SQL Server- How many IP Addresses used in SQL Server Clustering?

• 2 IP for heartbeat network (1 per node)

• 2 IP for public network (1 per node)

• 1 IP for Windows Cluster.

• 2 IP for SQL Server Virtual Network Name (SQL instance on each node)

• 1 IP for MSDTC (this is optional however required if you use distributed transaction like linked server)

For Single Instance single cluster ( active/passive)
In above instead of two you will only need one IP address for SQL Server virtual network name.