Viewing the MFT size on any modern Windows version

On Windows 10, you can get a lot of neat information about any given file's disk layout with this command:

fsutil volume filelayout c:\path\to\file.ext

The data size is reported in the Size row of the ::$DATA stream's section. That even works on the $MFT file (the Master File Table) for the volume. Unfortunately, the filelayout subcommand doesn't exist on older versions of Windows.

On earlier versions, the MFT size is reported with the general NTFS information:

fsutil fsinfo ntfsinfo c:

Look for the Mft Valid Data Length line. The value is the hexadecimal number of bytes.

Based on my Super User answer.