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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.

Network128.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
128.0.0.0
Broadcast address
135.255.255.255
First usable
128.0.0.1
Last usable
135.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
Type
Public public
Old class
B (default /16)
As numbers
Hex 80000000 · Integer 2147483648 to 2281701375
Reverse DNS zones
128.in-addr.arpa
129.in-addr.arpa
130.in-addr.arpa
131.in-addr.arpa
132.in-addr.arpa
133.in-addr.arpa
134.in-addr.arpa
135.in-addr.arpa
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000000.00000000.00000000.00000000128.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network10000000.00000000.00000000.00000000128.0.0.0
Broadcast10000111.11111111.11111111.11111111135.255.255.255
Split into smaller subnets/16
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

128.0.0.0/5 makes 2,048 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1128.0.0.0/16128.0.0.1 to 128.0.255.254128.0.255.25565,534
2128.1.0.0/16128.1.0.1 to 128.1.255.254128.1.255.25565,534
3128.2.0.0/16128.2.0.1 to 128.2.255.254128.2.255.25565,534
4128.3.0.0/16128.3.0.1 to 128.3.255.254128.3.255.25565,534
5128.4.0.0/16128.4.0.1 to 128.4.255.254128.4.255.25565,534
6128.5.0.0/16128.5.0.1 to 128.5.255.254128.5.255.25565,534
7128.6.0.0/16128.6.0.1 to 128.6.255.254128.6.255.25565,534
8128.7.0.0/16128.7.0.1 to 128.7.255.254128.7.255.25565,534
9128.8.0.0/16128.8.0.1 to 128.8.255.254128.8.255.25565,534
10128.9.0.0/16128.9.0.1 to 128.9.255.254128.9.255.25565,534
11128.10.0.0/16128.10.0.1 to 128.10.255.254128.10.255.25565,534
12128.11.0.0/16128.11.0.1 to 128.11.255.254128.11.255.25565,534
13128.12.0.0/16128.12.0.1 to 128.12.255.254128.12.255.25565,534
14128.13.0.0/16128.13.0.1 to 128.13.255.254128.13.255.25565,534
15128.14.0.0/16128.14.0.1 to 128.14.255.254128.14.255.25565,534
16128.15.0.0/16128.15.0.1 to 128.15.255.254128.15.255.25565,534
17128.16.0.0/16128.16.0.1 to 128.16.255.254128.16.255.25565,534
18128.17.0.0/16128.17.0.1 to 128.17.255.254128.17.255.25565,534
19128.18.0.0/16128.18.0.1 to 128.18.255.254128.18.255.25565,534
20128.19.0.0/16128.19.0.1 to 128.19.255.254128.19.255.25565,534
21128.20.0.0/16128.20.0.1 to 128.20.255.254128.20.255.25565,534
22128.21.0.0/16128.21.0.1 to 128.21.255.254128.21.255.25565,534
23128.22.0.0/16128.22.0.1 to 128.22.255.254128.22.255.25565,534
24128.23.0.0/16128.23.0.1 to 128.23.255.254128.23.255.25565,534
25128.24.0.0/16128.24.0.1 to 128.24.255.254128.24.255.25565,534
26128.25.0.0/16128.25.0.1 to 128.25.255.254128.25.255.25565,534
27128.26.0.0/16128.26.0.1 to 128.26.255.254128.26.255.25565,534
28128.27.0.0/16128.27.0.1 to 128.27.255.254128.27.255.25565,534
29128.28.0.0/16128.28.0.1 to 128.28.255.254128.28.255.25565,534
30128.29.0.0/16128.29.0.1 to 128.29.255.254128.29.255.25565,534
31128.30.0.0/16128.30.0.1 to 128.30.255.254128.30.255.25565,534
32128.31.0.0/16128.31.0.1 to 128.31.255.254128.31.255.25565,534
33128.32.0.0/16128.32.0.1 to 128.32.255.254128.32.255.25565,534
34128.33.0.0/16128.33.0.1 to 128.33.255.254128.33.255.25565,534
35128.34.0.0/16128.34.0.1 to 128.34.255.254128.34.255.25565,534
36128.35.0.0/16128.35.0.1 to 128.35.255.254128.35.255.25565,534
37128.36.0.0/16128.36.0.1 to 128.36.255.254128.36.255.25565,534
38128.37.0.0/16128.37.0.1 to 128.37.255.254128.37.255.25565,534
39128.38.0.0/16128.38.0.1 to 128.38.255.254128.38.255.25565,534
40128.39.0.0/16128.39.0.1 to 128.39.255.254128.39.255.25565,534
41128.40.0.0/16128.40.0.1 to 128.40.255.254128.40.255.25565,534
42128.41.0.0/16128.41.0.1 to 128.41.255.254128.41.255.25565,534
43128.42.0.0/16128.42.0.1 to 128.42.255.254128.42.255.25565,534
44128.43.0.0/16128.43.0.1 to 128.43.255.254128.43.255.25565,534
45128.44.0.0/16128.44.0.1 to 128.44.255.254128.44.255.25565,534
46128.45.0.0/16128.45.0.1 to 128.45.255.254128.45.255.25565,534
47128.46.0.0/16128.46.0.1 to 128.46.255.254128.46.255.25565,534
48128.47.0.0/16128.47.0.1 to 128.47.255.254128.47.255.25565,534
49128.48.0.0/16128.48.0.1 to 128.48.255.254128.48.255.25565,534
50128.49.0.0/16128.49.0.1 to 128.49.255.254128.49.255.25565,534
51128.50.0.0/16128.50.0.1 to 128.50.255.254128.50.255.25565,534
52128.51.0.0/16128.51.0.1 to 128.51.255.254128.51.255.25565,534
53128.52.0.0/16128.52.0.1 to 128.52.255.254128.52.255.25565,534
54128.53.0.0/16128.53.0.1 to 128.53.255.254128.53.255.25565,534
55128.54.0.0/16128.54.0.1 to 128.54.255.254128.54.255.25565,534
56128.55.0.0/16128.55.0.1 to 128.55.255.254128.55.255.25565,534
57128.56.0.0/16128.56.0.1 to 128.56.255.254128.56.255.25565,534
58128.57.0.0/16128.57.0.1 to 128.57.255.254128.57.255.25565,534
59128.58.0.0/16128.58.0.1 to 128.58.255.254128.58.255.25565,534
60128.59.0.0/16128.59.0.1 to 128.59.255.254128.59.255.25565,534
61128.60.0.0/16128.60.0.1 to 128.60.255.254128.60.255.25565,534
62128.61.0.0/16128.61.0.1 to 128.61.255.254128.61.255.25565,534
63128.62.0.0/16128.62.0.1 to 128.62.255.254128.62.255.25565,534
64128.63.0.0/16128.63.0.1 to 128.63.255.254128.63.255.25565,534
65128.64.0.0/16128.64.0.1 to 128.64.255.254128.64.255.25565,534
66128.65.0.0/16128.65.0.1 to 128.65.255.254128.65.255.25565,534
67128.66.0.0/16128.66.0.1 to 128.66.255.254128.66.255.25565,534
68128.67.0.0/16128.67.0.1 to 128.67.255.254128.67.255.25565,534
69128.68.0.0/16128.68.0.1 to 128.68.255.254128.68.255.25565,534
70128.69.0.0/16128.69.0.1 to 128.69.255.254128.69.255.25565,534
71128.70.0.0/16128.70.0.1 to 128.70.255.254128.70.255.25565,534
72128.71.0.0/16128.71.0.1 to 128.71.255.254128.71.255.25565,534
73128.72.0.0/16128.72.0.1 to 128.72.255.254128.72.255.25565,534
74128.73.0.0/16128.73.0.1 to 128.73.255.254128.73.255.25565,534
75128.74.0.0/16128.74.0.1 to 128.74.255.254128.74.255.25565,534
76128.75.0.0/16128.75.0.1 to 128.75.255.254128.75.255.25565,534
77128.76.0.0/16128.76.0.1 to 128.76.255.254128.76.255.25565,534
78128.77.0.0/16128.77.0.1 to 128.77.255.254128.77.255.25565,534
79128.78.0.0/16128.78.0.1 to 128.78.255.254128.78.255.25565,534
80128.79.0.0/16128.79.0.1 to 128.79.255.254128.79.255.25565,534
81128.80.0.0/16128.80.0.1 to 128.80.255.254128.80.255.25565,534
82128.81.0.0/16128.81.0.1 to 128.81.255.254128.81.255.25565,534
83128.82.0.0/16128.82.0.1 to 128.82.255.254128.82.255.25565,534
84128.83.0.0/16128.83.0.1 to 128.83.255.254128.83.255.25565,534
85128.84.0.0/16128.84.0.1 to 128.84.255.254128.84.255.25565,534
86128.85.0.0/16128.85.0.1 to 128.85.255.254128.85.255.25565,534
87128.86.0.0/16128.86.0.1 to 128.86.255.254128.86.255.25565,534
88128.87.0.0/16128.87.0.1 to 128.87.255.254128.87.255.25565,534
89128.88.0.0/16128.88.0.1 to 128.88.255.254128.88.255.25565,534
90128.89.0.0/16128.89.0.1 to 128.89.255.254128.89.255.25565,534
91128.90.0.0/16128.90.0.1 to 128.90.255.254128.90.255.25565,534
92128.91.0.0/16128.91.0.1 to 128.91.255.254128.91.255.25565,534
93128.92.0.0/16128.92.0.1 to 128.92.255.254128.92.255.25565,534
94128.93.0.0/16128.93.0.1 to 128.93.255.254128.93.255.25565,534
95128.94.0.0/16128.94.0.1 to 128.94.255.254128.94.255.25565,534
96128.95.0.0/16128.95.0.1 to 128.95.255.254128.95.255.25565,534
97128.96.0.0/16128.96.0.1 to 128.96.255.254128.96.255.25565,534
98128.97.0.0/16128.97.0.1 to 128.97.255.254128.97.255.25565,534
99128.98.0.0/16128.98.0.1 to 128.98.255.254128.98.255.25565,534
100128.99.0.0/16128.99.0.1 to 128.99.255.254128.99.255.25565,534
101128.100.0.0/16128.100.0.1 to 128.100.255.254128.100.255.25565,534
102128.101.0.0/16128.101.0.1 to 128.101.255.254128.101.255.25565,534
103128.102.0.0/16128.102.0.1 to 128.102.255.254128.102.255.25565,534
104128.103.0.0/16128.103.0.1 to 128.103.255.254128.103.255.25565,534
105128.104.0.0/16128.104.0.1 to 128.104.255.254128.104.255.25565,534
106128.105.0.0/16128.105.0.1 to 128.105.255.254128.105.255.25565,534
107128.106.0.0/16128.106.0.1 to 128.106.255.254128.106.255.25565,534
108128.107.0.0/16128.107.0.1 to 128.107.255.254128.107.255.25565,534
109128.108.0.0/16128.108.0.1 to 128.108.255.254128.108.255.25565,534
110128.109.0.0/16128.109.0.1 to 128.109.255.254128.109.255.25565,534
111128.110.0.0/16128.110.0.1 to 128.110.255.254128.110.255.25565,534
112128.111.0.0/16128.111.0.1 to 128.111.255.254128.111.255.25565,534
113128.112.0.0/16128.112.0.1 to 128.112.255.254128.112.255.25565,534
114128.113.0.0/16128.113.0.1 to 128.113.255.254128.113.255.25565,534
115128.114.0.0/16128.114.0.1 to 128.114.255.254128.114.255.25565,534
116128.115.0.0/16128.115.0.1 to 128.115.255.254128.115.255.25565,534
117128.116.0.0/16128.116.0.1 to 128.116.255.254128.116.255.25565,534
118128.117.0.0/16128.117.0.1 to 128.117.255.254128.117.255.25565,534
119128.118.0.0/16128.118.0.1 to 128.118.255.254128.118.255.25565,534
120128.119.0.0/16128.119.0.1 to 128.119.255.254128.119.255.25565,534
121128.120.0.0/16128.120.0.1 to 128.120.255.254128.120.255.25565,534
122128.121.0.0/16128.121.0.1 to 128.121.255.254128.121.255.25565,534
123128.122.0.0/16128.122.0.1 to 128.122.255.254128.122.255.25565,534
124128.123.0.0/16128.123.0.1 to 128.123.255.254128.123.255.25565,534
125128.124.0.0/16128.124.0.1 to 128.124.255.254128.124.255.25565,534
126128.125.0.0/16128.125.0.1 to 128.125.255.254128.125.255.25565,534
127128.126.0.0/16128.126.0.1 to 128.126.255.254128.126.255.25565,534
128128.127.0.0/16128.127.0.1 to 128.127.255.254128.127.255.25565,534
129128.128.0.0/16128.128.0.1 to 128.128.255.254128.128.255.25565,534
130128.129.0.0/16128.129.0.1 to 128.129.255.254128.129.255.25565,534
131128.130.0.0/16128.130.0.1 to 128.130.255.254128.130.255.25565,534
132128.131.0.0/16128.131.0.1 to 128.131.255.254128.131.255.25565,534
133128.132.0.0/16128.132.0.1 to 128.132.255.254128.132.255.25565,534
134128.133.0.0/16128.133.0.1 to 128.133.255.254128.133.255.25565,534
135128.134.0.0/16128.134.0.1 to 128.134.255.254128.134.255.25565,534
136128.135.0.0/16128.135.0.1 to 128.135.255.254128.135.255.25565,534
137128.136.0.0/16128.136.0.1 to 128.136.255.254128.136.255.25565,534
138128.137.0.0/16128.137.0.1 to 128.137.255.254128.137.255.25565,534
139128.138.0.0/16128.138.0.1 to 128.138.255.254128.138.255.25565,534
140128.139.0.0/16128.139.0.1 to 128.139.255.254128.139.255.25565,534
141128.140.0.0/16128.140.0.1 to 128.140.255.254128.140.255.25565,534
142128.141.0.0/16128.141.0.1 to 128.141.255.254128.141.255.25565,534
143128.142.0.0/16128.142.0.1 to 128.142.255.254128.142.255.25565,534
144128.143.0.0/16128.143.0.1 to 128.143.255.254128.143.255.25565,534
145128.144.0.0/16128.144.0.1 to 128.144.255.254128.144.255.25565,534
146128.145.0.0/16128.145.0.1 to 128.145.255.254128.145.255.25565,534
147128.146.0.0/16128.146.0.1 to 128.146.255.254128.146.255.25565,534
148128.147.0.0/16128.147.0.1 to 128.147.255.254128.147.255.25565,534
149128.148.0.0/16128.148.0.1 to 128.148.255.254128.148.255.25565,534
150128.149.0.0/16128.149.0.1 to 128.149.255.254128.149.255.25565,534
151128.150.0.0/16128.150.0.1 to 128.150.255.254128.150.255.25565,534
152128.151.0.0/16128.151.0.1 to 128.151.255.254128.151.255.25565,534
153128.152.0.0/16128.152.0.1 to 128.152.255.254128.152.255.25565,534
154128.153.0.0/16128.153.0.1 to 128.153.255.254128.153.255.25565,534
155128.154.0.0/16128.154.0.1 to 128.154.255.254128.154.255.25565,534
156128.155.0.0/16128.155.0.1 to 128.155.255.254128.155.255.25565,534
157128.156.0.0/16128.156.0.1 to 128.156.255.254128.156.255.25565,534
158128.157.0.0/16128.157.0.1 to 128.157.255.254128.157.255.25565,534
159128.158.0.0/16128.158.0.1 to 128.158.255.254128.158.255.25565,534
160128.159.0.0/16128.159.0.1 to 128.159.255.254128.159.255.25565,534
161128.160.0.0/16128.160.0.1 to 128.160.255.254128.160.255.25565,534
162128.161.0.0/16128.161.0.1 to 128.161.255.254128.161.255.25565,534
163128.162.0.0/16128.162.0.1 to 128.162.255.254128.162.255.25565,534
164128.163.0.0/16128.163.0.1 to 128.163.255.254128.163.255.25565,534
165128.164.0.0/16128.164.0.1 to 128.164.255.254128.164.255.25565,534
166128.165.0.0/16128.165.0.1 to 128.165.255.254128.165.255.25565,534
167128.166.0.0/16128.166.0.1 to 128.166.255.254128.166.255.25565,534
168128.167.0.0/16128.167.0.1 to 128.167.255.254128.167.255.25565,534
169128.168.0.0/16128.168.0.1 to 128.168.255.254128.168.255.25565,534
170128.169.0.0/16128.169.0.1 to 128.169.255.254128.169.255.25565,534
171128.170.0.0/16128.170.0.1 to 128.170.255.254128.170.255.25565,534
172128.171.0.0/16128.171.0.1 to 128.171.255.254128.171.255.25565,534
173128.172.0.0/16128.172.0.1 to 128.172.255.254128.172.255.25565,534
174128.173.0.0/16128.173.0.1 to 128.173.255.254128.173.255.25565,534
175128.174.0.0/16128.174.0.1 to 128.174.255.254128.174.255.25565,534
176128.175.0.0/16128.175.0.1 to 128.175.255.254128.175.255.25565,534
177128.176.0.0/16128.176.0.1 to 128.176.255.254128.176.255.25565,534
178128.177.0.0/16128.177.0.1 to 128.177.255.254128.177.255.25565,534
179128.178.0.0/16128.178.0.1 to 128.178.255.254128.178.255.25565,534
180128.179.0.0/16128.179.0.1 to 128.179.255.254128.179.255.25565,534
181128.180.0.0/16128.180.0.1 to 128.180.255.254128.180.255.25565,534
182128.181.0.0/16128.181.0.1 to 128.181.255.254128.181.255.25565,534
183128.182.0.0/16128.182.0.1 to 128.182.255.254128.182.255.25565,534
184128.183.0.0/16128.183.0.1 to 128.183.255.254128.183.255.25565,534
185128.184.0.0/16128.184.0.1 to 128.184.255.254128.184.255.25565,534
186128.185.0.0/16128.185.0.1 to 128.185.255.254128.185.255.25565,534
187128.186.0.0/16128.186.0.1 to 128.186.255.254128.186.255.25565,534
188128.187.0.0/16128.187.0.1 to 128.187.255.254128.187.255.25565,534
189128.188.0.0/16128.188.0.1 to 128.188.255.254128.188.255.25565,534
190128.189.0.0/16128.189.0.1 to 128.189.255.254128.189.255.25565,534
191128.190.0.0/16128.190.0.1 to 128.190.255.254128.190.255.25565,534
192128.191.0.0/16128.191.0.1 to 128.191.255.254128.191.255.25565,534
193128.192.0.0/16128.192.0.1 to 128.192.255.254128.192.255.25565,534
194128.193.0.0/16128.193.0.1 to 128.193.255.254128.193.255.25565,534
195128.194.0.0/16128.194.0.1 to 128.194.255.254128.194.255.25565,534
196128.195.0.0/16128.195.0.1 to 128.195.255.254128.195.255.25565,534
197128.196.0.0/16128.196.0.1 to 128.196.255.254128.196.255.25565,534
198128.197.0.0/16128.197.0.1 to 128.197.255.254128.197.255.25565,534
199128.198.0.0/16128.198.0.1 to 128.198.255.254128.198.255.25565,534
200128.199.0.0/16128.199.0.1 to 128.199.255.254128.199.255.25565,534
201128.200.0.0/16128.200.0.1 to 128.200.255.254128.200.255.25565,534
202128.201.0.0/16128.201.0.1 to 128.201.255.254128.201.255.25565,534
203128.202.0.0/16128.202.0.1 to 128.202.255.254128.202.255.25565,534
204128.203.0.0/16128.203.0.1 to 128.203.255.254128.203.255.25565,534
205128.204.0.0/16128.204.0.1 to 128.204.255.254128.204.255.25565,534
206128.205.0.0/16128.205.0.1 to 128.205.255.254128.205.255.25565,534
207128.206.0.0/16128.206.0.1 to 128.206.255.254128.206.255.25565,534
208128.207.0.0/16128.207.0.1 to 128.207.255.254128.207.255.25565,534
209128.208.0.0/16128.208.0.1 to 128.208.255.254128.208.255.25565,534
210128.209.0.0/16128.209.0.1 to 128.209.255.254128.209.255.25565,534
211128.210.0.0/16128.210.0.1 to 128.210.255.254128.210.255.25565,534
212128.211.0.0/16128.211.0.1 to 128.211.255.254128.211.255.25565,534
213128.212.0.0/16128.212.0.1 to 128.212.255.254128.212.255.25565,534
214128.213.0.0/16128.213.0.1 to 128.213.255.254128.213.255.25565,534
215128.214.0.0/16128.214.0.1 to 128.214.255.254128.214.255.25565,534
216128.215.0.0/16128.215.0.1 to 128.215.255.254128.215.255.25565,534
217128.216.0.0/16128.216.0.1 to 128.216.255.254128.216.255.25565,534
218128.217.0.0/16128.217.0.1 to 128.217.255.254128.217.255.25565,534
219128.218.0.0/16128.218.0.1 to 128.218.255.254128.218.255.25565,534
220128.219.0.0/16128.219.0.1 to 128.219.255.254128.219.255.25565,534
221128.220.0.0/16128.220.0.1 to 128.220.255.254128.220.255.25565,534
222128.221.0.0/16128.221.0.1 to 128.221.255.254128.221.255.25565,534
223128.222.0.0/16128.222.0.1 to 128.222.255.254128.222.255.25565,534
224128.223.0.0/16128.223.0.1 to 128.223.255.254128.223.255.25565,534
225128.224.0.0/16128.224.0.1 to 128.224.255.254128.224.255.25565,534
226128.225.0.0/16128.225.0.1 to 128.225.255.254128.225.255.25565,534
227128.226.0.0/16128.226.0.1 to 128.226.255.254128.226.255.25565,534
228128.227.0.0/16128.227.0.1 to 128.227.255.254128.227.255.25565,534
229128.228.0.0/16128.228.0.1 to 128.228.255.254128.228.255.25565,534
230128.229.0.0/16128.229.0.1 to 128.229.255.254128.229.255.25565,534
231128.230.0.0/16128.230.0.1 to 128.230.255.254128.230.255.25565,534
232128.231.0.0/16128.231.0.1 to 128.231.255.254128.231.255.25565,534
233128.232.0.0/16128.232.0.1 to 128.232.255.254128.232.255.25565,534
234128.233.0.0/16128.233.0.1 to 128.233.255.254128.233.255.25565,534
235128.234.0.0/16128.234.0.1 to 128.234.255.254128.234.255.25565,534
236128.235.0.0/16128.235.0.1 to 128.235.255.254128.235.255.25565,534
237128.236.0.0/16128.236.0.1 to 128.236.255.254128.236.255.25565,534
238128.237.0.0/16128.237.0.1 to 128.237.255.254128.237.255.25565,534
239128.238.0.0/16128.238.0.1 to 128.238.255.254128.238.255.25565,534
240128.239.0.0/16128.239.0.1 to 128.239.255.254128.239.255.25565,534
241128.240.0.0/16128.240.0.1 to 128.240.255.254128.240.255.25565,534
242128.241.0.0/16128.241.0.1 to 128.241.255.254128.241.255.25565,534
243128.242.0.0/16128.242.0.1 to 128.242.255.254128.242.255.25565,534
244128.243.0.0/16128.243.0.1 to 128.243.255.254128.243.255.25565,534
245128.244.0.0/16128.244.0.1 to 128.244.255.254128.244.255.25565,534
246128.245.0.0/16128.245.0.1 to 128.245.255.254128.245.255.25565,534
247128.246.0.0/16128.246.0.1 to 128.246.255.254128.246.255.25565,534
248128.247.0.0/16128.247.0.1 to 128.247.255.254128.247.255.25565,534
249128.248.0.0/16128.248.0.1 to 128.248.255.254128.248.255.25565,534
250128.249.0.0/16128.249.0.1 to 128.249.255.254128.249.255.25565,534
251128.250.0.0/16128.250.0.1 to 128.250.255.254128.250.255.25565,534
252128.251.0.0/16128.251.0.1 to 128.251.255.254128.251.255.25565,534
253128.252.0.0/16128.252.0.1 to 128.252.255.254128.252.255.25565,534
254128.253.0.0/16128.253.0.1 to 128.253.255.254128.253.255.25565,534
255128.254.0.0/16128.254.0.1 to 128.254.255.254128.254.255.25565,534
256128.255.0.0/16128.255.0.1 to 128.255.255.254128.255.255.25565,534

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.