SQL Server table index sizes

This will show the size of the indexes on a specific table

use MyDatabase

SELECT      i.name AS IndexName,

            SUM(s.used_page_count) * 8 AS IndexSizeKB

FROM        sys.dm_db_partition_stats AS s 

JOIN        sys.indexes AS i

ON          s.[object_id] = i.[object_id] AND s.index_id = i.index_id

WHERE       s.[object_id] = object_id('dbo.users')

GROUP BY    i.name

ORDER BY    i.name

Don't forget to substitute your own database name and table name!