Available Hosts and Networks for Class B and Class C IPv4 Networks

For Class B Networks

network network mask hosts networks total hosts
/count possible available
16 255.255.0.0 65536 65534 1 65534
17 255.255.128.0 32768 32766 2 65532
18 255.255.192.0 16384 16382 4 65528
19 255.255.224.0 8192 8190 8 65520
20 255.255.240.0 4096 4094 16 65504
21 255.255.248.0 2048 2046 32 65472
22 255.255.252.0 1024 1022 64 65408
23 255.255.254.0 512 510 128 65280
24 255.255.255.0 256 254 256 65024
25 255.255.255.128 128 126 512 64512
26 255.255.255.192 64 62 1024 63488
27 255.255.255.224 32 30 2048 61440
28 255.255.255.240 16 14 4096 57344
29 255.255.255.248 8 6 8192 48744
30 255.255.255.252 4 2 16384 32764

For Class C Networks

network network mask hosts networks total hosts
/count possible available
24 255.255.255.0 256 254 1 254
25 255.255.255.128 128 126 2 252
26 255.255.255.192 64 62 4 248
27 255.255.255.224 32 30 8 240
28 255.255.255.240 16 14 16 224
29 255.255.255.248 8 6 32 192
30 255.255.255.252 4 2 64 128

possible: number of mathematically possible hosts or networks.

available: number of hosts or networks after subtracting
all-zeros and all-ones identifiers.

Private IT Addresses:  These addresses can’t be used in public Internet.

Private IP addresses

IP classes A, B & C had been some reserved addresses, known as private IP addresses. These IPs can be used within a network, campus, company and are private to it. These addresses cannot be routed on the Internet.

Loopback IP Addresses

The IP address range 127.0.0.0 – 127.255.255.255 is reserved for loopback, i.e. a Host’s self-address, also known as localhost address. This loopback IP address is managed entirely by and within the operating system. Loopback address is useful for sending packets to an internal interface and testing the communication.