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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.

Network170.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
170.0.0.0
Broadcast address
171.255.255.255
First usable
170.0.0.1
Last usable
171.255.255.254
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 AA000000 · Integer 2852126720 to 2885681151
Reverse DNS zones
170.in-addr.arpa
171.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
Address10101010.00000000.00000000.00000000170.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10101010.00000000.00000000.00000000170.0.0.0
Broadcast10101011.11111111.11111111.11111111171.255.255.255
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)

170.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1170.0.0.0/15170.0.0.1 to 170.1.255.254170.1.255.255131,070
2170.2.0.0/15170.2.0.1 to 170.3.255.254170.3.255.255131,070
3170.4.0.0/15170.4.0.1 to 170.5.255.254170.5.255.255131,070
4170.6.0.0/15170.6.0.1 to 170.7.255.254170.7.255.255131,070
5170.8.0.0/15170.8.0.1 to 170.9.255.254170.9.255.255131,070
6170.10.0.0/15170.10.0.1 to 170.11.255.254170.11.255.255131,070
7170.12.0.0/15170.12.0.1 to 170.13.255.254170.13.255.255131,070
8170.14.0.0/15170.14.0.1 to 170.15.255.254170.15.255.255131,070
9170.16.0.0/15170.16.0.1 to 170.17.255.254170.17.255.255131,070
10170.18.0.0/15170.18.0.1 to 170.19.255.254170.19.255.255131,070
11170.20.0.0/15170.20.0.1 to 170.21.255.254170.21.255.255131,070
12170.22.0.0/15170.22.0.1 to 170.23.255.254170.23.255.255131,070
13170.24.0.0/15170.24.0.1 to 170.25.255.254170.25.255.255131,070
14170.26.0.0/15170.26.0.1 to 170.27.255.254170.27.255.255131,070
15170.28.0.0/15170.28.0.1 to 170.29.255.254170.29.255.255131,070
16170.30.0.0/15170.30.0.1 to 170.31.255.254170.31.255.255131,070
17170.32.0.0/15170.32.0.1 to 170.33.255.254170.33.255.255131,070
18170.34.0.0/15170.34.0.1 to 170.35.255.254170.35.255.255131,070
19170.36.0.0/15170.36.0.1 to 170.37.255.254170.37.255.255131,070
20170.38.0.0/15170.38.0.1 to 170.39.255.254170.39.255.255131,070
21170.40.0.0/15170.40.0.1 to 170.41.255.254170.41.255.255131,070
22170.42.0.0/15170.42.0.1 to 170.43.255.254170.43.255.255131,070
23170.44.0.0/15170.44.0.1 to 170.45.255.254170.45.255.255131,070
24170.46.0.0/15170.46.0.1 to 170.47.255.254170.47.255.255131,070
25170.48.0.0/15170.48.0.1 to 170.49.255.254170.49.255.255131,070
26170.50.0.0/15170.50.0.1 to 170.51.255.254170.51.255.255131,070
27170.52.0.0/15170.52.0.1 to 170.53.255.254170.53.255.255131,070
28170.54.0.0/15170.54.0.1 to 170.55.255.254170.55.255.255131,070
29170.56.0.0/15170.56.0.1 to 170.57.255.254170.57.255.255131,070
30170.58.0.0/15170.58.0.1 to 170.59.255.254170.59.255.255131,070
31170.60.0.0/15170.60.0.1 to 170.61.255.254170.61.255.255131,070
32170.62.0.0/15170.62.0.1 to 170.63.255.254170.63.255.255131,070
33170.64.0.0/15170.64.0.1 to 170.65.255.254170.65.255.255131,070
34170.66.0.0/15170.66.0.1 to 170.67.255.254170.67.255.255131,070
35170.68.0.0/15170.68.0.1 to 170.69.255.254170.69.255.255131,070
36170.70.0.0/15170.70.0.1 to 170.71.255.254170.71.255.255131,070
37170.72.0.0/15170.72.0.1 to 170.73.255.254170.73.255.255131,070
38170.74.0.0/15170.74.0.1 to 170.75.255.254170.75.255.255131,070
39170.76.0.0/15170.76.0.1 to 170.77.255.254170.77.255.255131,070
40170.78.0.0/15170.78.0.1 to 170.79.255.254170.79.255.255131,070
41170.80.0.0/15170.80.0.1 to 170.81.255.254170.81.255.255131,070
42170.82.0.0/15170.82.0.1 to 170.83.255.254170.83.255.255131,070
43170.84.0.0/15170.84.0.1 to 170.85.255.254170.85.255.255131,070
44170.86.0.0/15170.86.0.1 to 170.87.255.254170.87.255.255131,070
45170.88.0.0/15170.88.0.1 to 170.89.255.254170.89.255.255131,070
46170.90.0.0/15170.90.0.1 to 170.91.255.254170.91.255.255131,070
47170.92.0.0/15170.92.0.1 to 170.93.255.254170.93.255.255131,070
48170.94.0.0/15170.94.0.1 to 170.95.255.254170.95.255.255131,070
49170.96.0.0/15170.96.0.1 to 170.97.255.254170.97.255.255131,070
50170.98.0.0/15170.98.0.1 to 170.99.255.254170.99.255.255131,070
51170.100.0.0/15170.100.0.1 to 170.101.255.254170.101.255.255131,070
52170.102.0.0/15170.102.0.1 to 170.103.255.254170.103.255.255131,070
53170.104.0.0/15170.104.0.1 to 170.105.255.254170.105.255.255131,070
54170.106.0.0/15170.106.0.1 to 170.107.255.254170.107.255.255131,070
55170.108.0.0/15170.108.0.1 to 170.109.255.254170.109.255.255131,070
56170.110.0.0/15170.110.0.1 to 170.111.255.254170.111.255.255131,070
57170.112.0.0/15170.112.0.1 to 170.113.255.254170.113.255.255131,070
58170.114.0.0/15170.114.0.1 to 170.115.255.254170.115.255.255131,070
59170.116.0.0/15170.116.0.1 to 170.117.255.254170.117.255.255131,070
60170.118.0.0/15170.118.0.1 to 170.119.255.254170.119.255.255131,070
61170.120.0.0/15170.120.0.1 to 170.121.255.254170.121.255.255131,070
62170.122.0.0/15170.122.0.1 to 170.123.255.254170.123.255.255131,070
63170.124.0.0/15170.124.0.1 to 170.125.255.254170.125.255.255131,070
64170.126.0.0/15170.126.0.1 to 170.127.255.254170.127.255.255131,070
65170.128.0.0/15170.128.0.1 to 170.129.255.254170.129.255.255131,070
66170.130.0.0/15170.130.0.1 to 170.131.255.254170.131.255.255131,070
67170.132.0.0/15170.132.0.1 to 170.133.255.254170.133.255.255131,070
68170.134.0.0/15170.134.0.1 to 170.135.255.254170.135.255.255131,070
69170.136.0.0/15170.136.0.1 to 170.137.255.254170.137.255.255131,070
70170.138.0.0/15170.138.0.1 to 170.139.255.254170.139.255.255131,070
71170.140.0.0/15170.140.0.1 to 170.141.255.254170.141.255.255131,070
72170.142.0.0/15170.142.0.1 to 170.143.255.254170.143.255.255131,070
73170.144.0.0/15170.144.0.1 to 170.145.255.254170.145.255.255131,070
74170.146.0.0/15170.146.0.1 to 170.147.255.254170.147.255.255131,070
75170.148.0.0/15170.148.0.1 to 170.149.255.254170.149.255.255131,070
76170.150.0.0/15170.150.0.1 to 170.151.255.254170.151.255.255131,070
77170.152.0.0/15170.152.0.1 to 170.153.255.254170.153.255.255131,070
78170.154.0.0/15170.154.0.1 to 170.155.255.254170.155.255.255131,070
79170.156.0.0/15170.156.0.1 to 170.157.255.254170.157.255.255131,070
80170.158.0.0/15170.158.0.1 to 170.159.255.254170.159.255.255131,070
81170.160.0.0/15170.160.0.1 to 170.161.255.254170.161.255.255131,070
82170.162.0.0/15170.162.0.1 to 170.163.255.254170.163.255.255131,070
83170.164.0.0/15170.164.0.1 to 170.165.255.254170.165.255.255131,070
84170.166.0.0/15170.166.0.1 to 170.167.255.254170.167.255.255131,070
85170.168.0.0/15170.168.0.1 to 170.169.255.254170.169.255.255131,070
86170.170.0.0/15170.170.0.1 to 170.171.255.254170.171.255.255131,070
87170.172.0.0/15170.172.0.1 to 170.173.255.254170.173.255.255131,070
88170.174.0.0/15170.174.0.1 to 170.175.255.254170.175.255.255131,070
89170.176.0.0/15170.176.0.1 to 170.177.255.254170.177.255.255131,070
90170.178.0.0/15170.178.0.1 to 170.179.255.254170.179.255.255131,070
91170.180.0.0/15170.180.0.1 to 170.181.255.254170.181.255.255131,070
92170.182.0.0/15170.182.0.1 to 170.183.255.254170.183.255.255131,070
93170.184.0.0/15170.184.0.1 to 170.185.255.254170.185.255.255131,070
94170.186.0.0/15170.186.0.1 to 170.187.255.254170.187.255.255131,070
95170.188.0.0/15170.188.0.1 to 170.189.255.254170.189.255.255131,070
96170.190.0.0/15170.190.0.1 to 170.191.255.254170.191.255.255131,070
97170.192.0.0/15170.192.0.1 to 170.193.255.254170.193.255.255131,070
98170.194.0.0/15170.194.0.1 to 170.195.255.254170.195.255.255131,070
99170.196.0.0/15170.196.0.1 to 170.197.255.254170.197.255.255131,070
100170.198.0.0/15170.198.0.1 to 170.199.255.254170.199.255.255131,070
101170.200.0.0/15170.200.0.1 to 170.201.255.254170.201.255.255131,070
102170.202.0.0/15170.202.0.1 to 170.203.255.254170.203.255.255131,070
103170.204.0.0/15170.204.0.1 to 170.205.255.254170.205.255.255131,070
104170.206.0.0/15170.206.0.1 to 170.207.255.254170.207.255.255131,070
105170.208.0.0/15170.208.0.1 to 170.209.255.254170.209.255.255131,070
106170.210.0.0/15170.210.0.1 to 170.211.255.254170.211.255.255131,070
107170.212.0.0/15170.212.0.1 to 170.213.255.254170.213.255.255131,070
108170.214.0.0/15170.214.0.1 to 170.215.255.254170.215.255.255131,070
109170.216.0.0/15170.216.0.1 to 170.217.255.254170.217.255.255131,070
110170.218.0.0/15170.218.0.1 to 170.219.255.254170.219.255.255131,070
111170.220.0.0/15170.220.0.1 to 170.221.255.254170.221.255.255131,070
112170.222.0.0/15170.222.0.1 to 170.223.255.254170.223.255.255131,070
113170.224.0.0/15170.224.0.1 to 170.225.255.254170.225.255.255131,070
114170.226.0.0/15170.226.0.1 to 170.227.255.254170.227.255.255131,070
115170.228.0.0/15170.228.0.1 to 170.229.255.254170.229.255.255131,070
116170.230.0.0/15170.230.0.1 to 170.231.255.254170.231.255.255131,070
117170.232.0.0/15170.232.0.1 to 170.233.255.254170.233.255.255131,070
118170.234.0.0/15170.234.0.1 to 170.235.255.254170.235.255.255131,070
119170.236.0.0/15170.236.0.1 to 170.237.255.254170.237.255.255131,070
120170.238.0.0/15170.238.0.1 to 170.239.255.254170.239.255.255131,070
121170.240.0.0/15170.240.0.1 to 170.241.255.254170.241.255.255131,070
122170.242.0.0/15170.242.0.1 to 170.243.255.254170.243.255.255131,070
123170.244.0.0/15170.244.0.1 to 170.245.255.254170.245.255.255131,070
124170.246.0.0/15170.246.0.1 to 170.247.255.254170.247.255.255131,070
125170.248.0.0/15170.248.0.1 to 170.249.255.254170.249.255.255131,070
126170.250.0.0/15170.250.0.1 to 170.251.255.254170.251.255.255131,070
127170.252.0.0/15170.252.0.1 to 170.253.255.254170.253.255.255131,070
128170.254.0.0/15170.254.0.1 to 170.255.255.254170.255.255.255131,070
129171.0.0.0/15171.0.0.1 to 171.1.255.254171.1.255.255131,070
130171.2.0.0/15171.2.0.1 to 171.3.255.254171.3.255.255131,070
131171.4.0.0/15171.4.0.1 to 171.5.255.254171.5.255.255131,070
132171.6.0.0/15171.6.0.1 to 171.7.255.254171.7.255.255131,070
133171.8.0.0/15171.8.0.1 to 171.9.255.254171.9.255.255131,070
134171.10.0.0/15171.10.0.1 to 171.11.255.254171.11.255.255131,070
135171.12.0.0/15171.12.0.1 to 171.13.255.254171.13.255.255131,070
136171.14.0.0/15171.14.0.1 to 171.15.255.254171.15.255.255131,070
137171.16.0.0/15171.16.0.1 to 171.17.255.254171.17.255.255131,070
138171.18.0.0/15171.18.0.1 to 171.19.255.254171.19.255.255131,070
139171.20.0.0/15171.20.0.1 to 171.21.255.254171.21.255.255131,070
140171.22.0.0/15171.22.0.1 to 171.23.255.254171.23.255.255131,070
141171.24.0.0/15171.24.0.1 to 171.25.255.254171.25.255.255131,070
142171.26.0.0/15171.26.0.1 to 171.27.255.254171.27.255.255131,070
143171.28.0.0/15171.28.0.1 to 171.29.255.254171.29.255.255131,070
144171.30.0.0/15171.30.0.1 to 171.31.255.254171.31.255.255131,070
145171.32.0.0/15171.32.0.1 to 171.33.255.254171.33.255.255131,070
146171.34.0.0/15171.34.0.1 to 171.35.255.254171.35.255.255131,070
147171.36.0.0/15171.36.0.1 to 171.37.255.254171.37.255.255131,070
148171.38.0.0/15171.38.0.1 to 171.39.255.254171.39.255.255131,070
149171.40.0.0/15171.40.0.1 to 171.41.255.254171.41.255.255131,070
150171.42.0.0/15171.42.0.1 to 171.43.255.254171.43.255.255131,070
151171.44.0.0/15171.44.0.1 to 171.45.255.254171.45.255.255131,070
152171.46.0.0/15171.46.0.1 to 171.47.255.254171.47.255.255131,070
153171.48.0.0/15171.48.0.1 to 171.49.255.254171.49.255.255131,070
154171.50.0.0/15171.50.0.1 to 171.51.255.254171.51.255.255131,070
155171.52.0.0/15171.52.0.1 to 171.53.255.254171.53.255.255131,070
156171.54.0.0/15171.54.0.1 to 171.55.255.254171.55.255.255131,070
157171.56.0.0/15171.56.0.1 to 171.57.255.254171.57.255.255131,070
158171.58.0.0/15171.58.0.1 to 171.59.255.254171.59.255.255131,070
159171.60.0.0/15171.60.0.1 to 171.61.255.254171.61.255.255131,070
160171.62.0.0/15171.62.0.1 to 171.63.255.254171.63.255.255131,070
161171.64.0.0/15171.64.0.1 to 171.65.255.254171.65.255.255131,070
162171.66.0.0/15171.66.0.1 to 171.67.255.254171.67.255.255131,070
163171.68.0.0/15171.68.0.1 to 171.69.255.254171.69.255.255131,070
164171.70.0.0/15171.70.0.1 to 171.71.255.254171.71.255.255131,070
165171.72.0.0/15171.72.0.1 to 171.73.255.254171.73.255.255131,070
166171.74.0.0/15171.74.0.1 to 171.75.255.254171.75.255.255131,070
167171.76.0.0/15171.76.0.1 to 171.77.255.254171.77.255.255131,070
168171.78.0.0/15171.78.0.1 to 171.79.255.254171.79.255.255131,070
169171.80.0.0/15171.80.0.1 to 171.81.255.254171.81.255.255131,070
170171.82.0.0/15171.82.0.1 to 171.83.255.254171.83.255.255131,070
171171.84.0.0/15171.84.0.1 to 171.85.255.254171.85.255.255131,070
172171.86.0.0/15171.86.0.1 to 171.87.255.254171.87.255.255131,070
173171.88.0.0/15171.88.0.1 to 171.89.255.254171.89.255.255131,070
174171.90.0.0/15171.90.0.1 to 171.91.255.254171.91.255.255131,070
175171.92.0.0/15171.92.0.1 to 171.93.255.254171.93.255.255131,070
176171.94.0.0/15171.94.0.1 to 171.95.255.254171.95.255.255131,070
177171.96.0.0/15171.96.0.1 to 171.97.255.254171.97.255.255131,070
178171.98.0.0/15171.98.0.1 to 171.99.255.254171.99.255.255131,070
179171.100.0.0/15171.100.0.1 to 171.101.255.254171.101.255.255131,070
180171.102.0.0/15171.102.0.1 to 171.103.255.254171.103.255.255131,070
181171.104.0.0/15171.104.0.1 to 171.105.255.254171.105.255.255131,070
182171.106.0.0/15171.106.0.1 to 171.107.255.254171.107.255.255131,070
183171.108.0.0/15171.108.0.1 to 171.109.255.254171.109.255.255131,070
184171.110.0.0/15171.110.0.1 to 171.111.255.254171.111.255.255131,070
185171.112.0.0/15171.112.0.1 to 171.113.255.254171.113.255.255131,070
186171.114.0.0/15171.114.0.1 to 171.115.255.254171.115.255.255131,070
187171.116.0.0/15171.116.0.1 to 171.117.255.254171.117.255.255131,070
188171.118.0.0/15171.118.0.1 to 171.119.255.254171.119.255.255131,070
189171.120.0.0/15171.120.0.1 to 171.121.255.254171.121.255.255131,070
190171.122.0.0/15171.122.0.1 to 171.123.255.254171.123.255.255131,070
191171.124.0.0/15171.124.0.1 to 171.125.255.254171.125.255.255131,070
192171.126.0.0/15171.126.0.1 to 171.127.255.254171.127.255.255131,070
193171.128.0.0/15171.128.0.1 to 171.129.255.254171.129.255.255131,070
194171.130.0.0/15171.130.0.1 to 171.131.255.254171.131.255.255131,070
195171.132.0.0/15171.132.0.1 to 171.133.255.254171.133.255.255131,070
196171.134.0.0/15171.134.0.1 to 171.135.255.254171.135.255.255131,070
197171.136.0.0/15171.136.0.1 to 171.137.255.254171.137.255.255131,070
198171.138.0.0/15171.138.0.1 to 171.139.255.254171.139.255.255131,070
199171.140.0.0/15171.140.0.1 to 171.141.255.254171.141.255.255131,070
200171.142.0.0/15171.142.0.1 to 171.143.255.254171.143.255.255131,070
201171.144.0.0/15171.144.0.1 to 171.145.255.254171.145.255.255131,070
202171.146.0.0/15171.146.0.1 to 171.147.255.254171.147.255.255131,070
203171.148.0.0/15171.148.0.1 to 171.149.255.254171.149.255.255131,070
204171.150.0.0/15171.150.0.1 to 171.151.255.254171.151.255.255131,070
205171.152.0.0/15171.152.0.1 to 171.153.255.254171.153.255.255131,070
206171.154.0.0/15171.154.0.1 to 171.155.255.254171.155.255.255131,070
207171.156.0.0/15171.156.0.1 to 171.157.255.254171.157.255.255131,070
208171.158.0.0/15171.158.0.1 to 171.159.255.254171.159.255.255131,070
209171.160.0.0/15171.160.0.1 to 171.161.255.254171.161.255.255131,070
210171.162.0.0/15171.162.0.1 to 171.163.255.254171.163.255.255131,070
211171.164.0.0/15171.164.0.1 to 171.165.255.254171.165.255.255131,070
212171.166.0.0/15171.166.0.1 to 171.167.255.254171.167.255.255131,070
213171.168.0.0/15171.168.0.1 to 171.169.255.254171.169.255.255131,070
214171.170.0.0/15171.170.0.1 to 171.171.255.254171.171.255.255131,070
215171.172.0.0/15171.172.0.1 to 171.173.255.254171.173.255.255131,070
216171.174.0.0/15171.174.0.1 to 171.175.255.254171.175.255.255131,070
217171.176.0.0/15171.176.0.1 to 171.177.255.254171.177.255.255131,070
218171.178.0.0/15171.178.0.1 to 171.179.255.254171.179.255.255131,070
219171.180.0.0/15171.180.0.1 to 171.181.255.254171.181.255.255131,070
220171.182.0.0/15171.182.0.1 to 171.183.255.254171.183.255.255131,070
221171.184.0.0/15171.184.0.1 to 171.185.255.254171.185.255.255131,070
222171.186.0.0/15171.186.0.1 to 171.187.255.254171.187.255.255131,070
223171.188.0.0/15171.188.0.1 to 171.189.255.254171.189.255.255131,070
224171.190.0.0/15171.190.0.1 to 171.191.255.254171.191.255.255131,070
225171.192.0.0/15171.192.0.1 to 171.193.255.254171.193.255.255131,070
226171.194.0.0/15171.194.0.1 to 171.195.255.254171.195.255.255131,070
227171.196.0.0/15171.196.0.1 to 171.197.255.254171.197.255.255131,070
228171.198.0.0/15171.198.0.1 to 171.199.255.254171.199.255.255131,070
229171.200.0.0/15171.200.0.1 to 171.201.255.254171.201.255.255131,070
230171.202.0.0/15171.202.0.1 to 171.203.255.254171.203.255.255131,070
231171.204.0.0/15171.204.0.1 to 171.205.255.254171.205.255.255131,070
232171.206.0.0/15171.206.0.1 to 171.207.255.254171.207.255.255131,070
233171.208.0.0/15171.208.0.1 to 171.209.255.254171.209.255.255131,070
234171.210.0.0/15171.210.0.1 to 171.211.255.254171.211.255.255131,070
235171.212.0.0/15171.212.0.1 to 171.213.255.254171.213.255.255131,070
236171.214.0.0/15171.214.0.1 to 171.215.255.254171.215.255.255131,070
237171.216.0.0/15171.216.0.1 to 171.217.255.254171.217.255.255131,070
238171.218.0.0/15171.218.0.1 to 171.219.255.254171.219.255.255131,070
239171.220.0.0/15171.220.0.1 to 171.221.255.254171.221.255.255131,070
240171.222.0.0/15171.222.0.1 to 171.223.255.254171.223.255.255131,070
241171.224.0.0/15171.224.0.1 to 171.225.255.254171.225.255.255131,070
242171.226.0.0/15171.226.0.1 to 171.227.255.254171.227.255.255131,070
243171.228.0.0/15171.228.0.1 to 171.229.255.254171.229.255.255131,070
244171.230.0.0/15171.230.0.1 to 171.231.255.254171.231.255.255131,070
245171.232.0.0/15171.232.0.1 to 171.233.255.254171.233.255.255131,070
246171.234.0.0/15171.234.0.1 to 171.235.255.254171.235.255.255131,070
247171.236.0.0/15171.236.0.1 to 171.237.255.254171.237.255.255131,070
248171.238.0.0/15171.238.0.1 to 171.239.255.254171.239.255.255131,070
249171.240.0.0/15171.240.0.1 to 171.241.255.254171.241.255.255131,070
250171.242.0.0/15171.242.0.1 to 171.243.255.254171.243.255.255131,070
251171.244.0.0/15171.244.0.1 to 171.245.255.254171.245.255.255131,070
252171.246.0.0/15171.246.0.1 to 171.247.255.254171.247.255.255131,070
253171.248.0.0/15171.248.0.1 to 171.249.255.254171.249.255.255131,070
254171.250.0.0/15171.250.0.1 to 171.251.255.254171.251.255.255131,070
255171.252.0.0/15171.252.0.1 to 171.253.255.254171.253.255.255131,070
256171.254.0.0/15171.254.0.1 to 171.255.255.254171.255.255.255131,070

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.