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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.

Network97.7.240.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
97.7.240.0
Broadcast address
97.7.255.255
First usable
97.7.240.1
Last usable
97.7.255.254
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 6107F000 · Integer 1627910144 to 1627914239
Reverse DNS zones
240.7.97.in-addr.arpa
241.7.97.in-addr.arpa
242.7.97.in-addr.arpa
243.7.97.in-addr.arpa
244.7.97.in-addr.arpa
245.7.97.in-addr.arpa
246.7.97.in-addr.arpa
247.7.97.in-addr.arpa
248.7.97.in-addr.arpa
249.7.97.in-addr.arpa
250.7.97.in-addr.arpa
251.7.97.in-addr.arpa
252.7.97.in-addr.arpa
253.7.97.in-addr.arpa
254.7.97.in-addr.arpa
255.7.97.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
Address01100001.00000111.11110000.0000000097.7.240.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01100001.00000111.11110000.0000000097.7.240.0
Broadcast01100001.00000111.11111111.1111111197.7.255.255
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)

97.7.240.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
197.7.240.0/3297.7.240.0 to 97.7.240.0—1
297.7.240.1/3297.7.240.1 to 97.7.240.1—1
397.7.240.2/3297.7.240.2 to 97.7.240.2—1
497.7.240.3/3297.7.240.3 to 97.7.240.3—1
597.7.240.4/3297.7.240.4 to 97.7.240.4—1
697.7.240.5/3297.7.240.5 to 97.7.240.5—1
797.7.240.6/3297.7.240.6 to 97.7.240.6—1
897.7.240.7/3297.7.240.7 to 97.7.240.7—1
997.7.240.8/3297.7.240.8 to 97.7.240.8—1
1097.7.240.9/3297.7.240.9 to 97.7.240.9—1
1197.7.240.10/3297.7.240.10 to 97.7.240.10—1
1297.7.240.11/3297.7.240.11 to 97.7.240.11—1
1397.7.240.12/3297.7.240.12 to 97.7.240.12—1
1497.7.240.13/3297.7.240.13 to 97.7.240.13—1
1597.7.240.14/3297.7.240.14 to 97.7.240.14—1
1697.7.240.15/3297.7.240.15 to 97.7.240.15—1
1797.7.240.16/3297.7.240.16 to 97.7.240.16—1
1897.7.240.17/3297.7.240.17 to 97.7.240.17—1
1997.7.240.18/3297.7.240.18 to 97.7.240.18—1
2097.7.240.19/3297.7.240.19 to 97.7.240.19—1
2197.7.240.20/3297.7.240.20 to 97.7.240.20—1
2297.7.240.21/3297.7.240.21 to 97.7.240.21—1
2397.7.240.22/3297.7.240.22 to 97.7.240.22—1
2497.7.240.23/3297.7.240.23 to 97.7.240.23—1
2597.7.240.24/3297.7.240.24 to 97.7.240.24—1
2697.7.240.25/3297.7.240.25 to 97.7.240.25—1
2797.7.240.26/3297.7.240.26 to 97.7.240.26—1
2897.7.240.27/3297.7.240.27 to 97.7.240.27—1
2997.7.240.28/3297.7.240.28 to 97.7.240.28—1
3097.7.240.29/3297.7.240.29 to 97.7.240.29—1
3197.7.240.30/3297.7.240.30 to 97.7.240.30—1
3297.7.240.31/3297.7.240.31 to 97.7.240.31—1
3397.7.240.32/3297.7.240.32 to 97.7.240.32—1
3497.7.240.33/3297.7.240.33 to 97.7.240.33—1
3597.7.240.34/3297.7.240.34 to 97.7.240.34—1
3697.7.240.35/3297.7.240.35 to 97.7.240.35—1
3797.7.240.36/3297.7.240.36 to 97.7.240.36—1
3897.7.240.37/3297.7.240.37 to 97.7.240.37—1
3997.7.240.38/3297.7.240.38 to 97.7.240.38—1
4097.7.240.39/3297.7.240.39 to 97.7.240.39—1
4197.7.240.40/3297.7.240.40 to 97.7.240.40—1
4297.7.240.41/3297.7.240.41 to 97.7.240.41—1
4397.7.240.42/3297.7.240.42 to 97.7.240.42—1
4497.7.240.43/3297.7.240.43 to 97.7.240.43—1
4597.7.240.44/3297.7.240.44 to 97.7.240.44—1
4697.7.240.45/3297.7.240.45 to 97.7.240.45—1
4797.7.240.46/3297.7.240.46 to 97.7.240.46—1
4897.7.240.47/3297.7.240.47 to 97.7.240.47—1
4997.7.240.48/3297.7.240.48 to 97.7.240.48—1
5097.7.240.49/3297.7.240.49 to 97.7.240.49—1
5197.7.240.50/3297.7.240.50 to 97.7.240.50—1
5297.7.240.51/3297.7.240.51 to 97.7.240.51—1
5397.7.240.52/3297.7.240.52 to 97.7.240.52—1
5497.7.240.53/3297.7.240.53 to 97.7.240.53—1
5597.7.240.54/3297.7.240.54 to 97.7.240.54—1
5697.7.240.55/3297.7.240.55 to 97.7.240.55—1
5797.7.240.56/3297.7.240.56 to 97.7.240.56—1
5897.7.240.57/3297.7.240.57 to 97.7.240.57—1
5997.7.240.58/3297.7.240.58 to 97.7.240.58—1
6097.7.240.59/3297.7.240.59 to 97.7.240.59—1
6197.7.240.60/3297.7.240.60 to 97.7.240.60—1
6297.7.240.61/3297.7.240.61 to 97.7.240.61—1
6397.7.240.62/3297.7.240.62 to 97.7.240.62—1
6497.7.240.63/3297.7.240.63 to 97.7.240.63—1
6597.7.240.64/3297.7.240.64 to 97.7.240.64—1
6697.7.240.65/3297.7.240.65 to 97.7.240.65—1
6797.7.240.66/3297.7.240.66 to 97.7.240.66—1
6897.7.240.67/3297.7.240.67 to 97.7.240.67—1
6997.7.240.68/3297.7.240.68 to 97.7.240.68—1
7097.7.240.69/3297.7.240.69 to 97.7.240.69—1
7197.7.240.70/3297.7.240.70 to 97.7.240.70—1
7297.7.240.71/3297.7.240.71 to 97.7.240.71—1
7397.7.240.72/3297.7.240.72 to 97.7.240.72—1
7497.7.240.73/3297.7.240.73 to 97.7.240.73—1
7597.7.240.74/3297.7.240.74 to 97.7.240.74—1
7697.7.240.75/3297.7.240.75 to 97.7.240.75—1
7797.7.240.76/3297.7.240.76 to 97.7.240.76—1
7897.7.240.77/3297.7.240.77 to 97.7.240.77—1
7997.7.240.78/3297.7.240.78 to 97.7.240.78—1
8097.7.240.79/3297.7.240.79 to 97.7.240.79—1
8197.7.240.80/3297.7.240.80 to 97.7.240.80—1
8297.7.240.81/3297.7.240.81 to 97.7.240.81—1
8397.7.240.82/3297.7.240.82 to 97.7.240.82—1
8497.7.240.83/3297.7.240.83 to 97.7.240.83—1
8597.7.240.84/3297.7.240.84 to 97.7.240.84—1
8697.7.240.85/3297.7.240.85 to 97.7.240.85—1
8797.7.240.86/3297.7.240.86 to 97.7.240.86—1
8897.7.240.87/3297.7.240.87 to 97.7.240.87—1
8997.7.240.88/3297.7.240.88 to 97.7.240.88—1
9097.7.240.89/3297.7.240.89 to 97.7.240.89—1
9197.7.240.90/3297.7.240.90 to 97.7.240.90—1
9297.7.240.91/3297.7.240.91 to 97.7.240.91—1
9397.7.240.92/3297.7.240.92 to 97.7.240.92—1
9497.7.240.93/3297.7.240.93 to 97.7.240.93—1
9597.7.240.94/3297.7.240.94 to 97.7.240.94—1
9697.7.240.95/3297.7.240.95 to 97.7.240.95—1
9797.7.240.96/3297.7.240.96 to 97.7.240.96—1
9897.7.240.97/3297.7.240.97 to 97.7.240.97—1
9997.7.240.98/3297.7.240.98 to 97.7.240.98—1
10097.7.240.99/3297.7.240.99 to 97.7.240.99—1
10197.7.240.100/3297.7.240.100 to 97.7.240.100—1
10297.7.240.101/3297.7.240.101 to 97.7.240.101—1
10397.7.240.102/3297.7.240.102 to 97.7.240.102—1
10497.7.240.103/3297.7.240.103 to 97.7.240.103—1
10597.7.240.104/3297.7.240.104 to 97.7.240.104—1
10697.7.240.105/3297.7.240.105 to 97.7.240.105—1
10797.7.240.106/3297.7.240.106 to 97.7.240.106—1
10897.7.240.107/3297.7.240.107 to 97.7.240.107—1
10997.7.240.108/3297.7.240.108 to 97.7.240.108—1
11097.7.240.109/3297.7.240.109 to 97.7.240.109—1
11197.7.240.110/3297.7.240.110 to 97.7.240.110—1
11297.7.240.111/3297.7.240.111 to 97.7.240.111—1
11397.7.240.112/3297.7.240.112 to 97.7.240.112—1
11497.7.240.113/3297.7.240.113 to 97.7.240.113—1
11597.7.240.114/3297.7.240.114 to 97.7.240.114—1
11697.7.240.115/3297.7.240.115 to 97.7.240.115—1
11797.7.240.116/3297.7.240.116 to 97.7.240.116—1
11897.7.240.117/3297.7.240.117 to 97.7.240.117—1
11997.7.240.118/3297.7.240.118 to 97.7.240.118—1
12097.7.240.119/3297.7.240.119 to 97.7.240.119—1
12197.7.240.120/3297.7.240.120 to 97.7.240.120—1
12297.7.240.121/3297.7.240.121 to 97.7.240.121—1
12397.7.240.122/3297.7.240.122 to 97.7.240.122—1
12497.7.240.123/3297.7.240.123 to 97.7.240.123—1
12597.7.240.124/3297.7.240.124 to 97.7.240.124—1
12697.7.240.125/3297.7.240.125 to 97.7.240.125—1
12797.7.240.126/3297.7.240.126 to 97.7.240.126—1
12897.7.240.127/3297.7.240.127 to 97.7.240.127—1
12997.7.240.128/3297.7.240.128 to 97.7.240.128—1
13097.7.240.129/3297.7.240.129 to 97.7.240.129—1
13197.7.240.130/3297.7.240.130 to 97.7.240.130—1
13297.7.240.131/3297.7.240.131 to 97.7.240.131—1
13397.7.240.132/3297.7.240.132 to 97.7.240.132—1
13497.7.240.133/3297.7.240.133 to 97.7.240.133—1
13597.7.240.134/3297.7.240.134 to 97.7.240.134—1
13697.7.240.135/3297.7.240.135 to 97.7.240.135—1
13797.7.240.136/3297.7.240.136 to 97.7.240.136—1
13897.7.240.137/3297.7.240.137 to 97.7.240.137—1
13997.7.240.138/3297.7.240.138 to 97.7.240.138—1
14097.7.240.139/3297.7.240.139 to 97.7.240.139—1
14197.7.240.140/3297.7.240.140 to 97.7.240.140—1
14297.7.240.141/3297.7.240.141 to 97.7.240.141—1
14397.7.240.142/3297.7.240.142 to 97.7.240.142—1
14497.7.240.143/3297.7.240.143 to 97.7.240.143—1
14597.7.240.144/3297.7.240.144 to 97.7.240.144—1
14697.7.240.145/3297.7.240.145 to 97.7.240.145—1
14797.7.240.146/3297.7.240.146 to 97.7.240.146—1
14897.7.240.147/3297.7.240.147 to 97.7.240.147—1
14997.7.240.148/3297.7.240.148 to 97.7.240.148—1
15097.7.240.149/3297.7.240.149 to 97.7.240.149—1
15197.7.240.150/3297.7.240.150 to 97.7.240.150—1
15297.7.240.151/3297.7.240.151 to 97.7.240.151—1
15397.7.240.152/3297.7.240.152 to 97.7.240.152—1
15497.7.240.153/3297.7.240.153 to 97.7.240.153—1
15597.7.240.154/3297.7.240.154 to 97.7.240.154—1
15697.7.240.155/3297.7.240.155 to 97.7.240.155—1
15797.7.240.156/3297.7.240.156 to 97.7.240.156—1
15897.7.240.157/3297.7.240.157 to 97.7.240.157—1
15997.7.240.158/3297.7.240.158 to 97.7.240.158—1
16097.7.240.159/3297.7.240.159 to 97.7.240.159—1
16197.7.240.160/3297.7.240.160 to 97.7.240.160—1
16297.7.240.161/3297.7.240.161 to 97.7.240.161—1
16397.7.240.162/3297.7.240.162 to 97.7.240.162—1
16497.7.240.163/3297.7.240.163 to 97.7.240.163—1
16597.7.240.164/3297.7.240.164 to 97.7.240.164—1
16697.7.240.165/3297.7.240.165 to 97.7.240.165—1
16797.7.240.166/3297.7.240.166 to 97.7.240.166—1
16897.7.240.167/3297.7.240.167 to 97.7.240.167—1
16997.7.240.168/3297.7.240.168 to 97.7.240.168—1
17097.7.240.169/3297.7.240.169 to 97.7.240.169—1
17197.7.240.170/3297.7.240.170 to 97.7.240.170—1
17297.7.240.171/3297.7.240.171 to 97.7.240.171—1
17397.7.240.172/3297.7.240.172 to 97.7.240.172—1
17497.7.240.173/3297.7.240.173 to 97.7.240.173—1
17597.7.240.174/3297.7.240.174 to 97.7.240.174—1
17697.7.240.175/3297.7.240.175 to 97.7.240.175—1
17797.7.240.176/3297.7.240.176 to 97.7.240.176—1
17897.7.240.177/3297.7.240.177 to 97.7.240.177—1
17997.7.240.178/3297.7.240.178 to 97.7.240.178—1
18097.7.240.179/3297.7.240.179 to 97.7.240.179—1
18197.7.240.180/3297.7.240.180 to 97.7.240.180—1
18297.7.240.181/3297.7.240.181 to 97.7.240.181—1
18397.7.240.182/3297.7.240.182 to 97.7.240.182—1
18497.7.240.183/3297.7.240.183 to 97.7.240.183—1
18597.7.240.184/3297.7.240.184 to 97.7.240.184—1
18697.7.240.185/3297.7.240.185 to 97.7.240.185—1
18797.7.240.186/3297.7.240.186 to 97.7.240.186—1
18897.7.240.187/3297.7.240.187 to 97.7.240.187—1
18997.7.240.188/3297.7.240.188 to 97.7.240.188—1
19097.7.240.189/3297.7.240.189 to 97.7.240.189—1
19197.7.240.190/3297.7.240.190 to 97.7.240.190—1
19297.7.240.191/3297.7.240.191 to 97.7.240.191—1
19397.7.240.192/3297.7.240.192 to 97.7.240.192—1
19497.7.240.193/3297.7.240.193 to 97.7.240.193—1
19597.7.240.194/3297.7.240.194 to 97.7.240.194—1
19697.7.240.195/3297.7.240.195 to 97.7.240.195—1
19797.7.240.196/3297.7.240.196 to 97.7.240.196—1
19897.7.240.197/3297.7.240.197 to 97.7.240.197—1
19997.7.240.198/3297.7.240.198 to 97.7.240.198—1
20097.7.240.199/3297.7.240.199 to 97.7.240.199—1
20197.7.240.200/3297.7.240.200 to 97.7.240.200—1
20297.7.240.201/3297.7.240.201 to 97.7.240.201—1
20397.7.240.202/3297.7.240.202 to 97.7.240.202—1
20497.7.240.203/3297.7.240.203 to 97.7.240.203—1
20597.7.240.204/3297.7.240.204 to 97.7.240.204—1
20697.7.240.205/3297.7.240.205 to 97.7.240.205—1
20797.7.240.206/3297.7.240.206 to 97.7.240.206—1
20897.7.240.207/3297.7.240.207 to 97.7.240.207—1
20997.7.240.208/3297.7.240.208 to 97.7.240.208—1
21097.7.240.209/3297.7.240.209 to 97.7.240.209—1
21197.7.240.210/3297.7.240.210 to 97.7.240.210—1
21297.7.240.211/3297.7.240.211 to 97.7.240.211—1
21397.7.240.212/3297.7.240.212 to 97.7.240.212—1
21497.7.240.213/3297.7.240.213 to 97.7.240.213—1
21597.7.240.214/3297.7.240.214 to 97.7.240.214—1
21697.7.240.215/3297.7.240.215 to 97.7.240.215—1
21797.7.240.216/3297.7.240.216 to 97.7.240.216—1
21897.7.240.217/3297.7.240.217 to 97.7.240.217—1
21997.7.240.218/3297.7.240.218 to 97.7.240.218—1
22097.7.240.219/3297.7.240.219 to 97.7.240.219—1
22197.7.240.220/3297.7.240.220 to 97.7.240.220—1
22297.7.240.221/3297.7.240.221 to 97.7.240.221—1
22397.7.240.222/3297.7.240.222 to 97.7.240.222—1
22497.7.240.223/3297.7.240.223 to 97.7.240.223—1
22597.7.240.224/3297.7.240.224 to 97.7.240.224—1
22697.7.240.225/3297.7.240.225 to 97.7.240.225—1
22797.7.240.226/3297.7.240.226 to 97.7.240.226—1
22897.7.240.227/3297.7.240.227 to 97.7.240.227—1
22997.7.240.228/3297.7.240.228 to 97.7.240.228—1
23097.7.240.229/3297.7.240.229 to 97.7.240.229—1
23197.7.240.230/3297.7.240.230 to 97.7.240.230—1
23297.7.240.231/3297.7.240.231 to 97.7.240.231—1
23397.7.240.232/3297.7.240.232 to 97.7.240.232—1
23497.7.240.233/3297.7.240.233 to 97.7.240.233—1
23597.7.240.234/3297.7.240.234 to 97.7.240.234—1
23697.7.240.235/3297.7.240.235 to 97.7.240.235—1
23797.7.240.236/3297.7.240.236 to 97.7.240.236—1
23897.7.240.237/3297.7.240.237 to 97.7.240.237—1
23997.7.240.238/3297.7.240.238 to 97.7.240.238—1
24097.7.240.239/3297.7.240.239 to 97.7.240.239—1
24197.7.240.240/3297.7.240.240 to 97.7.240.240—1
24297.7.240.241/3297.7.240.241 to 97.7.240.241—1
24397.7.240.242/3297.7.240.242 to 97.7.240.242—1
24497.7.240.243/3297.7.240.243 to 97.7.240.243—1
24597.7.240.244/3297.7.240.244 to 97.7.240.244—1
24697.7.240.245/3297.7.240.245 to 97.7.240.245—1
24797.7.240.246/3297.7.240.246 to 97.7.240.246—1
24897.7.240.247/3297.7.240.247 to 97.7.240.247—1
24997.7.240.248/3297.7.240.248 to 97.7.240.248—1
25097.7.240.249/3297.7.240.249 to 97.7.240.249—1
25197.7.240.250/3297.7.240.250 to 97.7.240.250—1
25297.7.240.251/3297.7.240.251 to 97.7.240.251—1
25397.7.240.252/3297.7.240.252 to 97.7.240.252—1
25497.7.240.253/3297.7.240.253 to 97.7.240.253—1
25597.7.240.254/3297.7.240.254 to 97.7.240.254—1
25697.7.240.255/3297.7.240.255 to 97.7.240.255—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.