionCursor(session_id=upload_session_info.session_id,offset=f.tell())

            print("Chunk uploaded in append: ", f.tell()/(1024*1024))
            time.sleep(1)



f.close()  

I had been researchin on this, and found that, I should replace

cursor = dropbox.files.UploadSessionCursor(session_id=upload_session_info.session_id,offset=f.tell())  

with

cursor = f.tell()

Don't know if it was the issue, but, the error is gone. I tried cutting off my network and it gave me a similar issue, so, it could've related to network connectivity as well.