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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.

Network243.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
243.80.0.0
Broadcast address
243.95.255.255
First usable
243.80.0.1
Last usable
243.95.255.254
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 F3500000 · Integer 4082106368 to 4083154943
Reverse DNS zones
80.243.in-addr.arpa
81.243.in-addr.arpa
82.243.in-addr.arpa
83.243.in-addr.arpa
84.243.in-addr.arpa
85.243.in-addr.arpa
86.243.in-addr.arpa
87.243.in-addr.arpa
88.243.in-addr.arpa
89.243.in-addr.arpa
90.243.in-addr.arpa
91.243.in-addr.arpa
92.243.in-addr.arpa
93.243.in-addr.arpa
94.243.in-addr.arpa
95.243.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
Address11110011.01010000.00000000.00000000243.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11110011.01010000.00000000.00000000243.80.0.0
Broadcast11110011.01011111.11111111.11111111243.95.255.255
Split into smaller subnets/24
/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)

243.80.0.0/12 makes 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1243.80.0.0/24243.80.0.1 to 243.80.0.254243.80.0.255254
2243.80.1.0/24243.80.1.1 to 243.80.1.254243.80.1.255254
3243.80.2.0/24243.80.2.1 to 243.80.2.254243.80.2.255254
4243.80.3.0/24243.80.3.1 to 243.80.3.254243.80.3.255254
5243.80.4.0/24243.80.4.1 to 243.80.4.254243.80.4.255254
6243.80.5.0/24243.80.5.1 to 243.80.5.254243.80.5.255254
7243.80.6.0/24243.80.6.1 to 243.80.6.254243.80.6.255254
8243.80.7.0/24243.80.7.1 to 243.80.7.254243.80.7.255254
9243.80.8.0/24243.80.8.1 to 243.80.8.254243.80.8.255254
10243.80.9.0/24243.80.9.1 to 243.80.9.254243.80.9.255254
11243.80.10.0/24243.80.10.1 to 243.80.10.254243.80.10.255254
12243.80.11.0/24243.80.11.1 to 243.80.11.254243.80.11.255254
13243.80.12.0/24243.80.12.1 to 243.80.12.254243.80.12.255254
14243.80.13.0/24243.80.13.1 to 243.80.13.254243.80.13.255254
15243.80.14.0/24243.80.14.1 to 243.80.14.254243.80.14.255254
16243.80.15.0/24243.80.15.1 to 243.80.15.254243.80.15.255254
17243.80.16.0/24243.80.16.1 to 243.80.16.254243.80.16.255254
18243.80.17.0/24243.80.17.1 to 243.80.17.254243.80.17.255254
19243.80.18.0/24243.80.18.1 to 243.80.18.254243.80.18.255254
20243.80.19.0/24243.80.19.1 to 243.80.19.254243.80.19.255254
21243.80.20.0/24243.80.20.1 to 243.80.20.254243.80.20.255254
22243.80.21.0/24243.80.21.1 to 243.80.21.254243.80.21.255254
23243.80.22.0/24243.80.22.1 to 243.80.22.254243.80.22.255254
24243.80.23.0/24243.80.23.1 to 243.80.23.254243.80.23.255254
25243.80.24.0/24243.80.24.1 to 243.80.24.254243.80.24.255254
26243.80.25.0/24243.80.25.1 to 243.80.25.254243.80.25.255254
27243.80.26.0/24243.80.26.1 to 243.80.26.254243.80.26.255254
28243.80.27.0/24243.80.27.1 to 243.80.27.254243.80.27.255254
29243.80.28.0/24243.80.28.1 to 243.80.28.254243.80.28.255254
30243.80.29.0/24243.80.29.1 to 243.80.29.254243.80.29.255254
31243.80.30.0/24243.80.30.1 to 243.80.30.254243.80.30.255254
32243.80.31.0/24243.80.31.1 to 243.80.31.254243.80.31.255254
33243.80.32.0/24243.80.32.1 to 243.80.32.254243.80.32.255254
34243.80.33.0/24243.80.33.1 to 243.80.33.254243.80.33.255254
35243.80.34.0/24243.80.34.1 to 243.80.34.254243.80.34.255254
36243.80.35.0/24243.80.35.1 to 243.80.35.254243.80.35.255254
37243.80.36.0/24243.80.36.1 to 243.80.36.254243.80.36.255254
38243.80.37.0/24243.80.37.1 to 243.80.37.254243.80.37.255254
39243.80.38.0/24243.80.38.1 to 243.80.38.254243.80.38.255254
40243.80.39.0/24243.80.39.1 to 243.80.39.254243.80.39.255254
41243.80.40.0/24243.80.40.1 to 243.80.40.254243.80.40.255254
42243.80.41.0/24243.80.41.1 to 243.80.41.254243.80.41.255254
43243.80.42.0/24243.80.42.1 to 243.80.42.254243.80.42.255254
44243.80.43.0/24243.80.43.1 to 243.80.43.254243.80.43.255254
45243.80.44.0/24243.80.44.1 to 243.80.44.254243.80.44.255254
46243.80.45.0/24243.80.45.1 to 243.80.45.254243.80.45.255254
47243.80.46.0/24243.80.46.1 to 243.80.46.254243.80.46.255254
48243.80.47.0/24243.80.47.1 to 243.80.47.254243.80.47.255254
49243.80.48.0/24243.80.48.1 to 243.80.48.254243.80.48.255254
50243.80.49.0/24243.80.49.1 to 243.80.49.254243.80.49.255254
51243.80.50.0/24243.80.50.1 to 243.80.50.254243.80.50.255254
52243.80.51.0/24243.80.51.1 to 243.80.51.254243.80.51.255254
53243.80.52.0/24243.80.52.1 to 243.80.52.254243.80.52.255254
54243.80.53.0/24243.80.53.1 to 243.80.53.254243.80.53.255254
55243.80.54.0/24243.80.54.1 to 243.80.54.254243.80.54.255254
56243.80.55.0/24243.80.55.1 to 243.80.55.254243.80.55.255254
57243.80.56.0/24243.80.56.1 to 243.80.56.254243.80.56.255254
58243.80.57.0/24243.80.57.1 to 243.80.57.254243.80.57.255254
59243.80.58.0/24243.80.58.1 to 243.80.58.254243.80.58.255254
60243.80.59.0/24243.80.59.1 to 243.80.59.254243.80.59.255254
61243.80.60.0/24243.80.60.1 to 243.80.60.254243.80.60.255254
62243.80.61.0/24243.80.61.1 to 243.80.61.254243.80.61.255254
63243.80.62.0/24243.80.62.1 to 243.80.62.254243.80.62.255254
64243.80.63.0/24243.80.63.1 to 243.80.63.254243.80.63.255254
65243.80.64.0/24243.80.64.1 to 243.80.64.254243.80.64.255254
66243.80.65.0/24243.80.65.1 to 243.80.65.254243.80.65.255254
67243.80.66.0/24243.80.66.1 to 243.80.66.254243.80.66.255254
68243.80.67.0/24243.80.67.1 to 243.80.67.254243.80.67.255254
69243.80.68.0/24243.80.68.1 to 243.80.68.254243.80.68.255254
70243.80.69.0/24243.80.69.1 to 243.80.69.254243.80.69.255254
71243.80.70.0/24243.80.70.1 to 243.80.70.254243.80.70.255254
72243.80.71.0/24243.80.71.1 to 243.80.71.254243.80.71.255254
73243.80.72.0/24243.80.72.1 to 243.80.72.254243.80.72.255254
74243.80.73.0/24243.80.73.1 to 243.80.73.254243.80.73.255254
75243.80.74.0/24243.80.74.1 to 243.80.74.254243.80.74.255254
76243.80.75.0/24243.80.75.1 to 243.80.75.254243.80.75.255254
77243.80.76.0/24243.80.76.1 to 243.80.76.254243.80.76.255254
78243.80.77.0/24243.80.77.1 to 243.80.77.254243.80.77.255254
79243.80.78.0/24243.80.78.1 to 243.80.78.254243.80.78.255254
80243.80.79.0/24243.80.79.1 to 243.80.79.254243.80.79.255254
81243.80.80.0/24243.80.80.1 to 243.80.80.254243.80.80.255254
82243.80.81.0/24243.80.81.1 to 243.80.81.254243.80.81.255254
83243.80.82.0/24243.80.82.1 to 243.80.82.254243.80.82.255254
84243.80.83.0/24243.80.83.1 to 243.80.83.254243.80.83.255254
85243.80.84.0/24243.80.84.1 to 243.80.84.254243.80.84.255254
86243.80.85.0/24243.80.85.1 to 243.80.85.254243.80.85.255254
87243.80.86.0/24243.80.86.1 to 243.80.86.254243.80.86.255254
88243.80.87.0/24243.80.87.1 to 243.80.87.254243.80.87.255254
89243.80.88.0/24243.80.88.1 to 243.80.88.254243.80.88.255254
90243.80.89.0/24243.80.89.1 to 243.80.89.254243.80.89.255254
91243.80.90.0/24243.80.90.1 to 243.80.90.254243.80.90.255254
92243.80.91.0/24243.80.91.1 to 243.80.91.254243.80.91.255254
93243.80.92.0/24243.80.92.1 to 243.80.92.254243.80.92.255254
94243.80.93.0/24243.80.93.1 to 243.80.93.254243.80.93.255254
95243.80.94.0/24243.80.94.1 to 243.80.94.254243.80.94.255254
96243.80.95.0/24243.80.95.1 to 243.80.95.254243.80.95.255254
97243.80.96.0/24243.80.96.1 to 243.80.96.254243.80.96.255254
98243.80.97.0/24243.80.97.1 to 243.80.97.254243.80.97.255254
99243.80.98.0/24243.80.98.1 to 243.80.98.254243.80.98.255254
100243.80.99.0/24243.80.99.1 to 243.80.99.254243.80.99.255254
101243.80.100.0/24243.80.100.1 to 243.80.100.254243.80.100.255254
102243.80.101.0/24243.80.101.1 to 243.80.101.254243.80.101.255254
103243.80.102.0/24243.80.102.1 to 243.80.102.254243.80.102.255254
104243.80.103.0/24243.80.103.1 to 243.80.103.254243.80.103.255254
105243.80.104.0/24243.80.104.1 to 243.80.104.254243.80.104.255254
106243.80.105.0/24243.80.105.1 to 243.80.105.254243.80.105.255254
107243.80.106.0/24243.80.106.1 to 243.80.106.254243.80.106.255254
108243.80.107.0/24243.80.107.1 to 243.80.107.254243.80.107.255254
109243.80.108.0/24243.80.108.1 to 243.80.108.254243.80.108.255254
110243.80.109.0/24243.80.109.1 to 243.80.109.254243.80.109.255254
111243.80.110.0/24243.80.110.1 to 243.80.110.254243.80.110.255254
112243.80.111.0/24243.80.111.1 to 243.80.111.254243.80.111.255254
113243.80.112.0/24243.80.112.1 to 243.80.112.254243.80.112.255254
114243.80.113.0/24243.80.113.1 to 243.80.113.254243.80.113.255254
115243.80.114.0/24243.80.114.1 to 243.80.114.254243.80.114.255254
116243.80.115.0/24243.80.115.1 to 243.80.115.254243.80.115.255254
117243.80.116.0/24243.80.116.1 to 243.80.116.254243.80.116.255254
118243.80.117.0/24243.80.117.1 to 243.80.117.254243.80.117.255254
119243.80.118.0/24243.80.118.1 to 243.80.118.254243.80.118.255254
120243.80.119.0/24243.80.119.1 to 243.80.119.254243.80.119.255254
121243.80.120.0/24243.80.120.1 to 243.80.120.254243.80.120.255254
122243.80.121.0/24243.80.121.1 to 243.80.121.254243.80.121.255254
123243.80.122.0/24243.80.122.1 to 243.80.122.254243.80.122.255254
124243.80.123.0/24243.80.123.1 to 243.80.123.254243.80.123.255254
125243.80.124.0/24243.80.124.1 to 243.80.124.254243.80.124.255254
126243.80.125.0/24243.80.125.1 to 243.80.125.254243.80.125.255254
127243.80.126.0/24243.80.126.1 to 243.80.126.254243.80.126.255254
128243.80.127.0/24243.80.127.1 to 243.80.127.254243.80.127.255254
129243.80.128.0/24243.80.128.1 to 243.80.128.254243.80.128.255254
130243.80.129.0/24243.80.129.1 to 243.80.129.254243.80.129.255254
131243.80.130.0/24243.80.130.1 to 243.80.130.254243.80.130.255254
132243.80.131.0/24243.80.131.1 to 243.80.131.254243.80.131.255254
133243.80.132.0/24243.80.132.1 to 243.80.132.254243.80.132.255254
134243.80.133.0/24243.80.133.1 to 243.80.133.254243.80.133.255254
135243.80.134.0/24243.80.134.1 to 243.80.134.254243.80.134.255254
136243.80.135.0/24243.80.135.1 to 243.80.135.254243.80.135.255254
137243.80.136.0/24243.80.136.1 to 243.80.136.254243.80.136.255254
138243.80.137.0/24243.80.137.1 to 243.80.137.254243.80.137.255254
139243.80.138.0/24243.80.138.1 to 243.80.138.254243.80.138.255254
140243.80.139.0/24243.80.139.1 to 243.80.139.254243.80.139.255254
141243.80.140.0/24243.80.140.1 to 243.80.140.254243.80.140.255254
142243.80.141.0/24243.80.141.1 to 243.80.141.254243.80.141.255254
143243.80.142.0/24243.80.142.1 to 243.80.142.254243.80.142.255254
144243.80.143.0/24243.80.143.1 to 243.80.143.254243.80.143.255254
145243.80.144.0/24243.80.144.1 to 243.80.144.254243.80.144.255254
146243.80.145.0/24243.80.145.1 to 243.80.145.254243.80.145.255254
147243.80.146.0/24243.80.146.1 to 243.80.146.254243.80.146.255254
148243.80.147.0/24243.80.147.1 to 243.80.147.254243.80.147.255254
149243.80.148.0/24243.80.148.1 to 243.80.148.254243.80.148.255254
150243.80.149.0/24243.80.149.1 to 243.80.149.254243.80.149.255254
151243.80.150.0/24243.80.150.1 to 243.80.150.254243.80.150.255254
152243.80.151.0/24243.80.151.1 to 243.80.151.254243.80.151.255254
153243.80.152.0/24243.80.152.1 to 243.80.152.254243.80.152.255254
154243.80.153.0/24243.80.153.1 to 243.80.153.254243.80.153.255254
155243.80.154.0/24243.80.154.1 to 243.80.154.254243.80.154.255254
156243.80.155.0/24243.80.155.1 to 243.80.155.254243.80.155.255254
157243.80.156.0/24243.80.156.1 to 243.80.156.254243.80.156.255254
158243.80.157.0/24243.80.157.1 to 243.80.157.254243.80.157.255254
159243.80.158.0/24243.80.158.1 to 243.80.158.254243.80.158.255254
160243.80.159.0/24243.80.159.1 to 243.80.159.254243.80.159.255254
161243.80.160.0/24243.80.160.1 to 243.80.160.254243.80.160.255254
162243.80.161.0/24243.80.161.1 to 243.80.161.254243.80.161.255254
163243.80.162.0/24243.80.162.1 to 243.80.162.254243.80.162.255254
164243.80.163.0/24243.80.163.1 to 243.80.163.254243.80.163.255254
165243.80.164.0/24243.80.164.1 to 243.80.164.254243.80.164.255254
166243.80.165.0/24243.80.165.1 to 243.80.165.254243.80.165.255254
167243.80.166.0/24243.80.166.1 to 243.80.166.254243.80.166.255254
168243.80.167.0/24243.80.167.1 to 243.80.167.254243.80.167.255254
169243.80.168.0/24243.80.168.1 to 243.80.168.254243.80.168.255254
170243.80.169.0/24243.80.169.1 to 243.80.169.254243.80.169.255254
171243.80.170.0/24243.80.170.1 to 243.80.170.254243.80.170.255254
172243.80.171.0/24243.80.171.1 to 243.80.171.254243.80.171.255254
173243.80.172.0/24243.80.172.1 to 243.80.172.254243.80.172.255254
174243.80.173.0/24243.80.173.1 to 243.80.173.254243.80.173.255254
175243.80.174.0/24243.80.174.1 to 243.80.174.254243.80.174.255254
176243.80.175.0/24243.80.175.1 to 243.80.175.254243.80.175.255254
177243.80.176.0/24243.80.176.1 to 243.80.176.254243.80.176.255254
178243.80.177.0/24243.80.177.1 to 243.80.177.254243.80.177.255254
179243.80.178.0/24243.80.178.1 to 243.80.178.254243.80.178.255254
180243.80.179.0/24243.80.179.1 to 243.80.179.254243.80.179.255254
181243.80.180.0/24243.80.180.1 to 243.80.180.254243.80.180.255254
182243.80.181.0/24243.80.181.1 to 243.80.181.254243.80.181.255254
183243.80.182.0/24243.80.182.1 to 243.80.182.254243.80.182.255254
184243.80.183.0/24243.80.183.1 to 243.80.183.254243.80.183.255254
185243.80.184.0/24243.80.184.1 to 243.80.184.254243.80.184.255254
186243.80.185.0/24243.80.185.1 to 243.80.185.254243.80.185.255254
187243.80.186.0/24243.80.186.1 to 243.80.186.254243.80.186.255254
188243.80.187.0/24243.80.187.1 to 243.80.187.254243.80.187.255254
189243.80.188.0/24243.80.188.1 to 243.80.188.254243.80.188.255254
190243.80.189.0/24243.80.189.1 to 243.80.189.254243.80.189.255254
191243.80.190.0/24243.80.190.1 to 243.80.190.254243.80.190.255254
192243.80.191.0/24243.80.191.1 to 243.80.191.254243.80.191.255254
193243.80.192.0/24243.80.192.1 to 243.80.192.254243.80.192.255254
194243.80.193.0/24243.80.193.1 to 243.80.193.254243.80.193.255254
195243.80.194.0/24243.80.194.1 to 243.80.194.254243.80.194.255254
196243.80.195.0/24243.80.195.1 to 243.80.195.254243.80.195.255254
197243.80.196.0/24243.80.196.1 to 243.80.196.254243.80.196.255254
198243.80.197.0/24243.80.197.1 to 243.80.197.254243.80.197.255254
199243.80.198.0/24243.80.198.1 to 243.80.198.254243.80.198.255254
200243.80.199.0/24243.80.199.1 to 243.80.199.254243.80.199.255254
201243.80.200.0/24243.80.200.1 to 243.80.200.254243.80.200.255254
202243.80.201.0/24243.80.201.1 to 243.80.201.254243.80.201.255254
203243.80.202.0/24243.80.202.1 to 243.80.202.254243.80.202.255254
204243.80.203.0/24243.80.203.1 to 243.80.203.254243.80.203.255254
205243.80.204.0/24243.80.204.1 to 243.80.204.254243.80.204.255254
206243.80.205.0/24243.80.205.1 to 243.80.205.254243.80.205.255254
207243.80.206.0/24243.80.206.1 to 243.80.206.254243.80.206.255254
208243.80.207.0/24243.80.207.1 to 243.80.207.254243.80.207.255254
209243.80.208.0/24243.80.208.1 to 243.80.208.254243.80.208.255254
210243.80.209.0/24243.80.209.1 to 243.80.209.254243.80.209.255254
211243.80.210.0/24243.80.210.1 to 243.80.210.254243.80.210.255254
212243.80.211.0/24243.80.211.1 to 243.80.211.254243.80.211.255254
213243.80.212.0/24243.80.212.1 to 243.80.212.254243.80.212.255254
214243.80.213.0/24243.80.213.1 to 243.80.213.254243.80.213.255254
215243.80.214.0/24243.80.214.1 to 243.80.214.254243.80.214.255254
216243.80.215.0/24243.80.215.1 to 243.80.215.254243.80.215.255254
217243.80.216.0/24243.80.216.1 to 243.80.216.254243.80.216.255254
218243.80.217.0/24243.80.217.1 to 243.80.217.254243.80.217.255254
219243.80.218.0/24243.80.218.1 to 243.80.218.254243.80.218.255254
220243.80.219.0/24243.80.219.1 to 243.80.219.254243.80.219.255254
221243.80.220.0/24243.80.220.1 to 243.80.220.254243.80.220.255254
222243.80.221.0/24243.80.221.1 to 243.80.221.254243.80.221.255254
223243.80.222.0/24243.80.222.1 to 243.80.222.254243.80.222.255254
224243.80.223.0/24243.80.223.1 to 243.80.223.254243.80.223.255254
225243.80.224.0/24243.80.224.1 to 243.80.224.254243.80.224.255254
226243.80.225.0/24243.80.225.1 to 243.80.225.254243.80.225.255254
227243.80.226.0/24243.80.226.1 to 243.80.226.254243.80.226.255254
228243.80.227.0/24243.80.227.1 to 243.80.227.254243.80.227.255254
229243.80.228.0/24243.80.228.1 to 243.80.228.254243.80.228.255254
230243.80.229.0/24243.80.229.1 to 243.80.229.254243.80.229.255254
231243.80.230.0/24243.80.230.1 to 243.80.230.254243.80.230.255254
232243.80.231.0/24243.80.231.1 to 243.80.231.254243.80.231.255254
233243.80.232.0/24243.80.232.1 to 243.80.232.254243.80.232.255254
234243.80.233.0/24243.80.233.1 to 243.80.233.254243.80.233.255254
235243.80.234.0/24243.80.234.1 to 243.80.234.254243.80.234.255254
236243.80.235.0/24243.80.235.1 to 243.80.235.254243.80.235.255254
237243.80.236.0/24243.80.236.1 to 243.80.236.254243.80.236.255254
238243.80.237.0/24243.80.237.1 to 243.80.237.254243.80.237.255254
239243.80.238.0/24243.80.238.1 to 243.80.238.254243.80.238.255254
240243.80.239.0/24243.80.239.1 to 243.80.239.254243.80.239.255254
241243.80.240.0/24243.80.240.1 to 243.80.240.254243.80.240.255254
242243.80.241.0/24243.80.241.1 to 243.80.241.254243.80.241.255254
243243.80.242.0/24243.80.242.1 to 243.80.242.254243.80.242.255254
244243.80.243.0/24243.80.243.1 to 243.80.243.254243.80.243.255254
245243.80.244.0/24243.80.244.1 to 243.80.244.254243.80.244.255254
246243.80.245.0/24243.80.245.1 to 243.80.245.254243.80.245.255254
247243.80.246.0/24243.80.246.1 to 243.80.246.254243.80.246.255254
248243.80.247.0/24243.80.247.1 to 243.80.247.254243.80.247.255254
249243.80.248.0/24243.80.248.1 to 243.80.248.254243.80.248.255254
250243.80.249.0/24243.80.249.1 to 243.80.249.254243.80.249.255254
251243.80.250.0/24243.80.250.1 to 243.80.250.254243.80.250.255254
252243.80.251.0/24243.80.251.1 to 243.80.251.254243.80.251.255254
253243.80.252.0/24243.80.252.1 to 243.80.252.254243.80.252.255254
254243.80.253.0/24243.80.253.1 to 243.80.253.254243.80.253.255254
255243.80.254.0/24243.80.254.1 to 243.80.254.254243.80.254.255254
256243.80.255.0/24243.80.255.1 to 243.80.255.254243.80.255.255254

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.