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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.

Network42.2.32.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
42.2.32.0
Broadcast address
42.2.47.255
First usable
42.2.32.1
Last usable
42.2.47.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 2A022000 · Integer 704782336 to 704786431
Reverse DNS zones
32.2.42.in-addr.arpa
33.2.42.in-addr.arpa
34.2.42.in-addr.arpa
35.2.42.in-addr.arpa
36.2.42.in-addr.arpa
37.2.42.in-addr.arpa
38.2.42.in-addr.arpa
39.2.42.in-addr.arpa
40.2.42.in-addr.arpa
41.2.42.in-addr.arpa
42.2.42.in-addr.arpa
43.2.42.in-addr.arpa
44.2.42.in-addr.arpa
45.2.42.in-addr.arpa
46.2.42.in-addr.arpa
47.2.42.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101010.00000010.00100000.0000000042.2.32.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00101010.00000010.00100000.0000000042.2.32.0
Broadcast00101010.00000010.00101111.1111111142.2.47.255
Split into smaller subnets/32
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

42.2.32.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
142.2.32.0/3242.2.32.0 to 42.2.32.0—1
242.2.32.1/3242.2.32.1 to 42.2.32.1—1
342.2.32.2/3242.2.32.2 to 42.2.32.2—1
442.2.32.3/3242.2.32.3 to 42.2.32.3—1
542.2.32.4/3242.2.32.4 to 42.2.32.4—1
642.2.32.5/3242.2.32.5 to 42.2.32.5—1
742.2.32.6/3242.2.32.6 to 42.2.32.6—1
842.2.32.7/3242.2.32.7 to 42.2.32.7—1
942.2.32.8/3242.2.32.8 to 42.2.32.8—1
1042.2.32.9/3242.2.32.9 to 42.2.32.9—1
1142.2.32.10/3242.2.32.10 to 42.2.32.10—1
1242.2.32.11/3242.2.32.11 to 42.2.32.11—1
1342.2.32.12/3242.2.32.12 to 42.2.32.12—1
1442.2.32.13/3242.2.32.13 to 42.2.32.13—1
1542.2.32.14/3242.2.32.14 to 42.2.32.14—1
1642.2.32.15/3242.2.32.15 to 42.2.32.15—1
1742.2.32.16/3242.2.32.16 to 42.2.32.16—1
1842.2.32.17/3242.2.32.17 to 42.2.32.17—1
1942.2.32.18/3242.2.32.18 to 42.2.32.18—1
2042.2.32.19/3242.2.32.19 to 42.2.32.19—1
2142.2.32.20/3242.2.32.20 to 42.2.32.20—1
2242.2.32.21/3242.2.32.21 to 42.2.32.21—1
2342.2.32.22/3242.2.32.22 to 42.2.32.22—1
2442.2.32.23/3242.2.32.23 to 42.2.32.23—1
2542.2.32.24/3242.2.32.24 to 42.2.32.24—1
2642.2.32.25/3242.2.32.25 to 42.2.32.25—1
2742.2.32.26/3242.2.32.26 to 42.2.32.26—1
2842.2.32.27/3242.2.32.27 to 42.2.32.27—1
2942.2.32.28/3242.2.32.28 to 42.2.32.28—1
3042.2.32.29/3242.2.32.29 to 42.2.32.29—1
3142.2.32.30/3242.2.32.30 to 42.2.32.30—1
3242.2.32.31/3242.2.32.31 to 42.2.32.31—1
3342.2.32.32/3242.2.32.32 to 42.2.32.32—1
3442.2.32.33/3242.2.32.33 to 42.2.32.33—1
3542.2.32.34/3242.2.32.34 to 42.2.32.34—1
3642.2.32.35/3242.2.32.35 to 42.2.32.35—1
3742.2.32.36/3242.2.32.36 to 42.2.32.36—1
3842.2.32.37/3242.2.32.37 to 42.2.32.37—1
3942.2.32.38/3242.2.32.38 to 42.2.32.38—1
4042.2.32.39/3242.2.32.39 to 42.2.32.39—1
4142.2.32.40/3242.2.32.40 to 42.2.32.40—1
4242.2.32.41/3242.2.32.41 to 42.2.32.41—1
4342.2.32.42/3242.2.32.42 to 42.2.32.42—1
4442.2.32.43/3242.2.32.43 to 42.2.32.43—1
4542.2.32.44/3242.2.32.44 to 42.2.32.44—1
4642.2.32.45/3242.2.32.45 to 42.2.32.45—1
4742.2.32.46/3242.2.32.46 to 42.2.32.46—1
4842.2.32.47/3242.2.32.47 to 42.2.32.47—1
4942.2.32.48/3242.2.32.48 to 42.2.32.48—1
5042.2.32.49/3242.2.32.49 to 42.2.32.49—1
5142.2.32.50/3242.2.32.50 to 42.2.32.50—1
5242.2.32.51/3242.2.32.51 to 42.2.32.51—1
5342.2.32.52/3242.2.32.52 to 42.2.32.52—1
5442.2.32.53/3242.2.32.53 to 42.2.32.53—1
5542.2.32.54/3242.2.32.54 to 42.2.32.54—1
5642.2.32.55/3242.2.32.55 to 42.2.32.55—1
5742.2.32.56/3242.2.32.56 to 42.2.32.56—1
5842.2.32.57/3242.2.32.57 to 42.2.32.57—1
5942.2.32.58/3242.2.32.58 to 42.2.32.58—1
6042.2.32.59/3242.2.32.59 to 42.2.32.59—1
6142.2.32.60/3242.2.32.60 to 42.2.32.60—1
6242.2.32.61/3242.2.32.61 to 42.2.32.61—1
6342.2.32.62/3242.2.32.62 to 42.2.32.62—1
6442.2.32.63/3242.2.32.63 to 42.2.32.63—1
6542.2.32.64/3242.2.32.64 to 42.2.32.64—1
6642.2.32.65/3242.2.32.65 to 42.2.32.65—1
6742.2.32.66/3242.2.32.66 to 42.2.32.66—1
6842.2.32.67/3242.2.32.67 to 42.2.32.67—1
6942.2.32.68/3242.2.32.68 to 42.2.32.68—1
7042.2.32.69/3242.2.32.69 to 42.2.32.69—1
7142.2.32.70/3242.2.32.70 to 42.2.32.70—1
7242.2.32.71/3242.2.32.71 to 42.2.32.71—1
7342.2.32.72/3242.2.32.72 to 42.2.32.72—1
7442.2.32.73/3242.2.32.73 to 42.2.32.73—1
7542.2.32.74/3242.2.32.74 to 42.2.32.74—1
7642.2.32.75/3242.2.32.75 to 42.2.32.75—1
7742.2.32.76/3242.2.32.76 to 42.2.32.76—1
7842.2.32.77/3242.2.32.77 to 42.2.32.77—1
7942.2.32.78/3242.2.32.78 to 42.2.32.78—1
8042.2.32.79/3242.2.32.79 to 42.2.32.79—1
8142.2.32.80/3242.2.32.80 to 42.2.32.80—1
8242.2.32.81/3242.2.32.81 to 42.2.32.81—1
8342.2.32.82/3242.2.32.82 to 42.2.32.82—1
8442.2.32.83/3242.2.32.83 to 42.2.32.83—1
8542.2.32.84/3242.2.32.84 to 42.2.32.84—1
8642.2.32.85/3242.2.32.85 to 42.2.32.85—1
8742.2.32.86/3242.2.32.86 to 42.2.32.86—1
8842.2.32.87/3242.2.32.87 to 42.2.32.87—1
8942.2.32.88/3242.2.32.88 to 42.2.32.88—1
9042.2.32.89/3242.2.32.89 to 42.2.32.89—1
9142.2.32.90/3242.2.32.90 to 42.2.32.90—1
9242.2.32.91/3242.2.32.91 to 42.2.32.91—1
9342.2.32.92/3242.2.32.92 to 42.2.32.92—1
9442.2.32.93/3242.2.32.93 to 42.2.32.93—1
9542.2.32.94/3242.2.32.94 to 42.2.32.94—1
9642.2.32.95/3242.2.32.95 to 42.2.32.95—1
9742.2.32.96/3242.2.32.96 to 42.2.32.96—1
9842.2.32.97/3242.2.32.97 to 42.2.32.97—1
9942.2.32.98/3242.2.32.98 to 42.2.32.98—1
10042.2.32.99/3242.2.32.99 to 42.2.32.99—1
10142.2.32.100/3242.2.32.100 to 42.2.32.100—1
10242.2.32.101/3242.2.32.101 to 42.2.32.101—1
10342.2.32.102/3242.2.32.102 to 42.2.32.102—1
10442.2.32.103/3242.2.32.103 to 42.2.32.103—1
10542.2.32.104/3242.2.32.104 to 42.2.32.104—1
10642.2.32.105/3242.2.32.105 to 42.2.32.105—1
10742.2.32.106/3242.2.32.106 to 42.2.32.106—1
10842.2.32.107/3242.2.32.107 to 42.2.32.107—1
10942.2.32.108/3242.2.32.108 to 42.2.32.108—1
11042.2.32.109/3242.2.32.109 to 42.2.32.109—1
11142.2.32.110/3242.2.32.110 to 42.2.32.110—1
11242.2.32.111/3242.2.32.111 to 42.2.32.111—1
11342.2.32.112/3242.2.32.112 to 42.2.32.112—1
11442.2.32.113/3242.2.32.113 to 42.2.32.113—1
11542.2.32.114/3242.2.32.114 to 42.2.32.114—1
11642.2.32.115/3242.2.32.115 to 42.2.32.115—1
11742.2.32.116/3242.2.32.116 to 42.2.32.116—1
11842.2.32.117/3242.2.32.117 to 42.2.32.117—1
11942.2.32.118/3242.2.32.118 to 42.2.32.118—1
12042.2.32.119/3242.2.32.119 to 42.2.32.119—1
12142.2.32.120/3242.2.32.120 to 42.2.32.120—1
12242.2.32.121/3242.2.32.121 to 42.2.32.121—1
12342.2.32.122/3242.2.32.122 to 42.2.32.122—1
12442.2.32.123/3242.2.32.123 to 42.2.32.123—1
12542.2.32.124/3242.2.32.124 to 42.2.32.124—1
12642.2.32.125/3242.2.32.125 to 42.2.32.125—1
12742.2.32.126/3242.2.32.126 to 42.2.32.126—1
12842.2.32.127/3242.2.32.127 to 42.2.32.127—1
12942.2.32.128/3242.2.32.128 to 42.2.32.128—1
13042.2.32.129/3242.2.32.129 to 42.2.32.129—1
13142.2.32.130/3242.2.32.130 to 42.2.32.130—1
13242.2.32.131/3242.2.32.131 to 42.2.32.131—1
13342.2.32.132/3242.2.32.132 to 42.2.32.132—1
13442.2.32.133/3242.2.32.133 to 42.2.32.133—1
13542.2.32.134/3242.2.32.134 to 42.2.32.134—1
13642.2.32.135/3242.2.32.135 to 42.2.32.135—1
13742.2.32.136/3242.2.32.136 to 42.2.32.136—1
13842.2.32.137/3242.2.32.137 to 42.2.32.137—1
13942.2.32.138/3242.2.32.138 to 42.2.32.138—1
14042.2.32.139/3242.2.32.139 to 42.2.32.139—1
14142.2.32.140/3242.2.32.140 to 42.2.32.140—1
14242.2.32.141/3242.2.32.141 to 42.2.32.141—1
14342.2.32.142/3242.2.32.142 to 42.2.32.142—1
14442.2.32.143/3242.2.32.143 to 42.2.32.143—1
14542.2.32.144/3242.2.32.144 to 42.2.32.144—1
14642.2.32.145/3242.2.32.145 to 42.2.32.145—1
14742.2.32.146/3242.2.32.146 to 42.2.32.146—1
14842.2.32.147/3242.2.32.147 to 42.2.32.147—1
14942.2.32.148/3242.2.32.148 to 42.2.32.148—1
15042.2.32.149/3242.2.32.149 to 42.2.32.149—1
15142.2.32.150/3242.2.32.150 to 42.2.32.150—1
15242.2.32.151/3242.2.32.151 to 42.2.32.151—1
15342.2.32.152/3242.2.32.152 to 42.2.32.152—1
15442.2.32.153/3242.2.32.153 to 42.2.32.153—1
15542.2.32.154/3242.2.32.154 to 42.2.32.154—1
15642.2.32.155/3242.2.32.155 to 42.2.32.155—1
15742.2.32.156/3242.2.32.156 to 42.2.32.156—1
15842.2.32.157/3242.2.32.157 to 42.2.32.157—1
15942.2.32.158/3242.2.32.158 to 42.2.32.158—1
16042.2.32.159/3242.2.32.159 to 42.2.32.159—1
16142.2.32.160/3242.2.32.160 to 42.2.32.160—1
16242.2.32.161/3242.2.32.161 to 42.2.32.161—1
16342.2.32.162/3242.2.32.162 to 42.2.32.162—1
16442.2.32.163/3242.2.32.163 to 42.2.32.163—1
16542.2.32.164/3242.2.32.164 to 42.2.32.164—1
16642.2.32.165/3242.2.32.165 to 42.2.32.165—1
16742.2.32.166/3242.2.32.166 to 42.2.32.166—1
16842.2.32.167/3242.2.32.167 to 42.2.32.167—1
16942.2.32.168/3242.2.32.168 to 42.2.32.168—1
17042.2.32.169/3242.2.32.169 to 42.2.32.169—1
17142.2.32.170/3242.2.32.170 to 42.2.32.170—1
17242.2.32.171/3242.2.32.171 to 42.2.32.171—1
17342.2.32.172/3242.2.32.172 to 42.2.32.172—1
17442.2.32.173/3242.2.32.173 to 42.2.32.173—1
17542.2.32.174/3242.2.32.174 to 42.2.32.174—1
17642.2.32.175/3242.2.32.175 to 42.2.32.175—1
17742.2.32.176/3242.2.32.176 to 42.2.32.176—1
17842.2.32.177/3242.2.32.177 to 42.2.32.177—1
17942.2.32.178/3242.2.32.178 to 42.2.32.178—1
18042.2.32.179/3242.2.32.179 to 42.2.32.179—1
18142.2.32.180/3242.2.32.180 to 42.2.32.180—1
18242.2.32.181/3242.2.32.181 to 42.2.32.181—1
18342.2.32.182/3242.2.32.182 to 42.2.32.182—1
18442.2.32.183/3242.2.32.183 to 42.2.32.183—1
18542.2.32.184/3242.2.32.184 to 42.2.32.184—1
18642.2.32.185/3242.2.32.185 to 42.2.32.185—1
18742.2.32.186/3242.2.32.186 to 42.2.32.186—1
18842.2.32.187/3242.2.32.187 to 42.2.32.187—1
18942.2.32.188/3242.2.32.188 to 42.2.32.188—1
19042.2.32.189/3242.2.32.189 to 42.2.32.189—1
19142.2.32.190/3242.2.32.190 to 42.2.32.190—1
19242.2.32.191/3242.2.32.191 to 42.2.32.191—1
19342.2.32.192/3242.2.32.192 to 42.2.32.192—1
19442.2.32.193/3242.2.32.193 to 42.2.32.193—1
19542.2.32.194/3242.2.32.194 to 42.2.32.194—1
19642.2.32.195/3242.2.32.195 to 42.2.32.195—1
19742.2.32.196/3242.2.32.196 to 42.2.32.196—1
19842.2.32.197/3242.2.32.197 to 42.2.32.197—1
19942.2.32.198/3242.2.32.198 to 42.2.32.198—1
20042.2.32.199/3242.2.32.199 to 42.2.32.199—1
20142.2.32.200/3242.2.32.200 to 42.2.32.200—1
20242.2.32.201/3242.2.32.201 to 42.2.32.201—1
20342.2.32.202/3242.2.32.202 to 42.2.32.202—1
20442.2.32.203/3242.2.32.203 to 42.2.32.203—1
20542.2.32.204/3242.2.32.204 to 42.2.32.204—1
20642.2.32.205/3242.2.32.205 to 42.2.32.205—1
20742.2.32.206/3242.2.32.206 to 42.2.32.206—1
20842.2.32.207/3242.2.32.207 to 42.2.32.207—1
20942.2.32.208/3242.2.32.208 to 42.2.32.208—1
21042.2.32.209/3242.2.32.209 to 42.2.32.209—1
21142.2.32.210/3242.2.32.210 to 42.2.32.210—1
21242.2.32.211/3242.2.32.211 to 42.2.32.211—1
21342.2.32.212/3242.2.32.212 to 42.2.32.212—1
21442.2.32.213/3242.2.32.213 to 42.2.32.213—1
21542.2.32.214/3242.2.32.214 to 42.2.32.214—1
21642.2.32.215/3242.2.32.215 to 42.2.32.215—1
21742.2.32.216/3242.2.32.216 to 42.2.32.216—1
21842.2.32.217/3242.2.32.217 to 42.2.32.217—1
21942.2.32.218/3242.2.32.218 to 42.2.32.218—1
22042.2.32.219/3242.2.32.219 to 42.2.32.219—1
22142.2.32.220/3242.2.32.220 to 42.2.32.220—1
22242.2.32.221/3242.2.32.221 to 42.2.32.221—1
22342.2.32.222/3242.2.32.222 to 42.2.32.222—1
22442.2.32.223/3242.2.32.223 to 42.2.32.223—1
22542.2.32.224/3242.2.32.224 to 42.2.32.224—1
22642.2.32.225/3242.2.32.225 to 42.2.32.225—1
22742.2.32.226/3242.2.32.226 to 42.2.32.226—1
22842.2.32.227/3242.2.32.227 to 42.2.32.227—1
22942.2.32.228/3242.2.32.228 to 42.2.32.228—1
23042.2.32.229/3242.2.32.229 to 42.2.32.229—1
23142.2.32.230/3242.2.32.230 to 42.2.32.230—1
23242.2.32.231/3242.2.32.231 to 42.2.32.231—1
23342.2.32.232/3242.2.32.232 to 42.2.32.232—1
23442.2.32.233/3242.2.32.233 to 42.2.32.233—1
23542.2.32.234/3242.2.32.234 to 42.2.32.234—1
23642.2.32.235/3242.2.32.235 to 42.2.32.235—1
23742.2.32.236/3242.2.32.236 to 42.2.32.236—1
23842.2.32.237/3242.2.32.237 to 42.2.32.237—1
23942.2.32.238/3242.2.32.238 to 42.2.32.238—1
24042.2.32.239/3242.2.32.239 to 42.2.32.239—1
24142.2.32.240/3242.2.32.240 to 42.2.32.240—1
24242.2.32.241/3242.2.32.241 to 42.2.32.241—1
24342.2.32.242/3242.2.32.242 to 42.2.32.242—1
24442.2.32.243/3242.2.32.243 to 42.2.32.243—1
24542.2.32.244/3242.2.32.244 to 42.2.32.244—1
24642.2.32.245/3242.2.32.245 to 42.2.32.245—1
24742.2.32.246/3242.2.32.246 to 42.2.32.246—1
24842.2.32.247/3242.2.32.247 to 42.2.32.247—1
24942.2.32.248/3242.2.32.248 to 42.2.32.248—1
25042.2.32.249/3242.2.32.249 to 42.2.32.249—1
25142.2.32.250/3242.2.32.250 to 42.2.32.250—1
25242.2.32.251/3242.2.32.251 to 42.2.32.251—1
25342.2.32.252/3242.2.32.252 to 42.2.32.252—1
25442.2.32.253/3242.2.32.253 to 42.2.32.253—1
25542.2.32.254/3242.2.32.254 to 42.2.32.254—1
25642.2.32.255/3242.2.32.255 to 42.2.32.255—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.