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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.

Network57.2.240.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
57.2.240.0
Broadcast address
57.2.255.255
First usable
57.2.240.1
Last usable
57.2.255.254
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 3902F000 · Integer 956493824 to 956497919
Reverse DNS zones
240.2.57.in-addr.arpa
241.2.57.in-addr.arpa
242.2.57.in-addr.arpa
243.2.57.in-addr.arpa
244.2.57.in-addr.arpa
245.2.57.in-addr.arpa
246.2.57.in-addr.arpa
247.2.57.in-addr.arpa
248.2.57.in-addr.arpa
249.2.57.in-addr.arpa
250.2.57.in-addr.arpa
251.2.57.in-addr.arpa
252.2.57.in-addr.arpa
253.2.57.in-addr.arpa
254.2.57.in-addr.arpa
255.2.57.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
Address00111001.00000010.11110000.0000000057.2.240.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00111001.00000010.11110000.0000000057.2.240.0
Broadcast00111001.00000010.11111111.1111111157.2.255.255
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)

57.2.240.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
157.2.240.0/3257.2.240.0 to 57.2.240.0—1
257.2.240.1/3257.2.240.1 to 57.2.240.1—1
357.2.240.2/3257.2.240.2 to 57.2.240.2—1
457.2.240.3/3257.2.240.3 to 57.2.240.3—1
557.2.240.4/3257.2.240.4 to 57.2.240.4—1
657.2.240.5/3257.2.240.5 to 57.2.240.5—1
757.2.240.6/3257.2.240.6 to 57.2.240.6—1
857.2.240.7/3257.2.240.7 to 57.2.240.7—1
957.2.240.8/3257.2.240.8 to 57.2.240.8—1
1057.2.240.9/3257.2.240.9 to 57.2.240.9—1
1157.2.240.10/3257.2.240.10 to 57.2.240.10—1
1257.2.240.11/3257.2.240.11 to 57.2.240.11—1
1357.2.240.12/3257.2.240.12 to 57.2.240.12—1
1457.2.240.13/3257.2.240.13 to 57.2.240.13—1
1557.2.240.14/3257.2.240.14 to 57.2.240.14—1
1657.2.240.15/3257.2.240.15 to 57.2.240.15—1
1757.2.240.16/3257.2.240.16 to 57.2.240.16—1
1857.2.240.17/3257.2.240.17 to 57.2.240.17—1
1957.2.240.18/3257.2.240.18 to 57.2.240.18—1
2057.2.240.19/3257.2.240.19 to 57.2.240.19—1
2157.2.240.20/3257.2.240.20 to 57.2.240.20—1
2257.2.240.21/3257.2.240.21 to 57.2.240.21—1
2357.2.240.22/3257.2.240.22 to 57.2.240.22—1
2457.2.240.23/3257.2.240.23 to 57.2.240.23—1
2557.2.240.24/3257.2.240.24 to 57.2.240.24—1
2657.2.240.25/3257.2.240.25 to 57.2.240.25—1
2757.2.240.26/3257.2.240.26 to 57.2.240.26—1
2857.2.240.27/3257.2.240.27 to 57.2.240.27—1
2957.2.240.28/3257.2.240.28 to 57.2.240.28—1
3057.2.240.29/3257.2.240.29 to 57.2.240.29—1
3157.2.240.30/3257.2.240.30 to 57.2.240.30—1
3257.2.240.31/3257.2.240.31 to 57.2.240.31—1
3357.2.240.32/3257.2.240.32 to 57.2.240.32—1
3457.2.240.33/3257.2.240.33 to 57.2.240.33—1
3557.2.240.34/3257.2.240.34 to 57.2.240.34—1
3657.2.240.35/3257.2.240.35 to 57.2.240.35—1
3757.2.240.36/3257.2.240.36 to 57.2.240.36—1
3857.2.240.37/3257.2.240.37 to 57.2.240.37—1
3957.2.240.38/3257.2.240.38 to 57.2.240.38—1
4057.2.240.39/3257.2.240.39 to 57.2.240.39—1
4157.2.240.40/3257.2.240.40 to 57.2.240.40—1
4257.2.240.41/3257.2.240.41 to 57.2.240.41—1
4357.2.240.42/3257.2.240.42 to 57.2.240.42—1
4457.2.240.43/3257.2.240.43 to 57.2.240.43—1
4557.2.240.44/3257.2.240.44 to 57.2.240.44—1
4657.2.240.45/3257.2.240.45 to 57.2.240.45—1
4757.2.240.46/3257.2.240.46 to 57.2.240.46—1
4857.2.240.47/3257.2.240.47 to 57.2.240.47—1
4957.2.240.48/3257.2.240.48 to 57.2.240.48—1
5057.2.240.49/3257.2.240.49 to 57.2.240.49—1
5157.2.240.50/3257.2.240.50 to 57.2.240.50—1
5257.2.240.51/3257.2.240.51 to 57.2.240.51—1
5357.2.240.52/3257.2.240.52 to 57.2.240.52—1
5457.2.240.53/3257.2.240.53 to 57.2.240.53—1
5557.2.240.54/3257.2.240.54 to 57.2.240.54—1
5657.2.240.55/3257.2.240.55 to 57.2.240.55—1
5757.2.240.56/3257.2.240.56 to 57.2.240.56—1
5857.2.240.57/3257.2.240.57 to 57.2.240.57—1
5957.2.240.58/3257.2.240.58 to 57.2.240.58—1
6057.2.240.59/3257.2.240.59 to 57.2.240.59—1
6157.2.240.60/3257.2.240.60 to 57.2.240.60—1
6257.2.240.61/3257.2.240.61 to 57.2.240.61—1
6357.2.240.62/3257.2.240.62 to 57.2.240.62—1
6457.2.240.63/3257.2.240.63 to 57.2.240.63—1
6557.2.240.64/3257.2.240.64 to 57.2.240.64—1
6657.2.240.65/3257.2.240.65 to 57.2.240.65—1
6757.2.240.66/3257.2.240.66 to 57.2.240.66—1
6857.2.240.67/3257.2.240.67 to 57.2.240.67—1
6957.2.240.68/3257.2.240.68 to 57.2.240.68—1
7057.2.240.69/3257.2.240.69 to 57.2.240.69—1
7157.2.240.70/3257.2.240.70 to 57.2.240.70—1
7257.2.240.71/3257.2.240.71 to 57.2.240.71—1
7357.2.240.72/3257.2.240.72 to 57.2.240.72—1
7457.2.240.73/3257.2.240.73 to 57.2.240.73—1
7557.2.240.74/3257.2.240.74 to 57.2.240.74—1
7657.2.240.75/3257.2.240.75 to 57.2.240.75—1
7757.2.240.76/3257.2.240.76 to 57.2.240.76—1
7857.2.240.77/3257.2.240.77 to 57.2.240.77—1
7957.2.240.78/3257.2.240.78 to 57.2.240.78—1
8057.2.240.79/3257.2.240.79 to 57.2.240.79—1
8157.2.240.80/3257.2.240.80 to 57.2.240.80—1
8257.2.240.81/3257.2.240.81 to 57.2.240.81—1
8357.2.240.82/3257.2.240.82 to 57.2.240.82—1
8457.2.240.83/3257.2.240.83 to 57.2.240.83—1
8557.2.240.84/3257.2.240.84 to 57.2.240.84—1
8657.2.240.85/3257.2.240.85 to 57.2.240.85—1
8757.2.240.86/3257.2.240.86 to 57.2.240.86—1
8857.2.240.87/3257.2.240.87 to 57.2.240.87—1
8957.2.240.88/3257.2.240.88 to 57.2.240.88—1
9057.2.240.89/3257.2.240.89 to 57.2.240.89—1
9157.2.240.90/3257.2.240.90 to 57.2.240.90—1
9257.2.240.91/3257.2.240.91 to 57.2.240.91—1
9357.2.240.92/3257.2.240.92 to 57.2.240.92—1
9457.2.240.93/3257.2.240.93 to 57.2.240.93—1
9557.2.240.94/3257.2.240.94 to 57.2.240.94—1
9657.2.240.95/3257.2.240.95 to 57.2.240.95—1
9757.2.240.96/3257.2.240.96 to 57.2.240.96—1
9857.2.240.97/3257.2.240.97 to 57.2.240.97—1
9957.2.240.98/3257.2.240.98 to 57.2.240.98—1
10057.2.240.99/3257.2.240.99 to 57.2.240.99—1
10157.2.240.100/3257.2.240.100 to 57.2.240.100—1
10257.2.240.101/3257.2.240.101 to 57.2.240.101—1
10357.2.240.102/3257.2.240.102 to 57.2.240.102—1
10457.2.240.103/3257.2.240.103 to 57.2.240.103—1
10557.2.240.104/3257.2.240.104 to 57.2.240.104—1
10657.2.240.105/3257.2.240.105 to 57.2.240.105—1
10757.2.240.106/3257.2.240.106 to 57.2.240.106—1
10857.2.240.107/3257.2.240.107 to 57.2.240.107—1
10957.2.240.108/3257.2.240.108 to 57.2.240.108—1
11057.2.240.109/3257.2.240.109 to 57.2.240.109—1
11157.2.240.110/3257.2.240.110 to 57.2.240.110—1
11257.2.240.111/3257.2.240.111 to 57.2.240.111—1
11357.2.240.112/3257.2.240.112 to 57.2.240.112—1
11457.2.240.113/3257.2.240.113 to 57.2.240.113—1
11557.2.240.114/3257.2.240.114 to 57.2.240.114—1
11657.2.240.115/3257.2.240.115 to 57.2.240.115—1
11757.2.240.116/3257.2.240.116 to 57.2.240.116—1
11857.2.240.117/3257.2.240.117 to 57.2.240.117—1
11957.2.240.118/3257.2.240.118 to 57.2.240.118—1
12057.2.240.119/3257.2.240.119 to 57.2.240.119—1
12157.2.240.120/3257.2.240.120 to 57.2.240.120—1
12257.2.240.121/3257.2.240.121 to 57.2.240.121—1
12357.2.240.122/3257.2.240.122 to 57.2.240.122—1
12457.2.240.123/3257.2.240.123 to 57.2.240.123—1
12557.2.240.124/3257.2.240.124 to 57.2.240.124—1
12657.2.240.125/3257.2.240.125 to 57.2.240.125—1
12757.2.240.126/3257.2.240.126 to 57.2.240.126—1
12857.2.240.127/3257.2.240.127 to 57.2.240.127—1
12957.2.240.128/3257.2.240.128 to 57.2.240.128—1
13057.2.240.129/3257.2.240.129 to 57.2.240.129—1
13157.2.240.130/3257.2.240.130 to 57.2.240.130—1
13257.2.240.131/3257.2.240.131 to 57.2.240.131—1
13357.2.240.132/3257.2.240.132 to 57.2.240.132—1
13457.2.240.133/3257.2.240.133 to 57.2.240.133—1
13557.2.240.134/3257.2.240.134 to 57.2.240.134—1
13657.2.240.135/3257.2.240.135 to 57.2.240.135—1
13757.2.240.136/3257.2.240.136 to 57.2.240.136—1
13857.2.240.137/3257.2.240.137 to 57.2.240.137—1
13957.2.240.138/3257.2.240.138 to 57.2.240.138—1
14057.2.240.139/3257.2.240.139 to 57.2.240.139—1
14157.2.240.140/3257.2.240.140 to 57.2.240.140—1
14257.2.240.141/3257.2.240.141 to 57.2.240.141—1
14357.2.240.142/3257.2.240.142 to 57.2.240.142—1
14457.2.240.143/3257.2.240.143 to 57.2.240.143—1
14557.2.240.144/3257.2.240.144 to 57.2.240.144—1
14657.2.240.145/3257.2.240.145 to 57.2.240.145—1
14757.2.240.146/3257.2.240.146 to 57.2.240.146—1
14857.2.240.147/3257.2.240.147 to 57.2.240.147—1
14957.2.240.148/3257.2.240.148 to 57.2.240.148—1
15057.2.240.149/3257.2.240.149 to 57.2.240.149—1
15157.2.240.150/3257.2.240.150 to 57.2.240.150—1
15257.2.240.151/3257.2.240.151 to 57.2.240.151—1
15357.2.240.152/3257.2.240.152 to 57.2.240.152—1
15457.2.240.153/3257.2.240.153 to 57.2.240.153—1
15557.2.240.154/3257.2.240.154 to 57.2.240.154—1
15657.2.240.155/3257.2.240.155 to 57.2.240.155—1
15757.2.240.156/3257.2.240.156 to 57.2.240.156—1
15857.2.240.157/3257.2.240.157 to 57.2.240.157—1
15957.2.240.158/3257.2.240.158 to 57.2.240.158—1
16057.2.240.159/3257.2.240.159 to 57.2.240.159—1
16157.2.240.160/3257.2.240.160 to 57.2.240.160—1
16257.2.240.161/3257.2.240.161 to 57.2.240.161—1
16357.2.240.162/3257.2.240.162 to 57.2.240.162—1
16457.2.240.163/3257.2.240.163 to 57.2.240.163—1
16557.2.240.164/3257.2.240.164 to 57.2.240.164—1
16657.2.240.165/3257.2.240.165 to 57.2.240.165—1
16757.2.240.166/3257.2.240.166 to 57.2.240.166—1
16857.2.240.167/3257.2.240.167 to 57.2.240.167—1
16957.2.240.168/3257.2.240.168 to 57.2.240.168—1
17057.2.240.169/3257.2.240.169 to 57.2.240.169—1
17157.2.240.170/3257.2.240.170 to 57.2.240.170—1
17257.2.240.171/3257.2.240.171 to 57.2.240.171—1
17357.2.240.172/3257.2.240.172 to 57.2.240.172—1
17457.2.240.173/3257.2.240.173 to 57.2.240.173—1
17557.2.240.174/3257.2.240.174 to 57.2.240.174—1
17657.2.240.175/3257.2.240.175 to 57.2.240.175—1
17757.2.240.176/3257.2.240.176 to 57.2.240.176—1
17857.2.240.177/3257.2.240.177 to 57.2.240.177—1
17957.2.240.178/3257.2.240.178 to 57.2.240.178—1
18057.2.240.179/3257.2.240.179 to 57.2.240.179—1
18157.2.240.180/3257.2.240.180 to 57.2.240.180—1
18257.2.240.181/3257.2.240.181 to 57.2.240.181—1
18357.2.240.182/3257.2.240.182 to 57.2.240.182—1
18457.2.240.183/3257.2.240.183 to 57.2.240.183—1
18557.2.240.184/3257.2.240.184 to 57.2.240.184—1
18657.2.240.185/3257.2.240.185 to 57.2.240.185—1
18757.2.240.186/3257.2.240.186 to 57.2.240.186—1
18857.2.240.187/3257.2.240.187 to 57.2.240.187—1
18957.2.240.188/3257.2.240.188 to 57.2.240.188—1
19057.2.240.189/3257.2.240.189 to 57.2.240.189—1
19157.2.240.190/3257.2.240.190 to 57.2.240.190—1
19257.2.240.191/3257.2.240.191 to 57.2.240.191—1
19357.2.240.192/3257.2.240.192 to 57.2.240.192—1
19457.2.240.193/3257.2.240.193 to 57.2.240.193—1
19557.2.240.194/3257.2.240.194 to 57.2.240.194—1
19657.2.240.195/3257.2.240.195 to 57.2.240.195—1
19757.2.240.196/3257.2.240.196 to 57.2.240.196—1
19857.2.240.197/3257.2.240.197 to 57.2.240.197—1
19957.2.240.198/3257.2.240.198 to 57.2.240.198—1
20057.2.240.199/3257.2.240.199 to 57.2.240.199—1
20157.2.240.200/3257.2.240.200 to 57.2.240.200—1
20257.2.240.201/3257.2.240.201 to 57.2.240.201—1
20357.2.240.202/3257.2.240.202 to 57.2.240.202—1
20457.2.240.203/3257.2.240.203 to 57.2.240.203—1
20557.2.240.204/3257.2.240.204 to 57.2.240.204—1
20657.2.240.205/3257.2.240.205 to 57.2.240.205—1
20757.2.240.206/3257.2.240.206 to 57.2.240.206—1
20857.2.240.207/3257.2.240.207 to 57.2.240.207—1
20957.2.240.208/3257.2.240.208 to 57.2.240.208—1
21057.2.240.209/3257.2.240.209 to 57.2.240.209—1
21157.2.240.210/3257.2.240.210 to 57.2.240.210—1
21257.2.240.211/3257.2.240.211 to 57.2.240.211—1
21357.2.240.212/3257.2.240.212 to 57.2.240.212—1
21457.2.240.213/3257.2.240.213 to 57.2.240.213—1
21557.2.240.214/3257.2.240.214 to 57.2.240.214—1
21657.2.240.215/3257.2.240.215 to 57.2.240.215—1
21757.2.240.216/3257.2.240.216 to 57.2.240.216—1
21857.2.240.217/3257.2.240.217 to 57.2.240.217—1
21957.2.240.218/3257.2.240.218 to 57.2.240.218—1
22057.2.240.219/3257.2.240.219 to 57.2.240.219—1
22157.2.240.220/3257.2.240.220 to 57.2.240.220—1
22257.2.240.221/3257.2.240.221 to 57.2.240.221—1
22357.2.240.222/3257.2.240.222 to 57.2.240.222—1
22457.2.240.223/3257.2.240.223 to 57.2.240.223—1
22557.2.240.224/3257.2.240.224 to 57.2.240.224—1
22657.2.240.225/3257.2.240.225 to 57.2.240.225—1
22757.2.240.226/3257.2.240.226 to 57.2.240.226—1
22857.2.240.227/3257.2.240.227 to 57.2.240.227—1
22957.2.240.228/3257.2.240.228 to 57.2.240.228—1
23057.2.240.229/3257.2.240.229 to 57.2.240.229—1
23157.2.240.230/3257.2.240.230 to 57.2.240.230—1
23257.2.240.231/3257.2.240.231 to 57.2.240.231—1
23357.2.240.232/3257.2.240.232 to 57.2.240.232—1
23457.2.240.233/3257.2.240.233 to 57.2.240.233—1
23557.2.240.234/3257.2.240.234 to 57.2.240.234—1
23657.2.240.235/3257.2.240.235 to 57.2.240.235—1
23757.2.240.236/3257.2.240.236 to 57.2.240.236—1
23857.2.240.237/3257.2.240.237 to 57.2.240.237—1
23957.2.240.238/3257.2.240.238 to 57.2.240.238—1
24057.2.240.239/3257.2.240.239 to 57.2.240.239—1
24157.2.240.240/3257.2.240.240 to 57.2.240.240—1
24257.2.240.241/3257.2.240.241 to 57.2.240.241—1
24357.2.240.242/3257.2.240.242 to 57.2.240.242—1
24457.2.240.243/3257.2.240.243 to 57.2.240.243—1
24557.2.240.244/3257.2.240.244 to 57.2.240.244—1
24657.2.240.245/3257.2.240.245 to 57.2.240.245—1
24757.2.240.246/3257.2.240.246 to 57.2.240.246—1
24857.2.240.247/3257.2.240.247 to 57.2.240.247—1
24957.2.240.248/3257.2.240.248 to 57.2.240.248—1
25057.2.240.249/3257.2.240.249 to 57.2.240.249—1
25157.2.240.250/3257.2.240.250 to 57.2.240.250—1
25257.2.240.251/3257.2.240.251 to 57.2.240.251—1
25357.2.240.252/3257.2.240.252 to 57.2.240.252—1
25457.2.240.253/3257.2.240.253 to 57.2.240.253—1
25557.2.240.254/3257.2.240.254 to 57.2.240.254—1
25657.2.240.255/3257.2.240.255 to 57.2.240.255—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.