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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.

Network186.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
186.0.0.0
Broadcast address
187.255.255.255
First usable
186.0.0.1
Last usable
187.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex BA000000 · Integer 3120562176 to 3154116607
Reverse DNS zones
186.in-addr.arpa
187.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111010.00000000.00000000.00000000186.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10111010.00000000.00000000.00000000186.0.0.0
Broadcast10111011.11111111.11111111.11111111187.255.255.255
Split into smaller subnets/15
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

186.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1186.0.0.0/15186.0.0.1 to 186.1.255.254186.1.255.255131,070
2186.2.0.0/15186.2.0.1 to 186.3.255.254186.3.255.255131,070
3186.4.0.0/15186.4.0.1 to 186.5.255.254186.5.255.255131,070
4186.6.0.0/15186.6.0.1 to 186.7.255.254186.7.255.255131,070
5186.8.0.0/15186.8.0.1 to 186.9.255.254186.9.255.255131,070
6186.10.0.0/15186.10.0.1 to 186.11.255.254186.11.255.255131,070
7186.12.0.0/15186.12.0.1 to 186.13.255.254186.13.255.255131,070
8186.14.0.0/15186.14.0.1 to 186.15.255.254186.15.255.255131,070
9186.16.0.0/15186.16.0.1 to 186.17.255.254186.17.255.255131,070
10186.18.0.0/15186.18.0.1 to 186.19.255.254186.19.255.255131,070
11186.20.0.0/15186.20.0.1 to 186.21.255.254186.21.255.255131,070
12186.22.0.0/15186.22.0.1 to 186.23.255.254186.23.255.255131,070
13186.24.0.0/15186.24.0.1 to 186.25.255.254186.25.255.255131,070
14186.26.0.0/15186.26.0.1 to 186.27.255.254186.27.255.255131,070
15186.28.0.0/15186.28.0.1 to 186.29.255.254186.29.255.255131,070
16186.30.0.0/15186.30.0.1 to 186.31.255.254186.31.255.255131,070
17186.32.0.0/15186.32.0.1 to 186.33.255.254186.33.255.255131,070
18186.34.0.0/15186.34.0.1 to 186.35.255.254186.35.255.255131,070
19186.36.0.0/15186.36.0.1 to 186.37.255.254186.37.255.255131,070
20186.38.0.0/15186.38.0.1 to 186.39.255.254186.39.255.255131,070
21186.40.0.0/15186.40.0.1 to 186.41.255.254186.41.255.255131,070
22186.42.0.0/15186.42.0.1 to 186.43.255.254186.43.255.255131,070
23186.44.0.0/15186.44.0.1 to 186.45.255.254186.45.255.255131,070
24186.46.0.0/15186.46.0.1 to 186.47.255.254186.47.255.255131,070
25186.48.0.0/15186.48.0.1 to 186.49.255.254186.49.255.255131,070
26186.50.0.0/15186.50.0.1 to 186.51.255.254186.51.255.255131,070
27186.52.0.0/15186.52.0.1 to 186.53.255.254186.53.255.255131,070
28186.54.0.0/15186.54.0.1 to 186.55.255.254186.55.255.255131,070
29186.56.0.0/15186.56.0.1 to 186.57.255.254186.57.255.255131,070
30186.58.0.0/15186.58.0.1 to 186.59.255.254186.59.255.255131,070
31186.60.0.0/15186.60.0.1 to 186.61.255.254186.61.255.255131,070
32186.62.0.0/15186.62.0.1 to 186.63.255.254186.63.255.255131,070
33186.64.0.0/15186.64.0.1 to 186.65.255.254186.65.255.255131,070
34186.66.0.0/15186.66.0.1 to 186.67.255.254186.67.255.255131,070
35186.68.0.0/15186.68.0.1 to 186.69.255.254186.69.255.255131,070
36186.70.0.0/15186.70.0.1 to 186.71.255.254186.71.255.255131,070
37186.72.0.0/15186.72.0.1 to 186.73.255.254186.73.255.255131,070
38186.74.0.0/15186.74.0.1 to 186.75.255.254186.75.255.255131,070
39186.76.0.0/15186.76.0.1 to 186.77.255.254186.77.255.255131,070
40186.78.0.0/15186.78.0.1 to 186.79.255.254186.79.255.255131,070
41186.80.0.0/15186.80.0.1 to 186.81.255.254186.81.255.255131,070
42186.82.0.0/15186.82.0.1 to 186.83.255.254186.83.255.255131,070
43186.84.0.0/15186.84.0.1 to 186.85.255.254186.85.255.255131,070
44186.86.0.0/15186.86.0.1 to 186.87.255.254186.87.255.255131,070
45186.88.0.0/15186.88.0.1 to 186.89.255.254186.89.255.255131,070
46186.90.0.0/15186.90.0.1 to 186.91.255.254186.91.255.255131,070
47186.92.0.0/15186.92.0.1 to 186.93.255.254186.93.255.255131,070
48186.94.0.0/15186.94.0.1 to 186.95.255.254186.95.255.255131,070
49186.96.0.0/15186.96.0.1 to 186.97.255.254186.97.255.255131,070
50186.98.0.0/15186.98.0.1 to 186.99.255.254186.99.255.255131,070
51186.100.0.0/15186.100.0.1 to 186.101.255.254186.101.255.255131,070
52186.102.0.0/15186.102.0.1 to 186.103.255.254186.103.255.255131,070
53186.104.0.0/15186.104.0.1 to 186.105.255.254186.105.255.255131,070
54186.106.0.0/15186.106.0.1 to 186.107.255.254186.107.255.255131,070
55186.108.0.0/15186.108.0.1 to 186.109.255.254186.109.255.255131,070
56186.110.0.0/15186.110.0.1 to 186.111.255.254186.111.255.255131,070
57186.112.0.0/15186.112.0.1 to 186.113.255.254186.113.255.255131,070
58186.114.0.0/15186.114.0.1 to 186.115.255.254186.115.255.255131,070
59186.116.0.0/15186.116.0.1 to 186.117.255.254186.117.255.255131,070
60186.118.0.0/15186.118.0.1 to 186.119.255.254186.119.255.255131,070
61186.120.0.0/15186.120.0.1 to 186.121.255.254186.121.255.255131,070
62186.122.0.0/15186.122.0.1 to 186.123.255.254186.123.255.255131,070
63186.124.0.0/15186.124.0.1 to 186.125.255.254186.125.255.255131,070
64186.126.0.0/15186.126.0.1 to 186.127.255.254186.127.255.255131,070
65186.128.0.0/15186.128.0.1 to 186.129.255.254186.129.255.255131,070
66186.130.0.0/15186.130.0.1 to 186.131.255.254186.131.255.255131,070
67186.132.0.0/15186.132.0.1 to 186.133.255.254186.133.255.255131,070
68186.134.0.0/15186.134.0.1 to 186.135.255.254186.135.255.255131,070
69186.136.0.0/15186.136.0.1 to 186.137.255.254186.137.255.255131,070
70186.138.0.0/15186.138.0.1 to 186.139.255.254186.139.255.255131,070
71186.140.0.0/15186.140.0.1 to 186.141.255.254186.141.255.255131,070
72186.142.0.0/15186.142.0.1 to 186.143.255.254186.143.255.255131,070
73186.144.0.0/15186.144.0.1 to 186.145.255.254186.145.255.255131,070
74186.146.0.0/15186.146.0.1 to 186.147.255.254186.147.255.255131,070
75186.148.0.0/15186.148.0.1 to 186.149.255.254186.149.255.255131,070
76186.150.0.0/15186.150.0.1 to 186.151.255.254186.151.255.255131,070
77186.152.0.0/15186.152.0.1 to 186.153.255.254186.153.255.255131,070
78186.154.0.0/15186.154.0.1 to 186.155.255.254186.155.255.255131,070
79186.156.0.0/15186.156.0.1 to 186.157.255.254186.157.255.255131,070
80186.158.0.0/15186.158.0.1 to 186.159.255.254186.159.255.255131,070
81186.160.0.0/15186.160.0.1 to 186.161.255.254186.161.255.255131,070
82186.162.0.0/15186.162.0.1 to 186.163.255.254186.163.255.255131,070
83186.164.0.0/15186.164.0.1 to 186.165.255.254186.165.255.255131,070
84186.166.0.0/15186.166.0.1 to 186.167.255.254186.167.255.255131,070
85186.168.0.0/15186.168.0.1 to 186.169.255.254186.169.255.255131,070
86186.170.0.0/15186.170.0.1 to 186.171.255.254186.171.255.255131,070
87186.172.0.0/15186.172.0.1 to 186.173.255.254186.173.255.255131,070
88186.174.0.0/15186.174.0.1 to 186.175.255.254186.175.255.255131,070
89186.176.0.0/15186.176.0.1 to 186.177.255.254186.177.255.255131,070
90186.178.0.0/15186.178.0.1 to 186.179.255.254186.179.255.255131,070
91186.180.0.0/15186.180.0.1 to 186.181.255.254186.181.255.255131,070
92186.182.0.0/15186.182.0.1 to 186.183.255.254186.183.255.255131,070
93186.184.0.0/15186.184.0.1 to 186.185.255.254186.185.255.255131,070
94186.186.0.0/15186.186.0.1 to 186.187.255.254186.187.255.255131,070
95186.188.0.0/15186.188.0.1 to 186.189.255.254186.189.255.255131,070
96186.190.0.0/15186.190.0.1 to 186.191.255.254186.191.255.255131,070
97186.192.0.0/15186.192.0.1 to 186.193.255.254186.193.255.255131,070
98186.194.0.0/15186.194.0.1 to 186.195.255.254186.195.255.255131,070
99186.196.0.0/15186.196.0.1 to 186.197.255.254186.197.255.255131,070
100186.198.0.0/15186.198.0.1 to 186.199.255.254186.199.255.255131,070
101186.200.0.0/15186.200.0.1 to 186.201.255.254186.201.255.255131,070
102186.202.0.0/15186.202.0.1 to 186.203.255.254186.203.255.255131,070
103186.204.0.0/15186.204.0.1 to 186.205.255.254186.205.255.255131,070
104186.206.0.0/15186.206.0.1 to 186.207.255.254186.207.255.255131,070
105186.208.0.0/15186.208.0.1 to 186.209.255.254186.209.255.255131,070
106186.210.0.0/15186.210.0.1 to 186.211.255.254186.211.255.255131,070
107186.212.0.0/15186.212.0.1 to 186.213.255.254186.213.255.255131,070
108186.214.0.0/15186.214.0.1 to 186.215.255.254186.215.255.255131,070
109186.216.0.0/15186.216.0.1 to 186.217.255.254186.217.255.255131,070
110186.218.0.0/15186.218.0.1 to 186.219.255.254186.219.255.255131,070
111186.220.0.0/15186.220.0.1 to 186.221.255.254186.221.255.255131,070
112186.222.0.0/15186.222.0.1 to 186.223.255.254186.223.255.255131,070
113186.224.0.0/15186.224.0.1 to 186.225.255.254186.225.255.255131,070
114186.226.0.0/15186.226.0.1 to 186.227.255.254186.227.255.255131,070
115186.228.0.0/15186.228.0.1 to 186.229.255.254186.229.255.255131,070
116186.230.0.0/15186.230.0.1 to 186.231.255.254186.231.255.255131,070
117186.232.0.0/15186.232.0.1 to 186.233.255.254186.233.255.255131,070
118186.234.0.0/15186.234.0.1 to 186.235.255.254186.235.255.255131,070
119186.236.0.0/15186.236.0.1 to 186.237.255.254186.237.255.255131,070
120186.238.0.0/15186.238.0.1 to 186.239.255.254186.239.255.255131,070
121186.240.0.0/15186.240.0.1 to 186.241.255.254186.241.255.255131,070
122186.242.0.0/15186.242.0.1 to 186.243.255.254186.243.255.255131,070
123186.244.0.0/15186.244.0.1 to 186.245.255.254186.245.255.255131,070
124186.246.0.0/15186.246.0.1 to 186.247.255.254186.247.255.255131,070
125186.248.0.0/15186.248.0.1 to 186.249.255.254186.249.255.255131,070
126186.250.0.0/15186.250.0.1 to 186.251.255.254186.251.255.255131,070
127186.252.0.0/15186.252.0.1 to 186.253.255.254186.253.255.255131,070
128186.254.0.0/15186.254.0.1 to 186.255.255.254186.255.255.255131,070
129187.0.0.0/15187.0.0.1 to 187.1.255.254187.1.255.255131,070
130187.2.0.0/15187.2.0.1 to 187.3.255.254187.3.255.255131,070
131187.4.0.0/15187.4.0.1 to 187.5.255.254187.5.255.255131,070
132187.6.0.0/15187.6.0.1 to 187.7.255.254187.7.255.255131,070
133187.8.0.0/15187.8.0.1 to 187.9.255.254187.9.255.255131,070
134187.10.0.0/15187.10.0.1 to 187.11.255.254187.11.255.255131,070
135187.12.0.0/15187.12.0.1 to 187.13.255.254187.13.255.255131,070
136187.14.0.0/15187.14.0.1 to 187.15.255.254187.15.255.255131,070
137187.16.0.0/15187.16.0.1 to 187.17.255.254187.17.255.255131,070
138187.18.0.0/15187.18.0.1 to 187.19.255.254187.19.255.255131,070
139187.20.0.0/15187.20.0.1 to 187.21.255.254187.21.255.255131,070
140187.22.0.0/15187.22.0.1 to 187.23.255.254187.23.255.255131,070
141187.24.0.0/15187.24.0.1 to 187.25.255.254187.25.255.255131,070
142187.26.0.0/15187.26.0.1 to 187.27.255.254187.27.255.255131,070
143187.28.0.0/15187.28.0.1 to 187.29.255.254187.29.255.255131,070
144187.30.0.0/15187.30.0.1 to 187.31.255.254187.31.255.255131,070
145187.32.0.0/15187.32.0.1 to 187.33.255.254187.33.255.255131,070
146187.34.0.0/15187.34.0.1 to 187.35.255.254187.35.255.255131,070
147187.36.0.0/15187.36.0.1 to 187.37.255.254187.37.255.255131,070
148187.38.0.0/15187.38.0.1 to 187.39.255.254187.39.255.255131,070
149187.40.0.0/15187.40.0.1 to 187.41.255.254187.41.255.255131,070
150187.42.0.0/15187.42.0.1 to 187.43.255.254187.43.255.255131,070
151187.44.0.0/15187.44.0.1 to 187.45.255.254187.45.255.255131,070
152187.46.0.0/15187.46.0.1 to 187.47.255.254187.47.255.255131,070
153187.48.0.0/15187.48.0.1 to 187.49.255.254187.49.255.255131,070
154187.50.0.0/15187.50.0.1 to 187.51.255.254187.51.255.255131,070
155187.52.0.0/15187.52.0.1 to 187.53.255.254187.53.255.255131,070
156187.54.0.0/15187.54.0.1 to 187.55.255.254187.55.255.255131,070
157187.56.0.0/15187.56.0.1 to 187.57.255.254187.57.255.255131,070
158187.58.0.0/15187.58.0.1 to 187.59.255.254187.59.255.255131,070
159187.60.0.0/15187.60.0.1 to 187.61.255.254187.61.255.255131,070
160187.62.0.0/15187.62.0.1 to 187.63.255.254187.63.255.255131,070
161187.64.0.0/15187.64.0.1 to 187.65.255.254187.65.255.255131,070
162187.66.0.0/15187.66.0.1 to 187.67.255.254187.67.255.255131,070
163187.68.0.0/15187.68.0.1 to 187.69.255.254187.69.255.255131,070
164187.70.0.0/15187.70.0.1 to 187.71.255.254187.71.255.255131,070
165187.72.0.0/15187.72.0.1 to 187.73.255.254187.73.255.255131,070
166187.74.0.0/15187.74.0.1 to 187.75.255.254187.75.255.255131,070
167187.76.0.0/15187.76.0.1 to 187.77.255.254187.77.255.255131,070
168187.78.0.0/15187.78.0.1 to 187.79.255.254187.79.255.255131,070
169187.80.0.0/15187.80.0.1 to 187.81.255.254187.81.255.255131,070
170187.82.0.0/15187.82.0.1 to 187.83.255.254187.83.255.255131,070
171187.84.0.0/15187.84.0.1 to 187.85.255.254187.85.255.255131,070
172187.86.0.0/15187.86.0.1 to 187.87.255.254187.87.255.255131,070
173187.88.0.0/15187.88.0.1 to 187.89.255.254187.89.255.255131,070
174187.90.0.0/15187.90.0.1 to 187.91.255.254187.91.255.255131,070
175187.92.0.0/15187.92.0.1 to 187.93.255.254187.93.255.255131,070
176187.94.0.0/15187.94.0.1 to 187.95.255.254187.95.255.255131,070
177187.96.0.0/15187.96.0.1 to 187.97.255.254187.97.255.255131,070
178187.98.0.0/15187.98.0.1 to 187.99.255.254187.99.255.255131,070
179187.100.0.0/15187.100.0.1 to 187.101.255.254187.101.255.255131,070
180187.102.0.0/15187.102.0.1 to 187.103.255.254187.103.255.255131,070
181187.104.0.0/15187.104.0.1 to 187.105.255.254187.105.255.255131,070
182187.106.0.0/15187.106.0.1 to 187.107.255.254187.107.255.255131,070
183187.108.0.0/15187.108.0.1 to 187.109.255.254187.109.255.255131,070
184187.110.0.0/15187.110.0.1 to 187.111.255.254187.111.255.255131,070
185187.112.0.0/15187.112.0.1 to 187.113.255.254187.113.255.255131,070
186187.114.0.0/15187.114.0.1 to 187.115.255.254187.115.255.255131,070
187187.116.0.0/15187.116.0.1 to 187.117.255.254187.117.255.255131,070
188187.118.0.0/15187.118.0.1 to 187.119.255.254187.119.255.255131,070
189187.120.0.0/15187.120.0.1 to 187.121.255.254187.121.255.255131,070
190187.122.0.0/15187.122.0.1 to 187.123.255.254187.123.255.255131,070
191187.124.0.0/15187.124.0.1 to 187.125.255.254187.125.255.255131,070
192187.126.0.0/15187.126.0.1 to 187.127.255.254187.127.255.255131,070
193187.128.0.0/15187.128.0.1 to 187.129.255.254187.129.255.255131,070
194187.130.0.0/15187.130.0.1 to 187.131.255.254187.131.255.255131,070
195187.132.0.0/15187.132.0.1 to 187.133.255.254187.133.255.255131,070
196187.134.0.0/15187.134.0.1 to 187.135.255.254187.135.255.255131,070
197187.136.0.0/15187.136.0.1 to 187.137.255.254187.137.255.255131,070
198187.138.0.0/15187.138.0.1 to 187.139.255.254187.139.255.255131,070
199187.140.0.0/15187.140.0.1 to 187.141.255.254187.141.255.255131,070
200187.142.0.0/15187.142.0.1 to 187.143.255.254187.143.255.255131,070
201187.144.0.0/15187.144.0.1 to 187.145.255.254187.145.255.255131,070
202187.146.0.0/15187.146.0.1 to 187.147.255.254187.147.255.255131,070
203187.148.0.0/15187.148.0.1 to 187.149.255.254187.149.255.255131,070
204187.150.0.0/15187.150.0.1 to 187.151.255.254187.151.255.255131,070
205187.152.0.0/15187.152.0.1 to 187.153.255.254187.153.255.255131,070
206187.154.0.0/15187.154.0.1 to 187.155.255.254187.155.255.255131,070
207187.156.0.0/15187.156.0.1 to 187.157.255.254187.157.255.255131,070
208187.158.0.0/15187.158.0.1 to 187.159.255.254187.159.255.255131,070
209187.160.0.0/15187.160.0.1 to 187.161.255.254187.161.255.255131,070
210187.162.0.0/15187.162.0.1 to 187.163.255.254187.163.255.255131,070
211187.164.0.0/15187.164.0.1 to 187.165.255.254187.165.255.255131,070
212187.166.0.0/15187.166.0.1 to 187.167.255.254187.167.255.255131,070
213187.168.0.0/15187.168.0.1 to 187.169.255.254187.169.255.255131,070
214187.170.0.0/15187.170.0.1 to 187.171.255.254187.171.255.255131,070
215187.172.0.0/15187.172.0.1 to 187.173.255.254187.173.255.255131,070
216187.174.0.0/15187.174.0.1 to 187.175.255.254187.175.255.255131,070
217187.176.0.0/15187.176.0.1 to 187.177.255.254187.177.255.255131,070
218187.178.0.0/15187.178.0.1 to 187.179.255.254187.179.255.255131,070
219187.180.0.0/15187.180.0.1 to 187.181.255.254187.181.255.255131,070
220187.182.0.0/15187.182.0.1 to 187.183.255.254187.183.255.255131,070
221187.184.0.0/15187.184.0.1 to 187.185.255.254187.185.255.255131,070
222187.186.0.0/15187.186.0.1 to 187.187.255.254187.187.255.255131,070
223187.188.0.0/15187.188.0.1 to 187.189.255.254187.189.255.255131,070
224187.190.0.0/15187.190.0.1 to 187.191.255.254187.191.255.255131,070
225187.192.0.0/15187.192.0.1 to 187.193.255.254187.193.255.255131,070
226187.194.0.0/15187.194.0.1 to 187.195.255.254187.195.255.255131,070
227187.196.0.0/15187.196.0.1 to 187.197.255.254187.197.255.255131,070
228187.198.0.0/15187.198.0.1 to 187.199.255.254187.199.255.255131,070
229187.200.0.0/15187.200.0.1 to 187.201.255.254187.201.255.255131,070
230187.202.0.0/15187.202.0.1 to 187.203.255.254187.203.255.255131,070
231187.204.0.0/15187.204.0.1 to 187.205.255.254187.205.255.255131,070
232187.206.0.0/15187.206.0.1 to 187.207.255.254187.207.255.255131,070
233187.208.0.0/15187.208.0.1 to 187.209.255.254187.209.255.255131,070
234187.210.0.0/15187.210.0.1 to 187.211.255.254187.211.255.255131,070
235187.212.0.0/15187.212.0.1 to 187.213.255.254187.213.255.255131,070
236187.214.0.0/15187.214.0.1 to 187.215.255.254187.215.255.255131,070
237187.216.0.0/15187.216.0.1 to 187.217.255.254187.217.255.255131,070
238187.218.0.0/15187.218.0.1 to 187.219.255.254187.219.255.255131,070
239187.220.0.0/15187.220.0.1 to 187.221.255.254187.221.255.255131,070
240187.222.0.0/15187.222.0.1 to 187.223.255.254187.223.255.255131,070
241187.224.0.0/15187.224.0.1 to 187.225.255.254187.225.255.255131,070
242187.226.0.0/15187.226.0.1 to 187.227.255.254187.227.255.255131,070
243187.228.0.0/15187.228.0.1 to 187.229.255.254187.229.255.255131,070
244187.230.0.0/15187.230.0.1 to 187.231.255.254187.231.255.255131,070
245187.232.0.0/15187.232.0.1 to 187.233.255.254187.233.255.255131,070
246187.234.0.0/15187.234.0.1 to 187.235.255.254187.235.255.255131,070
247187.236.0.0/15187.236.0.1 to 187.237.255.254187.237.255.255131,070
248187.238.0.0/15187.238.0.1 to 187.239.255.254187.239.255.255131,070
249187.240.0.0/15187.240.0.1 to 187.241.255.254187.241.255.255131,070
250187.242.0.0/15187.242.0.1 to 187.243.255.254187.243.255.255131,070
251187.244.0.0/15187.244.0.1 to 187.245.255.254187.245.255.255131,070
252187.246.0.0/15187.246.0.1 to 187.247.255.254187.247.255.255131,070
253187.248.0.0/15187.248.0.1 to 187.249.255.254187.249.255.255131,070
254187.250.0.0/15187.250.0.1 to 187.251.255.254187.251.255.255131,070
255187.252.0.0/15187.252.0.1 to 187.253.255.254187.253.255.255131,070
256187.254.0.0/15187.254.0.1 to 187.255.255.254187.255.255.255131,070

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.