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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.

Network208.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
208.0.0.0
Broadcast address
211.255.255.255
First usable
208.0.0.1
Last usable
211.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
C (default /24)
As numbers
Hex D0000000 · Integer 3489660928 to 3556769791
Reverse DNS zones
208.in-addr.arpa
209.in-addr.arpa
210.in-addr.arpa
211.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010000.00000000.00000000.00000000208.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11010000.00000000.00000000.00000000208.0.0.0
Broadcast11010011.11111111.11111111.11111111211.255.255.255
Split into smaller subnets/15
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

208.0.0.0/6 makes 512 subnets of /15; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1208.0.0.0/15208.0.0.1 to 208.1.255.254208.1.255.255131,070
2208.2.0.0/15208.2.0.1 to 208.3.255.254208.3.255.255131,070
3208.4.0.0/15208.4.0.1 to 208.5.255.254208.5.255.255131,070
4208.6.0.0/15208.6.0.1 to 208.7.255.254208.7.255.255131,070
5208.8.0.0/15208.8.0.1 to 208.9.255.254208.9.255.255131,070
6208.10.0.0/15208.10.0.1 to 208.11.255.254208.11.255.255131,070
7208.12.0.0/15208.12.0.1 to 208.13.255.254208.13.255.255131,070
8208.14.0.0/15208.14.0.1 to 208.15.255.254208.15.255.255131,070
9208.16.0.0/15208.16.0.1 to 208.17.255.254208.17.255.255131,070
10208.18.0.0/15208.18.0.1 to 208.19.255.254208.19.255.255131,070
11208.20.0.0/15208.20.0.1 to 208.21.255.254208.21.255.255131,070
12208.22.0.0/15208.22.0.1 to 208.23.255.254208.23.255.255131,070
13208.24.0.0/15208.24.0.1 to 208.25.255.254208.25.255.255131,070
14208.26.0.0/15208.26.0.1 to 208.27.255.254208.27.255.255131,070
15208.28.0.0/15208.28.0.1 to 208.29.255.254208.29.255.255131,070
16208.30.0.0/15208.30.0.1 to 208.31.255.254208.31.255.255131,070
17208.32.0.0/15208.32.0.1 to 208.33.255.254208.33.255.255131,070
18208.34.0.0/15208.34.0.1 to 208.35.255.254208.35.255.255131,070
19208.36.0.0/15208.36.0.1 to 208.37.255.254208.37.255.255131,070
20208.38.0.0/15208.38.0.1 to 208.39.255.254208.39.255.255131,070
21208.40.0.0/15208.40.0.1 to 208.41.255.254208.41.255.255131,070
22208.42.0.0/15208.42.0.1 to 208.43.255.254208.43.255.255131,070
23208.44.0.0/15208.44.0.1 to 208.45.255.254208.45.255.255131,070
24208.46.0.0/15208.46.0.1 to 208.47.255.254208.47.255.255131,070
25208.48.0.0/15208.48.0.1 to 208.49.255.254208.49.255.255131,070
26208.50.0.0/15208.50.0.1 to 208.51.255.254208.51.255.255131,070
27208.52.0.0/15208.52.0.1 to 208.53.255.254208.53.255.255131,070
28208.54.0.0/15208.54.0.1 to 208.55.255.254208.55.255.255131,070
29208.56.0.0/15208.56.0.1 to 208.57.255.254208.57.255.255131,070
30208.58.0.0/15208.58.0.1 to 208.59.255.254208.59.255.255131,070
31208.60.0.0/15208.60.0.1 to 208.61.255.254208.61.255.255131,070
32208.62.0.0/15208.62.0.1 to 208.63.255.254208.63.255.255131,070
33208.64.0.0/15208.64.0.1 to 208.65.255.254208.65.255.255131,070
34208.66.0.0/15208.66.0.1 to 208.67.255.254208.67.255.255131,070
35208.68.0.0/15208.68.0.1 to 208.69.255.254208.69.255.255131,070
36208.70.0.0/15208.70.0.1 to 208.71.255.254208.71.255.255131,070
37208.72.0.0/15208.72.0.1 to 208.73.255.254208.73.255.255131,070
38208.74.0.0/15208.74.0.1 to 208.75.255.254208.75.255.255131,070
39208.76.0.0/15208.76.0.1 to 208.77.255.254208.77.255.255131,070
40208.78.0.0/15208.78.0.1 to 208.79.255.254208.79.255.255131,070
41208.80.0.0/15208.80.0.1 to 208.81.255.254208.81.255.255131,070
42208.82.0.0/15208.82.0.1 to 208.83.255.254208.83.255.255131,070
43208.84.0.0/15208.84.0.1 to 208.85.255.254208.85.255.255131,070
44208.86.0.0/15208.86.0.1 to 208.87.255.254208.87.255.255131,070
45208.88.0.0/15208.88.0.1 to 208.89.255.254208.89.255.255131,070
46208.90.0.0/15208.90.0.1 to 208.91.255.254208.91.255.255131,070
47208.92.0.0/15208.92.0.1 to 208.93.255.254208.93.255.255131,070
48208.94.0.0/15208.94.0.1 to 208.95.255.254208.95.255.255131,070
49208.96.0.0/15208.96.0.1 to 208.97.255.254208.97.255.255131,070
50208.98.0.0/15208.98.0.1 to 208.99.255.254208.99.255.255131,070
51208.100.0.0/15208.100.0.1 to 208.101.255.254208.101.255.255131,070
52208.102.0.0/15208.102.0.1 to 208.103.255.254208.103.255.255131,070
53208.104.0.0/15208.104.0.1 to 208.105.255.254208.105.255.255131,070
54208.106.0.0/15208.106.0.1 to 208.107.255.254208.107.255.255131,070
55208.108.0.0/15208.108.0.1 to 208.109.255.254208.109.255.255131,070
56208.110.0.0/15208.110.0.1 to 208.111.255.254208.111.255.255131,070
57208.112.0.0/15208.112.0.1 to 208.113.255.254208.113.255.255131,070
58208.114.0.0/15208.114.0.1 to 208.115.255.254208.115.255.255131,070
59208.116.0.0/15208.116.0.1 to 208.117.255.254208.117.255.255131,070
60208.118.0.0/15208.118.0.1 to 208.119.255.254208.119.255.255131,070
61208.120.0.0/15208.120.0.1 to 208.121.255.254208.121.255.255131,070
62208.122.0.0/15208.122.0.1 to 208.123.255.254208.123.255.255131,070
63208.124.0.0/15208.124.0.1 to 208.125.255.254208.125.255.255131,070
64208.126.0.0/15208.126.0.1 to 208.127.255.254208.127.255.255131,070
65208.128.0.0/15208.128.0.1 to 208.129.255.254208.129.255.255131,070
66208.130.0.0/15208.130.0.1 to 208.131.255.254208.131.255.255131,070
67208.132.0.0/15208.132.0.1 to 208.133.255.254208.133.255.255131,070
68208.134.0.0/15208.134.0.1 to 208.135.255.254208.135.255.255131,070
69208.136.0.0/15208.136.0.1 to 208.137.255.254208.137.255.255131,070
70208.138.0.0/15208.138.0.1 to 208.139.255.254208.139.255.255131,070
71208.140.0.0/15208.140.0.1 to 208.141.255.254208.141.255.255131,070
72208.142.0.0/15208.142.0.1 to 208.143.255.254208.143.255.255131,070
73208.144.0.0/15208.144.0.1 to 208.145.255.254208.145.255.255131,070
74208.146.0.0/15208.146.0.1 to 208.147.255.254208.147.255.255131,070
75208.148.0.0/15208.148.0.1 to 208.149.255.254208.149.255.255131,070
76208.150.0.0/15208.150.0.1 to 208.151.255.254208.151.255.255131,070
77208.152.0.0/15208.152.0.1 to 208.153.255.254208.153.255.255131,070
78208.154.0.0/15208.154.0.1 to 208.155.255.254208.155.255.255131,070
79208.156.0.0/15208.156.0.1 to 208.157.255.254208.157.255.255131,070
80208.158.0.0/15208.158.0.1 to 208.159.255.254208.159.255.255131,070
81208.160.0.0/15208.160.0.1 to 208.161.255.254208.161.255.255131,070
82208.162.0.0/15208.162.0.1 to 208.163.255.254208.163.255.255131,070
83208.164.0.0/15208.164.0.1 to 208.165.255.254208.165.255.255131,070
84208.166.0.0/15208.166.0.1 to 208.167.255.254208.167.255.255131,070
85208.168.0.0/15208.168.0.1 to 208.169.255.254208.169.255.255131,070
86208.170.0.0/15208.170.0.1 to 208.171.255.254208.171.255.255131,070
87208.172.0.0/15208.172.0.1 to 208.173.255.254208.173.255.255131,070
88208.174.0.0/15208.174.0.1 to 208.175.255.254208.175.255.255131,070
89208.176.0.0/15208.176.0.1 to 208.177.255.254208.177.255.255131,070
90208.178.0.0/15208.178.0.1 to 208.179.255.254208.179.255.255131,070
91208.180.0.0/15208.180.0.1 to 208.181.255.254208.181.255.255131,070
92208.182.0.0/15208.182.0.1 to 208.183.255.254208.183.255.255131,070
93208.184.0.0/15208.184.0.1 to 208.185.255.254208.185.255.255131,070
94208.186.0.0/15208.186.0.1 to 208.187.255.254208.187.255.255131,070
95208.188.0.0/15208.188.0.1 to 208.189.255.254208.189.255.255131,070
96208.190.0.0/15208.190.0.1 to 208.191.255.254208.191.255.255131,070
97208.192.0.0/15208.192.0.1 to 208.193.255.254208.193.255.255131,070
98208.194.0.0/15208.194.0.1 to 208.195.255.254208.195.255.255131,070
99208.196.0.0/15208.196.0.1 to 208.197.255.254208.197.255.255131,070
100208.198.0.0/15208.198.0.1 to 208.199.255.254208.199.255.255131,070
101208.200.0.0/15208.200.0.1 to 208.201.255.254208.201.255.255131,070
102208.202.0.0/15208.202.0.1 to 208.203.255.254208.203.255.255131,070
103208.204.0.0/15208.204.0.1 to 208.205.255.254208.205.255.255131,070
104208.206.0.0/15208.206.0.1 to 208.207.255.254208.207.255.255131,070
105208.208.0.0/15208.208.0.1 to 208.209.255.254208.209.255.255131,070
106208.210.0.0/15208.210.0.1 to 208.211.255.254208.211.255.255131,070
107208.212.0.0/15208.212.0.1 to 208.213.255.254208.213.255.255131,070
108208.214.0.0/15208.214.0.1 to 208.215.255.254208.215.255.255131,070
109208.216.0.0/15208.216.0.1 to 208.217.255.254208.217.255.255131,070
110208.218.0.0/15208.218.0.1 to 208.219.255.254208.219.255.255131,070
111208.220.0.0/15208.220.0.1 to 208.221.255.254208.221.255.255131,070
112208.222.0.0/15208.222.0.1 to 208.223.255.254208.223.255.255131,070
113208.224.0.0/15208.224.0.1 to 208.225.255.254208.225.255.255131,070
114208.226.0.0/15208.226.0.1 to 208.227.255.254208.227.255.255131,070
115208.228.0.0/15208.228.0.1 to 208.229.255.254208.229.255.255131,070
116208.230.0.0/15208.230.0.1 to 208.231.255.254208.231.255.255131,070
117208.232.0.0/15208.232.0.1 to 208.233.255.254208.233.255.255131,070
118208.234.0.0/15208.234.0.1 to 208.235.255.254208.235.255.255131,070
119208.236.0.0/15208.236.0.1 to 208.237.255.254208.237.255.255131,070
120208.238.0.0/15208.238.0.1 to 208.239.255.254208.239.255.255131,070
121208.240.0.0/15208.240.0.1 to 208.241.255.254208.241.255.255131,070
122208.242.0.0/15208.242.0.1 to 208.243.255.254208.243.255.255131,070
123208.244.0.0/15208.244.0.1 to 208.245.255.254208.245.255.255131,070
124208.246.0.0/15208.246.0.1 to 208.247.255.254208.247.255.255131,070
125208.248.0.0/15208.248.0.1 to 208.249.255.254208.249.255.255131,070
126208.250.0.0/15208.250.0.1 to 208.251.255.254208.251.255.255131,070
127208.252.0.0/15208.252.0.1 to 208.253.255.254208.253.255.255131,070
128208.254.0.0/15208.254.0.1 to 208.255.255.254208.255.255.255131,070
129209.0.0.0/15209.0.0.1 to 209.1.255.254209.1.255.255131,070
130209.2.0.0/15209.2.0.1 to 209.3.255.254209.3.255.255131,070
131209.4.0.0/15209.4.0.1 to 209.5.255.254209.5.255.255131,070
132209.6.0.0/15209.6.0.1 to 209.7.255.254209.7.255.255131,070
133209.8.0.0/15209.8.0.1 to 209.9.255.254209.9.255.255131,070
134209.10.0.0/15209.10.0.1 to 209.11.255.254209.11.255.255131,070
135209.12.0.0/15209.12.0.1 to 209.13.255.254209.13.255.255131,070
136209.14.0.0/15209.14.0.1 to 209.15.255.254209.15.255.255131,070
137209.16.0.0/15209.16.0.1 to 209.17.255.254209.17.255.255131,070
138209.18.0.0/15209.18.0.1 to 209.19.255.254209.19.255.255131,070
139209.20.0.0/15209.20.0.1 to 209.21.255.254209.21.255.255131,070
140209.22.0.0/15209.22.0.1 to 209.23.255.254209.23.255.255131,070
141209.24.0.0/15209.24.0.1 to 209.25.255.254209.25.255.255131,070
142209.26.0.0/15209.26.0.1 to 209.27.255.254209.27.255.255131,070
143209.28.0.0/15209.28.0.1 to 209.29.255.254209.29.255.255131,070
144209.30.0.0/15209.30.0.1 to 209.31.255.254209.31.255.255131,070
145209.32.0.0/15209.32.0.1 to 209.33.255.254209.33.255.255131,070
146209.34.0.0/15209.34.0.1 to 209.35.255.254209.35.255.255131,070
147209.36.0.0/15209.36.0.1 to 209.37.255.254209.37.255.255131,070
148209.38.0.0/15209.38.0.1 to 209.39.255.254209.39.255.255131,070
149209.40.0.0/15209.40.0.1 to 209.41.255.254209.41.255.255131,070
150209.42.0.0/15209.42.0.1 to 209.43.255.254209.43.255.255131,070
151209.44.0.0/15209.44.0.1 to 209.45.255.254209.45.255.255131,070
152209.46.0.0/15209.46.0.1 to 209.47.255.254209.47.255.255131,070
153209.48.0.0/15209.48.0.1 to 209.49.255.254209.49.255.255131,070
154209.50.0.0/15209.50.0.1 to 209.51.255.254209.51.255.255131,070
155209.52.0.0/15209.52.0.1 to 209.53.255.254209.53.255.255131,070
156209.54.0.0/15209.54.0.1 to 209.55.255.254209.55.255.255131,070
157209.56.0.0/15209.56.0.1 to 209.57.255.254209.57.255.255131,070
158209.58.0.0/15209.58.0.1 to 209.59.255.254209.59.255.255131,070
159209.60.0.0/15209.60.0.1 to 209.61.255.254209.61.255.255131,070
160209.62.0.0/15209.62.0.1 to 209.63.255.254209.63.255.255131,070
161209.64.0.0/15209.64.0.1 to 209.65.255.254209.65.255.255131,070
162209.66.0.0/15209.66.0.1 to 209.67.255.254209.67.255.255131,070
163209.68.0.0/15209.68.0.1 to 209.69.255.254209.69.255.255131,070
164209.70.0.0/15209.70.0.1 to 209.71.255.254209.71.255.255131,070
165209.72.0.0/15209.72.0.1 to 209.73.255.254209.73.255.255131,070
166209.74.0.0/15209.74.0.1 to 209.75.255.254209.75.255.255131,070
167209.76.0.0/15209.76.0.1 to 209.77.255.254209.77.255.255131,070
168209.78.0.0/15209.78.0.1 to 209.79.255.254209.79.255.255131,070
169209.80.0.0/15209.80.0.1 to 209.81.255.254209.81.255.255131,070
170209.82.0.0/15209.82.0.1 to 209.83.255.254209.83.255.255131,070
171209.84.0.0/15209.84.0.1 to 209.85.255.254209.85.255.255131,070
172209.86.0.0/15209.86.0.1 to 209.87.255.254209.87.255.255131,070
173209.88.0.0/15209.88.0.1 to 209.89.255.254209.89.255.255131,070
174209.90.0.0/15209.90.0.1 to 209.91.255.254209.91.255.255131,070
175209.92.0.0/15209.92.0.1 to 209.93.255.254209.93.255.255131,070
176209.94.0.0/15209.94.0.1 to 209.95.255.254209.95.255.255131,070
177209.96.0.0/15209.96.0.1 to 209.97.255.254209.97.255.255131,070
178209.98.0.0/15209.98.0.1 to 209.99.255.254209.99.255.255131,070
179209.100.0.0/15209.100.0.1 to 209.101.255.254209.101.255.255131,070
180209.102.0.0/15209.102.0.1 to 209.103.255.254209.103.255.255131,070
181209.104.0.0/15209.104.0.1 to 209.105.255.254209.105.255.255131,070
182209.106.0.0/15209.106.0.1 to 209.107.255.254209.107.255.255131,070
183209.108.0.0/15209.108.0.1 to 209.109.255.254209.109.255.255131,070
184209.110.0.0/15209.110.0.1 to 209.111.255.254209.111.255.255131,070
185209.112.0.0/15209.112.0.1 to 209.113.255.254209.113.255.255131,070
186209.114.0.0/15209.114.0.1 to 209.115.255.254209.115.255.255131,070
187209.116.0.0/15209.116.0.1 to 209.117.255.254209.117.255.255131,070
188209.118.0.0/15209.118.0.1 to 209.119.255.254209.119.255.255131,070
189209.120.0.0/15209.120.0.1 to 209.121.255.254209.121.255.255131,070
190209.122.0.0/15209.122.0.1 to 209.123.255.254209.123.255.255131,070
191209.124.0.0/15209.124.0.1 to 209.125.255.254209.125.255.255131,070
192209.126.0.0/15209.126.0.1 to 209.127.255.254209.127.255.255131,070
193209.128.0.0/15209.128.0.1 to 209.129.255.254209.129.255.255131,070
194209.130.0.0/15209.130.0.1 to 209.131.255.254209.131.255.255131,070
195209.132.0.0/15209.132.0.1 to 209.133.255.254209.133.255.255131,070
196209.134.0.0/15209.134.0.1 to 209.135.255.254209.135.255.255131,070
197209.136.0.0/15209.136.0.1 to 209.137.255.254209.137.255.255131,070
198209.138.0.0/15209.138.0.1 to 209.139.255.254209.139.255.255131,070
199209.140.0.0/15209.140.0.1 to 209.141.255.254209.141.255.255131,070
200209.142.0.0/15209.142.0.1 to 209.143.255.254209.143.255.255131,070
201209.144.0.0/15209.144.0.1 to 209.145.255.254209.145.255.255131,070
202209.146.0.0/15209.146.0.1 to 209.147.255.254209.147.255.255131,070
203209.148.0.0/15209.148.0.1 to 209.149.255.254209.149.255.255131,070
204209.150.0.0/15209.150.0.1 to 209.151.255.254209.151.255.255131,070
205209.152.0.0/15209.152.0.1 to 209.153.255.254209.153.255.255131,070
206209.154.0.0/15209.154.0.1 to 209.155.255.254209.155.255.255131,070
207209.156.0.0/15209.156.0.1 to 209.157.255.254209.157.255.255131,070
208209.158.0.0/15209.158.0.1 to 209.159.255.254209.159.255.255131,070
209209.160.0.0/15209.160.0.1 to 209.161.255.254209.161.255.255131,070
210209.162.0.0/15209.162.0.1 to 209.163.255.254209.163.255.255131,070
211209.164.0.0/15209.164.0.1 to 209.165.255.254209.165.255.255131,070
212209.166.0.0/15209.166.0.1 to 209.167.255.254209.167.255.255131,070
213209.168.0.0/15209.168.0.1 to 209.169.255.254209.169.255.255131,070
214209.170.0.0/15209.170.0.1 to 209.171.255.254209.171.255.255131,070
215209.172.0.0/15209.172.0.1 to 209.173.255.254209.173.255.255131,070
216209.174.0.0/15209.174.0.1 to 209.175.255.254209.175.255.255131,070
217209.176.0.0/15209.176.0.1 to 209.177.255.254209.177.255.255131,070
218209.178.0.0/15209.178.0.1 to 209.179.255.254209.179.255.255131,070
219209.180.0.0/15209.180.0.1 to 209.181.255.254209.181.255.255131,070
220209.182.0.0/15209.182.0.1 to 209.183.255.254209.183.255.255131,070
221209.184.0.0/15209.184.0.1 to 209.185.255.254209.185.255.255131,070
222209.186.0.0/15209.186.0.1 to 209.187.255.254209.187.255.255131,070
223209.188.0.0/15209.188.0.1 to 209.189.255.254209.189.255.255131,070
224209.190.0.0/15209.190.0.1 to 209.191.255.254209.191.255.255131,070
225209.192.0.0/15209.192.0.1 to 209.193.255.254209.193.255.255131,070
226209.194.0.0/15209.194.0.1 to 209.195.255.254209.195.255.255131,070
227209.196.0.0/15209.196.0.1 to 209.197.255.254209.197.255.255131,070
228209.198.0.0/15209.198.0.1 to 209.199.255.254209.199.255.255131,070
229209.200.0.0/15209.200.0.1 to 209.201.255.254209.201.255.255131,070
230209.202.0.0/15209.202.0.1 to 209.203.255.254209.203.255.255131,070
231209.204.0.0/15209.204.0.1 to 209.205.255.254209.205.255.255131,070
232209.206.0.0/15209.206.0.1 to 209.207.255.254209.207.255.255131,070
233209.208.0.0/15209.208.0.1 to 209.209.255.254209.209.255.255131,070
234209.210.0.0/15209.210.0.1 to 209.211.255.254209.211.255.255131,070
235209.212.0.0/15209.212.0.1 to 209.213.255.254209.213.255.255131,070
236209.214.0.0/15209.214.0.1 to 209.215.255.254209.215.255.255131,070
237209.216.0.0/15209.216.0.1 to 209.217.255.254209.217.255.255131,070
238209.218.0.0/15209.218.0.1 to 209.219.255.254209.219.255.255131,070
239209.220.0.0/15209.220.0.1 to 209.221.255.254209.221.255.255131,070
240209.222.0.0/15209.222.0.1 to 209.223.255.254209.223.255.255131,070
241209.224.0.0/15209.224.0.1 to 209.225.255.254209.225.255.255131,070
242209.226.0.0/15209.226.0.1 to 209.227.255.254209.227.255.255131,070
243209.228.0.0/15209.228.0.1 to 209.229.255.254209.229.255.255131,070
244209.230.0.0/15209.230.0.1 to 209.231.255.254209.231.255.255131,070
245209.232.0.0/15209.232.0.1 to 209.233.255.254209.233.255.255131,070
246209.234.0.0/15209.234.0.1 to 209.235.255.254209.235.255.255131,070
247209.236.0.0/15209.236.0.1 to 209.237.255.254209.237.255.255131,070
248209.238.0.0/15209.238.0.1 to 209.239.255.254209.239.255.255131,070
249209.240.0.0/15209.240.0.1 to 209.241.255.254209.241.255.255131,070
250209.242.0.0/15209.242.0.1 to 209.243.255.254209.243.255.255131,070
251209.244.0.0/15209.244.0.1 to 209.245.255.254209.245.255.255131,070
252209.246.0.0/15209.246.0.1 to 209.247.255.254209.247.255.255131,070
253209.248.0.0/15209.248.0.1 to 209.249.255.254209.249.255.255131,070
254209.250.0.0/15209.250.0.1 to 209.251.255.254209.251.255.255131,070
255209.252.0.0/15209.252.0.1 to 209.253.255.254209.253.255.255131,070
256209.254.0.0/15209.254.0.1 to 209.255.255.254209.255.255.255131,070

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.