On the Nokia Mobile Internet Toolkit 3.0 the message area displays the size of the content after you encode the text based data for device simulator. However, Nokia does not provide any tools for the content and application developer to check the size of the content runtime, other than that too large decks are blocked by the Nokia WAP gateways.
The maximum item size is 1397 bytes binary (about 1.3KB without WSP headers) for the Nokia 7110/7190/6210/6250 and 2800 binary (about 2.7KB without WSP headers) for the Nokia 3330/6310/8310. This is the maximum size both for a WML deck and for an image including WSP headers. The WML deck and images are downloaded separately.