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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.

Network216.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
216.0.0.0
Broadcast address
217.255.255.255
First usable
216.0.0.1
Last usable
217.255.255.254
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
C (default /24)
As numbers
Hex D8000000 · Integer 3623878656 to 3657433087
Reverse DNS zones
216.in-addr.arpa
217.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
Address11011000.00000000.00000000.00000000216.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11011000.00000000.00000000.00000000216.0.0.0
Broadcast11011001.11111111.11111111.11111111217.255.255.255
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)

216.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1216.0.0.0/15216.0.0.1 to 216.1.255.254216.1.255.255131,070
2216.2.0.0/15216.2.0.1 to 216.3.255.254216.3.255.255131,070
3216.4.0.0/15216.4.0.1 to 216.5.255.254216.5.255.255131,070
4216.6.0.0/15216.6.0.1 to 216.7.255.254216.7.255.255131,070
5216.8.0.0/15216.8.0.1 to 216.9.255.254216.9.255.255131,070
6216.10.0.0/15216.10.0.1 to 216.11.255.254216.11.255.255131,070
7216.12.0.0/15216.12.0.1 to 216.13.255.254216.13.255.255131,070
8216.14.0.0/15216.14.0.1 to 216.15.255.254216.15.255.255131,070
9216.16.0.0/15216.16.0.1 to 216.17.255.254216.17.255.255131,070
10216.18.0.0/15216.18.0.1 to 216.19.255.254216.19.255.255131,070
11216.20.0.0/15216.20.0.1 to 216.21.255.254216.21.255.255131,070
12216.22.0.0/15216.22.0.1 to 216.23.255.254216.23.255.255131,070
13216.24.0.0/15216.24.0.1 to 216.25.255.254216.25.255.255131,070
14216.26.0.0/15216.26.0.1 to 216.27.255.254216.27.255.255131,070
15216.28.0.0/15216.28.0.1 to 216.29.255.254216.29.255.255131,070
16216.30.0.0/15216.30.0.1 to 216.31.255.254216.31.255.255131,070
17216.32.0.0/15216.32.0.1 to 216.33.255.254216.33.255.255131,070
18216.34.0.0/15216.34.0.1 to 216.35.255.254216.35.255.255131,070
19216.36.0.0/15216.36.0.1 to 216.37.255.254216.37.255.255131,070
20216.38.0.0/15216.38.0.1 to 216.39.255.254216.39.255.255131,070
21216.40.0.0/15216.40.0.1 to 216.41.255.254216.41.255.255131,070
22216.42.0.0/15216.42.0.1 to 216.43.255.254216.43.255.255131,070
23216.44.0.0/15216.44.0.1 to 216.45.255.254216.45.255.255131,070
24216.46.0.0/15216.46.0.1 to 216.47.255.254216.47.255.255131,070
25216.48.0.0/15216.48.0.1 to 216.49.255.254216.49.255.255131,070
26216.50.0.0/15216.50.0.1 to 216.51.255.254216.51.255.255131,070
27216.52.0.0/15216.52.0.1 to 216.53.255.254216.53.255.255131,070
28216.54.0.0/15216.54.0.1 to 216.55.255.254216.55.255.255131,070
29216.56.0.0/15216.56.0.1 to 216.57.255.254216.57.255.255131,070
30216.58.0.0/15216.58.0.1 to 216.59.255.254216.59.255.255131,070
31216.60.0.0/15216.60.0.1 to 216.61.255.254216.61.255.255131,070
32216.62.0.0/15216.62.0.1 to 216.63.255.254216.63.255.255131,070
33216.64.0.0/15216.64.0.1 to 216.65.255.254216.65.255.255131,070
34216.66.0.0/15216.66.0.1 to 216.67.255.254216.67.255.255131,070
35216.68.0.0/15216.68.0.1 to 216.69.255.254216.69.255.255131,070
36216.70.0.0/15216.70.0.1 to 216.71.255.254216.71.255.255131,070
37216.72.0.0/15216.72.0.1 to 216.73.255.254216.73.255.255131,070
38216.74.0.0/15216.74.0.1 to 216.75.255.254216.75.255.255131,070
39216.76.0.0/15216.76.0.1 to 216.77.255.254216.77.255.255131,070
40216.78.0.0/15216.78.0.1 to 216.79.255.254216.79.255.255131,070
41216.80.0.0/15216.80.0.1 to 216.81.255.254216.81.255.255131,070
42216.82.0.0/15216.82.0.1 to 216.83.255.254216.83.255.255131,070
43216.84.0.0/15216.84.0.1 to 216.85.255.254216.85.255.255131,070
44216.86.0.0/15216.86.0.1 to 216.87.255.254216.87.255.255131,070
45216.88.0.0/15216.88.0.1 to 216.89.255.254216.89.255.255131,070
46216.90.0.0/15216.90.0.1 to 216.91.255.254216.91.255.255131,070
47216.92.0.0/15216.92.0.1 to 216.93.255.254216.93.255.255131,070
48216.94.0.0/15216.94.0.1 to 216.95.255.254216.95.255.255131,070
49216.96.0.0/15216.96.0.1 to 216.97.255.254216.97.255.255131,070
50216.98.0.0/15216.98.0.1 to 216.99.255.254216.99.255.255131,070
51216.100.0.0/15216.100.0.1 to 216.101.255.254216.101.255.255131,070
52216.102.0.0/15216.102.0.1 to 216.103.255.254216.103.255.255131,070
53216.104.0.0/15216.104.0.1 to 216.105.255.254216.105.255.255131,070
54216.106.0.0/15216.106.0.1 to 216.107.255.254216.107.255.255131,070
55216.108.0.0/15216.108.0.1 to 216.109.255.254216.109.255.255131,070
56216.110.0.0/15216.110.0.1 to 216.111.255.254216.111.255.255131,070
57216.112.0.0/15216.112.0.1 to 216.113.255.254216.113.255.255131,070
58216.114.0.0/15216.114.0.1 to 216.115.255.254216.115.255.255131,070
59216.116.0.0/15216.116.0.1 to 216.117.255.254216.117.255.255131,070
60216.118.0.0/15216.118.0.1 to 216.119.255.254216.119.255.255131,070
61216.120.0.0/15216.120.0.1 to 216.121.255.254216.121.255.255131,070
62216.122.0.0/15216.122.0.1 to 216.123.255.254216.123.255.255131,070
63216.124.0.0/15216.124.0.1 to 216.125.255.254216.125.255.255131,070
64216.126.0.0/15216.126.0.1 to 216.127.255.254216.127.255.255131,070
65216.128.0.0/15216.128.0.1 to 216.129.255.254216.129.255.255131,070
66216.130.0.0/15216.130.0.1 to 216.131.255.254216.131.255.255131,070
67216.132.0.0/15216.132.0.1 to 216.133.255.254216.133.255.255131,070
68216.134.0.0/15216.134.0.1 to 216.135.255.254216.135.255.255131,070
69216.136.0.0/15216.136.0.1 to 216.137.255.254216.137.255.255131,070
70216.138.0.0/15216.138.0.1 to 216.139.255.254216.139.255.255131,070
71216.140.0.0/15216.140.0.1 to 216.141.255.254216.141.255.255131,070
72216.142.0.0/15216.142.0.1 to 216.143.255.254216.143.255.255131,070
73216.144.0.0/15216.144.0.1 to 216.145.255.254216.145.255.255131,070
74216.146.0.0/15216.146.0.1 to 216.147.255.254216.147.255.255131,070
75216.148.0.0/15216.148.0.1 to 216.149.255.254216.149.255.255131,070
76216.150.0.0/15216.150.0.1 to 216.151.255.254216.151.255.255131,070
77216.152.0.0/15216.152.0.1 to 216.153.255.254216.153.255.255131,070
78216.154.0.0/15216.154.0.1 to 216.155.255.254216.155.255.255131,070
79216.156.0.0/15216.156.0.1 to 216.157.255.254216.157.255.255131,070
80216.158.0.0/15216.158.0.1 to 216.159.255.254216.159.255.255131,070
81216.160.0.0/15216.160.0.1 to 216.161.255.254216.161.255.255131,070
82216.162.0.0/15216.162.0.1 to 216.163.255.254216.163.255.255131,070
83216.164.0.0/15216.164.0.1 to 216.165.255.254216.165.255.255131,070
84216.166.0.0/15216.166.0.1 to 216.167.255.254216.167.255.255131,070
85216.168.0.0/15216.168.0.1 to 216.169.255.254216.169.255.255131,070
86216.170.0.0/15216.170.0.1 to 216.171.255.254216.171.255.255131,070
87216.172.0.0/15216.172.0.1 to 216.173.255.254216.173.255.255131,070
88216.174.0.0/15216.174.0.1 to 216.175.255.254216.175.255.255131,070
89216.176.0.0/15216.176.0.1 to 216.177.255.254216.177.255.255131,070
90216.178.0.0/15216.178.0.1 to 216.179.255.254216.179.255.255131,070
91216.180.0.0/15216.180.0.1 to 216.181.255.254216.181.255.255131,070
92216.182.0.0/15216.182.0.1 to 216.183.255.254216.183.255.255131,070
93216.184.0.0/15216.184.0.1 to 216.185.255.254216.185.255.255131,070
94216.186.0.0/15216.186.0.1 to 216.187.255.254216.187.255.255131,070
95216.188.0.0/15216.188.0.1 to 216.189.255.254216.189.255.255131,070
96216.190.0.0/15216.190.0.1 to 216.191.255.254216.191.255.255131,070
97216.192.0.0/15216.192.0.1 to 216.193.255.254216.193.255.255131,070
98216.194.0.0/15216.194.0.1 to 216.195.255.254216.195.255.255131,070
99216.196.0.0/15216.196.0.1 to 216.197.255.254216.197.255.255131,070
100216.198.0.0/15216.198.0.1 to 216.199.255.254216.199.255.255131,070
101216.200.0.0/15216.200.0.1 to 216.201.255.254216.201.255.255131,070
102216.202.0.0/15216.202.0.1 to 216.203.255.254216.203.255.255131,070
103216.204.0.0/15216.204.0.1 to 216.205.255.254216.205.255.255131,070
104216.206.0.0/15216.206.0.1 to 216.207.255.254216.207.255.255131,070
105216.208.0.0/15216.208.0.1 to 216.209.255.254216.209.255.255131,070
106216.210.0.0/15216.210.0.1 to 216.211.255.254216.211.255.255131,070
107216.212.0.0/15216.212.0.1 to 216.213.255.254216.213.255.255131,070
108216.214.0.0/15216.214.0.1 to 216.215.255.254216.215.255.255131,070
109216.216.0.0/15216.216.0.1 to 216.217.255.254216.217.255.255131,070
110216.218.0.0/15216.218.0.1 to 216.219.255.254216.219.255.255131,070
111216.220.0.0/15216.220.0.1 to 216.221.255.254216.221.255.255131,070
112216.222.0.0/15216.222.0.1 to 216.223.255.254216.223.255.255131,070
113216.224.0.0/15216.224.0.1 to 216.225.255.254216.225.255.255131,070
114216.226.0.0/15216.226.0.1 to 216.227.255.254216.227.255.255131,070
115216.228.0.0/15216.228.0.1 to 216.229.255.254216.229.255.255131,070
116216.230.0.0/15216.230.0.1 to 216.231.255.254216.231.255.255131,070
117216.232.0.0/15216.232.0.1 to 216.233.255.254216.233.255.255131,070
118216.234.0.0/15216.234.0.1 to 216.235.255.254216.235.255.255131,070
119216.236.0.0/15216.236.0.1 to 216.237.255.254216.237.255.255131,070
120216.238.0.0/15216.238.0.1 to 216.239.255.254216.239.255.255131,070
121216.240.0.0/15216.240.0.1 to 216.241.255.254216.241.255.255131,070
122216.242.0.0/15216.242.0.1 to 216.243.255.254216.243.255.255131,070
123216.244.0.0/15216.244.0.1 to 216.245.255.254216.245.255.255131,070
124216.246.0.0/15216.246.0.1 to 216.247.255.254216.247.255.255131,070
125216.248.0.0/15216.248.0.1 to 216.249.255.254216.249.255.255131,070
126216.250.0.0/15216.250.0.1 to 216.251.255.254216.251.255.255131,070
127216.252.0.0/15216.252.0.1 to 216.253.255.254216.253.255.255131,070
128216.254.0.0/15216.254.0.1 to 216.255.255.254216.255.255.255131,070
129217.0.0.0/15217.0.0.1 to 217.1.255.254217.1.255.255131,070
130217.2.0.0/15217.2.0.1 to 217.3.255.254217.3.255.255131,070
131217.4.0.0/15217.4.0.1 to 217.5.255.254217.5.255.255131,070
132217.6.0.0/15217.6.0.1 to 217.7.255.254217.7.255.255131,070
133217.8.0.0/15217.8.0.1 to 217.9.255.254217.9.255.255131,070
134217.10.0.0/15217.10.0.1 to 217.11.255.254217.11.255.255131,070
135217.12.0.0/15217.12.0.1 to 217.13.255.254217.13.255.255131,070
136217.14.0.0/15217.14.0.1 to 217.15.255.254217.15.255.255131,070
137217.16.0.0/15217.16.0.1 to 217.17.255.254217.17.255.255131,070
138217.18.0.0/15217.18.0.1 to 217.19.255.254217.19.255.255131,070
139217.20.0.0/15217.20.0.1 to 217.21.255.254217.21.255.255131,070
140217.22.0.0/15217.22.0.1 to 217.23.255.254217.23.255.255131,070
141217.24.0.0/15217.24.0.1 to 217.25.255.254217.25.255.255131,070
142217.26.0.0/15217.26.0.1 to 217.27.255.254217.27.255.255131,070
143217.28.0.0/15217.28.0.1 to 217.29.255.254217.29.255.255131,070
144217.30.0.0/15217.30.0.1 to 217.31.255.254217.31.255.255131,070
145217.32.0.0/15217.32.0.1 to 217.33.255.254217.33.255.255131,070
146217.34.0.0/15217.34.0.1 to 217.35.255.254217.35.255.255131,070
147217.36.0.0/15217.36.0.1 to 217.37.255.254217.37.255.255131,070
148217.38.0.0/15217.38.0.1 to 217.39.255.254217.39.255.255131,070
149217.40.0.0/15217.40.0.1 to 217.41.255.254217.41.255.255131,070
150217.42.0.0/15217.42.0.1 to 217.43.255.254217.43.255.255131,070
151217.44.0.0/15217.44.0.1 to 217.45.255.254217.45.255.255131,070
152217.46.0.0/15217.46.0.1 to 217.47.255.254217.47.255.255131,070
153217.48.0.0/15217.48.0.1 to 217.49.255.254217.49.255.255131,070
154217.50.0.0/15217.50.0.1 to 217.51.255.254217.51.255.255131,070
155217.52.0.0/15217.52.0.1 to 217.53.255.254217.53.255.255131,070
156217.54.0.0/15217.54.0.1 to 217.55.255.254217.55.255.255131,070
157217.56.0.0/15217.56.0.1 to 217.57.255.254217.57.255.255131,070
158217.58.0.0/15217.58.0.1 to 217.59.255.254217.59.255.255131,070
159217.60.0.0/15217.60.0.1 to 217.61.255.254217.61.255.255131,070
160217.62.0.0/15217.62.0.1 to 217.63.255.254217.63.255.255131,070
161217.64.0.0/15217.64.0.1 to 217.65.255.254217.65.255.255131,070
162217.66.0.0/15217.66.0.1 to 217.67.255.254217.67.255.255131,070
163217.68.0.0/15217.68.0.1 to 217.69.255.254217.69.255.255131,070
164217.70.0.0/15217.70.0.1 to 217.71.255.254217.71.255.255131,070
165217.72.0.0/15217.72.0.1 to 217.73.255.254217.73.255.255131,070
166217.74.0.0/15217.74.0.1 to 217.75.255.254217.75.255.255131,070
167217.76.0.0/15217.76.0.1 to 217.77.255.254217.77.255.255131,070
168217.78.0.0/15217.78.0.1 to 217.79.255.254217.79.255.255131,070
169217.80.0.0/15217.80.0.1 to 217.81.255.254217.81.255.255131,070
170217.82.0.0/15217.82.0.1 to 217.83.255.254217.83.255.255131,070
171217.84.0.0/15217.84.0.1 to 217.85.255.254217.85.255.255131,070
172217.86.0.0/15217.86.0.1 to 217.87.255.254217.87.255.255131,070
173217.88.0.0/15217.88.0.1 to 217.89.255.254217.89.255.255131,070
174217.90.0.0/15217.90.0.1 to 217.91.255.254217.91.255.255131,070
175217.92.0.0/15217.92.0.1 to 217.93.255.254217.93.255.255131,070
176217.94.0.0/15217.94.0.1 to 217.95.255.254217.95.255.255131,070
177217.96.0.0/15217.96.0.1 to 217.97.255.254217.97.255.255131,070
178217.98.0.0/15217.98.0.1 to 217.99.255.254217.99.255.255131,070
179217.100.0.0/15217.100.0.1 to 217.101.255.254217.101.255.255131,070
180217.102.0.0/15217.102.0.1 to 217.103.255.254217.103.255.255131,070
181217.104.0.0/15217.104.0.1 to 217.105.255.254217.105.255.255131,070
182217.106.0.0/15217.106.0.1 to 217.107.255.254217.107.255.255131,070
183217.108.0.0/15217.108.0.1 to 217.109.255.254217.109.255.255131,070
184217.110.0.0/15217.110.0.1 to 217.111.255.254217.111.255.255131,070
185217.112.0.0/15217.112.0.1 to 217.113.255.254217.113.255.255131,070
186217.114.0.0/15217.114.0.1 to 217.115.255.254217.115.255.255131,070
187217.116.0.0/15217.116.0.1 to 217.117.255.254217.117.255.255131,070
188217.118.0.0/15217.118.0.1 to 217.119.255.254217.119.255.255131,070
189217.120.0.0/15217.120.0.1 to 217.121.255.254217.121.255.255131,070
190217.122.0.0/15217.122.0.1 to 217.123.255.254217.123.255.255131,070
191217.124.0.0/15217.124.0.1 to 217.125.255.254217.125.255.255131,070
192217.126.0.0/15217.126.0.1 to 217.127.255.254217.127.255.255131,070
193217.128.0.0/15217.128.0.1 to 217.129.255.254217.129.255.255131,070
194217.130.0.0/15217.130.0.1 to 217.131.255.254217.131.255.255131,070
195217.132.0.0/15217.132.0.1 to 217.133.255.254217.133.255.255131,070
196217.134.0.0/15217.134.0.1 to 217.135.255.254217.135.255.255131,070
197217.136.0.0/15217.136.0.1 to 217.137.255.254217.137.255.255131,070
198217.138.0.0/15217.138.0.1 to 217.139.255.254217.139.255.255131,070
199217.140.0.0/15217.140.0.1 to 217.141.255.254217.141.255.255131,070
200217.142.0.0/15217.142.0.1 to 217.143.255.254217.143.255.255131,070
201217.144.0.0/15217.144.0.1 to 217.145.255.254217.145.255.255131,070
202217.146.0.0/15217.146.0.1 to 217.147.255.254217.147.255.255131,070
203217.148.0.0/15217.148.0.1 to 217.149.255.254217.149.255.255131,070
204217.150.0.0/15217.150.0.1 to 217.151.255.254217.151.255.255131,070
205217.152.0.0/15217.152.0.1 to 217.153.255.254217.153.255.255131,070
206217.154.0.0/15217.154.0.1 to 217.155.255.254217.155.255.255131,070
207217.156.0.0/15217.156.0.1 to 217.157.255.254217.157.255.255131,070
208217.158.0.0/15217.158.0.1 to 217.159.255.254217.159.255.255131,070
209217.160.0.0/15217.160.0.1 to 217.161.255.254217.161.255.255131,070
210217.162.0.0/15217.162.0.1 to 217.163.255.254217.163.255.255131,070
211217.164.0.0/15217.164.0.1 to 217.165.255.254217.165.255.255131,070
212217.166.0.0/15217.166.0.1 to 217.167.255.254217.167.255.255131,070
213217.168.0.0/15217.168.0.1 to 217.169.255.254217.169.255.255131,070
214217.170.0.0/15217.170.0.1 to 217.171.255.254217.171.255.255131,070
215217.172.0.0/15217.172.0.1 to 217.173.255.254217.173.255.255131,070
216217.174.0.0/15217.174.0.1 to 217.175.255.254217.175.255.255131,070
217217.176.0.0/15217.176.0.1 to 217.177.255.254217.177.255.255131,070
218217.178.0.0/15217.178.0.1 to 217.179.255.254217.179.255.255131,070
219217.180.0.0/15217.180.0.1 to 217.181.255.254217.181.255.255131,070
220217.182.0.0/15217.182.0.1 to 217.183.255.254217.183.255.255131,070
221217.184.0.0/15217.184.0.1 to 217.185.255.254217.185.255.255131,070
222217.186.0.0/15217.186.0.1 to 217.187.255.254217.187.255.255131,070
223217.188.0.0/15217.188.0.1 to 217.189.255.254217.189.255.255131,070
224217.190.0.0/15217.190.0.1 to 217.191.255.254217.191.255.255131,070
225217.192.0.0/15217.192.0.1 to 217.193.255.254217.193.255.255131,070
226217.194.0.0/15217.194.0.1 to 217.195.255.254217.195.255.255131,070
227217.196.0.0/15217.196.0.1 to 217.197.255.254217.197.255.255131,070
228217.198.0.0/15217.198.0.1 to 217.199.255.254217.199.255.255131,070
229217.200.0.0/15217.200.0.1 to 217.201.255.254217.201.255.255131,070
230217.202.0.0/15217.202.0.1 to 217.203.255.254217.203.255.255131,070
231217.204.0.0/15217.204.0.1 to 217.205.255.254217.205.255.255131,070
232217.206.0.0/15217.206.0.1 to 217.207.255.254217.207.255.255131,070
233217.208.0.0/15217.208.0.1 to 217.209.255.254217.209.255.255131,070
234217.210.0.0/15217.210.0.1 to 217.211.255.254217.211.255.255131,070
235217.212.0.0/15217.212.0.1 to 217.213.255.254217.213.255.255131,070
236217.214.0.0/15217.214.0.1 to 217.215.255.254217.215.255.255131,070
237217.216.0.0/15217.216.0.1 to 217.217.255.254217.217.255.255131,070
238217.218.0.0/15217.218.0.1 to 217.219.255.254217.219.255.255131,070
239217.220.0.0/15217.220.0.1 to 217.221.255.254217.221.255.255131,070
240217.222.0.0/15217.222.0.1 to 217.223.255.254217.223.255.255131,070
241217.224.0.0/15217.224.0.1 to 217.225.255.254217.225.255.255131,070
242217.226.0.0/15217.226.0.1 to 217.227.255.254217.227.255.255131,070
243217.228.0.0/15217.228.0.1 to 217.229.255.254217.229.255.255131,070
244217.230.0.0/15217.230.0.1 to 217.231.255.254217.231.255.255131,070
245217.232.0.0/15217.232.0.1 to 217.233.255.254217.233.255.255131,070
246217.234.0.0/15217.234.0.1 to 217.235.255.254217.235.255.255131,070
247217.236.0.0/15217.236.0.1 to 217.237.255.254217.237.255.255131,070
248217.238.0.0/15217.238.0.1 to 217.239.255.254217.239.255.255131,070
249217.240.0.0/15217.240.0.1 to 217.241.255.254217.241.255.255131,070
250217.242.0.0/15217.242.0.1 to 217.243.255.254217.243.255.255131,070
251217.244.0.0/15217.244.0.1 to 217.245.255.254217.245.255.255131,070
252217.246.0.0/15217.246.0.1 to 217.247.255.254217.247.255.255131,070
253217.248.0.0/15217.248.0.1 to 217.249.255.254217.249.255.255131,070
254217.250.0.0/15217.250.0.1 to 217.251.255.254217.251.255.255131,070
255217.252.0.0/15217.252.0.1 to 217.253.255.254217.253.255.255131,070
256217.254.0.0/15217.254.0.1 to 217.255.255.254217.255.255.255131,070

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.