If you use the IP calculator and plug in your network address (or use a private network address) and then 22 and 24 in the net mask boxes, you will get the settings you need. If those blocks wont work for you then you can change these two numbers until you get the segment sizes you need. The more bits in the subnet mask the more subnets you will end up with but each will be smaller.

One thing to keep in mind is that depending on your network hardware capabilities you need not necessarily define only one IP sub net per physical network segment. This does get a little more complicated but can be usefull if you are really tight on addresses on one segment but have many extra in another segment. Regardless of this ability, from a management point of view I would never create a subnet using anything larger than a 27 bit network mask (30 nodes per subnet)