In this post, I am sharing one script to find the size of Indexes in SQL Server.

The first step for performance optimization is to measure the size of tables and indexes which helps you to find out more about fragmentation.

I have already shared a couple of articles on SQL Server Indexes like: find duplicate indexes, unused indexes and fragmentation of indexes.

You can also access these articles after below T-SQL.

SELECT
	OBJECT_SCHEMA_NAME(i.OBJECT_ID) AS SchemaName
	,OBJECT_NAME(i.OBJECT_ID) AS TableName
	,i.name AS IndexName
	,8 * SUM(au.used_pages) AS IndexSizeInKB
FROM sys.indexes AS i
JOIN sys.partitions AS p 
	ON p.OBJECT_ID = i.OBJECT_ID 
		AND p.index_id = i.index_id
JOIN sys.allocation_units AS au 
	ON au.container_id = p.partition_id
GROUP BY 
	i.OBJECT_ID
	,i.index_id
	,i.name
ORDER BY OBJECT_NAME(i.OBJECT_ID),i.index_id

Other related articles:

SQL Server: Find the total row count and size of the Tables

SQL Server: Script to find Redundant and Duplicate Indexes

SQL Server: Script to find usage of Database Indexes

SQL Server: Script to find Index Average Fragmentation in Percentage