I'm assuming you're using a 255.255.255.0 mask. Changing that to 255.255.0.0 would be more than enough room to grow.
To understand how subnetting works, you first must have a good basic understanding of IP addresses. An IP address is set of binary octets broken into quads. That definition may not have made any sense ...
We found several utilities to help calculate IP subnets, subnet ranges, and CIDR addressing. IP Subnet Calculator (free) is a good, basic subnet calculator that shows available subnets based on IP ...