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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network12.48.136.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
12.48.136.0
Broadcast address
12.48.137.255
First usable
12.48.136.1
Last usable
12.48.137.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Public public
Old class
A (default /8)
As numbers
Hex 0C308800 · Integer 204507136 to 204507647
Reverse DNS zones
136.48.12.in-addr.arpa
137.48.12.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001100.00110000.10001000.0000000012.48.136.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network00001100.00110000.10001000.0000000012.48.136.0
Broadcast00001100.00110000.10001001.1111111112.48.137.255
Split into smaller subnets/32
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

12.48.136.0/23 makes 512 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.48.136.0/3212.48.136.0 to 12.48.136.0—1
212.48.136.1/3212.48.136.1 to 12.48.136.1—1
312.48.136.2/3212.48.136.2 to 12.48.136.2—1
412.48.136.3/3212.48.136.3 to 12.48.136.3—1
512.48.136.4/3212.48.136.4 to 12.48.136.4—1
612.48.136.5/3212.48.136.5 to 12.48.136.5—1
712.48.136.6/3212.48.136.6 to 12.48.136.6—1
812.48.136.7/3212.48.136.7 to 12.48.136.7—1
912.48.136.8/3212.48.136.8 to 12.48.136.8—1
1012.48.136.9/3212.48.136.9 to 12.48.136.9—1
1112.48.136.10/3212.48.136.10 to 12.48.136.10—1
1212.48.136.11/3212.48.136.11 to 12.48.136.11—1
1312.48.136.12/3212.48.136.12 to 12.48.136.12—1
1412.48.136.13/3212.48.136.13 to 12.48.136.13—1
1512.48.136.14/3212.48.136.14 to 12.48.136.14—1
1612.48.136.15/3212.48.136.15 to 12.48.136.15—1
1712.48.136.16/3212.48.136.16 to 12.48.136.16—1
1812.48.136.17/3212.48.136.17 to 12.48.136.17—1
1912.48.136.18/3212.48.136.18 to 12.48.136.18—1
2012.48.136.19/3212.48.136.19 to 12.48.136.19—1
2112.48.136.20/3212.48.136.20 to 12.48.136.20—1
2212.48.136.21/3212.48.136.21 to 12.48.136.21—1
2312.48.136.22/3212.48.136.22 to 12.48.136.22—1
2412.48.136.23/3212.48.136.23 to 12.48.136.23—1
2512.48.136.24/3212.48.136.24 to 12.48.136.24—1
2612.48.136.25/3212.48.136.25 to 12.48.136.25—1
2712.48.136.26/3212.48.136.26 to 12.48.136.26—1
2812.48.136.27/3212.48.136.27 to 12.48.136.27—1
2912.48.136.28/3212.48.136.28 to 12.48.136.28—1
3012.48.136.29/3212.48.136.29 to 12.48.136.29—1
3112.48.136.30/3212.48.136.30 to 12.48.136.30—1
3212.48.136.31/3212.48.136.31 to 12.48.136.31—1
3312.48.136.32/3212.48.136.32 to 12.48.136.32—1
3412.48.136.33/3212.48.136.33 to 12.48.136.33—1
3512.48.136.34/3212.48.136.34 to 12.48.136.34—1
3612.48.136.35/3212.48.136.35 to 12.48.136.35—1
3712.48.136.36/3212.48.136.36 to 12.48.136.36—1
3812.48.136.37/3212.48.136.37 to 12.48.136.37—1
3912.48.136.38/3212.48.136.38 to 12.48.136.38—1
4012.48.136.39/3212.48.136.39 to 12.48.136.39—1
4112.48.136.40/3212.48.136.40 to 12.48.136.40—1
4212.48.136.41/3212.48.136.41 to 12.48.136.41—1
4312.48.136.42/3212.48.136.42 to 12.48.136.42—1
4412.48.136.43/3212.48.136.43 to 12.48.136.43—1
4512.48.136.44/3212.48.136.44 to 12.48.136.44—1
4612.48.136.45/3212.48.136.45 to 12.48.136.45—1
4712.48.136.46/3212.48.136.46 to 12.48.136.46—1
4812.48.136.47/3212.48.136.47 to 12.48.136.47—1
4912.48.136.48/3212.48.136.48 to 12.48.136.48—1
5012.48.136.49/3212.48.136.49 to 12.48.136.49—1
5112.48.136.50/3212.48.136.50 to 12.48.136.50—1
5212.48.136.51/3212.48.136.51 to 12.48.136.51—1
5312.48.136.52/3212.48.136.52 to 12.48.136.52—1
5412.48.136.53/3212.48.136.53 to 12.48.136.53—1
5512.48.136.54/3212.48.136.54 to 12.48.136.54—1
5612.48.136.55/3212.48.136.55 to 12.48.136.55—1
5712.48.136.56/3212.48.136.56 to 12.48.136.56—1
5812.48.136.57/3212.48.136.57 to 12.48.136.57—1
5912.48.136.58/3212.48.136.58 to 12.48.136.58—1
6012.48.136.59/3212.48.136.59 to 12.48.136.59—1
6112.48.136.60/3212.48.136.60 to 12.48.136.60—1
6212.48.136.61/3212.48.136.61 to 12.48.136.61—1
6312.48.136.62/3212.48.136.62 to 12.48.136.62—1
6412.48.136.63/3212.48.136.63 to 12.48.136.63—1
6512.48.136.64/3212.48.136.64 to 12.48.136.64—1
6612.48.136.65/3212.48.136.65 to 12.48.136.65—1
6712.48.136.66/3212.48.136.66 to 12.48.136.66—1
6812.48.136.67/3212.48.136.67 to 12.48.136.67—1
6912.48.136.68/3212.48.136.68 to 12.48.136.68—1
7012.48.136.69/3212.48.136.69 to 12.48.136.69—1
7112.48.136.70/3212.48.136.70 to 12.48.136.70—1
7212.48.136.71/3212.48.136.71 to 12.48.136.71—1
7312.48.136.72/3212.48.136.72 to 12.48.136.72—1
7412.48.136.73/3212.48.136.73 to 12.48.136.73—1
7512.48.136.74/3212.48.136.74 to 12.48.136.74—1
7612.48.136.75/3212.48.136.75 to 12.48.136.75—1
7712.48.136.76/3212.48.136.76 to 12.48.136.76—1
7812.48.136.77/3212.48.136.77 to 12.48.136.77—1
7912.48.136.78/3212.48.136.78 to 12.48.136.78—1
8012.48.136.79/3212.48.136.79 to 12.48.136.79—1
8112.48.136.80/3212.48.136.80 to 12.48.136.80—1
8212.48.136.81/3212.48.136.81 to 12.48.136.81—1
8312.48.136.82/3212.48.136.82 to 12.48.136.82—1
8412.48.136.83/3212.48.136.83 to 12.48.136.83—1
8512.48.136.84/3212.48.136.84 to 12.48.136.84—1
8612.48.136.85/3212.48.136.85 to 12.48.136.85—1
8712.48.136.86/3212.48.136.86 to 12.48.136.86—1
8812.48.136.87/3212.48.136.87 to 12.48.136.87—1
8912.48.136.88/3212.48.136.88 to 12.48.136.88—1
9012.48.136.89/3212.48.136.89 to 12.48.136.89—1
9112.48.136.90/3212.48.136.90 to 12.48.136.90—1
9212.48.136.91/3212.48.136.91 to 12.48.136.91—1
9312.48.136.92/3212.48.136.92 to 12.48.136.92—1
9412.48.136.93/3212.48.136.93 to 12.48.136.93—1
9512.48.136.94/3212.48.136.94 to 12.48.136.94—1
9612.48.136.95/3212.48.136.95 to 12.48.136.95—1
9712.48.136.96/3212.48.136.96 to 12.48.136.96—1
9812.48.136.97/3212.48.136.97 to 12.48.136.97—1
9912.48.136.98/3212.48.136.98 to 12.48.136.98—1
10012.48.136.99/3212.48.136.99 to 12.48.136.99—1
10112.48.136.100/3212.48.136.100 to 12.48.136.100—1
10212.48.136.101/3212.48.136.101 to 12.48.136.101—1
10312.48.136.102/3212.48.136.102 to 12.48.136.102—1
10412.48.136.103/3212.48.136.103 to 12.48.136.103—1
10512.48.136.104/3212.48.136.104 to 12.48.136.104—1
10612.48.136.105/3212.48.136.105 to 12.48.136.105—1
10712.48.136.106/3212.48.136.106 to 12.48.136.106—1
10812.48.136.107/3212.48.136.107 to 12.48.136.107—1
10912.48.136.108/3212.48.136.108 to 12.48.136.108—1
11012.48.136.109/3212.48.136.109 to 12.48.136.109—1
11112.48.136.110/3212.48.136.110 to 12.48.136.110—1
11212.48.136.111/3212.48.136.111 to 12.48.136.111—1
11312.48.136.112/3212.48.136.112 to 12.48.136.112—1
11412.48.136.113/3212.48.136.113 to 12.48.136.113—1
11512.48.136.114/3212.48.136.114 to 12.48.136.114—1
11612.48.136.115/3212.48.136.115 to 12.48.136.115—1
11712.48.136.116/3212.48.136.116 to 12.48.136.116—1
11812.48.136.117/3212.48.136.117 to 12.48.136.117—1
11912.48.136.118/3212.48.136.118 to 12.48.136.118—1
12012.48.136.119/3212.48.136.119 to 12.48.136.119—1
12112.48.136.120/3212.48.136.120 to 12.48.136.120—1
12212.48.136.121/3212.48.136.121 to 12.48.136.121—1
12312.48.136.122/3212.48.136.122 to 12.48.136.122—1
12412.48.136.123/3212.48.136.123 to 12.48.136.123—1
12512.48.136.124/3212.48.136.124 to 12.48.136.124—1
12612.48.136.125/3212.48.136.125 to 12.48.136.125—1
12712.48.136.126/3212.48.136.126 to 12.48.136.126—1
12812.48.136.127/3212.48.136.127 to 12.48.136.127—1
12912.48.136.128/3212.48.136.128 to 12.48.136.128—1
13012.48.136.129/3212.48.136.129 to 12.48.136.129—1
13112.48.136.130/3212.48.136.130 to 12.48.136.130—1
13212.48.136.131/3212.48.136.131 to 12.48.136.131—1
13312.48.136.132/3212.48.136.132 to 12.48.136.132—1
13412.48.136.133/3212.48.136.133 to 12.48.136.133—1
13512.48.136.134/3212.48.136.134 to 12.48.136.134—1
13612.48.136.135/3212.48.136.135 to 12.48.136.135—1
13712.48.136.136/3212.48.136.136 to 12.48.136.136—1
13812.48.136.137/3212.48.136.137 to 12.48.136.137—1
13912.48.136.138/3212.48.136.138 to 12.48.136.138—1
14012.48.136.139/3212.48.136.139 to 12.48.136.139—1
14112.48.136.140/3212.48.136.140 to 12.48.136.140—1
14212.48.136.141/3212.48.136.141 to 12.48.136.141—1
14312.48.136.142/3212.48.136.142 to 12.48.136.142—1
14412.48.136.143/3212.48.136.143 to 12.48.136.143—1
14512.48.136.144/3212.48.136.144 to 12.48.136.144—1
14612.48.136.145/3212.48.136.145 to 12.48.136.145—1
14712.48.136.146/3212.48.136.146 to 12.48.136.146—1
14812.48.136.147/3212.48.136.147 to 12.48.136.147—1
14912.48.136.148/3212.48.136.148 to 12.48.136.148—1
15012.48.136.149/3212.48.136.149 to 12.48.136.149—1
15112.48.136.150/3212.48.136.150 to 12.48.136.150—1
15212.48.136.151/3212.48.136.151 to 12.48.136.151—1
15312.48.136.152/3212.48.136.152 to 12.48.136.152—1
15412.48.136.153/3212.48.136.153 to 12.48.136.153—1
15512.48.136.154/3212.48.136.154 to 12.48.136.154—1
15612.48.136.155/3212.48.136.155 to 12.48.136.155—1
15712.48.136.156/3212.48.136.156 to 12.48.136.156—1
15812.48.136.157/3212.48.136.157 to 12.48.136.157—1
15912.48.136.158/3212.48.136.158 to 12.48.136.158—1
16012.48.136.159/3212.48.136.159 to 12.48.136.159—1
16112.48.136.160/3212.48.136.160 to 12.48.136.160—1
16212.48.136.161/3212.48.136.161 to 12.48.136.161—1
16312.48.136.162/3212.48.136.162 to 12.48.136.162—1
16412.48.136.163/3212.48.136.163 to 12.48.136.163—1
16512.48.136.164/3212.48.136.164 to 12.48.136.164—1
16612.48.136.165/3212.48.136.165 to 12.48.136.165—1
16712.48.136.166/3212.48.136.166 to 12.48.136.166—1
16812.48.136.167/3212.48.136.167 to 12.48.136.167—1
16912.48.136.168/3212.48.136.168 to 12.48.136.168—1
17012.48.136.169/3212.48.136.169 to 12.48.136.169—1
17112.48.136.170/3212.48.136.170 to 12.48.136.170—1
17212.48.136.171/3212.48.136.171 to 12.48.136.171—1
17312.48.136.172/3212.48.136.172 to 12.48.136.172—1
17412.48.136.173/3212.48.136.173 to 12.48.136.173—1
17512.48.136.174/3212.48.136.174 to 12.48.136.174—1
17612.48.136.175/3212.48.136.175 to 12.48.136.175—1
17712.48.136.176/3212.48.136.176 to 12.48.136.176—1
17812.48.136.177/3212.48.136.177 to 12.48.136.177—1
17912.48.136.178/3212.48.136.178 to 12.48.136.178—1
18012.48.136.179/3212.48.136.179 to 12.48.136.179—1
18112.48.136.180/3212.48.136.180 to 12.48.136.180—1
18212.48.136.181/3212.48.136.181 to 12.48.136.181—1
18312.48.136.182/3212.48.136.182 to 12.48.136.182—1
18412.48.136.183/3212.48.136.183 to 12.48.136.183—1
18512.48.136.184/3212.48.136.184 to 12.48.136.184—1
18612.48.136.185/3212.48.136.185 to 12.48.136.185—1
18712.48.136.186/3212.48.136.186 to 12.48.136.186—1
18812.48.136.187/3212.48.136.187 to 12.48.136.187—1
18912.48.136.188/3212.48.136.188 to 12.48.136.188—1
19012.48.136.189/3212.48.136.189 to 12.48.136.189—1
19112.48.136.190/3212.48.136.190 to 12.48.136.190—1
19212.48.136.191/3212.48.136.191 to 12.48.136.191—1
19312.48.136.192/3212.48.136.192 to 12.48.136.192—1
19412.48.136.193/3212.48.136.193 to 12.48.136.193—1
19512.48.136.194/3212.48.136.194 to 12.48.136.194—1
19612.48.136.195/3212.48.136.195 to 12.48.136.195—1
19712.48.136.196/3212.48.136.196 to 12.48.136.196—1
19812.48.136.197/3212.48.136.197 to 12.48.136.197—1
19912.48.136.198/3212.48.136.198 to 12.48.136.198—1
20012.48.136.199/3212.48.136.199 to 12.48.136.199—1
20112.48.136.200/3212.48.136.200 to 12.48.136.200—1
20212.48.136.201/3212.48.136.201 to 12.48.136.201—1
20312.48.136.202/3212.48.136.202 to 12.48.136.202—1
20412.48.136.203/3212.48.136.203 to 12.48.136.203—1
20512.48.136.204/3212.48.136.204 to 12.48.136.204—1
20612.48.136.205/3212.48.136.205 to 12.48.136.205—1
20712.48.136.206/3212.48.136.206 to 12.48.136.206—1
20812.48.136.207/3212.48.136.207 to 12.48.136.207—1
20912.48.136.208/3212.48.136.208 to 12.48.136.208—1
21012.48.136.209/3212.48.136.209 to 12.48.136.209—1
21112.48.136.210/3212.48.136.210 to 12.48.136.210—1
21212.48.136.211/3212.48.136.211 to 12.48.136.211—1
21312.48.136.212/3212.48.136.212 to 12.48.136.212—1
21412.48.136.213/3212.48.136.213 to 12.48.136.213—1
21512.48.136.214/3212.48.136.214 to 12.48.136.214—1
21612.48.136.215/3212.48.136.215 to 12.48.136.215—1
21712.48.136.216/3212.48.136.216 to 12.48.136.216—1
21812.48.136.217/3212.48.136.217 to 12.48.136.217—1
21912.48.136.218/3212.48.136.218 to 12.48.136.218—1
22012.48.136.219/3212.48.136.219 to 12.48.136.219—1
22112.48.136.220/3212.48.136.220 to 12.48.136.220—1
22212.48.136.221/3212.48.136.221 to 12.48.136.221—1
22312.48.136.222/3212.48.136.222 to 12.48.136.222—1
22412.48.136.223/3212.48.136.223 to 12.48.136.223—1
22512.48.136.224/3212.48.136.224 to 12.48.136.224—1
22612.48.136.225/3212.48.136.225 to 12.48.136.225—1
22712.48.136.226/3212.48.136.226 to 12.48.136.226—1
22812.48.136.227/3212.48.136.227 to 12.48.136.227—1
22912.48.136.228/3212.48.136.228 to 12.48.136.228—1
23012.48.136.229/3212.48.136.229 to 12.48.136.229—1
23112.48.136.230/3212.48.136.230 to 12.48.136.230—1
23212.48.136.231/3212.48.136.231 to 12.48.136.231—1
23312.48.136.232/3212.48.136.232 to 12.48.136.232—1
23412.48.136.233/3212.48.136.233 to 12.48.136.233—1
23512.48.136.234/3212.48.136.234 to 12.48.136.234—1
23612.48.136.235/3212.48.136.235 to 12.48.136.235—1
23712.48.136.236/3212.48.136.236 to 12.48.136.236—1
23812.48.136.237/3212.48.136.237 to 12.48.136.237—1
23912.48.136.238/3212.48.136.238 to 12.48.136.238—1
24012.48.136.239/3212.48.136.239 to 12.48.136.239—1
24112.48.136.240/3212.48.136.240 to 12.48.136.240—1
24212.48.136.241/3212.48.136.241 to 12.48.136.241—1
24312.48.136.242/3212.48.136.242 to 12.48.136.242—1
24412.48.136.243/3212.48.136.243 to 12.48.136.243—1
24512.48.136.244/3212.48.136.244 to 12.48.136.244—1
24612.48.136.245/3212.48.136.245 to 12.48.136.245—1
24712.48.136.246/3212.48.136.246 to 12.48.136.246—1
24812.48.136.247/3212.48.136.247 to 12.48.136.247—1
24912.48.136.248/3212.48.136.248 to 12.48.136.248—1
25012.48.136.249/3212.48.136.249 to 12.48.136.249—1
25112.48.136.250/3212.48.136.250 to 12.48.136.250—1
25212.48.136.251/3212.48.136.251 to 12.48.136.251—1
25312.48.136.252/3212.48.136.252 to 12.48.136.252—1
25412.48.136.253/3212.48.136.253 to 12.48.136.253—1
25512.48.136.254/3212.48.136.254 to 12.48.136.254—1
25612.48.136.255/3212.48.136.255 to 12.48.136.255—1

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.