Here is a table of all IP address ranges:
Subnet Mask # of Addresses Subnet Mask # of Addresses /1 128.0.0.0 2.1 billion /17 255.255.128.0 32,766 /2 192.0.0.0 1 billion /18 255.255.192.0 16,382 /3 224.0.0.0 536 million /19 255.255.224.0 8,190 /4 240.0.0.0 268 million /20 255.255.240.0 4,094 /5 248.0.0.0 134 million /21 255.255.248.0 2,046 /6 252.0.0.0 67 million /22 255.255.252.0 1,022 /7 254.0.0.0 34 million /23 255.255.254.0 510 /8 255.0.0.0 17 million (Class A) /24 255.255.255.0 254 (Class C) /9 255.128.0.0 8.4 million /25 255.255.255.128 126 /10 255.192.0.0 4.2 million /26 255.255.255.192 62 /11 255.224.0.0 2.1 million /27 255.255.255.224 30 /12 255.240.0.0 1 million /28 255.255.255.240 14 /13 255.248.0.0 524 thousand /29 255.255.255.248 6 /14 255.252.0.0 262 thousand /30 255.255.255.252 2 /15 255.254.0.0 131 thousand /31 255.255.255.254 RFC 3021 /16 255.255.0.0 65,534 (Class B) /32 255.255.255.255. Loopback address