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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.

Network128.0.0.0/3
Usable hosts536,870,910
Subnet mask224.0.0.0
Addresses536,870,912
Network address
128.0.0.0
Broadcast address
159.255.255.255
First usable
128.0.0.1
Last usable
159.255.255.254
Usable hosts
536,870,910 (536,870,912 less the network and broadcast addresses)
Subnet mask
224.0.0.0
Wildcard mask
31.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/3
Type
Public public
Old class
B (default /16)
As numbers
Hex 80000000 · Integer 2147483648 to 2684354559
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
136.in-addr.arpa
137.in-addr.arpa
138.in-addr.arpa
139.in-addr.arpa
140.in-addr.arpa
141.in-addr.arpa
142.in-addr.arpa
143.in-addr.arpa
and 16 more
/3 is not on a 8-bit boundary, so it takes 32 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000000.00000000.00000000.00000000128.0.0.0
Subnet mask11100000.00000000.00000000.00000000224.0.0.0
Network10000000.00000000.00000000.00000000128.0.0.0
Broadcast10011111.11111111.11111111.11111111159.255.255.255
Split into smaller subnets/15
/4 (2)/5 (4)/6 (8)/7 (16)/8 (32)/9 (64)/10 (128)/11 (256)/12 (512)/13 (1,024)/14 (2,048)/15 (4,096)

128.0.0.0/3 makes 4,096 subnets of /15; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1128.0.0.0/15128.0.0.1 to 128.1.255.254128.1.255.255131,070
2128.2.0.0/15128.2.0.1 to 128.3.255.254128.3.255.255131,070
3128.4.0.0/15128.4.0.1 to 128.5.255.254128.5.255.255131,070
4128.6.0.0/15128.6.0.1 to 128.7.255.254128.7.255.255131,070
5128.8.0.0/15128.8.0.1 to 128.9.255.254128.9.255.255131,070
6128.10.0.0/15128.10.0.1 to 128.11.255.254128.11.255.255131,070
7128.12.0.0/15128.12.0.1 to 128.13.255.254128.13.255.255131,070
8128.14.0.0/15128.14.0.1 to 128.15.255.254128.15.255.255131,070
9128.16.0.0/15128.16.0.1 to 128.17.255.254128.17.255.255131,070
10128.18.0.0/15128.18.0.1 to 128.19.255.254128.19.255.255131,070
11128.20.0.0/15128.20.0.1 to 128.21.255.254128.21.255.255131,070
12128.22.0.0/15128.22.0.1 to 128.23.255.254128.23.255.255131,070
13128.24.0.0/15128.24.0.1 to 128.25.255.254128.25.255.255131,070
14128.26.0.0/15128.26.0.1 to 128.27.255.254128.27.255.255131,070
15128.28.0.0/15128.28.0.1 to 128.29.255.254128.29.255.255131,070
16128.30.0.0/15128.30.0.1 to 128.31.255.254128.31.255.255131,070
17128.32.0.0/15128.32.0.1 to 128.33.255.254128.33.255.255131,070
18128.34.0.0/15128.34.0.1 to 128.35.255.254128.35.255.255131,070
19128.36.0.0/15128.36.0.1 to 128.37.255.254128.37.255.255131,070
20128.38.0.0/15128.38.0.1 to 128.39.255.254128.39.255.255131,070
21128.40.0.0/15128.40.0.1 to 128.41.255.254128.41.255.255131,070
22128.42.0.0/15128.42.0.1 to 128.43.255.254128.43.255.255131,070
23128.44.0.0/15128.44.0.1 to 128.45.255.254128.45.255.255131,070
24128.46.0.0/15128.46.0.1 to 128.47.255.254128.47.255.255131,070
25128.48.0.0/15128.48.0.1 to 128.49.255.254128.49.255.255131,070
26128.50.0.0/15128.50.0.1 to 128.51.255.254128.51.255.255131,070
27128.52.0.0/15128.52.0.1 to 128.53.255.254128.53.255.255131,070
28128.54.0.0/15128.54.0.1 to 128.55.255.254128.55.255.255131,070
29128.56.0.0/15128.56.0.1 to 128.57.255.254128.57.255.255131,070
30128.58.0.0/15128.58.0.1 to 128.59.255.254128.59.255.255131,070
31128.60.0.0/15128.60.0.1 to 128.61.255.254128.61.255.255131,070
32128.62.0.0/15128.62.0.1 to 128.63.255.254128.63.255.255131,070
33128.64.0.0/15128.64.0.1 to 128.65.255.254128.65.255.255131,070
34128.66.0.0/15128.66.0.1 to 128.67.255.254128.67.255.255131,070
35128.68.0.0/15128.68.0.1 to 128.69.255.254128.69.255.255131,070
36128.70.0.0/15128.70.0.1 to 128.71.255.254128.71.255.255131,070
37128.72.0.0/15128.72.0.1 to 128.73.255.254128.73.255.255131,070
38128.74.0.0/15128.74.0.1 to 128.75.255.254128.75.255.255131,070
39128.76.0.0/15128.76.0.1 to 128.77.255.254128.77.255.255131,070
40128.78.0.0/15128.78.0.1 to 128.79.255.254128.79.255.255131,070
41128.80.0.0/15128.80.0.1 to 128.81.255.254128.81.255.255131,070
42128.82.0.0/15128.82.0.1 to 128.83.255.254128.83.255.255131,070
43128.84.0.0/15128.84.0.1 to 128.85.255.254128.85.255.255131,070
44128.86.0.0/15128.86.0.1 to 128.87.255.254128.87.255.255131,070
45128.88.0.0/15128.88.0.1 to 128.89.255.254128.89.255.255131,070
46128.90.0.0/15128.90.0.1 to 128.91.255.254128.91.255.255131,070
47128.92.0.0/15128.92.0.1 to 128.93.255.254128.93.255.255131,070
48128.94.0.0/15128.94.0.1 to 128.95.255.254128.95.255.255131,070
49128.96.0.0/15128.96.0.1 to 128.97.255.254128.97.255.255131,070
50128.98.0.0/15128.98.0.1 to 128.99.255.254128.99.255.255131,070
51128.100.0.0/15128.100.0.1 to 128.101.255.254128.101.255.255131,070
52128.102.0.0/15128.102.0.1 to 128.103.255.254128.103.255.255131,070
53128.104.0.0/15128.104.0.1 to 128.105.255.254128.105.255.255131,070
54128.106.0.0/15128.106.0.1 to 128.107.255.254128.107.255.255131,070
55128.108.0.0/15128.108.0.1 to 128.109.255.254128.109.255.255131,070
56128.110.0.0/15128.110.0.1 to 128.111.255.254128.111.255.255131,070
57128.112.0.0/15128.112.0.1 to 128.113.255.254128.113.255.255131,070
58128.114.0.0/15128.114.0.1 to 128.115.255.254128.115.255.255131,070
59128.116.0.0/15128.116.0.1 to 128.117.255.254128.117.255.255131,070
60128.118.0.0/15128.118.0.1 to 128.119.255.254128.119.255.255131,070
61128.120.0.0/15128.120.0.1 to 128.121.255.254128.121.255.255131,070
62128.122.0.0/15128.122.0.1 to 128.123.255.254128.123.255.255131,070
63128.124.0.0/15128.124.0.1 to 128.125.255.254128.125.255.255131,070
64128.126.0.0/15128.126.0.1 to 128.127.255.254128.127.255.255131,070
65128.128.0.0/15128.128.0.1 to 128.129.255.254128.129.255.255131,070
66128.130.0.0/15128.130.0.1 to 128.131.255.254128.131.255.255131,070
67128.132.0.0/15128.132.0.1 to 128.133.255.254128.133.255.255131,070
68128.134.0.0/15128.134.0.1 to 128.135.255.254128.135.255.255131,070
69128.136.0.0/15128.136.0.1 to 128.137.255.254128.137.255.255131,070
70128.138.0.0/15128.138.0.1 to 128.139.255.254128.139.255.255131,070
71128.140.0.0/15128.140.0.1 to 128.141.255.254128.141.255.255131,070
72128.142.0.0/15128.142.0.1 to 128.143.255.254128.143.255.255131,070
73128.144.0.0/15128.144.0.1 to 128.145.255.254128.145.255.255131,070
74128.146.0.0/15128.146.0.1 to 128.147.255.254128.147.255.255131,070
75128.148.0.0/15128.148.0.1 to 128.149.255.254128.149.255.255131,070
76128.150.0.0/15128.150.0.1 to 128.151.255.254128.151.255.255131,070
77128.152.0.0/15128.152.0.1 to 128.153.255.254128.153.255.255131,070
78128.154.0.0/15128.154.0.1 to 128.155.255.254128.155.255.255131,070
79128.156.0.0/15128.156.0.1 to 128.157.255.254128.157.255.255131,070
80128.158.0.0/15128.158.0.1 to 128.159.255.254128.159.255.255131,070
81128.160.0.0/15128.160.0.1 to 128.161.255.254128.161.255.255131,070
82128.162.0.0/15128.162.0.1 to 128.163.255.254128.163.255.255131,070
83128.164.0.0/15128.164.0.1 to 128.165.255.254128.165.255.255131,070
84128.166.0.0/15128.166.0.1 to 128.167.255.254128.167.255.255131,070
85128.168.0.0/15128.168.0.1 to 128.169.255.254128.169.255.255131,070
86128.170.0.0/15128.170.0.1 to 128.171.255.254128.171.255.255131,070
87128.172.0.0/15128.172.0.1 to 128.173.255.254128.173.255.255131,070
88128.174.0.0/15128.174.0.1 to 128.175.255.254128.175.255.255131,070
89128.176.0.0/15128.176.0.1 to 128.177.255.254128.177.255.255131,070
90128.178.0.0/15128.178.0.1 to 128.179.255.254128.179.255.255131,070
91128.180.0.0/15128.180.0.1 to 128.181.255.254128.181.255.255131,070
92128.182.0.0/15128.182.0.1 to 128.183.255.254128.183.255.255131,070
93128.184.0.0/15128.184.0.1 to 128.185.255.254128.185.255.255131,070
94128.186.0.0/15128.186.0.1 to 128.187.255.254128.187.255.255131,070
95128.188.0.0/15128.188.0.1 to 128.189.255.254128.189.255.255131,070
96128.190.0.0/15128.190.0.1 to 128.191.255.254128.191.255.255131,070
97128.192.0.0/15128.192.0.1 to 128.193.255.254128.193.255.255131,070
98128.194.0.0/15128.194.0.1 to 128.195.255.254128.195.255.255131,070
99128.196.0.0/15128.196.0.1 to 128.197.255.254128.197.255.255131,070
100128.198.0.0/15128.198.0.1 to 128.199.255.254128.199.255.255131,070
101128.200.0.0/15128.200.0.1 to 128.201.255.254128.201.255.255131,070
102128.202.0.0/15128.202.0.1 to 128.203.255.254128.203.255.255131,070
103128.204.0.0/15128.204.0.1 to 128.205.255.254128.205.255.255131,070
104128.206.0.0/15128.206.0.1 to 128.207.255.254128.207.255.255131,070
105128.208.0.0/15128.208.0.1 to 128.209.255.254128.209.255.255131,070
106128.210.0.0/15128.210.0.1 to 128.211.255.254128.211.255.255131,070
107128.212.0.0/15128.212.0.1 to 128.213.255.254128.213.255.255131,070
108128.214.0.0/15128.214.0.1 to 128.215.255.254128.215.255.255131,070
109128.216.0.0/15128.216.0.1 to 128.217.255.254128.217.255.255131,070
110128.218.0.0/15128.218.0.1 to 128.219.255.254128.219.255.255131,070
111128.220.0.0/15128.220.0.1 to 128.221.255.254128.221.255.255131,070
112128.222.0.0/15128.222.0.1 to 128.223.255.254128.223.255.255131,070
113128.224.0.0/15128.224.0.1 to 128.225.255.254128.225.255.255131,070
114128.226.0.0/15128.226.0.1 to 128.227.255.254128.227.255.255131,070
115128.228.0.0/15128.228.0.1 to 128.229.255.254128.229.255.255131,070
116128.230.0.0/15128.230.0.1 to 128.231.255.254128.231.255.255131,070
117128.232.0.0/15128.232.0.1 to 128.233.255.254128.233.255.255131,070
118128.234.0.0/15128.234.0.1 to 128.235.255.254128.235.255.255131,070
119128.236.0.0/15128.236.0.1 to 128.237.255.254128.237.255.255131,070
120128.238.0.0/15128.238.0.1 to 128.239.255.254128.239.255.255131,070
121128.240.0.0/15128.240.0.1 to 128.241.255.254128.241.255.255131,070
122128.242.0.0/15128.242.0.1 to 128.243.255.254128.243.255.255131,070
123128.244.0.0/15128.244.0.1 to 128.245.255.254128.245.255.255131,070
124128.246.0.0/15128.246.0.1 to 128.247.255.254128.247.255.255131,070
125128.248.0.0/15128.248.0.1 to 128.249.255.254128.249.255.255131,070
126128.250.0.0/15128.250.0.1 to 128.251.255.254128.251.255.255131,070
127128.252.0.0/15128.252.0.1 to 128.253.255.254128.253.255.255131,070
128128.254.0.0/15128.254.0.1 to 128.255.255.254128.255.255.255131,070
129129.0.0.0/15129.0.0.1 to 129.1.255.254129.1.255.255131,070
130129.2.0.0/15129.2.0.1 to 129.3.255.254129.3.255.255131,070
131129.4.0.0/15129.4.0.1 to 129.5.255.254129.5.255.255131,070
132129.6.0.0/15129.6.0.1 to 129.7.255.254129.7.255.255131,070
133129.8.0.0/15129.8.0.1 to 129.9.255.254129.9.255.255131,070
134129.10.0.0/15129.10.0.1 to 129.11.255.254129.11.255.255131,070
135129.12.0.0/15129.12.0.1 to 129.13.255.254129.13.255.255131,070
136129.14.0.0/15129.14.0.1 to 129.15.255.254129.15.255.255131,070
137129.16.0.0/15129.16.0.1 to 129.17.255.254129.17.255.255131,070
138129.18.0.0/15129.18.0.1 to 129.19.255.254129.19.255.255131,070
139129.20.0.0/15129.20.0.1 to 129.21.255.254129.21.255.255131,070
140129.22.0.0/15129.22.0.1 to 129.23.255.254129.23.255.255131,070
141129.24.0.0/15129.24.0.1 to 129.25.255.254129.25.255.255131,070
142129.26.0.0/15129.26.0.1 to 129.27.255.254129.27.255.255131,070
143129.28.0.0/15129.28.0.1 to 129.29.255.254129.29.255.255131,070
144129.30.0.0/15129.30.0.1 to 129.31.255.254129.31.255.255131,070
145129.32.0.0/15129.32.0.1 to 129.33.255.254129.33.255.255131,070
146129.34.0.0/15129.34.0.1 to 129.35.255.254129.35.255.255131,070
147129.36.0.0/15129.36.0.1 to 129.37.255.254129.37.255.255131,070
148129.38.0.0/15129.38.0.1 to 129.39.255.254129.39.255.255131,070
149129.40.0.0/15129.40.0.1 to 129.41.255.254129.41.255.255131,070
150129.42.0.0/15129.42.0.1 to 129.43.255.254129.43.255.255131,070
151129.44.0.0/15129.44.0.1 to 129.45.255.254129.45.255.255131,070
152129.46.0.0/15129.46.0.1 to 129.47.255.254129.47.255.255131,070
153129.48.0.0/15129.48.0.1 to 129.49.255.254129.49.255.255131,070
154129.50.0.0/15129.50.0.1 to 129.51.255.254129.51.255.255131,070
155129.52.0.0/15129.52.0.1 to 129.53.255.254129.53.255.255131,070
156129.54.0.0/15129.54.0.1 to 129.55.255.254129.55.255.255131,070
157129.56.0.0/15129.56.0.1 to 129.57.255.254129.57.255.255131,070
158129.58.0.0/15129.58.0.1 to 129.59.255.254129.59.255.255131,070
159129.60.0.0/15129.60.0.1 to 129.61.255.254129.61.255.255131,070
160129.62.0.0/15129.62.0.1 to 129.63.255.254129.63.255.255131,070
161129.64.0.0/15129.64.0.1 to 129.65.255.254129.65.255.255131,070
162129.66.0.0/15129.66.0.1 to 129.67.255.254129.67.255.255131,070
163129.68.0.0/15129.68.0.1 to 129.69.255.254129.69.255.255131,070
164129.70.0.0/15129.70.0.1 to 129.71.255.254129.71.255.255131,070
165129.72.0.0/15129.72.0.1 to 129.73.255.254129.73.255.255131,070
166129.74.0.0/15129.74.0.1 to 129.75.255.254129.75.255.255131,070
167129.76.0.0/15129.76.0.1 to 129.77.255.254129.77.255.255131,070
168129.78.0.0/15129.78.0.1 to 129.79.255.254129.79.255.255131,070
169129.80.0.0/15129.80.0.1 to 129.81.255.254129.81.255.255131,070
170129.82.0.0/15129.82.0.1 to 129.83.255.254129.83.255.255131,070
171129.84.0.0/15129.84.0.1 to 129.85.255.254129.85.255.255131,070
172129.86.0.0/15129.86.0.1 to 129.87.255.254129.87.255.255131,070
173129.88.0.0/15129.88.0.1 to 129.89.255.254129.89.255.255131,070
174129.90.0.0/15129.90.0.1 to 129.91.255.254129.91.255.255131,070
175129.92.0.0/15129.92.0.1 to 129.93.255.254129.93.255.255131,070
176129.94.0.0/15129.94.0.1 to 129.95.255.254129.95.255.255131,070
177129.96.0.0/15129.96.0.1 to 129.97.255.254129.97.255.255131,070
178129.98.0.0/15129.98.0.1 to 129.99.255.254129.99.255.255131,070
179129.100.0.0/15129.100.0.1 to 129.101.255.254129.101.255.255131,070
180129.102.0.0/15129.102.0.1 to 129.103.255.254129.103.255.255131,070
181129.104.0.0/15129.104.0.1 to 129.105.255.254129.105.255.255131,070
182129.106.0.0/15129.106.0.1 to 129.107.255.254129.107.255.255131,070
183129.108.0.0/15129.108.0.1 to 129.109.255.254129.109.255.255131,070
184129.110.0.0/15129.110.0.1 to 129.111.255.254129.111.255.255131,070
185129.112.0.0/15129.112.0.1 to 129.113.255.254129.113.255.255131,070
186129.114.0.0/15129.114.0.1 to 129.115.255.254129.115.255.255131,070
187129.116.0.0/15129.116.0.1 to 129.117.255.254129.117.255.255131,070
188129.118.0.0/15129.118.0.1 to 129.119.255.254129.119.255.255131,070
189129.120.0.0/15129.120.0.1 to 129.121.255.254129.121.255.255131,070
190129.122.0.0/15129.122.0.1 to 129.123.255.254129.123.255.255131,070
191129.124.0.0/15129.124.0.1 to 129.125.255.254129.125.255.255131,070
192129.126.0.0/15129.126.0.1 to 129.127.255.254129.127.255.255131,070
193129.128.0.0/15129.128.0.1 to 129.129.255.254129.129.255.255131,070
194129.130.0.0/15129.130.0.1 to 129.131.255.254129.131.255.255131,070
195129.132.0.0/15129.132.0.1 to 129.133.255.254129.133.255.255131,070
196129.134.0.0/15129.134.0.1 to 129.135.255.254129.135.255.255131,070
197129.136.0.0/15129.136.0.1 to 129.137.255.254129.137.255.255131,070
198129.138.0.0/15129.138.0.1 to 129.139.255.254129.139.255.255131,070
199129.140.0.0/15129.140.0.1 to 129.141.255.254129.141.255.255131,070
200129.142.0.0/15129.142.0.1 to 129.143.255.254129.143.255.255131,070
201129.144.0.0/15129.144.0.1 to 129.145.255.254129.145.255.255131,070
202129.146.0.0/15129.146.0.1 to 129.147.255.254129.147.255.255131,070
203129.148.0.0/15129.148.0.1 to 129.149.255.254129.149.255.255131,070
204129.150.0.0/15129.150.0.1 to 129.151.255.254129.151.255.255131,070
205129.152.0.0/15129.152.0.1 to 129.153.255.254129.153.255.255131,070
206129.154.0.0/15129.154.0.1 to 129.155.255.254129.155.255.255131,070
207129.156.0.0/15129.156.0.1 to 129.157.255.254129.157.255.255131,070
208129.158.0.0/15129.158.0.1 to 129.159.255.254129.159.255.255131,070
209129.160.0.0/15129.160.0.1 to 129.161.255.254129.161.255.255131,070
210129.162.0.0/15129.162.0.1 to 129.163.255.254129.163.255.255131,070
211129.164.0.0/15129.164.0.1 to 129.165.255.254129.165.255.255131,070
212129.166.0.0/15129.166.0.1 to 129.167.255.254129.167.255.255131,070
213129.168.0.0/15129.168.0.1 to 129.169.255.254129.169.255.255131,070
214129.170.0.0/15129.170.0.1 to 129.171.255.254129.171.255.255131,070
215129.172.0.0/15129.172.0.1 to 129.173.255.254129.173.255.255131,070
216129.174.0.0/15129.174.0.1 to 129.175.255.254129.175.255.255131,070
217129.176.0.0/15129.176.0.1 to 129.177.255.254129.177.255.255131,070
218129.178.0.0/15129.178.0.1 to 129.179.255.254129.179.255.255131,070
219129.180.0.0/15129.180.0.1 to 129.181.255.254129.181.255.255131,070
220129.182.0.0/15129.182.0.1 to 129.183.255.254129.183.255.255131,070
221129.184.0.0/15129.184.0.1 to 129.185.255.254129.185.255.255131,070
222129.186.0.0/15129.186.0.1 to 129.187.255.254129.187.255.255131,070
223129.188.0.0/15129.188.0.1 to 129.189.255.254129.189.255.255131,070
224129.190.0.0/15129.190.0.1 to 129.191.255.254129.191.255.255131,070
225129.192.0.0/15129.192.0.1 to 129.193.255.254129.193.255.255131,070
226129.194.0.0/15129.194.0.1 to 129.195.255.254129.195.255.255131,070
227129.196.0.0/15129.196.0.1 to 129.197.255.254129.197.255.255131,070
228129.198.0.0/15129.198.0.1 to 129.199.255.254129.199.255.255131,070
229129.200.0.0/15129.200.0.1 to 129.201.255.254129.201.255.255131,070
230129.202.0.0/15129.202.0.1 to 129.203.255.254129.203.255.255131,070
231129.204.0.0/15129.204.0.1 to 129.205.255.254129.205.255.255131,070
232129.206.0.0/15129.206.0.1 to 129.207.255.254129.207.255.255131,070
233129.208.0.0/15129.208.0.1 to 129.209.255.254129.209.255.255131,070
234129.210.0.0/15129.210.0.1 to 129.211.255.254129.211.255.255131,070
235129.212.0.0/15129.212.0.1 to 129.213.255.254129.213.255.255131,070
236129.214.0.0/15129.214.0.1 to 129.215.255.254129.215.255.255131,070
237129.216.0.0/15129.216.0.1 to 129.217.255.254129.217.255.255131,070
238129.218.0.0/15129.218.0.1 to 129.219.255.254129.219.255.255131,070
239129.220.0.0/15129.220.0.1 to 129.221.255.254129.221.255.255131,070
240129.222.0.0/15129.222.0.1 to 129.223.255.254129.223.255.255131,070
241129.224.0.0/15129.224.0.1 to 129.225.255.254129.225.255.255131,070
242129.226.0.0/15129.226.0.1 to 129.227.255.254129.227.255.255131,070
243129.228.0.0/15129.228.0.1 to 129.229.255.254129.229.255.255131,070
244129.230.0.0/15129.230.0.1 to 129.231.255.254129.231.255.255131,070
245129.232.0.0/15129.232.0.1 to 129.233.255.254129.233.255.255131,070
246129.234.0.0/15129.234.0.1 to 129.235.255.254129.235.255.255131,070
247129.236.0.0/15129.236.0.1 to 129.237.255.254129.237.255.255131,070
248129.238.0.0/15129.238.0.1 to 129.239.255.254129.239.255.255131,070
249129.240.0.0/15129.240.0.1 to 129.241.255.254129.241.255.255131,070
250129.242.0.0/15129.242.0.1 to 129.243.255.254129.243.255.255131,070
251129.244.0.0/15129.244.0.1 to 129.245.255.254129.245.255.255131,070
252129.246.0.0/15129.246.0.1 to 129.247.255.254129.247.255.255131,070
253129.248.0.0/15129.248.0.1 to 129.249.255.254129.249.255.255131,070
254129.250.0.0/15129.250.0.1 to 129.251.255.254129.251.255.255131,070
255129.252.0.0/15129.252.0.1 to 129.253.255.254129.253.255.255131,070
256129.254.0.0/15129.254.0.1 to 129.255.255.254129.255.255.255131,070

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.