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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.

Network181.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
181.0.0.0
Broadcast address
181.255.255.255
First usable
181.0.0.1
Last usable
181.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex B5000000 · Integer 3036676096 to 3053453311
Reverse DNS zone
181.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110101..00000000.00000000.00000000181.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10110101..00000000.00000000.00000000181.0.0.0
Broadcast10110101..11111111.11111111.11111111181.255.255.255
Split into smaller subnets/16
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

181.0.0.0/8 makes 256 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.0.0.0/16181.0.0.1 to 181.0.255.254181.0.255.25565,534
2181.1.0.0/16181.1.0.1 to 181.1.255.254181.1.255.25565,534
3181.2.0.0/16181.2.0.1 to 181.2.255.254181.2.255.25565,534
4181.3.0.0/16181.3.0.1 to 181.3.255.254181.3.255.25565,534
5181.4.0.0/16181.4.0.1 to 181.4.255.254181.4.255.25565,534
6181.5.0.0/16181.5.0.1 to 181.5.255.254181.5.255.25565,534
7181.6.0.0/16181.6.0.1 to 181.6.255.254181.6.255.25565,534
8181.7.0.0/16181.7.0.1 to 181.7.255.254181.7.255.25565,534
9181.8.0.0/16181.8.0.1 to 181.8.255.254181.8.255.25565,534
10181.9.0.0/16181.9.0.1 to 181.9.255.254181.9.255.25565,534
11181.10.0.0/16181.10.0.1 to 181.10.255.254181.10.255.25565,534
12181.11.0.0/16181.11.0.1 to 181.11.255.254181.11.255.25565,534
13181.12.0.0/16181.12.0.1 to 181.12.255.254181.12.255.25565,534
14181.13.0.0/16181.13.0.1 to 181.13.255.254181.13.255.25565,534
15181.14.0.0/16181.14.0.1 to 181.14.255.254181.14.255.25565,534
16181.15.0.0/16181.15.0.1 to 181.15.255.254181.15.255.25565,534
17181.16.0.0/16181.16.0.1 to 181.16.255.254181.16.255.25565,534
18181.17.0.0/16181.17.0.1 to 181.17.255.254181.17.255.25565,534
19181.18.0.0/16181.18.0.1 to 181.18.255.254181.18.255.25565,534
20181.19.0.0/16181.19.0.1 to 181.19.255.254181.19.255.25565,534
21181.20.0.0/16181.20.0.1 to 181.20.255.254181.20.255.25565,534
22181.21.0.0/16181.21.0.1 to 181.21.255.254181.21.255.25565,534
23181.22.0.0/16181.22.0.1 to 181.22.255.254181.22.255.25565,534
24181.23.0.0/16181.23.0.1 to 181.23.255.254181.23.255.25565,534
25181.24.0.0/16181.24.0.1 to 181.24.255.254181.24.255.25565,534
26181.25.0.0/16181.25.0.1 to 181.25.255.254181.25.255.25565,534
27181.26.0.0/16181.26.0.1 to 181.26.255.254181.26.255.25565,534
28181.27.0.0/16181.27.0.1 to 181.27.255.254181.27.255.25565,534
29181.28.0.0/16181.28.0.1 to 181.28.255.254181.28.255.25565,534
30181.29.0.0/16181.29.0.1 to 181.29.255.254181.29.255.25565,534
31181.30.0.0/16181.30.0.1 to 181.30.255.254181.30.255.25565,534
32181.31.0.0/16181.31.0.1 to 181.31.255.254181.31.255.25565,534
33181.32.0.0/16181.32.0.1 to 181.32.255.254181.32.255.25565,534
34181.33.0.0/16181.33.0.1 to 181.33.255.254181.33.255.25565,534
35181.34.0.0/16181.34.0.1 to 181.34.255.254181.34.255.25565,534
36181.35.0.0/16181.35.0.1 to 181.35.255.254181.35.255.25565,534
37181.36.0.0/16181.36.0.1 to 181.36.255.254181.36.255.25565,534
38181.37.0.0/16181.37.0.1 to 181.37.255.254181.37.255.25565,534
39181.38.0.0/16181.38.0.1 to 181.38.255.254181.38.255.25565,534
40181.39.0.0/16181.39.0.1 to 181.39.255.254181.39.255.25565,534
41181.40.0.0/16181.40.0.1 to 181.40.255.254181.40.255.25565,534
42181.41.0.0/16181.41.0.1 to 181.41.255.254181.41.255.25565,534
43181.42.0.0/16181.42.0.1 to 181.42.255.254181.42.255.25565,534
44181.43.0.0/16181.43.0.1 to 181.43.255.254181.43.255.25565,534
45181.44.0.0/16181.44.0.1 to 181.44.255.254181.44.255.25565,534
46181.45.0.0/16181.45.0.1 to 181.45.255.254181.45.255.25565,534
47181.46.0.0/16181.46.0.1 to 181.46.255.254181.46.255.25565,534
48181.47.0.0/16181.47.0.1 to 181.47.255.254181.47.255.25565,534
49181.48.0.0/16181.48.0.1 to 181.48.255.254181.48.255.25565,534
50181.49.0.0/16181.49.0.1 to 181.49.255.254181.49.255.25565,534
51181.50.0.0/16181.50.0.1 to 181.50.255.254181.50.255.25565,534
52181.51.0.0/16181.51.0.1 to 181.51.255.254181.51.255.25565,534
53181.52.0.0/16181.52.0.1 to 181.52.255.254181.52.255.25565,534
54181.53.0.0/16181.53.0.1 to 181.53.255.254181.53.255.25565,534
55181.54.0.0/16181.54.0.1 to 181.54.255.254181.54.255.25565,534
56181.55.0.0/16181.55.0.1 to 181.55.255.254181.55.255.25565,534
57181.56.0.0/16181.56.0.1 to 181.56.255.254181.56.255.25565,534
58181.57.0.0/16181.57.0.1 to 181.57.255.254181.57.255.25565,534
59181.58.0.0/16181.58.0.1 to 181.58.255.254181.58.255.25565,534
60181.59.0.0/16181.59.0.1 to 181.59.255.254181.59.255.25565,534
61181.60.0.0/16181.60.0.1 to 181.60.255.254181.60.255.25565,534
62181.61.0.0/16181.61.0.1 to 181.61.255.254181.61.255.25565,534
63181.62.0.0/16181.62.0.1 to 181.62.255.254181.62.255.25565,534
64181.63.0.0/16181.63.0.1 to 181.63.255.254181.63.255.25565,534
65181.64.0.0/16181.64.0.1 to 181.64.255.254181.64.255.25565,534
66181.65.0.0/16181.65.0.1 to 181.65.255.254181.65.255.25565,534
67181.66.0.0/16181.66.0.1 to 181.66.255.254181.66.255.25565,534
68181.67.0.0/16181.67.0.1 to 181.67.255.254181.67.255.25565,534
69181.68.0.0/16181.68.0.1 to 181.68.255.254181.68.255.25565,534
70181.69.0.0/16181.69.0.1 to 181.69.255.254181.69.255.25565,534
71181.70.0.0/16181.70.0.1 to 181.70.255.254181.70.255.25565,534
72181.71.0.0/16181.71.0.1 to 181.71.255.254181.71.255.25565,534
73181.72.0.0/16181.72.0.1 to 181.72.255.254181.72.255.25565,534
74181.73.0.0/16181.73.0.1 to 181.73.255.254181.73.255.25565,534
75181.74.0.0/16181.74.0.1 to 181.74.255.254181.74.255.25565,534
76181.75.0.0/16181.75.0.1 to 181.75.255.254181.75.255.25565,534
77181.76.0.0/16181.76.0.1 to 181.76.255.254181.76.255.25565,534
78181.77.0.0/16181.77.0.1 to 181.77.255.254181.77.255.25565,534
79181.78.0.0/16181.78.0.1 to 181.78.255.254181.78.255.25565,534
80181.79.0.0/16181.79.0.1 to 181.79.255.254181.79.255.25565,534
81181.80.0.0/16181.80.0.1 to 181.80.255.254181.80.255.25565,534
82181.81.0.0/16181.81.0.1 to 181.81.255.254181.81.255.25565,534
83181.82.0.0/16181.82.0.1 to 181.82.255.254181.82.255.25565,534
84181.83.0.0/16181.83.0.1 to 181.83.255.254181.83.255.25565,534
85181.84.0.0/16181.84.0.1 to 181.84.255.254181.84.255.25565,534
86181.85.0.0/16181.85.0.1 to 181.85.255.254181.85.255.25565,534
87181.86.0.0/16181.86.0.1 to 181.86.255.254181.86.255.25565,534
88181.87.0.0/16181.87.0.1 to 181.87.255.254181.87.255.25565,534
89181.88.0.0/16181.88.0.1 to 181.88.255.254181.88.255.25565,534
90181.89.0.0/16181.89.0.1 to 181.89.255.254181.89.255.25565,534
91181.90.0.0/16181.90.0.1 to 181.90.255.254181.90.255.25565,534
92181.91.0.0/16181.91.0.1 to 181.91.255.254181.91.255.25565,534
93181.92.0.0/16181.92.0.1 to 181.92.255.254181.92.255.25565,534
94181.93.0.0/16181.93.0.1 to 181.93.255.254181.93.255.25565,534
95181.94.0.0/16181.94.0.1 to 181.94.255.254181.94.255.25565,534
96181.95.0.0/16181.95.0.1 to 181.95.255.254181.95.255.25565,534
97181.96.0.0/16181.96.0.1 to 181.96.255.254181.96.255.25565,534
98181.97.0.0/16181.97.0.1 to 181.97.255.254181.97.255.25565,534
99181.98.0.0/16181.98.0.1 to 181.98.255.254181.98.255.25565,534
100181.99.0.0/16181.99.0.1 to 181.99.255.254181.99.255.25565,534
101181.100.0.0/16181.100.0.1 to 181.100.255.254181.100.255.25565,534
102181.101.0.0/16181.101.0.1 to 181.101.255.254181.101.255.25565,534
103181.102.0.0/16181.102.0.1 to 181.102.255.254181.102.255.25565,534
104181.103.0.0/16181.103.0.1 to 181.103.255.254181.103.255.25565,534
105181.104.0.0/16181.104.0.1 to 181.104.255.254181.104.255.25565,534
106181.105.0.0/16181.105.0.1 to 181.105.255.254181.105.255.25565,534
107181.106.0.0/16181.106.0.1 to 181.106.255.254181.106.255.25565,534
108181.107.0.0/16181.107.0.1 to 181.107.255.254181.107.255.25565,534
109181.108.0.0/16181.108.0.1 to 181.108.255.254181.108.255.25565,534
110181.109.0.0/16181.109.0.1 to 181.109.255.254181.109.255.25565,534
111181.110.0.0/16181.110.0.1 to 181.110.255.254181.110.255.25565,534
112181.111.0.0/16181.111.0.1 to 181.111.255.254181.111.255.25565,534
113181.112.0.0/16181.112.0.1 to 181.112.255.254181.112.255.25565,534
114181.113.0.0/16181.113.0.1 to 181.113.255.254181.113.255.25565,534
115181.114.0.0/16181.114.0.1 to 181.114.255.254181.114.255.25565,534
116181.115.0.0/16181.115.0.1 to 181.115.255.254181.115.255.25565,534
117181.116.0.0/16181.116.0.1 to 181.116.255.254181.116.255.25565,534
118181.117.0.0/16181.117.0.1 to 181.117.255.254181.117.255.25565,534
119181.118.0.0/16181.118.0.1 to 181.118.255.254181.118.255.25565,534
120181.119.0.0/16181.119.0.1 to 181.119.255.254181.119.255.25565,534
121181.120.0.0/16181.120.0.1 to 181.120.255.254181.120.255.25565,534
122181.121.0.0/16181.121.0.1 to 181.121.255.254181.121.255.25565,534
123181.122.0.0/16181.122.0.1 to 181.122.255.254181.122.255.25565,534
124181.123.0.0/16181.123.0.1 to 181.123.255.254181.123.255.25565,534
125181.124.0.0/16181.124.0.1 to 181.124.255.254181.124.255.25565,534
126181.125.0.0/16181.125.0.1 to 181.125.255.254181.125.255.25565,534
127181.126.0.0/16181.126.0.1 to 181.126.255.254181.126.255.25565,534
128181.127.0.0/16181.127.0.1 to 181.127.255.254181.127.255.25565,534
129181.128.0.0/16181.128.0.1 to 181.128.255.254181.128.255.25565,534
130181.129.0.0/16181.129.0.1 to 181.129.255.254181.129.255.25565,534
131181.130.0.0/16181.130.0.1 to 181.130.255.254181.130.255.25565,534
132181.131.0.0/16181.131.0.1 to 181.131.255.254181.131.255.25565,534
133181.132.0.0/16181.132.0.1 to 181.132.255.254181.132.255.25565,534
134181.133.0.0/16181.133.0.1 to 181.133.255.254181.133.255.25565,534
135181.134.0.0/16181.134.0.1 to 181.134.255.254181.134.255.25565,534
136181.135.0.0/16181.135.0.1 to 181.135.255.254181.135.255.25565,534
137181.136.0.0/16181.136.0.1 to 181.136.255.254181.136.255.25565,534
138181.137.0.0/16181.137.0.1 to 181.137.255.254181.137.255.25565,534
139181.138.0.0/16181.138.0.1 to 181.138.255.254181.138.255.25565,534
140181.139.0.0/16181.139.0.1 to 181.139.255.254181.139.255.25565,534
141181.140.0.0/16181.140.0.1 to 181.140.255.254181.140.255.25565,534
142181.141.0.0/16181.141.0.1 to 181.141.255.254181.141.255.25565,534
143181.142.0.0/16181.142.0.1 to 181.142.255.254181.142.255.25565,534
144181.143.0.0/16181.143.0.1 to 181.143.255.254181.143.255.25565,534
145181.144.0.0/16181.144.0.1 to 181.144.255.254181.144.255.25565,534
146181.145.0.0/16181.145.0.1 to 181.145.255.254181.145.255.25565,534
147181.146.0.0/16181.146.0.1 to 181.146.255.254181.146.255.25565,534
148181.147.0.0/16181.147.0.1 to 181.147.255.254181.147.255.25565,534
149181.148.0.0/16181.148.0.1 to 181.148.255.254181.148.255.25565,534
150181.149.0.0/16181.149.0.1 to 181.149.255.254181.149.255.25565,534
151181.150.0.0/16181.150.0.1 to 181.150.255.254181.150.255.25565,534
152181.151.0.0/16181.151.0.1 to 181.151.255.254181.151.255.25565,534
153181.152.0.0/16181.152.0.1 to 181.152.255.254181.152.255.25565,534
154181.153.0.0/16181.153.0.1 to 181.153.255.254181.153.255.25565,534
155181.154.0.0/16181.154.0.1 to 181.154.255.254181.154.255.25565,534
156181.155.0.0/16181.155.0.1 to 181.155.255.254181.155.255.25565,534
157181.156.0.0/16181.156.0.1 to 181.156.255.254181.156.255.25565,534
158181.157.0.0/16181.157.0.1 to 181.157.255.254181.157.255.25565,534
159181.158.0.0/16181.158.0.1 to 181.158.255.254181.158.255.25565,534
160181.159.0.0/16181.159.0.1 to 181.159.255.254181.159.255.25565,534
161181.160.0.0/16181.160.0.1 to 181.160.255.254181.160.255.25565,534
162181.161.0.0/16181.161.0.1 to 181.161.255.254181.161.255.25565,534
163181.162.0.0/16181.162.0.1 to 181.162.255.254181.162.255.25565,534
164181.163.0.0/16181.163.0.1 to 181.163.255.254181.163.255.25565,534
165181.164.0.0/16181.164.0.1 to 181.164.255.254181.164.255.25565,534
166181.165.0.0/16181.165.0.1 to 181.165.255.254181.165.255.25565,534
167181.166.0.0/16181.166.0.1 to 181.166.255.254181.166.255.25565,534
168181.167.0.0/16181.167.0.1 to 181.167.255.254181.167.255.25565,534
169181.168.0.0/16181.168.0.1 to 181.168.255.254181.168.255.25565,534
170181.169.0.0/16181.169.0.1 to 181.169.255.254181.169.255.25565,534
171181.170.0.0/16181.170.0.1 to 181.170.255.254181.170.255.25565,534
172181.171.0.0/16181.171.0.1 to 181.171.255.254181.171.255.25565,534
173181.172.0.0/16181.172.0.1 to 181.172.255.254181.172.255.25565,534
174181.173.0.0/16181.173.0.1 to 181.173.255.254181.173.255.25565,534
175181.174.0.0/16181.174.0.1 to 181.174.255.254181.174.255.25565,534
176181.175.0.0/16181.175.0.1 to 181.175.255.254181.175.255.25565,534
177181.176.0.0/16181.176.0.1 to 181.176.255.254181.176.255.25565,534
178181.177.0.0/16181.177.0.1 to 181.177.255.254181.177.255.25565,534
179181.178.0.0/16181.178.0.1 to 181.178.255.254181.178.255.25565,534
180181.179.0.0/16181.179.0.1 to 181.179.255.254181.179.255.25565,534
181181.180.0.0/16181.180.0.1 to 181.180.255.254181.180.255.25565,534
182181.181.0.0/16181.181.0.1 to 181.181.255.254181.181.255.25565,534
183181.182.0.0/16181.182.0.1 to 181.182.255.254181.182.255.25565,534
184181.183.0.0/16181.183.0.1 to 181.183.255.254181.183.255.25565,534
185181.184.0.0/16181.184.0.1 to 181.184.255.254181.184.255.25565,534
186181.185.0.0/16181.185.0.1 to 181.185.255.254181.185.255.25565,534
187181.186.0.0/16181.186.0.1 to 181.186.255.254181.186.255.25565,534
188181.187.0.0/16181.187.0.1 to 181.187.255.254181.187.255.25565,534
189181.188.0.0/16181.188.0.1 to 181.188.255.254181.188.255.25565,534
190181.189.0.0/16181.189.0.1 to 181.189.255.254181.189.255.25565,534
191181.190.0.0/16181.190.0.1 to 181.190.255.254181.190.255.25565,534
192181.191.0.0/16181.191.0.1 to 181.191.255.254181.191.255.25565,534
193181.192.0.0/16181.192.0.1 to 181.192.255.254181.192.255.25565,534
194181.193.0.0/16181.193.0.1 to 181.193.255.254181.193.255.25565,534
195181.194.0.0/16181.194.0.1 to 181.194.255.254181.194.255.25565,534
196181.195.0.0/16181.195.0.1 to 181.195.255.254181.195.255.25565,534
197181.196.0.0/16181.196.0.1 to 181.196.255.254181.196.255.25565,534
198181.197.0.0/16181.197.0.1 to 181.197.255.254181.197.255.25565,534
199181.198.0.0/16181.198.0.1 to 181.198.255.254181.198.255.25565,534
200181.199.0.0/16181.199.0.1 to 181.199.255.254181.199.255.25565,534
201181.200.0.0/16181.200.0.1 to 181.200.255.254181.200.255.25565,534
202181.201.0.0/16181.201.0.1 to 181.201.255.254181.201.255.25565,534
203181.202.0.0/16181.202.0.1 to 181.202.255.254181.202.255.25565,534
204181.203.0.0/16181.203.0.1 to 181.203.255.254181.203.255.25565,534
205181.204.0.0/16181.204.0.1 to 181.204.255.254181.204.255.25565,534
206181.205.0.0/16181.205.0.1 to 181.205.255.254181.205.255.25565,534
207181.206.0.0/16181.206.0.1 to 181.206.255.254181.206.255.25565,534
208181.207.0.0/16181.207.0.1 to 181.207.255.254181.207.255.25565,534
209181.208.0.0/16181.208.0.1 to 181.208.255.254181.208.255.25565,534
210181.209.0.0/16181.209.0.1 to 181.209.255.254181.209.255.25565,534
211181.210.0.0/16181.210.0.1 to 181.210.255.254181.210.255.25565,534
212181.211.0.0/16181.211.0.1 to 181.211.255.254181.211.255.25565,534
213181.212.0.0/16181.212.0.1 to 181.212.255.254181.212.255.25565,534
214181.213.0.0/16181.213.0.1 to 181.213.255.254181.213.255.25565,534
215181.214.0.0/16181.214.0.1 to 181.214.255.254181.214.255.25565,534
216181.215.0.0/16181.215.0.1 to 181.215.255.254181.215.255.25565,534
217181.216.0.0/16181.216.0.1 to 181.216.255.254181.216.255.25565,534
218181.217.0.0/16181.217.0.1 to 181.217.255.254181.217.255.25565,534
219181.218.0.0/16181.218.0.1 to 181.218.255.254181.218.255.25565,534
220181.219.0.0/16181.219.0.1 to 181.219.255.254181.219.255.25565,534
221181.220.0.0/16181.220.0.1 to 181.220.255.254181.220.255.25565,534
222181.221.0.0/16181.221.0.1 to 181.221.255.254181.221.255.25565,534
223181.222.0.0/16181.222.0.1 to 181.222.255.254181.222.255.25565,534
224181.223.0.0/16181.223.0.1 to 181.223.255.254181.223.255.25565,534
225181.224.0.0/16181.224.0.1 to 181.224.255.254181.224.255.25565,534
226181.225.0.0/16181.225.0.1 to 181.225.255.254181.225.255.25565,534
227181.226.0.0/16181.226.0.1 to 181.226.255.254181.226.255.25565,534
228181.227.0.0/16181.227.0.1 to 181.227.255.254181.227.255.25565,534
229181.228.0.0/16181.228.0.1 to 181.228.255.254181.228.255.25565,534
230181.229.0.0/16181.229.0.1 to 181.229.255.254181.229.255.25565,534
231181.230.0.0/16181.230.0.1 to 181.230.255.254181.230.255.25565,534
232181.231.0.0/16181.231.0.1 to 181.231.255.254181.231.255.25565,534
233181.232.0.0/16181.232.0.1 to 181.232.255.254181.232.255.25565,534
234181.233.0.0/16181.233.0.1 to 181.233.255.254181.233.255.25565,534
235181.234.0.0/16181.234.0.1 to 181.234.255.254181.234.255.25565,534
236181.235.0.0/16181.235.0.1 to 181.235.255.254181.235.255.25565,534
237181.236.0.0/16181.236.0.1 to 181.236.255.254181.236.255.25565,534
238181.237.0.0/16181.237.0.1 to 181.237.255.254181.237.255.25565,534
239181.238.0.0/16181.238.0.1 to 181.238.255.254181.238.255.25565,534
240181.239.0.0/16181.239.0.1 to 181.239.255.254181.239.255.25565,534
241181.240.0.0/16181.240.0.1 to 181.240.255.254181.240.255.25565,534
242181.241.0.0/16181.241.0.1 to 181.241.255.254181.241.255.25565,534
243181.242.0.0/16181.242.0.1 to 181.242.255.254181.242.255.25565,534
244181.243.0.0/16181.243.0.1 to 181.243.255.254181.243.255.25565,534
245181.244.0.0/16181.244.0.1 to 181.244.255.254181.244.255.25565,534
246181.245.0.0/16181.245.0.1 to 181.245.255.254181.245.255.25565,534
247181.246.0.0/16181.246.0.1 to 181.246.255.254181.246.255.25565,534
248181.247.0.0/16181.247.0.1 to 181.247.255.254181.247.255.25565,534
249181.248.0.0/16181.248.0.1 to 181.248.255.254181.248.255.25565,534
250181.249.0.0/16181.249.0.1 to 181.249.255.254181.249.255.25565,534
251181.250.0.0/16181.250.0.1 to 181.250.255.254181.250.255.25565,534
252181.251.0.0/16181.251.0.1 to 181.251.255.254181.251.255.25565,534
253181.252.0.0/16181.252.0.1 to 181.252.255.254181.252.255.25565,534
254181.253.0.0/16181.253.0.1 to 181.253.255.254181.253.255.25565,534
255181.254.0.0/16181.254.0.1 to 181.254.255.254181.254.255.25565,534
256181.255.0.0/16181.255.0.1 to 181.255.255.254181.255.255.25565,534

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.