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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.

Network178.7.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
178.7.0.0
Broadcast address
178.7.31.255
First usable
178.7.0.1
Last usable
178.7.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
B (default /16)
As numbers
Hex B2070000 · Integer 2986803200 to 2986811391
Reverse DNS zones
0.7.178.in-addr.arpa
1.7.178.in-addr.arpa
2.7.178.in-addr.arpa
3.7.178.in-addr.arpa
4.7.178.in-addr.arpa
5.7.178.in-addr.arpa
6.7.178.in-addr.arpa
7.7.178.in-addr.arpa
8.7.178.in-addr.arpa
9.7.178.in-addr.arpa
10.7.178.in-addr.arpa
11.7.178.in-addr.arpa
12.7.178.in-addr.arpa
13.7.178.in-addr.arpa
14.7.178.in-addr.arpa
15.7.178.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110010.00000111.00000000.00000000178.7.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10110010.00000111.00000000.00000000178.7.0.0
Broadcast10110010.00000111.00011111.11111111178.7.31.255
Split into smaller subnets/31
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

178.7.0.0/19 makes 4,096 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1178.7.0.0/31178.7.0.0 to 178.7.0.1—2
2178.7.0.2/31178.7.0.2 to 178.7.0.3—2
3178.7.0.4/31178.7.0.4 to 178.7.0.5—2
4178.7.0.6/31178.7.0.6 to 178.7.0.7—2
5178.7.0.8/31178.7.0.8 to 178.7.0.9—2
6178.7.0.10/31178.7.0.10 to 178.7.0.11—2
7178.7.0.12/31178.7.0.12 to 178.7.0.13—2
8178.7.0.14/31178.7.0.14 to 178.7.0.15—2
9178.7.0.16/31178.7.0.16 to 178.7.0.17—2
10178.7.0.18/31178.7.0.18 to 178.7.0.19—2
11178.7.0.20/31178.7.0.20 to 178.7.0.21—2
12178.7.0.22/31178.7.0.22 to 178.7.0.23—2
13178.7.0.24/31178.7.0.24 to 178.7.0.25—2
14178.7.0.26/31178.7.0.26 to 178.7.0.27—2
15178.7.0.28/31178.7.0.28 to 178.7.0.29—2
16178.7.0.30/31178.7.0.30 to 178.7.0.31—2
17178.7.0.32/31178.7.0.32 to 178.7.0.33—2
18178.7.0.34/31178.7.0.34 to 178.7.0.35—2
19178.7.0.36/31178.7.0.36 to 178.7.0.37—2
20178.7.0.38/31178.7.0.38 to 178.7.0.39—2
21178.7.0.40/31178.7.0.40 to 178.7.0.41—2
22178.7.0.42/31178.7.0.42 to 178.7.0.43—2
23178.7.0.44/31178.7.0.44 to 178.7.0.45—2
24178.7.0.46/31178.7.0.46 to 178.7.0.47—2
25178.7.0.48/31178.7.0.48 to 178.7.0.49—2
26178.7.0.50/31178.7.0.50 to 178.7.0.51—2
27178.7.0.52/31178.7.0.52 to 178.7.0.53—2
28178.7.0.54/31178.7.0.54 to 178.7.0.55—2
29178.7.0.56/31178.7.0.56 to 178.7.0.57—2
30178.7.0.58/31178.7.0.58 to 178.7.0.59—2
31178.7.0.60/31178.7.0.60 to 178.7.0.61—2
32178.7.0.62/31178.7.0.62 to 178.7.0.63—2
33178.7.0.64/31178.7.0.64 to 178.7.0.65—2
34178.7.0.66/31178.7.0.66 to 178.7.0.67—2
35178.7.0.68/31178.7.0.68 to 178.7.0.69—2
36178.7.0.70/31178.7.0.70 to 178.7.0.71—2
37178.7.0.72/31178.7.0.72 to 178.7.0.73—2
38178.7.0.74/31178.7.0.74 to 178.7.0.75—2
39178.7.0.76/31178.7.0.76 to 178.7.0.77—2
40178.7.0.78/31178.7.0.78 to 178.7.0.79—2
41178.7.0.80/31178.7.0.80 to 178.7.0.81—2
42178.7.0.82/31178.7.0.82 to 178.7.0.83—2
43178.7.0.84/31178.7.0.84 to 178.7.0.85—2
44178.7.0.86/31178.7.0.86 to 178.7.0.87—2
45178.7.0.88/31178.7.0.88 to 178.7.0.89—2
46178.7.0.90/31178.7.0.90 to 178.7.0.91—2
47178.7.0.92/31178.7.0.92 to 178.7.0.93—2
48178.7.0.94/31178.7.0.94 to 178.7.0.95—2
49178.7.0.96/31178.7.0.96 to 178.7.0.97—2
50178.7.0.98/31178.7.0.98 to 178.7.0.99—2
51178.7.0.100/31178.7.0.100 to 178.7.0.101—2
52178.7.0.102/31178.7.0.102 to 178.7.0.103—2
53178.7.0.104/31178.7.0.104 to 178.7.0.105—2
54178.7.0.106/31178.7.0.106 to 178.7.0.107—2
55178.7.0.108/31178.7.0.108 to 178.7.0.109—2
56178.7.0.110/31178.7.0.110 to 178.7.0.111—2
57178.7.0.112/31178.7.0.112 to 178.7.0.113—2
58178.7.0.114/31178.7.0.114 to 178.7.0.115—2
59178.7.0.116/31178.7.0.116 to 178.7.0.117—2
60178.7.0.118/31178.7.0.118 to 178.7.0.119—2
61178.7.0.120/31178.7.0.120 to 178.7.0.121—2
62178.7.0.122/31178.7.0.122 to 178.7.0.123—2
63178.7.0.124/31178.7.0.124 to 178.7.0.125—2
64178.7.0.126/31178.7.0.126 to 178.7.0.127—2
65178.7.0.128/31178.7.0.128 to 178.7.0.129—2
66178.7.0.130/31178.7.0.130 to 178.7.0.131—2
67178.7.0.132/31178.7.0.132 to 178.7.0.133—2
68178.7.0.134/31178.7.0.134 to 178.7.0.135—2
69178.7.0.136/31178.7.0.136 to 178.7.0.137—2
70178.7.0.138/31178.7.0.138 to 178.7.0.139—2
71178.7.0.140/31178.7.0.140 to 178.7.0.141—2
72178.7.0.142/31178.7.0.142 to 178.7.0.143—2
73178.7.0.144/31178.7.0.144 to 178.7.0.145—2
74178.7.0.146/31178.7.0.146 to 178.7.0.147—2
75178.7.0.148/31178.7.0.148 to 178.7.0.149—2
76178.7.0.150/31178.7.0.150 to 178.7.0.151—2
77178.7.0.152/31178.7.0.152 to 178.7.0.153—2
78178.7.0.154/31178.7.0.154 to 178.7.0.155—2
79178.7.0.156/31178.7.0.156 to 178.7.0.157—2
80178.7.0.158/31178.7.0.158 to 178.7.0.159—2
81178.7.0.160/31178.7.0.160 to 178.7.0.161—2
82178.7.0.162/31178.7.0.162 to 178.7.0.163—2
83178.7.0.164/31178.7.0.164 to 178.7.0.165—2
84178.7.0.166/31178.7.0.166 to 178.7.0.167—2
85178.7.0.168/31178.7.0.168 to 178.7.0.169—2
86178.7.0.170/31178.7.0.170 to 178.7.0.171—2
87178.7.0.172/31178.7.0.172 to 178.7.0.173—2
88178.7.0.174/31178.7.0.174 to 178.7.0.175—2
89178.7.0.176/31178.7.0.176 to 178.7.0.177—2
90178.7.0.178/31178.7.0.178 to 178.7.0.179—2
91178.7.0.180/31178.7.0.180 to 178.7.0.181—2
92178.7.0.182/31178.7.0.182 to 178.7.0.183—2
93178.7.0.184/31178.7.0.184 to 178.7.0.185—2
94178.7.0.186/31178.7.0.186 to 178.7.0.187—2
95178.7.0.188/31178.7.0.188 to 178.7.0.189—2
96178.7.0.190/31178.7.0.190 to 178.7.0.191—2
97178.7.0.192/31178.7.0.192 to 178.7.0.193—2
98178.7.0.194/31178.7.0.194 to 178.7.0.195—2
99178.7.0.196/31178.7.0.196 to 178.7.0.197—2
100178.7.0.198/31178.7.0.198 to 178.7.0.199—2
101178.7.0.200/31178.7.0.200 to 178.7.0.201—2
102178.7.0.202/31178.7.0.202 to 178.7.0.203—2
103178.7.0.204/31178.7.0.204 to 178.7.0.205—2
104178.7.0.206/31178.7.0.206 to 178.7.0.207—2
105178.7.0.208/31178.7.0.208 to 178.7.0.209—2
106178.7.0.210/31178.7.0.210 to 178.7.0.211—2
107178.7.0.212/31178.7.0.212 to 178.7.0.213—2
108178.7.0.214/31178.7.0.214 to 178.7.0.215—2
109178.7.0.216/31178.7.0.216 to 178.7.0.217—2
110178.7.0.218/31178.7.0.218 to 178.7.0.219—2
111178.7.0.220/31178.7.0.220 to 178.7.0.221—2
112178.7.0.222/31178.7.0.222 to 178.7.0.223—2
113178.7.0.224/31178.7.0.224 to 178.7.0.225—2
114178.7.0.226/31178.7.0.226 to 178.7.0.227—2
115178.7.0.228/31178.7.0.228 to 178.7.0.229—2
116178.7.0.230/31178.7.0.230 to 178.7.0.231—2
117178.7.0.232/31178.7.0.232 to 178.7.0.233—2
118178.7.0.234/31178.7.0.234 to 178.7.0.235—2
119178.7.0.236/31178.7.0.236 to 178.7.0.237—2
120178.7.0.238/31178.7.0.238 to 178.7.0.239—2
121178.7.0.240/31178.7.0.240 to 178.7.0.241—2
122178.7.0.242/31178.7.0.242 to 178.7.0.243—2
123178.7.0.244/31178.7.0.244 to 178.7.0.245—2
124178.7.0.246/31178.7.0.246 to 178.7.0.247—2
125178.7.0.248/31178.7.0.248 to 178.7.0.249—2
126178.7.0.250/31178.7.0.250 to 178.7.0.251—2
127178.7.0.252/31178.7.0.252 to 178.7.0.253—2
128178.7.0.254/31178.7.0.254 to 178.7.0.255—2
129178.7.1.0/31178.7.1.0 to 178.7.1.1—2
130178.7.1.2/31178.7.1.2 to 178.7.1.3—2
131178.7.1.4/31178.7.1.4 to 178.7.1.5—2
132178.7.1.6/31178.7.1.6 to 178.7.1.7—2
133178.7.1.8/31178.7.1.8 to 178.7.1.9—2
134178.7.1.10/31178.7.1.10 to 178.7.1.11—2
135178.7.1.12/31178.7.1.12 to 178.7.1.13—2
136178.7.1.14/31178.7.1.14 to 178.7.1.15—2
137178.7.1.16/31178.7.1.16 to 178.7.1.17—2
138178.7.1.18/31178.7.1.18 to 178.7.1.19—2
139178.7.1.20/31178.7.1.20 to 178.7.1.21—2
140178.7.1.22/31178.7.1.22 to 178.7.1.23—2
141178.7.1.24/31178.7.1.24 to 178.7.1.25—2
142178.7.1.26/31178.7.1.26 to 178.7.1.27—2
143178.7.1.28/31178.7.1.28 to 178.7.1.29—2
144178.7.1.30/31178.7.1.30 to 178.7.1.31—2
145178.7.1.32/31178.7.1.32 to 178.7.1.33—2
146178.7.1.34/31178.7.1.34 to 178.7.1.35—2
147178.7.1.36/31178.7.1.36 to 178.7.1.37—2
148178.7.1.38/31178.7.1.38 to 178.7.1.39—2
149178.7.1.40/31178.7.1.40 to 178.7.1.41—2
150178.7.1.42/31178.7.1.42 to 178.7.1.43—2
151178.7.1.44/31178.7.1.44 to 178.7.1.45—2
152178.7.1.46/31178.7.1.46 to 178.7.1.47—2
153178.7.1.48/31178.7.1.48 to 178.7.1.49—2
154178.7.1.50/31178.7.1.50 to 178.7.1.51—2
155178.7.1.52/31178.7.1.52 to 178.7.1.53—2
156178.7.1.54/31178.7.1.54 to 178.7.1.55—2
157178.7.1.56/31178.7.1.56 to 178.7.1.57—2
158178.7.1.58/31178.7.1.58 to 178.7.1.59—2
159178.7.1.60/31178.7.1.60 to 178.7.1.61—2
160178.7.1.62/31178.7.1.62 to 178.7.1.63—2
161178.7.1.64/31178.7.1.64 to 178.7.1.65—2
162178.7.1.66/31178.7.1.66 to 178.7.1.67—2
163178.7.1.68/31178.7.1.68 to 178.7.1.69—2
164178.7.1.70/31178.7.1.70 to 178.7.1.71—2
165178.7.1.72/31178.7.1.72 to 178.7.1.73—2
166178.7.1.74/31178.7.1.74 to 178.7.1.75—2
167178.7.1.76/31178.7.1.76 to 178.7.1.77—2
168178.7.1.78/31178.7.1.78 to 178.7.1.79—2
169178.7.1.80/31178.7.1.80 to 178.7.1.81—2
170178.7.1.82/31178.7.1.82 to 178.7.1.83—2
171178.7.1.84/31178.7.1.84 to 178.7.1.85—2
172178.7.1.86/31178.7.1.86 to 178.7.1.87—2
173178.7.1.88/31178.7.1.88 to 178.7.1.89—2
174178.7.1.90/31178.7.1.90 to 178.7.1.91—2
175178.7.1.92/31178.7.1.92 to 178.7.1.93—2
176178.7.1.94/31178.7.1.94 to 178.7.1.95—2
177178.7.1.96/31178.7.1.96 to 178.7.1.97—2
178178.7.1.98/31178.7.1.98 to 178.7.1.99—2
179178.7.1.100/31178.7.1.100 to 178.7.1.101—2
180178.7.1.102/31178.7.1.102 to 178.7.1.103—2
181178.7.1.104/31178.7.1.104 to 178.7.1.105—2
182178.7.1.106/31178.7.1.106 to 178.7.1.107—2
183178.7.1.108/31178.7.1.108 to 178.7.1.109—2
184178.7.1.110/31178.7.1.110 to 178.7.1.111—2
185178.7.1.112/31178.7.1.112 to 178.7.1.113—2
186178.7.1.114/31178.7.1.114 to 178.7.1.115—2
187178.7.1.116/31178.7.1.116 to 178.7.1.117—2
188178.7.1.118/31178.7.1.118 to 178.7.1.119—2
189178.7.1.120/31178.7.1.120 to 178.7.1.121—2
190178.7.1.122/31178.7.1.122 to 178.7.1.123—2
191178.7.1.124/31178.7.1.124 to 178.7.1.125—2
192178.7.1.126/31178.7.1.126 to 178.7.1.127—2
193178.7.1.128/31178.7.1.128 to 178.7.1.129—2
194178.7.1.130/31178.7.1.130 to 178.7.1.131—2
195178.7.1.132/31178.7.1.132 to 178.7.1.133—2
196178.7.1.134/31178.7.1.134 to 178.7.1.135—2
197178.7.1.136/31178.7.1.136 to 178.7.1.137—2
198178.7.1.138/31178.7.1.138 to 178.7.1.139—2
199178.7.1.140/31178.7.1.140 to 178.7.1.141—2
200178.7.1.142/31178.7.1.142 to 178.7.1.143—2
201178.7.1.144/31178.7.1.144 to 178.7.1.145—2
202178.7.1.146/31178.7.1.146 to 178.7.1.147—2
203178.7.1.148/31178.7.1.148 to 178.7.1.149—2
204178.7.1.150/31178.7.1.150 to 178.7.1.151—2
205178.7.1.152/31178.7.1.152 to 178.7.1.153—2
206178.7.1.154/31178.7.1.154 to 178.7.1.155—2
207178.7.1.156/31178.7.1.156 to 178.7.1.157—2
208178.7.1.158/31178.7.1.158 to 178.7.1.159—2
209178.7.1.160/31178.7.1.160 to 178.7.1.161—2
210178.7.1.162/31178.7.1.162 to 178.7.1.163—2
211178.7.1.164/31178.7.1.164 to 178.7.1.165—2
212178.7.1.166/31178.7.1.166 to 178.7.1.167—2
213178.7.1.168/31178.7.1.168 to 178.7.1.169—2
214178.7.1.170/31178.7.1.170 to 178.7.1.171—2
215178.7.1.172/31178.7.1.172 to 178.7.1.173—2
216178.7.1.174/31178.7.1.174 to 178.7.1.175—2
217178.7.1.176/31178.7.1.176 to 178.7.1.177—2
218178.7.1.178/31178.7.1.178 to 178.7.1.179—2
219178.7.1.180/31178.7.1.180 to 178.7.1.181—2
220178.7.1.182/31178.7.1.182 to 178.7.1.183—2
221178.7.1.184/31178.7.1.184 to 178.7.1.185—2
222178.7.1.186/31178.7.1.186 to 178.7.1.187—2
223178.7.1.188/31178.7.1.188 to 178.7.1.189—2
224178.7.1.190/31178.7.1.190 to 178.7.1.191—2
225178.7.1.192/31178.7.1.192 to 178.7.1.193—2
226178.7.1.194/31178.7.1.194 to 178.7.1.195—2
227178.7.1.196/31178.7.1.196 to 178.7.1.197—2
228178.7.1.198/31178.7.1.198 to 178.7.1.199—2
229178.7.1.200/31178.7.1.200 to 178.7.1.201—2
230178.7.1.202/31178.7.1.202 to 178.7.1.203—2
231178.7.1.204/31178.7.1.204 to 178.7.1.205—2
232178.7.1.206/31178.7.1.206 to 178.7.1.207—2
233178.7.1.208/31178.7.1.208 to 178.7.1.209—2
234178.7.1.210/31178.7.1.210 to 178.7.1.211—2
235178.7.1.212/31178.7.1.212 to 178.7.1.213—2
236178.7.1.214/31178.7.1.214 to 178.7.1.215—2
237178.7.1.216/31178.7.1.216 to 178.7.1.217—2
238178.7.1.218/31178.7.1.218 to 178.7.1.219—2
239178.7.1.220/31178.7.1.220 to 178.7.1.221—2
240178.7.1.222/31178.7.1.222 to 178.7.1.223—2
241178.7.1.224/31178.7.1.224 to 178.7.1.225—2
242178.7.1.226/31178.7.1.226 to 178.7.1.227—2
243178.7.1.228/31178.7.1.228 to 178.7.1.229—2
244178.7.1.230/31178.7.1.230 to 178.7.1.231—2
245178.7.1.232/31178.7.1.232 to 178.7.1.233—2
246178.7.1.234/31178.7.1.234 to 178.7.1.235—2
247178.7.1.236/31178.7.1.236 to 178.7.1.237—2
248178.7.1.238/31178.7.1.238 to 178.7.1.239—2
249178.7.1.240/31178.7.1.240 to 178.7.1.241—2
250178.7.1.242/31178.7.1.242 to 178.7.1.243—2
251178.7.1.244/31178.7.1.244 to 178.7.1.245—2
252178.7.1.246/31178.7.1.246 to 178.7.1.247—2
253178.7.1.248/31178.7.1.248 to 178.7.1.249—2
254178.7.1.250/31178.7.1.250 to 178.7.1.251—2
255178.7.1.252/31178.7.1.252 to 178.7.1.253—2
256178.7.1.254/31178.7.1.254 to 178.7.1.255—2

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.