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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.

Network239.240.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
239.240.0.0
Broadcast address
239.255.255.255
First usable
239.240.0.1
Last usable
239.255.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EFF00000 · Integer 4025483264 to 4026531839
Reverse DNS zones
240.239.in-addr.arpa
241.239.in-addr.arpa
242.239.in-addr.arpa
243.239.in-addr.arpa
244.239.in-addr.arpa
245.239.in-addr.arpa
246.239.in-addr.arpa
247.239.in-addr.arpa
248.239.in-addr.arpa
249.239.in-addr.arpa
250.239.in-addr.arpa
251.239.in-addr.arpa
252.239.in-addr.arpa
253.239.in-addr.arpa
254.239.in-addr.arpa
255.239.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
Address11101111.11110000.00000000.00000000239.240.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11101111.11110000.00000000.00000000239.240.0.0
Broadcast11101111.11111111.11111111.11111111239.255.255.255
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)

239.240.0.0/12 makes 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1239.240.0.0/24239.240.0.1 to 239.240.0.254239.240.0.255254
2239.240.1.0/24239.240.1.1 to 239.240.1.254239.240.1.255254
3239.240.2.0/24239.240.2.1 to 239.240.2.254239.240.2.255254
4239.240.3.0/24239.240.3.1 to 239.240.3.254239.240.3.255254
5239.240.4.0/24239.240.4.1 to 239.240.4.254239.240.4.255254
6239.240.5.0/24239.240.5.1 to 239.240.5.254239.240.5.255254
7239.240.6.0/24239.240.6.1 to 239.240.6.254239.240.6.255254
8239.240.7.0/24239.240.7.1 to 239.240.7.254239.240.7.255254
9239.240.8.0/24239.240.8.1 to 239.240.8.254239.240.8.255254
10239.240.9.0/24239.240.9.1 to 239.240.9.254239.240.9.255254
11239.240.10.0/24239.240.10.1 to 239.240.10.254239.240.10.255254
12239.240.11.0/24239.240.11.1 to 239.240.11.254239.240.11.255254
13239.240.12.0/24239.240.12.1 to 239.240.12.254239.240.12.255254
14239.240.13.0/24239.240.13.1 to 239.240.13.254239.240.13.255254
15239.240.14.0/24239.240.14.1 to 239.240.14.254239.240.14.255254
16239.240.15.0/24239.240.15.1 to 239.240.15.254239.240.15.255254
17239.240.16.0/24239.240.16.1 to 239.240.16.254239.240.16.255254
18239.240.17.0/24239.240.17.1 to 239.240.17.254239.240.17.255254
19239.240.18.0/24239.240.18.1 to 239.240.18.254239.240.18.255254
20239.240.19.0/24239.240.19.1 to 239.240.19.254239.240.19.255254
21239.240.20.0/24239.240.20.1 to 239.240.20.254239.240.20.255254
22239.240.21.0/24239.240.21.1 to 239.240.21.254239.240.21.255254
23239.240.22.0/24239.240.22.1 to 239.240.22.254239.240.22.255254
24239.240.23.0/24239.240.23.1 to 239.240.23.254239.240.23.255254
25239.240.24.0/24239.240.24.1 to 239.240.24.254239.240.24.255254
26239.240.25.0/24239.240.25.1 to 239.240.25.254239.240.25.255254
27239.240.26.0/24239.240.26.1 to 239.240.26.254239.240.26.255254
28239.240.27.0/24239.240.27.1 to 239.240.27.254239.240.27.255254
29239.240.28.0/24239.240.28.1 to 239.240.28.254239.240.28.255254
30239.240.29.0/24239.240.29.1 to 239.240.29.254239.240.29.255254
31239.240.30.0/24239.240.30.1 to 239.240.30.254239.240.30.255254
32239.240.31.0/24239.240.31.1 to 239.240.31.254239.240.31.255254
33239.240.32.0/24239.240.32.1 to 239.240.32.254239.240.32.255254
34239.240.33.0/24239.240.33.1 to 239.240.33.254239.240.33.255254
35239.240.34.0/24239.240.34.1 to 239.240.34.254239.240.34.255254
36239.240.35.0/24239.240.35.1 to 239.240.35.254239.240.35.255254
37239.240.36.0/24239.240.36.1 to 239.240.36.254239.240.36.255254
38239.240.37.0/24239.240.37.1 to 239.240.37.254239.240.37.255254
39239.240.38.0/24239.240.38.1 to 239.240.38.254239.240.38.255254
40239.240.39.0/24239.240.39.1 to 239.240.39.254239.240.39.255254
41239.240.40.0/24239.240.40.1 to 239.240.40.254239.240.40.255254
42239.240.41.0/24239.240.41.1 to 239.240.41.254239.240.41.255254
43239.240.42.0/24239.240.42.1 to 239.240.42.254239.240.42.255254
44239.240.43.0/24239.240.43.1 to 239.240.43.254239.240.43.255254
45239.240.44.0/24239.240.44.1 to 239.240.44.254239.240.44.255254
46239.240.45.0/24239.240.45.1 to 239.240.45.254239.240.45.255254
47239.240.46.0/24239.240.46.1 to 239.240.46.254239.240.46.255254
48239.240.47.0/24239.240.47.1 to 239.240.47.254239.240.47.255254
49239.240.48.0/24239.240.48.1 to 239.240.48.254239.240.48.255254
50239.240.49.0/24239.240.49.1 to 239.240.49.254239.240.49.255254
51239.240.50.0/24239.240.50.1 to 239.240.50.254239.240.50.255254
52239.240.51.0/24239.240.51.1 to 239.240.51.254239.240.51.255254
53239.240.52.0/24239.240.52.1 to 239.240.52.254239.240.52.255254
54239.240.53.0/24239.240.53.1 to 239.240.53.254239.240.53.255254
55239.240.54.0/24239.240.54.1 to 239.240.54.254239.240.54.255254
56239.240.55.0/24239.240.55.1 to 239.240.55.254239.240.55.255254
57239.240.56.0/24239.240.56.1 to 239.240.56.254239.240.56.255254
58239.240.57.0/24239.240.57.1 to 239.240.57.254239.240.57.255254
59239.240.58.0/24239.240.58.1 to 239.240.58.254239.240.58.255254
60239.240.59.0/24239.240.59.1 to 239.240.59.254239.240.59.255254
61239.240.60.0/24239.240.60.1 to 239.240.60.254239.240.60.255254
62239.240.61.0/24239.240.61.1 to 239.240.61.254239.240.61.255254
63239.240.62.0/24239.240.62.1 to 239.240.62.254239.240.62.255254
64239.240.63.0/24239.240.63.1 to 239.240.63.254239.240.63.255254
65239.240.64.0/24239.240.64.1 to 239.240.64.254239.240.64.255254
66239.240.65.0/24239.240.65.1 to 239.240.65.254239.240.65.255254
67239.240.66.0/24239.240.66.1 to 239.240.66.254239.240.66.255254
68239.240.67.0/24239.240.67.1 to 239.240.67.254239.240.67.255254
69239.240.68.0/24239.240.68.1 to 239.240.68.254239.240.68.255254
70239.240.69.0/24239.240.69.1 to 239.240.69.254239.240.69.255254
71239.240.70.0/24239.240.70.1 to 239.240.70.254239.240.70.255254
72239.240.71.0/24239.240.71.1 to 239.240.71.254239.240.71.255254
73239.240.72.0/24239.240.72.1 to 239.240.72.254239.240.72.255254
74239.240.73.0/24239.240.73.1 to 239.240.73.254239.240.73.255254
75239.240.74.0/24239.240.74.1 to 239.240.74.254239.240.74.255254
76239.240.75.0/24239.240.75.1 to 239.240.75.254239.240.75.255254
77239.240.76.0/24239.240.76.1 to 239.240.76.254239.240.76.255254
78239.240.77.0/24239.240.77.1 to 239.240.77.254239.240.77.255254
79239.240.78.0/24239.240.78.1 to 239.240.78.254239.240.78.255254
80239.240.79.0/24239.240.79.1 to 239.240.79.254239.240.79.255254
81239.240.80.0/24239.240.80.1 to 239.240.80.254239.240.80.255254
82239.240.81.0/24239.240.81.1 to 239.240.81.254239.240.81.255254
83239.240.82.0/24239.240.82.1 to 239.240.82.254239.240.82.255254
84239.240.83.0/24239.240.83.1 to 239.240.83.254239.240.83.255254
85239.240.84.0/24239.240.84.1 to 239.240.84.254239.240.84.255254
86239.240.85.0/24239.240.85.1 to 239.240.85.254239.240.85.255254
87239.240.86.0/24239.240.86.1 to 239.240.86.254239.240.86.255254
88239.240.87.0/24239.240.87.1 to 239.240.87.254239.240.87.255254
89239.240.88.0/24239.240.88.1 to 239.240.88.254239.240.88.255254
90239.240.89.0/24239.240.89.1 to 239.240.89.254239.240.89.255254
91239.240.90.0/24239.240.90.1 to 239.240.90.254239.240.90.255254
92239.240.91.0/24239.240.91.1 to 239.240.91.254239.240.91.255254
93239.240.92.0/24239.240.92.1 to 239.240.92.254239.240.92.255254
94239.240.93.0/24239.240.93.1 to 239.240.93.254239.240.93.255254
95239.240.94.0/24239.240.94.1 to 239.240.94.254239.240.94.255254
96239.240.95.0/24239.240.95.1 to 239.240.95.254239.240.95.255254
97239.240.96.0/24239.240.96.1 to 239.240.96.254239.240.96.255254
98239.240.97.0/24239.240.97.1 to 239.240.97.254239.240.97.255254
99239.240.98.0/24239.240.98.1 to 239.240.98.254239.240.98.255254
100239.240.99.0/24239.240.99.1 to 239.240.99.254239.240.99.255254
101239.240.100.0/24239.240.100.1 to 239.240.100.254239.240.100.255254
102239.240.101.0/24239.240.101.1 to 239.240.101.254239.240.101.255254
103239.240.102.0/24239.240.102.1 to 239.240.102.254239.240.102.255254
104239.240.103.0/24239.240.103.1 to 239.240.103.254239.240.103.255254
105239.240.104.0/24239.240.104.1 to 239.240.104.254239.240.104.255254
106239.240.105.0/24239.240.105.1 to 239.240.105.254239.240.105.255254
107239.240.106.0/24239.240.106.1 to 239.240.106.254239.240.106.255254
108239.240.107.0/24239.240.107.1 to 239.240.107.254239.240.107.255254
109239.240.108.0/24239.240.108.1 to 239.240.108.254239.240.108.255254
110239.240.109.0/24239.240.109.1 to 239.240.109.254239.240.109.255254
111239.240.110.0/24239.240.110.1 to 239.240.110.254239.240.110.255254
112239.240.111.0/24239.240.111.1 to 239.240.111.254239.240.111.255254
113239.240.112.0/24239.240.112.1 to 239.240.112.254239.240.112.255254
114239.240.113.0/24239.240.113.1 to 239.240.113.254239.240.113.255254
115239.240.114.0/24239.240.114.1 to 239.240.114.254239.240.114.255254
116239.240.115.0/24239.240.115.1 to 239.240.115.254239.240.115.255254
117239.240.116.0/24239.240.116.1 to 239.240.116.254239.240.116.255254
118239.240.117.0/24239.240.117.1 to 239.240.117.254239.240.117.255254
119239.240.118.0/24239.240.118.1 to 239.240.118.254239.240.118.255254
120239.240.119.0/24239.240.119.1 to 239.240.119.254239.240.119.255254
121239.240.120.0/24239.240.120.1 to 239.240.120.254239.240.120.255254
122239.240.121.0/24239.240.121.1 to 239.240.121.254239.240.121.255254
123239.240.122.0/24239.240.122.1 to 239.240.122.254239.240.122.255254
124239.240.123.0/24239.240.123.1 to 239.240.123.254239.240.123.255254
125239.240.124.0/24239.240.124.1 to 239.240.124.254239.240.124.255254
126239.240.125.0/24239.240.125.1 to 239.240.125.254239.240.125.255254
127239.240.126.0/24239.240.126.1 to 239.240.126.254239.240.126.255254
128239.240.127.0/24239.240.127.1 to 239.240.127.254239.240.127.255254
129239.240.128.0/24239.240.128.1 to 239.240.128.254239.240.128.255254
130239.240.129.0/24239.240.129.1 to 239.240.129.254239.240.129.255254
131239.240.130.0/24239.240.130.1 to 239.240.130.254239.240.130.255254
132239.240.131.0/24239.240.131.1 to 239.240.131.254239.240.131.255254
133239.240.132.0/24239.240.132.1 to 239.240.132.254239.240.132.255254
134239.240.133.0/24239.240.133.1 to 239.240.133.254239.240.133.255254
135239.240.134.0/24239.240.134.1 to 239.240.134.254239.240.134.255254
136239.240.135.0/24239.240.135.1 to 239.240.135.254239.240.135.255254
137239.240.136.0/24239.240.136.1 to 239.240.136.254239.240.136.255254
138239.240.137.0/24239.240.137.1 to 239.240.137.254239.240.137.255254
139239.240.138.0/24239.240.138.1 to 239.240.138.254239.240.138.255254
140239.240.139.0/24239.240.139.1 to 239.240.139.254239.240.139.255254
141239.240.140.0/24239.240.140.1 to 239.240.140.254239.240.140.255254
142239.240.141.0/24239.240.141.1 to 239.240.141.254239.240.141.255254
143239.240.142.0/24239.240.142.1 to 239.240.142.254239.240.142.255254
144239.240.143.0/24239.240.143.1 to 239.240.143.254239.240.143.255254
145239.240.144.0/24239.240.144.1 to 239.240.144.254239.240.144.255254
146239.240.145.0/24239.240.145.1 to 239.240.145.254239.240.145.255254
147239.240.146.0/24239.240.146.1 to 239.240.146.254239.240.146.255254
148239.240.147.0/24239.240.147.1 to 239.240.147.254239.240.147.255254
149239.240.148.0/24239.240.148.1 to 239.240.148.254239.240.148.255254
150239.240.149.0/24239.240.149.1 to 239.240.149.254239.240.149.255254
151239.240.150.0/24239.240.150.1 to 239.240.150.254239.240.150.255254
152239.240.151.0/24239.240.151.1 to 239.240.151.254239.240.151.255254
153239.240.152.0/24239.240.152.1 to 239.240.152.254239.240.152.255254
154239.240.153.0/24239.240.153.1 to 239.240.153.254239.240.153.255254
155239.240.154.0/24239.240.154.1 to 239.240.154.254239.240.154.255254
156239.240.155.0/24239.240.155.1 to 239.240.155.254239.240.155.255254
157239.240.156.0/24239.240.156.1 to 239.240.156.254239.240.156.255254
158239.240.157.0/24239.240.157.1 to 239.240.157.254239.240.157.255254
159239.240.158.0/24239.240.158.1 to 239.240.158.254239.240.158.255254
160239.240.159.0/24239.240.159.1 to 239.240.159.254239.240.159.255254
161239.240.160.0/24239.240.160.1 to 239.240.160.254239.240.160.255254
162239.240.161.0/24239.240.161.1 to 239.240.161.254239.240.161.255254
163239.240.162.0/24239.240.162.1 to 239.240.162.254239.240.162.255254
164239.240.163.0/24239.240.163.1 to 239.240.163.254239.240.163.255254
165239.240.164.0/24239.240.164.1 to 239.240.164.254239.240.164.255254
166239.240.165.0/24239.240.165.1 to 239.240.165.254239.240.165.255254
167239.240.166.0/24239.240.166.1 to 239.240.166.254239.240.166.255254
168239.240.167.0/24239.240.167.1 to 239.240.167.254239.240.167.255254
169239.240.168.0/24239.240.168.1 to 239.240.168.254239.240.168.255254
170239.240.169.0/24239.240.169.1 to 239.240.169.254239.240.169.255254
171239.240.170.0/24239.240.170.1 to 239.240.170.254239.240.170.255254
172239.240.171.0/24239.240.171.1 to 239.240.171.254239.240.171.255254
173239.240.172.0/24239.240.172.1 to 239.240.172.254239.240.172.255254
174239.240.173.0/24239.240.173.1 to 239.240.173.254239.240.173.255254
175239.240.174.0/24239.240.174.1 to 239.240.174.254239.240.174.255254
176239.240.175.0/24239.240.175.1 to 239.240.175.254239.240.175.255254
177239.240.176.0/24239.240.176.1 to 239.240.176.254239.240.176.255254
178239.240.177.0/24239.240.177.1 to 239.240.177.254239.240.177.255254
179239.240.178.0/24239.240.178.1 to 239.240.178.254239.240.178.255254
180239.240.179.0/24239.240.179.1 to 239.240.179.254239.240.179.255254
181239.240.180.0/24239.240.180.1 to 239.240.180.254239.240.180.255254
182239.240.181.0/24239.240.181.1 to 239.240.181.254239.240.181.255254
183239.240.182.0/24239.240.182.1 to 239.240.182.254239.240.182.255254
184239.240.183.0/24239.240.183.1 to 239.240.183.254239.240.183.255254
185239.240.184.0/24239.240.184.1 to 239.240.184.254239.240.184.255254
186239.240.185.0/24239.240.185.1 to 239.240.185.254239.240.185.255254
187239.240.186.0/24239.240.186.1 to 239.240.186.254239.240.186.255254
188239.240.187.0/24239.240.187.1 to 239.240.187.254239.240.187.255254
189239.240.188.0/24239.240.188.1 to 239.240.188.254239.240.188.255254
190239.240.189.0/24239.240.189.1 to 239.240.189.254239.240.189.255254
191239.240.190.0/24239.240.190.1 to 239.240.190.254239.240.190.255254
192239.240.191.0/24239.240.191.1 to 239.240.191.254239.240.191.255254
193239.240.192.0/24239.240.192.1 to 239.240.192.254239.240.192.255254
194239.240.193.0/24239.240.193.1 to 239.240.193.254239.240.193.255254
195239.240.194.0/24239.240.194.1 to 239.240.194.254239.240.194.255254
196239.240.195.0/24239.240.195.1 to 239.240.195.254239.240.195.255254
197239.240.196.0/24239.240.196.1 to 239.240.196.254239.240.196.255254
198239.240.197.0/24239.240.197.1 to 239.240.197.254239.240.197.255254
199239.240.198.0/24239.240.198.1 to 239.240.198.254239.240.198.255254
200239.240.199.0/24239.240.199.1 to 239.240.199.254239.240.199.255254
201239.240.200.0/24239.240.200.1 to 239.240.200.254239.240.200.255254
202239.240.201.0/24239.240.201.1 to 239.240.201.254239.240.201.255254
203239.240.202.0/24239.240.202.1 to 239.240.202.254239.240.202.255254
204239.240.203.0/24239.240.203.1 to 239.240.203.254239.240.203.255254
205239.240.204.0/24239.240.204.1 to 239.240.204.254239.240.204.255254
206239.240.205.0/24239.240.205.1 to 239.240.205.254239.240.205.255254
207239.240.206.0/24239.240.206.1 to 239.240.206.254239.240.206.255254
208239.240.207.0/24239.240.207.1 to 239.240.207.254239.240.207.255254
209239.240.208.0/24239.240.208.1 to 239.240.208.254239.240.208.255254
210239.240.209.0/24239.240.209.1 to 239.240.209.254239.240.209.255254
211239.240.210.0/24239.240.210.1 to 239.240.210.254239.240.210.255254
212239.240.211.0/24239.240.211.1 to 239.240.211.254239.240.211.255254
213239.240.212.0/24239.240.212.1 to 239.240.212.254239.240.212.255254
214239.240.213.0/24239.240.213.1 to 239.240.213.254239.240.213.255254
215239.240.214.0/24239.240.214.1 to 239.240.214.254239.240.214.255254
216239.240.215.0/24239.240.215.1 to 239.240.215.254239.240.215.255254
217239.240.216.0/24239.240.216.1 to 239.240.216.254239.240.216.255254
218239.240.217.0/24239.240.217.1 to 239.240.217.254239.240.217.255254
219239.240.218.0/24239.240.218.1 to 239.240.218.254239.240.218.255254
220239.240.219.0/24239.240.219.1 to 239.240.219.254239.240.219.255254
221239.240.220.0/24239.240.220.1 to 239.240.220.254239.240.220.255254
222239.240.221.0/24239.240.221.1 to 239.240.221.254239.240.221.255254
223239.240.222.0/24239.240.222.1 to 239.240.222.254239.240.222.255254
224239.240.223.0/24239.240.223.1 to 239.240.223.254239.240.223.255254
225239.240.224.0/24239.240.224.1 to 239.240.224.254239.240.224.255254
226239.240.225.0/24239.240.225.1 to 239.240.225.254239.240.225.255254
227239.240.226.0/24239.240.226.1 to 239.240.226.254239.240.226.255254
228239.240.227.0/24239.240.227.1 to 239.240.227.254239.240.227.255254
229239.240.228.0/24239.240.228.1 to 239.240.228.254239.240.228.255254
230239.240.229.0/24239.240.229.1 to 239.240.229.254239.240.229.255254
231239.240.230.0/24239.240.230.1 to 239.240.230.254239.240.230.255254
232239.240.231.0/24239.240.231.1 to 239.240.231.254239.240.231.255254
233239.240.232.0/24239.240.232.1 to 239.240.232.254239.240.232.255254
234239.240.233.0/24239.240.233.1 to 239.240.233.254239.240.233.255254
235239.240.234.0/24239.240.234.1 to 239.240.234.254239.240.234.255254
236239.240.235.0/24239.240.235.1 to 239.240.235.254239.240.235.255254
237239.240.236.0/24239.240.236.1 to 239.240.236.254239.240.236.255254
238239.240.237.0/24239.240.237.1 to 239.240.237.254239.240.237.255254
239239.240.238.0/24239.240.238.1 to 239.240.238.254239.240.238.255254
240239.240.239.0/24239.240.239.1 to 239.240.239.254239.240.239.255254
241239.240.240.0/24239.240.240.1 to 239.240.240.254239.240.240.255254
242239.240.241.0/24239.240.241.1 to 239.240.241.254239.240.241.255254
243239.240.242.0/24239.240.242.1 to 239.240.242.254239.240.242.255254
244239.240.243.0/24239.240.243.1 to 239.240.243.254239.240.243.255254
245239.240.244.0/24239.240.244.1 to 239.240.244.254239.240.244.255254
246239.240.245.0/24239.240.245.1 to 239.240.245.254239.240.245.255254
247239.240.246.0/24239.240.246.1 to 239.240.246.254239.240.246.255254
248239.240.247.0/24239.240.247.1 to 239.240.247.254239.240.247.255254
249239.240.248.0/24239.240.248.1 to 239.240.248.254239.240.248.255254
250239.240.249.0/24239.240.249.1 to 239.240.249.254239.240.249.255254
251239.240.250.0/24239.240.250.1 to 239.240.250.254239.240.250.255254
252239.240.251.0/24239.240.251.1 to 239.240.251.254239.240.251.255254
253239.240.252.0/24239.240.252.1 to 239.240.252.254239.240.252.255254
254239.240.253.0/24239.240.253.1 to 239.240.253.254239.240.253.255254
255239.240.254.0/24239.240.254.1 to 239.240.254.254239.240.254.255254
256239.240.255.0/24239.240.255.1 to 239.240.255.254239.240.255.255254

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.