You can use the filestats command with the sizes option to specify the breakdown of sizes.
The following example shows the file size section of the output when filestats sizes 500K,2M,1G volume vol0 snapshot hourly.1 is entered to display file sizes in four categories—files with less than 500 kilobytes, files with less than 2 megabytes, files with less than 1 gigabyte, and all other files.
FILE SIZE CUMULATIVE COUNT CUMULATIVE TOTAL KB 500K 862 4969 2M 866 10748 1G 882 146000 MAX 882 146000