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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.

Network240.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
240.0.0.0
Broadcast address
240.31.255.255
First usable
240.0.0.1
Last usable
240.31.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F0000000 · Integer 4026531840 to 4028628991
Reverse DNS zones
0.240.in-addr.arpa
1.240.in-addr.arpa
2.240.in-addr.arpa
3.240.in-addr.arpa
4.240.in-addr.arpa
5.240.in-addr.arpa
6.240.in-addr.arpa
7.240.in-addr.arpa
8.240.in-addr.arpa
9.240.in-addr.arpa
10.240.in-addr.arpa
11.240.in-addr.arpa
12.240.in-addr.arpa
13.240.in-addr.arpa
14.240.in-addr.arpa
15.240.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110000.00000000.00000000.00000000240.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network11110000.00000000.00000000.00000000240.0.0.0
Broadcast11110000.00011111.11111111.11111111240.31.255.255
Split into smaller subnets/23
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

240.0.0.0/11 makes 4,096 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.0.0.0/23240.0.0.1 to 240.0.1.254240.0.1.255510
2240.0.2.0/23240.0.2.1 to 240.0.3.254240.0.3.255510
3240.0.4.0/23240.0.4.1 to 240.0.5.254240.0.5.255510
4240.0.6.0/23240.0.6.1 to 240.0.7.254240.0.7.255510
5240.0.8.0/23240.0.8.1 to 240.0.9.254240.0.9.255510
6240.0.10.0/23240.0.10.1 to 240.0.11.254240.0.11.255510
7240.0.12.0/23240.0.12.1 to 240.0.13.254240.0.13.255510
8240.0.14.0/23240.0.14.1 to 240.0.15.254240.0.15.255510
9240.0.16.0/23240.0.16.1 to 240.0.17.254240.0.17.255510
10240.0.18.0/23240.0.18.1 to 240.0.19.254240.0.19.255510
11240.0.20.0/23240.0.20.1 to 240.0.21.254240.0.21.255510
12240.0.22.0/23240.0.22.1 to 240.0.23.254240.0.23.255510
13240.0.24.0/23240.0.24.1 to 240.0.25.254240.0.25.255510
14240.0.26.0/23240.0.26.1 to 240.0.27.254240.0.27.255510
15240.0.28.0/23240.0.28.1 to 240.0.29.254240.0.29.255510
16240.0.30.0/23240.0.30.1 to 240.0.31.254240.0.31.255510
17240.0.32.0/23240.0.32.1 to 240.0.33.254240.0.33.255510
18240.0.34.0/23240.0.34.1 to 240.0.35.254240.0.35.255510
19240.0.36.0/23240.0.36.1 to 240.0.37.254240.0.37.255510
20240.0.38.0/23240.0.38.1 to 240.0.39.254240.0.39.255510
21240.0.40.0/23240.0.40.1 to 240.0.41.254240.0.41.255510
22240.0.42.0/23240.0.42.1 to 240.0.43.254240.0.43.255510
23240.0.44.0/23240.0.44.1 to 240.0.45.254240.0.45.255510
24240.0.46.0/23240.0.46.1 to 240.0.47.254240.0.47.255510
25240.0.48.0/23240.0.48.1 to 240.0.49.254240.0.49.255510
26240.0.50.0/23240.0.50.1 to 240.0.51.254240.0.51.255510
27240.0.52.0/23240.0.52.1 to 240.0.53.254240.0.53.255510
28240.0.54.0/23240.0.54.1 to 240.0.55.254240.0.55.255510
29240.0.56.0/23240.0.56.1 to 240.0.57.254240.0.57.255510
30240.0.58.0/23240.0.58.1 to 240.0.59.254240.0.59.255510
31240.0.60.0/23240.0.60.1 to 240.0.61.254240.0.61.255510
32240.0.62.0/23240.0.62.1 to 240.0.63.254240.0.63.255510
33240.0.64.0/23240.0.64.1 to 240.0.65.254240.0.65.255510
34240.0.66.0/23240.0.66.1 to 240.0.67.254240.0.67.255510
35240.0.68.0/23240.0.68.1 to 240.0.69.254240.0.69.255510
36240.0.70.0/23240.0.70.1 to 240.0.71.254240.0.71.255510
37240.0.72.0/23240.0.72.1 to 240.0.73.254240.0.73.255510
38240.0.74.0/23240.0.74.1 to 240.0.75.254240.0.75.255510
39240.0.76.0/23240.0.76.1 to 240.0.77.254240.0.77.255510
40240.0.78.0/23240.0.78.1 to 240.0.79.254240.0.79.255510
41240.0.80.0/23240.0.80.1 to 240.0.81.254240.0.81.255510
42240.0.82.0/23240.0.82.1 to 240.0.83.254240.0.83.255510
43240.0.84.0/23240.0.84.1 to 240.0.85.254240.0.85.255510
44240.0.86.0/23240.0.86.1 to 240.0.87.254240.0.87.255510
45240.0.88.0/23240.0.88.1 to 240.0.89.254240.0.89.255510
46240.0.90.0/23240.0.90.1 to 240.0.91.254240.0.91.255510
47240.0.92.0/23240.0.92.1 to 240.0.93.254240.0.93.255510
48240.0.94.0/23240.0.94.1 to 240.0.95.254240.0.95.255510
49240.0.96.0/23240.0.96.1 to 240.0.97.254240.0.97.255510
50240.0.98.0/23240.0.98.1 to 240.0.99.254240.0.99.255510
51240.0.100.0/23240.0.100.1 to 240.0.101.254240.0.101.255510
52240.0.102.0/23240.0.102.1 to 240.0.103.254240.0.103.255510
53240.0.104.0/23240.0.104.1 to 240.0.105.254240.0.105.255510
54240.0.106.0/23240.0.106.1 to 240.0.107.254240.0.107.255510
55240.0.108.0/23240.0.108.1 to 240.0.109.254240.0.109.255510
56240.0.110.0/23240.0.110.1 to 240.0.111.254240.0.111.255510
57240.0.112.0/23240.0.112.1 to 240.0.113.254240.0.113.255510
58240.0.114.0/23240.0.114.1 to 240.0.115.254240.0.115.255510
59240.0.116.0/23240.0.116.1 to 240.0.117.254240.0.117.255510
60240.0.118.0/23240.0.118.1 to 240.0.119.254240.0.119.255510
61240.0.120.0/23240.0.120.1 to 240.0.121.254240.0.121.255510
62240.0.122.0/23240.0.122.1 to 240.0.123.254240.0.123.255510
63240.0.124.0/23240.0.124.1 to 240.0.125.254240.0.125.255510
64240.0.126.0/23240.0.126.1 to 240.0.127.254240.0.127.255510
65240.0.128.0/23240.0.128.1 to 240.0.129.254240.0.129.255510
66240.0.130.0/23240.0.130.1 to 240.0.131.254240.0.131.255510
67240.0.132.0/23240.0.132.1 to 240.0.133.254240.0.133.255510
68240.0.134.0/23240.0.134.1 to 240.0.135.254240.0.135.255510
69240.0.136.0/23240.0.136.1 to 240.0.137.254240.0.137.255510
70240.0.138.0/23240.0.138.1 to 240.0.139.254240.0.139.255510
71240.0.140.0/23240.0.140.1 to 240.0.141.254240.0.141.255510
72240.0.142.0/23240.0.142.1 to 240.0.143.254240.0.143.255510
73240.0.144.0/23240.0.144.1 to 240.0.145.254240.0.145.255510
74240.0.146.0/23240.0.146.1 to 240.0.147.254240.0.147.255510
75240.0.148.0/23240.0.148.1 to 240.0.149.254240.0.149.255510
76240.0.150.0/23240.0.150.1 to 240.0.151.254240.0.151.255510
77240.0.152.0/23240.0.152.1 to 240.0.153.254240.0.153.255510
78240.0.154.0/23240.0.154.1 to 240.0.155.254240.0.155.255510
79240.0.156.0/23240.0.156.1 to 240.0.157.254240.0.157.255510
80240.0.158.0/23240.0.158.1 to 240.0.159.254240.0.159.255510
81240.0.160.0/23240.0.160.1 to 240.0.161.254240.0.161.255510
82240.0.162.0/23240.0.162.1 to 240.0.163.254240.0.163.255510
83240.0.164.0/23240.0.164.1 to 240.0.165.254240.0.165.255510
84240.0.166.0/23240.0.166.1 to 240.0.167.254240.0.167.255510
85240.0.168.0/23240.0.168.1 to 240.0.169.254240.0.169.255510
86240.0.170.0/23240.0.170.1 to 240.0.171.254240.0.171.255510
87240.0.172.0/23240.0.172.1 to 240.0.173.254240.0.173.255510
88240.0.174.0/23240.0.174.1 to 240.0.175.254240.0.175.255510
89240.0.176.0/23240.0.176.1 to 240.0.177.254240.0.177.255510
90240.0.178.0/23240.0.178.1 to 240.0.179.254240.0.179.255510
91240.0.180.0/23240.0.180.1 to 240.0.181.254240.0.181.255510
92240.0.182.0/23240.0.182.1 to 240.0.183.254240.0.183.255510
93240.0.184.0/23240.0.184.1 to 240.0.185.254240.0.185.255510
94240.0.186.0/23240.0.186.1 to 240.0.187.254240.0.187.255510
95240.0.188.0/23240.0.188.1 to 240.0.189.254240.0.189.255510
96240.0.190.0/23240.0.190.1 to 240.0.191.254240.0.191.255510
97240.0.192.0/23240.0.192.1 to 240.0.193.254240.0.193.255510
98240.0.194.0/23240.0.194.1 to 240.0.195.254240.0.195.255510
99240.0.196.0/23240.0.196.1 to 240.0.197.254240.0.197.255510
100240.0.198.0/23240.0.198.1 to 240.0.199.254240.0.199.255510
101240.0.200.0/23240.0.200.1 to 240.0.201.254240.0.201.255510
102240.0.202.0/23240.0.202.1 to 240.0.203.254240.0.203.255510
103240.0.204.0/23240.0.204.1 to 240.0.205.254240.0.205.255510
104240.0.206.0/23240.0.206.1 to 240.0.207.254240.0.207.255510
105240.0.208.0/23240.0.208.1 to 240.0.209.254240.0.209.255510
106240.0.210.0/23240.0.210.1 to 240.0.211.254240.0.211.255510
107240.0.212.0/23240.0.212.1 to 240.0.213.254240.0.213.255510
108240.0.214.0/23240.0.214.1 to 240.0.215.254240.0.215.255510
109240.0.216.0/23240.0.216.1 to 240.0.217.254240.0.217.255510
110240.0.218.0/23240.0.218.1 to 240.0.219.254240.0.219.255510
111240.0.220.0/23240.0.220.1 to 240.0.221.254240.0.221.255510
112240.0.222.0/23240.0.222.1 to 240.0.223.254240.0.223.255510
113240.0.224.0/23240.0.224.1 to 240.0.225.254240.0.225.255510
114240.0.226.0/23240.0.226.1 to 240.0.227.254240.0.227.255510
115240.0.228.0/23240.0.228.1 to 240.0.229.254240.0.229.255510
116240.0.230.0/23240.0.230.1 to 240.0.231.254240.0.231.255510
117240.0.232.0/23240.0.232.1 to 240.0.233.254240.0.233.255510
118240.0.234.0/23240.0.234.1 to 240.0.235.254240.0.235.255510
119240.0.236.0/23240.0.236.1 to 240.0.237.254240.0.237.255510
120240.0.238.0/23240.0.238.1 to 240.0.239.254240.0.239.255510
121240.0.240.0/23240.0.240.1 to 240.0.241.254240.0.241.255510
122240.0.242.0/23240.0.242.1 to 240.0.243.254240.0.243.255510
123240.0.244.0/23240.0.244.1 to 240.0.245.254240.0.245.255510
124240.0.246.0/23240.0.246.1 to 240.0.247.254240.0.247.255510
125240.0.248.0/23240.0.248.1 to 240.0.249.254240.0.249.255510
126240.0.250.0/23240.0.250.1 to 240.0.251.254240.0.251.255510
127240.0.252.0/23240.0.252.1 to 240.0.253.254240.0.253.255510
128240.0.254.0/23240.0.254.1 to 240.0.255.254240.0.255.255510
129240.1.0.0/23240.1.0.1 to 240.1.1.254240.1.1.255510
130240.1.2.0/23240.1.2.1 to 240.1.3.254240.1.3.255510
131240.1.4.0/23240.1.4.1 to 240.1.5.254240.1.5.255510
132240.1.6.0/23240.1.6.1 to 240.1.7.254240.1.7.255510
133240.1.8.0/23240.1.8.1 to 240.1.9.254240.1.9.255510
134240.1.10.0/23240.1.10.1 to 240.1.11.254240.1.11.255510
135240.1.12.0/23240.1.12.1 to 240.1.13.254240.1.13.255510
136240.1.14.0/23240.1.14.1 to 240.1.15.254240.1.15.255510
137240.1.16.0/23240.1.16.1 to 240.1.17.254240.1.17.255510
138240.1.18.0/23240.1.18.1 to 240.1.19.254240.1.19.255510
139240.1.20.0/23240.1.20.1 to 240.1.21.254240.1.21.255510
140240.1.22.0/23240.1.22.1 to 240.1.23.254240.1.23.255510
141240.1.24.0/23240.1.24.1 to 240.1.25.254240.1.25.255510
142240.1.26.0/23240.1.26.1 to 240.1.27.254240.1.27.255510
143240.1.28.0/23240.1.28.1 to 240.1.29.254240.1.29.255510
144240.1.30.0/23240.1.30.1 to 240.1.31.254240.1.31.255510
145240.1.32.0/23240.1.32.1 to 240.1.33.254240.1.33.255510
146240.1.34.0/23240.1.34.1 to 240.1.35.254240.1.35.255510
147240.1.36.0/23240.1.36.1 to 240.1.37.254240.1.37.255510
148240.1.38.0/23240.1.38.1 to 240.1.39.254240.1.39.255510
149240.1.40.0/23240.1.40.1 to 240.1.41.254240.1.41.255510
150240.1.42.0/23240.1.42.1 to 240.1.43.254240.1.43.255510
151240.1.44.0/23240.1.44.1 to 240.1.45.254240.1.45.255510
152240.1.46.0/23240.1.46.1 to 240.1.47.254240.1.47.255510
153240.1.48.0/23240.1.48.1 to 240.1.49.254240.1.49.255510
154240.1.50.0/23240.1.50.1 to 240.1.51.254240.1.51.255510
155240.1.52.0/23240.1.52.1 to 240.1.53.254240.1.53.255510
156240.1.54.0/23240.1.54.1 to 240.1.55.254240.1.55.255510
157240.1.56.0/23240.1.56.1 to 240.1.57.254240.1.57.255510
158240.1.58.0/23240.1.58.1 to 240.1.59.254240.1.59.255510
159240.1.60.0/23240.1.60.1 to 240.1.61.254240.1.61.255510
160240.1.62.0/23240.1.62.1 to 240.1.63.254240.1.63.255510
161240.1.64.0/23240.1.64.1 to 240.1.65.254240.1.65.255510
162240.1.66.0/23240.1.66.1 to 240.1.67.254240.1.67.255510
163240.1.68.0/23240.1.68.1 to 240.1.69.254240.1.69.255510
164240.1.70.0/23240.1.70.1 to 240.1.71.254240.1.71.255510
165240.1.72.0/23240.1.72.1 to 240.1.73.254240.1.73.255510
166240.1.74.0/23240.1.74.1 to 240.1.75.254240.1.75.255510
167240.1.76.0/23240.1.76.1 to 240.1.77.254240.1.77.255510
168240.1.78.0/23240.1.78.1 to 240.1.79.254240.1.79.255510
169240.1.80.0/23240.1.80.1 to 240.1.81.254240.1.81.255510
170240.1.82.0/23240.1.82.1 to 240.1.83.254240.1.83.255510
171240.1.84.0/23240.1.84.1 to 240.1.85.254240.1.85.255510
172240.1.86.0/23240.1.86.1 to 240.1.87.254240.1.87.255510
173240.1.88.0/23240.1.88.1 to 240.1.89.254240.1.89.255510
174240.1.90.0/23240.1.90.1 to 240.1.91.254240.1.91.255510
175240.1.92.0/23240.1.92.1 to 240.1.93.254240.1.93.255510
176240.1.94.0/23240.1.94.1 to 240.1.95.254240.1.95.255510
177240.1.96.0/23240.1.96.1 to 240.1.97.254240.1.97.255510
178240.1.98.0/23240.1.98.1 to 240.1.99.254240.1.99.255510
179240.1.100.0/23240.1.100.1 to 240.1.101.254240.1.101.255510
180240.1.102.0/23240.1.102.1 to 240.1.103.254240.1.103.255510
181240.1.104.0/23240.1.104.1 to 240.1.105.254240.1.105.255510
182240.1.106.0/23240.1.106.1 to 240.1.107.254240.1.107.255510
183240.1.108.0/23240.1.108.1 to 240.1.109.254240.1.109.255510
184240.1.110.0/23240.1.110.1 to 240.1.111.254240.1.111.255510
185240.1.112.0/23240.1.112.1 to 240.1.113.254240.1.113.255510
186240.1.114.0/23240.1.114.1 to 240.1.115.254240.1.115.255510
187240.1.116.0/23240.1.116.1 to 240.1.117.254240.1.117.255510
188240.1.118.0/23240.1.118.1 to 240.1.119.254240.1.119.255510
189240.1.120.0/23240.1.120.1 to 240.1.121.254240.1.121.255510
190240.1.122.0/23240.1.122.1 to 240.1.123.254240.1.123.255510
191240.1.124.0/23240.1.124.1 to 240.1.125.254240.1.125.255510
192240.1.126.0/23240.1.126.1 to 240.1.127.254240.1.127.255510
193240.1.128.0/23240.1.128.1 to 240.1.129.254240.1.129.255510
194240.1.130.0/23240.1.130.1 to 240.1.131.254240.1.131.255510
195240.1.132.0/23240.1.132.1 to 240.1.133.254240.1.133.255510
196240.1.134.0/23240.1.134.1 to 240.1.135.254240.1.135.255510
197240.1.136.0/23240.1.136.1 to 240.1.137.254240.1.137.255510
198240.1.138.0/23240.1.138.1 to 240.1.139.254240.1.139.255510
199240.1.140.0/23240.1.140.1 to 240.1.141.254240.1.141.255510
200240.1.142.0/23240.1.142.1 to 240.1.143.254240.1.143.255510
201240.1.144.0/23240.1.144.1 to 240.1.145.254240.1.145.255510
202240.1.146.0/23240.1.146.1 to 240.1.147.254240.1.147.255510
203240.1.148.0/23240.1.148.1 to 240.1.149.254240.1.149.255510
204240.1.150.0/23240.1.150.1 to 240.1.151.254240.1.151.255510
205240.1.152.0/23240.1.152.1 to 240.1.153.254240.1.153.255510
206240.1.154.0/23240.1.154.1 to 240.1.155.254240.1.155.255510
207240.1.156.0/23240.1.156.1 to 240.1.157.254240.1.157.255510
208240.1.158.0/23240.1.158.1 to 240.1.159.254240.1.159.255510
209240.1.160.0/23240.1.160.1 to 240.1.161.254240.1.161.255510
210240.1.162.0/23240.1.162.1 to 240.1.163.254240.1.163.255510
211240.1.164.0/23240.1.164.1 to 240.1.165.254240.1.165.255510
212240.1.166.0/23240.1.166.1 to 240.1.167.254240.1.167.255510
213240.1.168.0/23240.1.168.1 to 240.1.169.254240.1.169.255510
214240.1.170.0/23240.1.170.1 to 240.1.171.254240.1.171.255510
215240.1.172.0/23240.1.172.1 to 240.1.173.254240.1.173.255510
216240.1.174.0/23240.1.174.1 to 240.1.175.254240.1.175.255510
217240.1.176.0/23240.1.176.1 to 240.1.177.254240.1.177.255510
218240.1.178.0/23240.1.178.1 to 240.1.179.254240.1.179.255510
219240.1.180.0/23240.1.180.1 to 240.1.181.254240.1.181.255510
220240.1.182.0/23240.1.182.1 to 240.1.183.254240.1.183.255510
221240.1.184.0/23240.1.184.1 to 240.1.185.254240.1.185.255510
222240.1.186.0/23240.1.186.1 to 240.1.187.254240.1.187.255510
223240.1.188.0/23240.1.188.1 to 240.1.189.254240.1.189.255510
224240.1.190.0/23240.1.190.1 to 240.1.191.254240.1.191.255510
225240.1.192.0/23240.1.192.1 to 240.1.193.254240.1.193.255510
226240.1.194.0/23240.1.194.1 to 240.1.195.254240.1.195.255510
227240.1.196.0/23240.1.196.1 to 240.1.197.254240.1.197.255510
228240.1.198.0/23240.1.198.1 to 240.1.199.254240.1.199.255510
229240.1.200.0/23240.1.200.1 to 240.1.201.254240.1.201.255510
230240.1.202.0/23240.1.202.1 to 240.1.203.254240.1.203.255510
231240.1.204.0/23240.1.204.1 to 240.1.205.254240.1.205.255510
232240.1.206.0/23240.1.206.1 to 240.1.207.254240.1.207.255510
233240.1.208.0/23240.1.208.1 to 240.1.209.254240.1.209.255510
234240.1.210.0/23240.1.210.1 to 240.1.211.254240.1.211.255510
235240.1.212.0/23240.1.212.1 to 240.1.213.254240.1.213.255510
236240.1.214.0/23240.1.214.1 to 240.1.215.254240.1.215.255510
237240.1.216.0/23240.1.216.1 to 240.1.217.254240.1.217.255510
238240.1.218.0/23240.1.218.1 to 240.1.219.254240.1.219.255510
239240.1.220.0/23240.1.220.1 to 240.1.221.254240.1.221.255510
240240.1.222.0/23240.1.222.1 to 240.1.223.254240.1.223.255510
241240.1.224.0/23240.1.224.1 to 240.1.225.254240.1.225.255510
242240.1.226.0/23240.1.226.1 to 240.1.227.254240.1.227.255510
243240.1.228.0/23240.1.228.1 to 240.1.229.254240.1.229.255510
244240.1.230.0/23240.1.230.1 to 240.1.231.254240.1.231.255510
245240.1.232.0/23240.1.232.1 to 240.1.233.254240.1.233.255510
246240.1.234.0/23240.1.234.1 to 240.1.235.254240.1.235.255510
247240.1.236.0/23240.1.236.1 to 240.1.237.254240.1.237.255510
248240.1.238.0/23240.1.238.1 to 240.1.239.254240.1.239.255510
249240.1.240.0/23240.1.240.1 to 240.1.241.254240.1.241.255510
250240.1.242.0/23240.1.242.1 to 240.1.243.254240.1.243.255510
251240.1.244.0/23240.1.244.1 to 240.1.245.254240.1.245.255510
252240.1.246.0/23240.1.246.1 to 240.1.247.254240.1.247.255510
253240.1.248.0/23240.1.248.1 to 240.1.249.254240.1.249.255510
254240.1.250.0/23240.1.250.1 to 240.1.251.254240.1.251.255510
255240.1.252.0/23240.1.252.1 to 240.1.253.254240.1.253.255510
256240.1.254.0/23240.1.254.1 to 240.1.255.254240.1.255.255510

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.