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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.

Network255.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
255.80.0.0
Broadcast address
255.95.255.255
First usable
255.80.0.1
Last usable
255.95.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FF500000 · Integer 4283432960 to 4284481535
Reverse DNS zones
80.255.in-addr.arpa
81.255.in-addr.arpa
82.255.in-addr.arpa
83.255.in-addr.arpa
84.255.in-addr.arpa
85.255.in-addr.arpa
86.255.in-addr.arpa
87.255.in-addr.arpa
88.255.in-addr.arpa
89.255.in-addr.arpa
90.255.in-addr.arpa
91.255.in-addr.arpa
92.255.in-addr.arpa
93.255.in-addr.arpa
94.255.in-addr.arpa
95.255.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111111.01010000.00000000.00000000255.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11111111.01010000.00000000.00000000255.80.0.0
Broadcast11111111.01011111.11111111.11111111255.95.255.255
Split into smaller subnets/23
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

255.80.0.0/12 makes 2,048 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1255.80.0.0/23255.80.0.1 to 255.80.1.254255.80.1.255510
2255.80.2.0/23255.80.2.1 to 255.80.3.254255.80.3.255510
3255.80.4.0/23255.80.4.1 to 255.80.5.254255.80.5.255510
4255.80.6.0/23255.80.6.1 to 255.80.7.254255.80.7.255510
5255.80.8.0/23255.80.8.1 to 255.80.9.254255.80.9.255510
6255.80.10.0/23255.80.10.1 to 255.80.11.254255.80.11.255510
7255.80.12.0/23255.80.12.1 to 255.80.13.254255.80.13.255510
8255.80.14.0/23255.80.14.1 to 255.80.15.254255.80.15.255510
9255.80.16.0/23255.80.16.1 to 255.80.17.254255.80.17.255510
10255.80.18.0/23255.80.18.1 to 255.80.19.254255.80.19.255510
11255.80.20.0/23255.80.20.1 to 255.80.21.254255.80.21.255510
12255.80.22.0/23255.80.22.1 to 255.80.23.254255.80.23.255510
13255.80.24.0/23255.80.24.1 to 255.80.25.254255.80.25.255510
14255.80.26.0/23255.80.26.1 to 255.80.27.254255.80.27.255510
15255.80.28.0/23255.80.28.1 to 255.80.29.254255.80.29.255510
16255.80.30.0/23255.80.30.1 to 255.80.31.254255.80.31.255510
17255.80.32.0/23255.80.32.1 to 255.80.33.254255.80.33.255510
18255.80.34.0/23255.80.34.1 to 255.80.35.254255.80.35.255510
19255.80.36.0/23255.80.36.1 to 255.80.37.254255.80.37.255510
20255.80.38.0/23255.80.38.1 to 255.80.39.254255.80.39.255510
21255.80.40.0/23255.80.40.1 to 255.80.41.254255.80.41.255510
22255.80.42.0/23255.80.42.1 to 255.80.43.254255.80.43.255510
23255.80.44.0/23255.80.44.1 to 255.80.45.254255.80.45.255510
24255.80.46.0/23255.80.46.1 to 255.80.47.254255.80.47.255510
25255.80.48.0/23255.80.48.1 to 255.80.49.254255.80.49.255510
26255.80.50.0/23255.80.50.1 to 255.80.51.254255.80.51.255510
27255.80.52.0/23255.80.52.1 to 255.80.53.254255.80.53.255510
28255.80.54.0/23255.80.54.1 to 255.80.55.254255.80.55.255510
29255.80.56.0/23255.80.56.1 to 255.80.57.254255.80.57.255510
30255.80.58.0/23255.80.58.1 to 255.80.59.254255.80.59.255510
31255.80.60.0/23255.80.60.1 to 255.80.61.254255.80.61.255510
32255.80.62.0/23255.80.62.1 to 255.80.63.254255.80.63.255510
33255.80.64.0/23255.80.64.1 to 255.80.65.254255.80.65.255510
34255.80.66.0/23255.80.66.1 to 255.80.67.254255.80.67.255510
35255.80.68.0/23255.80.68.1 to 255.80.69.254255.80.69.255510
36255.80.70.0/23255.80.70.1 to 255.80.71.254255.80.71.255510
37255.80.72.0/23255.80.72.1 to 255.80.73.254255.80.73.255510
38255.80.74.0/23255.80.74.1 to 255.80.75.254255.80.75.255510
39255.80.76.0/23255.80.76.1 to 255.80.77.254255.80.77.255510
40255.80.78.0/23255.80.78.1 to 255.80.79.254255.80.79.255510
41255.80.80.0/23255.80.80.1 to 255.80.81.254255.80.81.255510
42255.80.82.0/23255.80.82.1 to 255.80.83.254255.80.83.255510
43255.80.84.0/23255.80.84.1 to 255.80.85.254255.80.85.255510
44255.80.86.0/23255.80.86.1 to 255.80.87.254255.80.87.255510
45255.80.88.0/23255.80.88.1 to 255.80.89.254255.80.89.255510
46255.80.90.0/23255.80.90.1 to 255.80.91.254255.80.91.255510
47255.80.92.0/23255.80.92.1 to 255.80.93.254255.80.93.255510
48255.80.94.0/23255.80.94.1 to 255.80.95.254255.80.95.255510
49255.80.96.0/23255.80.96.1 to 255.80.97.254255.80.97.255510
50255.80.98.0/23255.80.98.1 to 255.80.99.254255.80.99.255510
51255.80.100.0/23255.80.100.1 to 255.80.101.254255.80.101.255510
52255.80.102.0/23255.80.102.1 to 255.80.103.254255.80.103.255510
53255.80.104.0/23255.80.104.1 to 255.80.105.254255.80.105.255510
54255.80.106.0/23255.80.106.1 to 255.80.107.254255.80.107.255510
55255.80.108.0/23255.80.108.1 to 255.80.109.254255.80.109.255510
56255.80.110.0/23255.80.110.1 to 255.80.111.254255.80.111.255510
57255.80.112.0/23255.80.112.1 to 255.80.113.254255.80.113.255510
58255.80.114.0/23255.80.114.1 to 255.80.115.254255.80.115.255510
59255.80.116.0/23255.80.116.1 to 255.80.117.254255.80.117.255510
60255.80.118.0/23255.80.118.1 to 255.80.119.254255.80.119.255510
61255.80.120.0/23255.80.120.1 to 255.80.121.254255.80.121.255510
62255.80.122.0/23255.80.122.1 to 255.80.123.254255.80.123.255510
63255.80.124.0/23255.80.124.1 to 255.80.125.254255.80.125.255510
64255.80.126.0/23255.80.126.1 to 255.80.127.254255.80.127.255510
65255.80.128.0/23255.80.128.1 to 255.80.129.254255.80.129.255510
66255.80.130.0/23255.80.130.1 to 255.80.131.254255.80.131.255510
67255.80.132.0/23255.80.132.1 to 255.80.133.254255.80.133.255510
68255.80.134.0/23255.80.134.1 to 255.80.135.254255.80.135.255510
69255.80.136.0/23255.80.136.1 to 255.80.137.254255.80.137.255510
70255.80.138.0/23255.80.138.1 to 255.80.139.254255.80.139.255510
71255.80.140.0/23255.80.140.1 to 255.80.141.254255.80.141.255510
72255.80.142.0/23255.80.142.1 to 255.80.143.254255.80.143.255510
73255.80.144.0/23255.80.144.1 to 255.80.145.254255.80.145.255510
74255.80.146.0/23255.80.146.1 to 255.80.147.254255.80.147.255510
75255.80.148.0/23255.80.148.1 to 255.80.149.254255.80.149.255510
76255.80.150.0/23255.80.150.1 to 255.80.151.254255.80.151.255510
77255.80.152.0/23255.80.152.1 to 255.80.153.254255.80.153.255510
78255.80.154.0/23255.80.154.1 to 255.80.155.254255.80.155.255510
79255.80.156.0/23255.80.156.1 to 255.80.157.254255.80.157.255510
80255.80.158.0/23255.80.158.1 to 255.80.159.254255.80.159.255510
81255.80.160.0/23255.80.160.1 to 255.80.161.254255.80.161.255510
82255.80.162.0/23255.80.162.1 to 255.80.163.254255.80.163.255510
83255.80.164.0/23255.80.164.1 to 255.80.165.254255.80.165.255510
84255.80.166.0/23255.80.166.1 to 255.80.167.254255.80.167.255510
85255.80.168.0/23255.80.168.1 to 255.80.169.254255.80.169.255510
86255.80.170.0/23255.80.170.1 to 255.80.171.254255.80.171.255510
87255.80.172.0/23255.80.172.1 to 255.80.173.254255.80.173.255510
88255.80.174.0/23255.80.174.1 to 255.80.175.254255.80.175.255510
89255.80.176.0/23255.80.176.1 to 255.80.177.254255.80.177.255510
90255.80.178.0/23255.80.178.1 to 255.80.179.254255.80.179.255510
91255.80.180.0/23255.80.180.1 to 255.80.181.254255.80.181.255510
92255.80.182.0/23255.80.182.1 to 255.80.183.254255.80.183.255510
93255.80.184.0/23255.80.184.1 to 255.80.185.254255.80.185.255510
94255.80.186.0/23255.80.186.1 to 255.80.187.254255.80.187.255510
95255.80.188.0/23255.80.188.1 to 255.80.189.254255.80.189.255510
96255.80.190.0/23255.80.190.1 to 255.80.191.254255.80.191.255510
97255.80.192.0/23255.80.192.1 to 255.80.193.254255.80.193.255510
98255.80.194.0/23255.80.194.1 to 255.80.195.254255.80.195.255510
99255.80.196.0/23255.80.196.1 to 255.80.197.254255.80.197.255510
100255.80.198.0/23255.80.198.1 to 255.80.199.254255.80.199.255510
101255.80.200.0/23255.80.200.1 to 255.80.201.254255.80.201.255510
102255.80.202.0/23255.80.202.1 to 255.80.203.254255.80.203.255510
103255.80.204.0/23255.80.204.1 to 255.80.205.254255.80.205.255510
104255.80.206.0/23255.80.206.1 to 255.80.207.254255.80.207.255510
105255.80.208.0/23255.80.208.1 to 255.80.209.254255.80.209.255510
106255.80.210.0/23255.80.210.1 to 255.80.211.254255.80.211.255510
107255.80.212.0/23255.80.212.1 to 255.80.213.254255.80.213.255510
108255.80.214.0/23255.80.214.1 to 255.80.215.254255.80.215.255510
109255.80.216.0/23255.80.216.1 to 255.80.217.254255.80.217.255510
110255.80.218.0/23255.80.218.1 to 255.80.219.254255.80.219.255510
111255.80.220.0/23255.80.220.1 to 255.80.221.254255.80.221.255510
112255.80.222.0/23255.80.222.1 to 255.80.223.254255.80.223.255510
113255.80.224.0/23255.80.224.1 to 255.80.225.254255.80.225.255510
114255.80.226.0/23255.80.226.1 to 255.80.227.254255.80.227.255510
115255.80.228.0/23255.80.228.1 to 255.80.229.254255.80.229.255510
116255.80.230.0/23255.80.230.1 to 255.80.231.254255.80.231.255510
117255.80.232.0/23255.80.232.1 to 255.80.233.254255.80.233.255510
118255.80.234.0/23255.80.234.1 to 255.80.235.254255.80.235.255510
119255.80.236.0/23255.80.236.1 to 255.80.237.254255.80.237.255510
120255.80.238.0/23255.80.238.1 to 255.80.239.254255.80.239.255510
121255.80.240.0/23255.80.240.1 to 255.80.241.254255.80.241.255510
122255.80.242.0/23255.80.242.1 to 255.80.243.254255.80.243.255510
123255.80.244.0/23255.80.244.1 to 255.80.245.254255.80.245.255510
124255.80.246.0/23255.80.246.1 to 255.80.247.254255.80.247.255510
125255.80.248.0/23255.80.248.1 to 255.80.249.254255.80.249.255510
126255.80.250.0/23255.80.250.1 to 255.80.251.254255.80.251.255510
127255.80.252.0/23255.80.252.1 to 255.80.253.254255.80.253.255510
128255.80.254.0/23255.80.254.1 to 255.80.255.254255.80.255.255510
129255.81.0.0/23255.81.0.1 to 255.81.1.254255.81.1.255510
130255.81.2.0/23255.81.2.1 to 255.81.3.254255.81.3.255510
131255.81.4.0/23255.81.4.1 to 255.81.5.254255.81.5.255510
132255.81.6.0/23255.81.6.1 to 255.81.7.254255.81.7.255510
133255.81.8.0/23255.81.8.1 to 255.81.9.254255.81.9.255510
134255.81.10.0/23255.81.10.1 to 255.81.11.254255.81.11.255510
135255.81.12.0/23255.81.12.1 to 255.81.13.254255.81.13.255510
136255.81.14.0/23255.81.14.1 to 255.81.15.254255.81.15.255510
137255.81.16.0/23255.81.16.1 to 255.81.17.254255.81.17.255510
138255.81.18.0/23255.81.18.1 to 255.81.19.254255.81.19.255510
139255.81.20.0/23255.81.20.1 to 255.81.21.254255.81.21.255510
140255.81.22.0/23255.81.22.1 to 255.81.23.254255.81.23.255510
141255.81.24.0/23255.81.24.1 to 255.81.25.254255.81.25.255510
142255.81.26.0/23255.81.26.1 to 255.81.27.254255.81.27.255510
143255.81.28.0/23255.81.28.1 to 255.81.29.254255.81.29.255510
144255.81.30.0/23255.81.30.1 to 255.81.31.254255.81.31.255510
145255.81.32.0/23255.81.32.1 to 255.81.33.254255.81.33.255510
146255.81.34.0/23255.81.34.1 to 255.81.35.254255.81.35.255510
147255.81.36.0/23255.81.36.1 to 255.81.37.254255.81.37.255510
148255.81.38.0/23255.81.38.1 to 255.81.39.254255.81.39.255510
149255.81.40.0/23255.81.40.1 to 255.81.41.254255.81.41.255510
150255.81.42.0/23255.81.42.1 to 255.81.43.254255.81.43.255510
151255.81.44.0/23255.81.44.1 to 255.81.45.254255.81.45.255510
152255.81.46.0/23255.81.46.1 to 255.81.47.254255.81.47.255510
153255.81.48.0/23255.81.48.1 to 255.81.49.254255.81.49.255510
154255.81.50.0/23255.81.50.1 to 255.81.51.254255.81.51.255510
155255.81.52.0/23255.81.52.1 to 255.81.53.254255.81.53.255510
156255.81.54.0/23255.81.54.1 to 255.81.55.254255.81.55.255510
157255.81.56.0/23255.81.56.1 to 255.81.57.254255.81.57.255510
158255.81.58.0/23255.81.58.1 to 255.81.59.254255.81.59.255510
159255.81.60.0/23255.81.60.1 to 255.81.61.254255.81.61.255510
160255.81.62.0/23255.81.62.1 to 255.81.63.254255.81.63.255510
161255.81.64.0/23255.81.64.1 to 255.81.65.254255.81.65.255510
162255.81.66.0/23255.81.66.1 to 255.81.67.254255.81.67.255510
163255.81.68.0/23255.81.68.1 to 255.81.69.254255.81.69.255510
164255.81.70.0/23255.81.70.1 to 255.81.71.254255.81.71.255510
165255.81.72.0/23255.81.72.1 to 255.81.73.254255.81.73.255510
166255.81.74.0/23255.81.74.1 to 255.81.75.254255.81.75.255510
167255.81.76.0/23255.81.76.1 to 255.81.77.254255.81.77.255510
168255.81.78.0/23255.81.78.1 to 255.81.79.254255.81.79.255510
169255.81.80.0/23255.81.80.1 to 255.81.81.254255.81.81.255510
170255.81.82.0/23255.81.82.1 to 255.81.83.254255.81.83.255510
171255.81.84.0/23255.81.84.1 to 255.81.85.254255.81.85.255510
172255.81.86.0/23255.81.86.1 to 255.81.87.254255.81.87.255510
173255.81.88.0/23255.81.88.1 to 255.81.89.254255.81.89.255510
174255.81.90.0/23255.81.90.1 to 255.81.91.254255.81.91.255510
175255.81.92.0/23255.81.92.1 to 255.81.93.254255.81.93.255510
176255.81.94.0/23255.81.94.1 to 255.81.95.254255.81.95.255510
177255.81.96.0/23255.81.96.1 to 255.81.97.254255.81.97.255510
178255.81.98.0/23255.81.98.1 to 255.81.99.254255.81.99.255510
179255.81.100.0/23255.81.100.1 to 255.81.101.254255.81.101.255510
180255.81.102.0/23255.81.102.1 to 255.81.103.254255.81.103.255510
181255.81.104.0/23255.81.104.1 to 255.81.105.254255.81.105.255510
182255.81.106.0/23255.81.106.1 to 255.81.107.254255.81.107.255510
183255.81.108.0/23255.81.108.1 to 255.81.109.254255.81.109.255510
184255.81.110.0/23255.81.110.1 to 255.81.111.254255.81.111.255510
185255.81.112.0/23255.81.112.1 to 255.81.113.254255.81.113.255510
186255.81.114.0/23255.81.114.1 to 255.81.115.254255.81.115.255510
187255.81.116.0/23255.81.116.1 to 255.81.117.254255.81.117.255510
188255.81.118.0/23255.81.118.1 to 255.81.119.254255.81.119.255510
189255.81.120.0/23255.81.120.1 to 255.81.121.254255.81.121.255510
190255.81.122.0/23255.81.122.1 to 255.81.123.254255.81.123.255510
191255.81.124.0/23255.81.124.1 to 255.81.125.254255.81.125.255510
192255.81.126.0/23255.81.126.1 to 255.81.127.254255.81.127.255510
193255.81.128.0/23255.81.128.1 to 255.81.129.254255.81.129.255510
194255.81.130.0/23255.81.130.1 to 255.81.131.254255.81.131.255510
195255.81.132.0/23255.81.132.1 to 255.81.133.254255.81.133.255510
196255.81.134.0/23255.81.134.1 to 255.81.135.254255.81.135.255510
197255.81.136.0/23255.81.136.1 to 255.81.137.254255.81.137.255510
198255.81.138.0/23255.81.138.1 to 255.81.139.254255.81.139.255510
199255.81.140.0/23255.81.140.1 to 255.81.141.254255.81.141.255510
200255.81.142.0/23255.81.142.1 to 255.81.143.254255.81.143.255510
201255.81.144.0/23255.81.144.1 to 255.81.145.254255.81.145.255510
202255.81.146.0/23255.81.146.1 to 255.81.147.254255.81.147.255510
203255.81.148.0/23255.81.148.1 to 255.81.149.254255.81.149.255510
204255.81.150.0/23255.81.150.1 to 255.81.151.254255.81.151.255510
205255.81.152.0/23255.81.152.1 to 255.81.153.254255.81.153.255510
206255.81.154.0/23255.81.154.1 to 255.81.155.254255.81.155.255510
207255.81.156.0/23255.81.156.1 to 255.81.157.254255.81.157.255510
208255.81.158.0/23255.81.158.1 to 255.81.159.254255.81.159.255510
209255.81.160.0/23255.81.160.1 to 255.81.161.254255.81.161.255510
210255.81.162.0/23255.81.162.1 to 255.81.163.254255.81.163.255510
211255.81.164.0/23255.81.164.1 to 255.81.165.254255.81.165.255510
212255.81.166.0/23255.81.166.1 to 255.81.167.254255.81.167.255510
213255.81.168.0/23255.81.168.1 to 255.81.169.254255.81.169.255510
214255.81.170.0/23255.81.170.1 to 255.81.171.254255.81.171.255510
215255.81.172.0/23255.81.172.1 to 255.81.173.254255.81.173.255510
216255.81.174.0/23255.81.174.1 to 255.81.175.254255.81.175.255510
217255.81.176.0/23255.81.176.1 to 255.81.177.254255.81.177.255510
218255.81.178.0/23255.81.178.1 to 255.81.179.254255.81.179.255510
219255.81.180.0/23255.81.180.1 to 255.81.181.254255.81.181.255510
220255.81.182.0/23255.81.182.1 to 255.81.183.254255.81.183.255510
221255.81.184.0/23255.81.184.1 to 255.81.185.254255.81.185.255510
222255.81.186.0/23255.81.186.1 to 255.81.187.254255.81.187.255510
223255.81.188.0/23255.81.188.1 to 255.81.189.254255.81.189.255510
224255.81.190.0/23255.81.190.1 to 255.81.191.254255.81.191.255510
225255.81.192.0/23255.81.192.1 to 255.81.193.254255.81.193.255510
226255.81.194.0/23255.81.194.1 to 255.81.195.254255.81.195.255510
227255.81.196.0/23255.81.196.1 to 255.81.197.254255.81.197.255510
228255.81.198.0/23255.81.198.1 to 255.81.199.254255.81.199.255510
229255.81.200.0/23255.81.200.1 to 255.81.201.254255.81.201.255510
230255.81.202.0/23255.81.202.1 to 255.81.203.254255.81.203.255510
231255.81.204.0/23255.81.204.1 to 255.81.205.254255.81.205.255510
232255.81.206.0/23255.81.206.1 to 255.81.207.254255.81.207.255510
233255.81.208.0/23255.81.208.1 to 255.81.209.254255.81.209.255510
234255.81.210.0/23255.81.210.1 to 255.81.211.254255.81.211.255510
235255.81.212.0/23255.81.212.1 to 255.81.213.254255.81.213.255510
236255.81.214.0/23255.81.214.1 to 255.81.215.254255.81.215.255510
237255.81.216.0/23255.81.216.1 to 255.81.217.254255.81.217.255510
238255.81.218.0/23255.81.218.1 to 255.81.219.254255.81.219.255510
239255.81.220.0/23255.81.220.1 to 255.81.221.254255.81.221.255510
240255.81.222.0/23255.81.222.1 to 255.81.223.254255.81.223.255510
241255.81.224.0/23255.81.224.1 to 255.81.225.254255.81.225.255510
242255.81.226.0/23255.81.226.1 to 255.81.227.254255.81.227.255510
243255.81.228.0/23255.81.228.1 to 255.81.229.254255.81.229.255510
244255.81.230.0/23255.81.230.1 to 255.81.231.254255.81.231.255510
245255.81.232.0/23255.81.232.1 to 255.81.233.254255.81.233.255510
246255.81.234.0/23255.81.234.1 to 255.81.235.254255.81.235.255510
247255.81.236.0/23255.81.236.1 to 255.81.237.254255.81.237.255510
248255.81.238.0/23255.81.238.1 to 255.81.239.254255.81.239.255510
249255.81.240.0/23255.81.240.1 to 255.81.241.254255.81.241.255510
250255.81.242.0/23255.81.242.1 to 255.81.243.254255.81.243.255510
251255.81.244.0/23255.81.244.1 to 255.81.245.254255.81.245.255510
252255.81.246.0/23255.81.246.1 to 255.81.247.254255.81.247.255510
253255.81.248.0/23255.81.248.1 to 255.81.249.254255.81.249.255510
254255.81.250.0/23255.81.250.1 to 255.81.251.254255.81.251.255510
255255.81.252.0/23255.81.252.1 to 255.81.253.254255.81.253.255510
256255.81.254.0/23255.81.254.1 to 255.81.255.254255.81.255.255510

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.