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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.

Network240.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
240.0.0.0
Broadcast address
247.255.255.255
First usable
240.0.0.1
Last usable
247.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
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 4160749567
Reverse DNS zones
240.in-addr.arpa
241.in-addr.arpa
242.in-addr.arpa
243.in-addr.arpa
244.in-addr.arpa
245.in-addr.arpa
246.in-addr.arpa
247.in-addr.arpa
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110000.00000000.00000000.00000000240.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network11110000.00000000.00000000.00000000240.0.0.0
Broadcast11110111.11111111.11111111.11111111247.255.255.255
Split into smaller subnets/16
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

240.0.0.0/5 makes 2,048 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.0.0.0/16240.0.0.1 to 240.0.255.254240.0.255.25565,534
2240.1.0.0/16240.1.0.1 to 240.1.255.254240.1.255.25565,534
3240.2.0.0/16240.2.0.1 to 240.2.255.254240.2.255.25565,534
4240.3.0.0/16240.3.0.1 to 240.3.255.254240.3.255.25565,534
5240.4.0.0/16240.4.0.1 to 240.4.255.254240.4.255.25565,534
6240.5.0.0/16240.5.0.1 to 240.5.255.254240.5.255.25565,534
7240.6.0.0/16240.6.0.1 to 240.6.255.254240.6.255.25565,534
8240.7.0.0/16240.7.0.1 to 240.7.255.254240.7.255.25565,534
9240.8.0.0/16240.8.0.1 to 240.8.255.254240.8.255.25565,534
10240.9.0.0/16240.9.0.1 to 240.9.255.254240.9.255.25565,534
11240.10.0.0/16240.10.0.1 to 240.10.255.254240.10.255.25565,534
12240.11.0.0/16240.11.0.1 to 240.11.255.254240.11.255.25565,534
13240.12.0.0/16240.12.0.1 to 240.12.255.254240.12.255.25565,534
14240.13.0.0/16240.13.0.1 to 240.13.255.254240.13.255.25565,534
15240.14.0.0/16240.14.0.1 to 240.14.255.254240.14.255.25565,534
16240.15.0.0/16240.15.0.1 to 240.15.255.254240.15.255.25565,534
17240.16.0.0/16240.16.0.1 to 240.16.255.254240.16.255.25565,534
18240.17.0.0/16240.17.0.1 to 240.17.255.254240.17.255.25565,534
19240.18.0.0/16240.18.0.1 to 240.18.255.254240.18.255.25565,534
20240.19.0.0/16240.19.0.1 to 240.19.255.254240.19.255.25565,534
21240.20.0.0/16240.20.0.1 to 240.20.255.254240.20.255.25565,534
22240.21.0.0/16240.21.0.1 to 240.21.255.254240.21.255.25565,534
23240.22.0.0/16240.22.0.1 to 240.22.255.254240.22.255.25565,534
24240.23.0.0/16240.23.0.1 to 240.23.255.254240.23.255.25565,534
25240.24.0.0/16240.24.0.1 to 240.24.255.254240.24.255.25565,534
26240.25.0.0/16240.25.0.1 to 240.25.255.254240.25.255.25565,534
27240.26.0.0/16240.26.0.1 to 240.26.255.254240.26.255.25565,534
28240.27.0.0/16240.27.0.1 to 240.27.255.254240.27.255.25565,534
29240.28.0.0/16240.28.0.1 to 240.28.255.254240.28.255.25565,534
30240.29.0.0/16240.29.0.1 to 240.29.255.254240.29.255.25565,534
31240.30.0.0/16240.30.0.1 to 240.30.255.254240.30.255.25565,534
32240.31.0.0/16240.31.0.1 to 240.31.255.254240.31.255.25565,534
33240.32.0.0/16240.32.0.1 to 240.32.255.254240.32.255.25565,534
34240.33.0.0/16240.33.0.1 to 240.33.255.254240.33.255.25565,534
35240.34.0.0/16240.34.0.1 to 240.34.255.254240.34.255.25565,534
36240.35.0.0/16240.35.0.1 to 240.35.255.254240.35.255.25565,534
37240.36.0.0/16240.36.0.1 to 240.36.255.254240.36.255.25565,534
38240.37.0.0/16240.37.0.1 to 240.37.255.254240.37.255.25565,534
39240.38.0.0/16240.38.0.1 to 240.38.255.254240.38.255.25565,534
40240.39.0.0/16240.39.0.1 to 240.39.255.254240.39.255.25565,534
41240.40.0.0/16240.40.0.1 to 240.40.255.254240.40.255.25565,534
42240.41.0.0/16240.41.0.1 to 240.41.255.254240.41.255.25565,534
43240.42.0.0/16240.42.0.1 to 240.42.255.254240.42.255.25565,534
44240.43.0.0/16240.43.0.1 to 240.43.255.254240.43.255.25565,534
45240.44.0.0/16240.44.0.1 to 240.44.255.254240.44.255.25565,534
46240.45.0.0/16240.45.0.1 to 240.45.255.254240.45.255.25565,534
47240.46.0.0/16240.46.0.1 to 240.46.255.254240.46.255.25565,534
48240.47.0.0/16240.47.0.1 to 240.47.255.254240.47.255.25565,534
49240.48.0.0/16240.48.0.1 to 240.48.255.254240.48.255.25565,534
50240.49.0.0/16240.49.0.1 to 240.49.255.254240.49.255.25565,534
51240.50.0.0/16240.50.0.1 to 240.50.255.254240.50.255.25565,534
52240.51.0.0/16240.51.0.1 to 240.51.255.254240.51.255.25565,534
53240.52.0.0/16240.52.0.1 to 240.52.255.254240.52.255.25565,534
54240.53.0.0/16240.53.0.1 to 240.53.255.254240.53.255.25565,534
55240.54.0.0/16240.54.0.1 to 240.54.255.254240.54.255.25565,534
56240.55.0.0/16240.55.0.1 to 240.55.255.254240.55.255.25565,534
57240.56.0.0/16240.56.0.1 to 240.56.255.254240.56.255.25565,534
58240.57.0.0/16240.57.0.1 to 240.57.255.254240.57.255.25565,534
59240.58.0.0/16240.58.0.1 to 240.58.255.254240.58.255.25565,534
60240.59.0.0/16240.59.0.1 to 240.59.255.254240.59.255.25565,534
61240.60.0.0/16240.60.0.1 to 240.60.255.254240.60.255.25565,534
62240.61.0.0/16240.61.0.1 to 240.61.255.254240.61.255.25565,534
63240.62.0.0/16240.62.0.1 to 240.62.255.254240.62.255.25565,534
64240.63.0.0/16240.63.0.1 to 240.63.255.254240.63.255.25565,534
65240.64.0.0/16240.64.0.1 to 240.64.255.254240.64.255.25565,534
66240.65.0.0/16240.65.0.1 to 240.65.255.254240.65.255.25565,534
67240.66.0.0/16240.66.0.1 to 240.66.255.254240.66.255.25565,534
68240.67.0.0/16240.67.0.1 to 240.67.255.254240.67.255.25565,534
69240.68.0.0/16240.68.0.1 to 240.68.255.254240.68.255.25565,534
70240.69.0.0/16240.69.0.1 to 240.69.255.254240.69.255.25565,534
71240.70.0.0/16240.70.0.1 to 240.70.255.254240.70.255.25565,534
72240.71.0.0/16240.71.0.1 to 240.71.255.254240.71.255.25565,534
73240.72.0.0/16240.72.0.1 to 240.72.255.254240.72.255.25565,534
74240.73.0.0/16240.73.0.1 to 240.73.255.254240.73.255.25565,534
75240.74.0.0/16240.74.0.1 to 240.74.255.254240.74.255.25565,534
76240.75.0.0/16240.75.0.1 to 240.75.255.254240.75.255.25565,534
77240.76.0.0/16240.76.0.1 to 240.76.255.254240.76.255.25565,534
78240.77.0.0/16240.77.0.1 to 240.77.255.254240.77.255.25565,534
79240.78.0.0/16240.78.0.1 to 240.78.255.254240.78.255.25565,534
80240.79.0.0/16240.79.0.1 to 240.79.255.254240.79.255.25565,534
81240.80.0.0/16240.80.0.1 to 240.80.255.254240.80.255.25565,534
82240.81.0.0/16240.81.0.1 to 240.81.255.254240.81.255.25565,534
83240.82.0.0/16240.82.0.1 to 240.82.255.254240.82.255.25565,534
84240.83.0.0/16240.83.0.1 to 240.83.255.254240.83.255.25565,534
85240.84.0.0/16240.84.0.1 to 240.84.255.254240.84.255.25565,534
86240.85.0.0/16240.85.0.1 to 240.85.255.254240.85.255.25565,534
87240.86.0.0/16240.86.0.1 to 240.86.255.254240.86.255.25565,534
88240.87.0.0/16240.87.0.1 to 240.87.255.254240.87.255.25565,534
89240.88.0.0/16240.88.0.1 to 240.88.255.254240.88.255.25565,534
90240.89.0.0/16240.89.0.1 to 240.89.255.254240.89.255.25565,534
91240.90.0.0/16240.90.0.1 to 240.90.255.254240.90.255.25565,534
92240.91.0.0/16240.91.0.1 to 240.91.255.254240.91.255.25565,534
93240.92.0.0/16240.92.0.1 to 240.92.255.254240.92.255.25565,534
94240.93.0.0/16240.93.0.1 to 240.93.255.254240.93.255.25565,534
95240.94.0.0/16240.94.0.1 to 240.94.255.254240.94.255.25565,534
96240.95.0.0/16240.95.0.1 to 240.95.255.254240.95.255.25565,534
97240.96.0.0/16240.96.0.1 to 240.96.255.254240.96.255.25565,534
98240.97.0.0/16240.97.0.1 to 240.97.255.254240.97.255.25565,534
99240.98.0.0/16240.98.0.1 to 240.98.255.254240.98.255.25565,534
100240.99.0.0/16240.99.0.1 to 240.99.255.254240.99.255.25565,534
101240.100.0.0/16240.100.0.1 to 240.100.255.254240.100.255.25565,534
102240.101.0.0/16240.101.0.1 to 240.101.255.254240.101.255.25565,534
103240.102.0.0/16240.102.0.1 to 240.102.255.254240.102.255.25565,534
104240.103.0.0/16240.103.0.1 to 240.103.255.254240.103.255.25565,534
105240.104.0.0/16240.104.0.1 to 240.104.255.254240.104.255.25565,534
106240.105.0.0/16240.105.0.1 to 240.105.255.254240.105.255.25565,534
107240.106.0.0/16240.106.0.1 to 240.106.255.254240.106.255.25565,534
108240.107.0.0/16240.107.0.1 to 240.107.255.254240.107.255.25565,534
109240.108.0.0/16240.108.0.1 to 240.108.255.254240.108.255.25565,534
110240.109.0.0/16240.109.0.1 to 240.109.255.254240.109.255.25565,534
111240.110.0.0/16240.110.0.1 to 240.110.255.254240.110.255.25565,534
112240.111.0.0/16240.111.0.1 to 240.111.255.254240.111.255.25565,534
113240.112.0.0/16240.112.0.1 to 240.112.255.254240.112.255.25565,534
114240.113.0.0/16240.113.0.1 to 240.113.255.254240.113.255.25565,534
115240.114.0.0/16240.114.0.1 to 240.114.255.254240.114.255.25565,534
116240.115.0.0/16240.115.0.1 to 240.115.255.254240.115.255.25565,534
117240.116.0.0/16240.116.0.1 to 240.116.255.254240.116.255.25565,534
118240.117.0.0/16240.117.0.1 to 240.117.255.254240.117.255.25565,534
119240.118.0.0/16240.118.0.1 to 240.118.255.254240.118.255.25565,534
120240.119.0.0/16240.119.0.1 to 240.119.255.254240.119.255.25565,534
121240.120.0.0/16240.120.0.1 to 240.120.255.254240.120.255.25565,534
122240.121.0.0/16240.121.0.1 to 240.121.255.254240.121.255.25565,534
123240.122.0.0/16240.122.0.1 to 240.122.255.254240.122.255.25565,534
124240.123.0.0/16240.123.0.1 to 240.123.255.254240.123.255.25565,534
125240.124.0.0/16240.124.0.1 to 240.124.255.254240.124.255.25565,534
126240.125.0.0/16240.125.0.1 to 240.125.255.254240.125.255.25565,534
127240.126.0.0/16240.126.0.1 to 240.126.255.254240.126.255.25565,534
128240.127.0.0/16240.127.0.1 to 240.127.255.254240.127.255.25565,534
129240.128.0.0/16240.128.0.1 to 240.128.255.254240.128.255.25565,534
130240.129.0.0/16240.129.0.1 to 240.129.255.254240.129.255.25565,534
131240.130.0.0/16240.130.0.1 to 240.130.255.254240.130.255.25565,534
132240.131.0.0/16240.131.0.1 to 240.131.255.254240.131.255.25565,534
133240.132.0.0/16240.132.0.1 to 240.132.255.254240.132.255.25565,534
134240.133.0.0/16240.133.0.1 to 240.133.255.254240.133.255.25565,534
135240.134.0.0/16240.134.0.1 to 240.134.255.254240.134.255.25565,534
136240.135.0.0/16240.135.0.1 to 240.135.255.254240.135.255.25565,534
137240.136.0.0/16240.136.0.1 to 240.136.255.254240.136.255.25565,534
138240.137.0.0/16240.137.0.1 to 240.137.255.254240.137.255.25565,534
139240.138.0.0/16240.138.0.1 to 240.138.255.254240.138.255.25565,534
140240.139.0.0/16240.139.0.1 to 240.139.255.254240.139.255.25565,534
141240.140.0.0/16240.140.0.1 to 240.140.255.254240.140.255.25565,534
142240.141.0.0/16240.141.0.1 to 240.141.255.254240.141.255.25565,534
143240.142.0.0/16240.142.0.1 to 240.142.255.254240.142.255.25565,534
144240.143.0.0/16240.143.0.1 to 240.143.255.254240.143.255.25565,534
145240.144.0.0/16240.144.0.1 to 240.144.255.254240.144.255.25565,534
146240.145.0.0/16240.145.0.1 to 240.145.255.254240.145.255.25565,534
147240.146.0.0/16240.146.0.1 to 240.146.255.254240.146.255.25565,534
148240.147.0.0/16240.147.0.1 to 240.147.255.254240.147.255.25565,534
149240.148.0.0/16240.148.0.1 to 240.148.255.254240.148.255.25565,534
150240.149.0.0/16240.149.0.1 to 240.149.255.254240.149.255.25565,534
151240.150.0.0/16240.150.0.1 to 240.150.255.254240.150.255.25565,534
152240.151.0.0/16240.151.0.1 to 240.151.255.254240.151.255.25565,534
153240.152.0.0/16240.152.0.1 to 240.152.255.254240.152.255.25565,534
154240.153.0.0/16240.153.0.1 to 240.153.255.254240.153.255.25565,534
155240.154.0.0/16240.154.0.1 to 240.154.255.254240.154.255.25565,534
156240.155.0.0/16240.155.0.1 to 240.155.255.254240.155.255.25565,534
157240.156.0.0/16240.156.0.1 to 240.156.255.254240.156.255.25565,534
158240.157.0.0/16240.157.0.1 to 240.157.255.254240.157.255.25565,534
159240.158.0.0/16240.158.0.1 to 240.158.255.254240.158.255.25565,534
160240.159.0.0/16240.159.0.1 to 240.159.255.254240.159.255.25565,534
161240.160.0.0/16240.160.0.1 to 240.160.255.254240.160.255.25565,534
162240.161.0.0/16240.161.0.1 to 240.161.255.254240.161.255.25565,534
163240.162.0.0/16240.162.0.1 to 240.162.255.254240.162.255.25565,534
164240.163.0.0/16240.163.0.1 to 240.163.255.254240.163.255.25565,534
165240.164.0.0/16240.164.0.1 to 240.164.255.254240.164.255.25565,534
166240.165.0.0/16240.165.0.1 to 240.165.255.254240.165.255.25565,534
167240.166.0.0/16240.166.0.1 to 240.166.255.254240.166.255.25565,534
168240.167.0.0/16240.167.0.1 to 240.167.255.254240.167.255.25565,534
169240.168.0.0/16240.168.0.1 to 240.168.255.254240.168.255.25565,534
170240.169.0.0/16240.169.0.1 to 240.169.255.254240.169.255.25565,534
171240.170.0.0/16240.170.0.1 to 240.170.255.254240.170.255.25565,534
172240.171.0.0/16240.171.0.1 to 240.171.255.254240.171.255.25565,534
173240.172.0.0/16240.172.0.1 to 240.172.255.254240.172.255.25565,534
174240.173.0.0/16240.173.0.1 to 240.173.255.254240.173.255.25565,534
175240.174.0.0/16240.174.0.1 to 240.174.255.254240.174.255.25565,534
176240.175.0.0/16240.175.0.1 to 240.175.255.254240.175.255.25565,534
177240.176.0.0/16240.176.0.1 to 240.176.255.254240.176.255.25565,534
178240.177.0.0/16240.177.0.1 to 240.177.255.254240.177.255.25565,534
179240.178.0.0/16240.178.0.1 to 240.178.255.254240.178.255.25565,534
180240.179.0.0/16240.179.0.1 to 240.179.255.254240.179.255.25565,534
181240.180.0.0/16240.180.0.1 to 240.180.255.254240.180.255.25565,534
182240.181.0.0/16240.181.0.1 to 240.181.255.254240.181.255.25565,534
183240.182.0.0/16240.182.0.1 to 240.182.255.254240.182.255.25565,534
184240.183.0.0/16240.183.0.1 to 240.183.255.254240.183.255.25565,534
185240.184.0.0/16240.184.0.1 to 240.184.255.254240.184.255.25565,534
186240.185.0.0/16240.185.0.1 to 240.185.255.254240.185.255.25565,534
187240.186.0.0/16240.186.0.1 to 240.186.255.254240.186.255.25565,534
188240.187.0.0/16240.187.0.1 to 240.187.255.254240.187.255.25565,534
189240.188.0.0/16240.188.0.1 to 240.188.255.254240.188.255.25565,534
190240.189.0.0/16240.189.0.1 to 240.189.255.254240.189.255.25565,534
191240.190.0.0/16240.190.0.1 to 240.190.255.254240.190.255.25565,534
192240.191.0.0/16240.191.0.1 to 240.191.255.254240.191.255.25565,534
193240.192.0.0/16240.192.0.1 to 240.192.255.254240.192.255.25565,534
194240.193.0.0/16240.193.0.1 to 240.193.255.254240.193.255.25565,534
195240.194.0.0/16240.194.0.1 to 240.194.255.254240.194.255.25565,534
196240.195.0.0/16240.195.0.1 to 240.195.255.254240.195.255.25565,534
197240.196.0.0/16240.196.0.1 to 240.196.255.254240.196.255.25565,534
198240.197.0.0/16240.197.0.1 to 240.197.255.254240.197.255.25565,534
199240.198.0.0/16240.198.0.1 to 240.198.255.254240.198.255.25565,534
200240.199.0.0/16240.199.0.1 to 240.199.255.254240.199.255.25565,534
201240.200.0.0/16240.200.0.1 to 240.200.255.254240.200.255.25565,534
202240.201.0.0/16240.201.0.1 to 240.201.255.254240.201.255.25565,534
203240.202.0.0/16240.202.0.1 to 240.202.255.254240.202.255.25565,534
204240.203.0.0/16240.203.0.1 to 240.203.255.254240.203.255.25565,534
205240.204.0.0/16240.204.0.1 to 240.204.255.254240.204.255.25565,534
206240.205.0.0/16240.205.0.1 to 240.205.255.254240.205.255.25565,534
207240.206.0.0/16240.206.0.1 to 240.206.255.254240.206.255.25565,534
208240.207.0.0/16240.207.0.1 to 240.207.255.254240.207.255.25565,534
209240.208.0.0/16240.208.0.1 to 240.208.255.254240.208.255.25565,534
210240.209.0.0/16240.209.0.1 to 240.209.255.254240.209.255.25565,534
211240.210.0.0/16240.210.0.1 to 240.210.255.254240.210.255.25565,534
212240.211.0.0/16240.211.0.1 to 240.211.255.254240.211.255.25565,534
213240.212.0.0/16240.212.0.1 to 240.212.255.254240.212.255.25565,534
214240.213.0.0/16240.213.0.1 to 240.213.255.254240.213.255.25565,534
215240.214.0.0/16240.214.0.1 to 240.214.255.254240.214.255.25565,534
216240.215.0.0/16240.215.0.1 to 240.215.255.254240.215.255.25565,534
217240.216.0.0/16240.216.0.1 to 240.216.255.254240.216.255.25565,534
218240.217.0.0/16240.217.0.1 to 240.217.255.254240.217.255.25565,534
219240.218.0.0/16240.218.0.1 to 240.218.255.254240.218.255.25565,534
220240.219.0.0/16240.219.0.1 to 240.219.255.254240.219.255.25565,534
221240.220.0.0/16240.220.0.1 to 240.220.255.254240.220.255.25565,534
222240.221.0.0/16240.221.0.1 to 240.221.255.254240.221.255.25565,534
223240.222.0.0/16240.222.0.1 to 240.222.255.254240.222.255.25565,534
224240.223.0.0/16240.223.0.1 to 240.223.255.254240.223.255.25565,534
225240.224.0.0/16240.224.0.1 to 240.224.255.254240.224.255.25565,534
226240.225.0.0/16240.225.0.1 to 240.225.255.254240.225.255.25565,534
227240.226.0.0/16240.226.0.1 to 240.226.255.254240.226.255.25565,534
228240.227.0.0/16240.227.0.1 to 240.227.255.254240.227.255.25565,534
229240.228.0.0/16240.228.0.1 to 240.228.255.254240.228.255.25565,534
230240.229.0.0/16240.229.0.1 to 240.229.255.254240.229.255.25565,534
231240.230.0.0/16240.230.0.1 to 240.230.255.254240.230.255.25565,534
232240.231.0.0/16240.231.0.1 to 240.231.255.254240.231.255.25565,534
233240.232.0.0/16240.232.0.1 to 240.232.255.254240.232.255.25565,534
234240.233.0.0/16240.233.0.1 to 240.233.255.254240.233.255.25565,534
235240.234.0.0/16240.234.0.1 to 240.234.255.254240.234.255.25565,534
236240.235.0.0/16240.235.0.1 to 240.235.255.254240.235.255.25565,534
237240.236.0.0/16240.236.0.1 to 240.236.255.254240.236.255.25565,534
238240.237.0.0/16240.237.0.1 to 240.237.255.254240.237.255.25565,534
239240.238.0.0/16240.238.0.1 to 240.238.255.254240.238.255.25565,534
240240.239.0.0/16240.239.0.1 to 240.239.255.254240.239.255.25565,534
241240.240.0.0/16240.240.0.1 to 240.240.255.254240.240.255.25565,534
242240.241.0.0/16240.241.0.1 to 240.241.255.254240.241.255.25565,534
243240.242.0.0/16240.242.0.1 to 240.242.255.254240.242.255.25565,534
244240.243.0.0/16240.243.0.1 to 240.243.255.254240.243.255.25565,534
245240.244.0.0/16240.244.0.1 to 240.244.255.254240.244.255.25565,534
246240.245.0.0/16240.245.0.1 to 240.245.255.254240.245.255.25565,534
247240.246.0.0/16240.246.0.1 to 240.246.255.254240.246.255.25565,534
248240.247.0.0/16240.247.0.1 to 240.247.255.254240.247.255.25565,534
249240.248.0.0/16240.248.0.1 to 240.248.255.254240.248.255.25565,534
250240.249.0.0/16240.249.0.1 to 240.249.255.254240.249.255.25565,534
251240.250.0.0/16240.250.0.1 to 240.250.255.254240.250.255.25565,534
252240.251.0.0/16240.251.0.1 to 240.251.255.254240.251.255.25565,534
253240.252.0.0/16240.252.0.1 to 240.252.255.254240.252.255.25565,534
254240.253.0.0/16240.253.0.1 to 240.253.255.254240.253.255.25565,534
255240.254.0.0/16240.254.0.1 to 240.254.255.254240.254.255.25565,534
256240.255.0.0/16240.255.0.1 to 240.255.255.254240.255.255.25565,534

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.