Subnetting Cheat Charts

March 8, 2008 – 7:10 PM

I won’t get into a whole subnetting lesson here but, if you already know subnetting, then you’ll know exactly what these charts are and what they mean.I find them very helpful to have around. It saves lots of precious time.

Class A Subnetting

# bits Subnet Mask CIDR # Subnets # Hosts Nets * Hosts
2 255.192.0.0 /10 2 4194302 8388604
3 255.224.0.0 /11 6 2097150 12582900
4 255.240.0.0 /12 14 1048574 14680036
5 255.248.0.0 /13 30 524286 15728580
6 255.252.0.0 /14 62 262142 16252804
7 255.254.0.0 /15 126 131070 16514820
8 255.255.0.0 /16 254 65534 16645636
9 255.255.128.0 /17 510 32766 16710660
10 255.255.192.0 /18 1022 16382 16742404
11 255.255.224.0 /19 2046 8190 16756740
12 255.255.240.0 /20 4094 4094 16760836
13 255.255.248.0 /21 8190 2046 16756740
14 255.255.252.0 /22 16382 1022 16742404
15 255.255.254.0 /23 32766 510 16710660
16 255.255.255.0 /24 65534 254 16645636
17 255.255.255.128 /25 131070 126 16514820
18 255.255.255.192 /26 262142 62 16252804
19 255.255.255.224 /27 524286 30 15728580
20 255.255.255.240 /28 1048574 14 14680036
21 255.255.255.248 /29 2097150 6 12582900
22 255.255.255.252 /30 4194302 2 8388604

Class B Subnetting

# bits Subnet Mask CIDR # Subnets # Hosts Nets * Hosts
2 255.255.192.0 /18 2 16382 32764
3 255.255.224.0 /19 6 8190 49140
4 255.255.240.0 /20 14 4094 57316
5 255.255.248.0 /21 30 2046 61380
6 255.255.252.0 /22 62 1022 63364
7 255.255.254.0 /23 126 510 64260
8 255.255.255.0 /24 254 254 64516
9 255.255.255.128 /25 510 126 64260
10 255.255.255.192 /26 1022 62 63364
11 255.255.255.224 /27 2046 30 61380
12 255.255.255.240 /28 4094 14 57316
13 255.255.255.248 /29 8190 6 49140
14 255.255.255.252 /30 16382 2 32764

Class C Subnetting

# bits Subnet Mask CIDR # Subnets # Hosts Nets * Hosts
2 255.255.255.192 /26 2 62 124
3 255.255.255.224 /27 6 30 180
4 255.255.255.240 /28 14 14 196
5 255.255.255.248 /29 30 6 180
6 255.255.255.252 /30 62 2 124

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