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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.

Network251.64.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
251.64.0.0
Broadcast address
251.127.255.255
First usable
251.64.0.1
Last usable
251.127.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FB400000 · Integer 4215275520 to 4219469823
Reverse DNS zones
64.251.in-addr.arpa
65.251.in-addr.arpa
66.251.in-addr.arpa
67.251.in-addr.arpa
68.251.in-addr.arpa
69.251.in-addr.arpa
70.251.in-addr.arpa
71.251.in-addr.arpa
72.251.in-addr.arpa
73.251.in-addr.arpa
74.251.in-addr.arpa
75.251.in-addr.arpa
76.251.in-addr.arpa
77.251.in-addr.arpa
78.251.in-addr.arpa
79.251.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111011.01000000.00000000.00000000251.64.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11111011.01000000.00000000.00000000251.64.0.0
Broadcast11111011.01111111.11111111.11111111251.127.255.255
Split into smaller subnets/22
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

251.64.0.0/10 makes 4,096 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1251.64.0.0/22251.64.0.1 to 251.64.3.254251.64.3.2551,022
2251.64.4.0/22251.64.4.1 to 251.64.7.254251.64.7.2551,022
3251.64.8.0/22251.64.8.1 to 251.64.11.254251.64.11.2551,022
4251.64.12.0/22251.64.12.1 to 251.64.15.254251.64.15.2551,022
5251.64.16.0/22251.64.16.1 to 251.64.19.254251.64.19.2551,022
6251.64.20.0/22251.64.20.1 to 251.64.23.254251.64.23.2551,022
7251.64.24.0/22251.64.24.1 to 251.64.27.254251.64.27.2551,022
8251.64.28.0/22251.64.28.1 to 251.64.31.254251.64.31.2551,022
9251.64.32.0/22251.64.32.1 to 251.64.35.254251.64.35.2551,022
10251.64.36.0/22251.64.36.1 to 251.64.39.254251.64.39.2551,022
11251.64.40.0/22251.64.40.1 to 251.64.43.254251.64.43.2551,022
12251.64.44.0/22251.64.44.1 to 251.64.47.254251.64.47.2551,022
13251.64.48.0/22251.64.48.1 to 251.64.51.254251.64.51.2551,022
14251.64.52.0/22251.64.52.1 to 251.64.55.254251.64.55.2551,022
15251.64.56.0/22251.64.56.1 to 251.64.59.254251.64.59.2551,022
16251.64.60.0/22251.64.60.1 to 251.64.63.254251.64.63.2551,022
17251.64.64.0/22251.64.64.1 to 251.64.67.254251.64.67.2551,022
18251.64.68.0/22251.64.68.1 to 251.64.71.254251.64.71.2551,022
19251.64.72.0/22251.64.72.1 to 251.64.75.254251.64.75.2551,022
20251.64.76.0/22251.64.76.1 to 251.64.79.254251.64.79.2551,022
21251.64.80.0/22251.64.80.1 to 251.64.83.254251.64.83.2551,022
22251.64.84.0/22251.64.84.1 to 251.64.87.254251.64.87.2551,022
23251.64.88.0/22251.64.88.1 to 251.64.91.254251.64.91.2551,022
24251.64.92.0/22251.64.92.1 to 251.64.95.254251.64.95.2551,022
25251.64.96.0/22251.64.96.1 to 251.64.99.254251.64.99.2551,022
26251.64.100.0/22251.64.100.1 to 251.64.103.254251.64.103.2551,022
27251.64.104.0/22251.64.104.1 to 251.64.107.254251.64.107.2551,022
28251.64.108.0/22251.64.108.1 to 251.64.111.254251.64.111.2551,022
29251.64.112.0/22251.64.112.1 to 251.64.115.254251.64.115.2551,022
30251.64.116.0/22251.64.116.1 to 251.64.119.254251.64.119.2551,022
31251.64.120.0/22251.64.120.1 to 251.64.123.254251.64.123.2551,022
32251.64.124.0/22251.64.124.1 to 251.64.127.254251.64.127.2551,022
33251.64.128.0/22251.64.128.1 to 251.64.131.254251.64.131.2551,022
34251.64.132.0/22251.64.132.1 to 251.64.135.254251.64.135.2551,022
35251.64.136.0/22251.64.136.1 to 251.64.139.254251.64.139.2551,022
36251.64.140.0/22251.64.140.1 to 251.64.143.254251.64.143.2551,022
37251.64.144.0/22251.64.144.1 to 251.64.147.254251.64.147.2551,022
38251.64.148.0/22251.64.148.1 to 251.64.151.254251.64.151.2551,022
39251.64.152.0/22251.64.152.1 to 251.64.155.254251.64.155.2551,022
40251.64.156.0/22251.64.156.1 to 251.64.159.254251.64.159.2551,022
41251.64.160.0/22251.64.160.1 to 251.64.163.254251.64.163.2551,022
42251.64.164.0/22251.64.164.1 to 251.64.167.254251.64.167.2551,022
43251.64.168.0/22251.64.168.1 to 251.64.171.254251.64.171.2551,022
44251.64.172.0/22251.64.172.1 to 251.64.175.254251.64.175.2551,022
45251.64.176.0/22251.64.176.1 to 251.64.179.254251.64.179.2551,022
46251.64.180.0/22251.64.180.1 to 251.64.183.254251.64.183.2551,022
47251.64.184.0/22251.64.184.1 to 251.64.187.254251.64.187.2551,022
48251.64.188.0/22251.64.188.1 to 251.64.191.254251.64.191.2551,022
49251.64.192.0/22251.64.192.1 to 251.64.195.254251.64.195.2551,022
50251.64.196.0/22251.64.196.1 to 251.64.199.254251.64.199.2551,022
51251.64.200.0/22251.64.200.1 to 251.64.203.254251.64.203.2551,022
52251.64.204.0/22251.64.204.1 to 251.64.207.254251.64.207.2551,022
53251.64.208.0/22251.64.208.1 to 251.64.211.254251.64.211.2551,022
54251.64.212.0/22251.64.212.1 to 251.64.215.254251.64.215.2551,022
55251.64.216.0/22251.64.216.1 to 251.64.219.254251.64.219.2551,022
56251.64.220.0/22251.64.220.1 to 251.64.223.254251.64.223.2551,022
57251.64.224.0/22251.64.224.1 to 251.64.227.254251.64.227.2551,022
58251.64.228.0/22251.64.228.1 to 251.64.231.254251.64.231.2551,022
59251.64.232.0/22251.64.232.1 to 251.64.235.254251.64.235.2551,022
60251.64.236.0/22251.64.236.1 to 251.64.239.254251.64.239.2551,022
61251.64.240.0/22251.64.240.1 to 251.64.243.254251.64.243.2551,022
62251.64.244.0/22251.64.244.1 to 251.64.247.254251.64.247.2551,022
63251.64.248.0/22251.64.248.1 to 251.64.251.254251.64.251.2551,022
64251.64.252.0/22251.64.252.1 to 251.64.255.254251.64.255.2551,022
65251.65.0.0/22251.65.0.1 to 251.65.3.254251.65.3.2551,022
66251.65.4.0/22251.65.4.1 to 251.65.7.254251.65.7.2551,022
67251.65.8.0/22251.65.8.1 to 251.65.11.254251.65.11.2551,022
68251.65.12.0/22251.65.12.1 to 251.65.15.254251.65.15.2551,022
69251.65.16.0/22251.65.16.1 to 251.65.19.254251.65.19.2551,022
70251.65.20.0/22251.65.20.1 to 251.65.23.254251.65.23.2551,022
71251.65.24.0/22251.65.24.1 to 251.65.27.254251.65.27.2551,022
72251.65.28.0/22251.65.28.1 to 251.65.31.254251.65.31.2551,022
73251.65.32.0/22251.65.32.1 to 251.65.35.254251.65.35.2551,022
74251.65.36.0/22251.65.36.1 to 251.65.39.254251.65.39.2551,022
75251.65.40.0/22251.65.40.1 to 251.65.43.254251.65.43.2551,022
76251.65.44.0/22251.65.44.1 to 251.65.47.254251.65.47.2551,022
77251.65.48.0/22251.65.48.1 to 251.65.51.254251.65.51.2551,022
78251.65.52.0/22251.65.52.1 to 251.65.55.254251.65.55.2551,022
79251.65.56.0/22251.65.56.1 to 251.65.59.254251.65.59.2551,022
80251.65.60.0/22251.65.60.1 to 251.65.63.254251.65.63.2551,022
81251.65.64.0/22251.65.64.1 to 251.65.67.254251.65.67.2551,022
82251.65.68.0/22251.65.68.1 to 251.65.71.254251.65.71.2551,022
83251.65.72.0/22251.65.72.1 to 251.65.75.254251.65.75.2551,022
84251.65.76.0/22251.65.76.1 to 251.65.79.254251.65.79.2551,022
85251.65.80.0/22251.65.80.1 to 251.65.83.254251.65.83.2551,022
86251.65.84.0/22251.65.84.1 to 251.65.87.254251.65.87.2551,022
87251.65.88.0/22251.65.88.1 to 251.65.91.254251.65.91.2551,022
88251.65.92.0/22251.65.92.1 to 251.65.95.254251.65.95.2551,022
89251.65.96.0/22251.65.96.1 to 251.65.99.254251.65.99.2551,022
90251.65.100.0/22251.65.100.1 to 251.65.103.254251.65.103.2551,022
91251.65.104.0/22251.65.104.1 to 251.65.107.254251.65.107.2551,022
92251.65.108.0/22251.65.108.1 to 251.65.111.254251.65.111.2551,022
93251.65.112.0/22251.65.112.1 to 251.65.115.254251.65.115.2551,022
94251.65.116.0/22251.65.116.1 to 251.65.119.254251.65.119.2551,022
95251.65.120.0/22251.65.120.1 to 251.65.123.254251.65.123.2551,022
96251.65.124.0/22251.65.124.1 to 251.65.127.254251.65.127.2551,022
97251.65.128.0/22251.65.128.1 to 251.65.131.254251.65.131.2551,022
98251.65.132.0/22251.65.132.1 to 251.65.135.254251.65.135.2551,022
99251.65.136.0/22251.65.136.1 to 251.65.139.254251.65.139.2551,022
100251.65.140.0/22251.65.140.1 to 251.65.143.254251.65.143.2551,022
101251.65.144.0/22251.65.144.1 to 251.65.147.254251.65.147.2551,022
102251.65.148.0/22251.65.148.1 to 251.65.151.254251.65.151.2551,022
103251.65.152.0/22251.65.152.1 to 251.65.155.254251.65.155.2551,022
104251.65.156.0/22251.65.156.1 to 251.65.159.254251.65.159.2551,022
105251.65.160.0/22251.65.160.1 to 251.65.163.254251.65.163.2551,022
106251.65.164.0/22251.65.164.1 to 251.65.167.254251.65.167.2551,022
107251.65.168.0/22251.65.168.1 to 251.65.171.254251.65.171.2551,022
108251.65.172.0/22251.65.172.1 to 251.65.175.254251.65.175.2551,022
109251.65.176.0/22251.65.176.1 to 251.65.179.254251.65.179.2551,022
110251.65.180.0/22251.65.180.1 to 251.65.183.254251.65.183.2551,022
111251.65.184.0/22251.65.184.1 to 251.65.187.254251.65.187.2551,022
112251.65.188.0/22251.65.188.1 to 251.65.191.254251.65.191.2551,022
113251.65.192.0/22251.65.192.1 to 251.65.195.254251.65.195.2551,022
114251.65.196.0/22251.65.196.1 to 251.65.199.254251.65.199.2551,022
115251.65.200.0/22251.65.200.1 to 251.65.203.254251.65.203.2551,022
116251.65.204.0/22251.65.204.1 to 251.65.207.254251.65.207.2551,022
117251.65.208.0/22251.65.208.1 to 251.65.211.254251.65.211.2551,022
118251.65.212.0/22251.65.212.1 to 251.65.215.254251.65.215.2551,022
119251.65.216.0/22251.65.216.1 to 251.65.219.254251.65.219.2551,022
120251.65.220.0/22251.65.220.1 to 251.65.223.254251.65.223.2551,022
121251.65.224.0/22251.65.224.1 to 251.65.227.254251.65.227.2551,022
122251.65.228.0/22251.65.228.1 to 251.65.231.254251.65.231.2551,022
123251.65.232.0/22251.65.232.1 to 251.65.235.254251.65.235.2551,022
124251.65.236.0/22251.65.236.1 to 251.65.239.254251.65.239.2551,022
125251.65.240.0/22251.65.240.1 to 251.65.243.254251.65.243.2551,022
126251.65.244.0/22251.65.244.1 to 251.65.247.254251.65.247.2551,022
127251.65.248.0/22251.65.248.1 to 251.65.251.254251.65.251.2551,022
128251.65.252.0/22251.65.252.1 to 251.65.255.254251.65.255.2551,022
129251.66.0.0/22251.66.0.1 to 251.66.3.254251.66.3.2551,022
130251.66.4.0/22251.66.4.1 to 251.66.7.254251.66.7.2551,022
131251.66.8.0/22251.66.8.1 to 251.66.11.254251.66.11.2551,022
132251.66.12.0/22251.66.12.1 to 251.66.15.254251.66.15.2551,022
133251.66.16.0/22251.66.16.1 to 251.66.19.254251.66.19.2551,022
134251.66.20.0/22251.66.20.1 to 251.66.23.254251.66.23.2551,022
135251.66.24.0/22251.66.24.1 to 251.66.27.254251.66.27.2551,022
136251.66.28.0/22251.66.28.1 to 251.66.31.254251.66.31.2551,022
137251.66.32.0/22251.66.32.1 to 251.66.35.254251.66.35.2551,022
138251.66.36.0/22251.66.36.1 to 251.66.39.254251.66.39.2551,022
139251.66.40.0/22251.66.40.1 to 251.66.43.254251.66.43.2551,022
140251.66.44.0/22251.66.44.1 to 251.66.47.254251.66.47.2551,022
141251.66.48.0/22251.66.48.1 to 251.66.51.254251.66.51.2551,022
142251.66.52.0/22251.66.52.1 to 251.66.55.254251.66.55.2551,022
143251.66.56.0/22251.66.56.1 to 251.66.59.254251.66.59.2551,022
144251.66.60.0/22251.66.60.1 to 251.66.63.254251.66.63.2551,022
145251.66.64.0/22251.66.64.1 to 251.66.67.254251.66.67.2551,022
146251.66.68.0/22251.66.68.1 to 251.66.71.254251.66.71.2551,022
147251.66.72.0/22251.66.72.1 to 251.66.75.254251.66.75.2551,022
148251.66.76.0/22251.66.76.1 to 251.66.79.254251.66.79.2551,022
149251.66.80.0/22251.66.80.1 to 251.66.83.254251.66.83.2551,022
150251.66.84.0/22251.66.84.1 to 251.66.87.254251.66.87.2551,022
151251.66.88.0/22251.66.88.1 to 251.66.91.254251.66.91.2551,022
152251.66.92.0/22251.66.92.1 to 251.66.95.254251.66.95.2551,022
153251.66.96.0/22251.66.96.1 to 251.66.99.254251.66.99.2551,022
154251.66.100.0/22251.66.100.1 to 251.66.103.254251.66.103.2551,022
155251.66.104.0/22251.66.104.1 to 251.66.107.254251.66.107.2551,022
156251.66.108.0/22251.66.108.1 to 251.66.111.254251.66.111.2551,022
157251.66.112.0/22251.66.112.1 to 251.66.115.254251.66.115.2551,022
158251.66.116.0/22251.66.116.1 to 251.66.119.254251.66.119.2551,022
159251.66.120.0/22251.66.120.1 to 251.66.123.254251.66.123.2551,022
160251.66.124.0/22251.66.124.1 to 251.66.127.254251.66.127.2551,022
161251.66.128.0/22251.66.128.1 to 251.66.131.254251.66.131.2551,022
162251.66.132.0/22251.66.132.1 to 251.66.135.254251.66.135.2551,022
163251.66.136.0/22251.66.136.1 to 251.66.139.254251.66.139.2551,022
164251.66.140.0/22251.66.140.1 to 251.66.143.254251.66.143.2551,022
165251.66.144.0/22251.66.144.1 to 251.66.147.254251.66.147.2551,022
166251.66.148.0/22251.66.148.1 to 251.66.151.254251.66.151.2551,022
167251.66.152.0/22251.66.152.1 to 251.66.155.254251.66.155.2551,022
168251.66.156.0/22251.66.156.1 to 251.66.159.254251.66.159.2551,022
169251.66.160.0/22251.66.160.1 to 251.66.163.254251.66.163.2551,022
170251.66.164.0/22251.66.164.1 to 251.66.167.254251.66.167.2551,022
171251.66.168.0/22251.66.168.1 to 251.66.171.254251.66.171.2551,022
172251.66.172.0/22251.66.172.1 to 251.66.175.254251.66.175.2551,022
173251.66.176.0/22251.66.176.1 to 251.66.179.254251.66.179.2551,022
174251.66.180.0/22251.66.180.1 to 251.66.183.254251.66.183.2551,022
175251.66.184.0/22251.66.184.1 to 251.66.187.254251.66.187.2551,022
176251.66.188.0/22251.66.188.1 to 251.66.191.254251.66.191.2551,022
177251.66.192.0/22251.66.192.1 to 251.66.195.254251.66.195.2551,022
178251.66.196.0/22251.66.196.1 to 251.66.199.254251.66.199.2551,022
179251.66.200.0/22251.66.200.1 to 251.66.203.254251.66.203.2551,022
180251.66.204.0/22251.66.204.1 to 251.66.207.254251.66.207.2551,022
181251.66.208.0/22251.66.208.1 to 251.66.211.254251.66.211.2551,022
182251.66.212.0/22251.66.212.1 to 251.66.215.254251.66.215.2551,022
183251.66.216.0/22251.66.216.1 to 251.66.219.254251.66.219.2551,022
184251.66.220.0/22251.66.220.1 to 251.66.223.254251.66.223.2551,022
185251.66.224.0/22251.66.224.1 to 251.66.227.254251.66.227.2551,022
186251.66.228.0/22251.66.228.1 to 251.66.231.254251.66.231.2551,022
187251.66.232.0/22251.66.232.1 to 251.66.235.254251.66.235.2551,022
188251.66.236.0/22251.66.236.1 to 251.66.239.254251.66.239.2551,022
189251.66.240.0/22251.66.240.1 to 251.66.243.254251.66.243.2551,022
190251.66.244.0/22251.66.244.1 to 251.66.247.254251.66.247.2551,022
191251.66.248.0/22251.66.248.1 to 251.66.251.254251.66.251.2551,022
192251.66.252.0/22251.66.252.1 to 251.66.255.254251.66.255.2551,022
193251.67.0.0/22251.67.0.1 to 251.67.3.254251.67.3.2551,022
194251.67.4.0/22251.67.4.1 to 251.67.7.254251.67.7.2551,022
195251.67.8.0/22251.67.8.1 to 251.67.11.254251.67.11.2551,022
196251.67.12.0/22251.67.12.1 to 251.67.15.254251.67.15.2551,022
197251.67.16.0/22251.67.16.1 to 251.67.19.254251.67.19.2551,022
198251.67.20.0/22251.67.20.1 to 251.67.23.254251.67.23.2551,022
199251.67.24.0/22251.67.24.1 to 251.67.27.254251.67.27.2551,022
200251.67.28.0/22251.67.28.1 to 251.67.31.254251.67.31.2551,022
201251.67.32.0/22251.67.32.1 to 251.67.35.254251.67.35.2551,022
202251.67.36.0/22251.67.36.1 to 251.67.39.254251.67.39.2551,022
203251.67.40.0/22251.67.40.1 to 251.67.43.254251.67.43.2551,022
204251.67.44.0/22251.67.44.1 to 251.67.47.254251.67.47.2551,022
205251.67.48.0/22251.67.48.1 to 251.67.51.254251.67.51.2551,022
206251.67.52.0/22251.67.52.1 to 251.67.55.254251.67.55.2551,022
207251.67.56.0/22251.67.56.1 to 251.67.59.254251.67.59.2551,022
208251.67.60.0/22251.67.60.1 to 251.67.63.254251.67.63.2551,022
209251.67.64.0/22251.67.64.1 to 251.67.67.254251.67.67.2551,022
210251.67.68.0/22251.67.68.1 to 251.67.71.254251.67.71.2551,022
211251.67.72.0/22251.67.72.1 to 251.67.75.254251.67.75.2551,022
212251.67.76.0/22251.67.76.1 to 251.67.79.254251.67.79.2551,022
213251.67.80.0/22251.67.80.1 to 251.67.83.254251.67.83.2551,022
214251.67.84.0/22251.67.84.1 to 251.67.87.254251.67.87.2551,022
215251.67.88.0/22251.67.88.1 to 251.67.91.254251.67.91.2551,022
216251.67.92.0/22251.67.92.1 to 251.67.95.254251.67.95.2551,022
217251.67.96.0/22251.67.96.1 to 251.67.99.254251.67.99.2551,022
218251.67.100.0/22251.67.100.1 to 251.67.103.254251.67.103.2551,022
219251.67.104.0/22251.67.104.1 to 251.67.107.254251.67.107.2551,022
220251.67.108.0/22251.67.108.1 to 251.67.111.254251.67.111.2551,022
221251.67.112.0/22251.67.112.1 to 251.67.115.254251.67.115.2551,022
222251.67.116.0/22251.67.116.1 to 251.67.119.254251.67.119.2551,022
223251.67.120.0/22251.67.120.1 to 251.67.123.254251.67.123.2551,022
224251.67.124.0/22251.67.124.1 to 251.67.127.254251.67.127.2551,022
225251.67.128.0/22251.67.128.1 to 251.67.131.254251.67.131.2551,022
226251.67.132.0/22251.67.132.1 to 251.67.135.254251.67.135.2551,022
227251.67.136.0/22251.67.136.1 to 251.67.139.254251.67.139.2551,022
228251.67.140.0/22251.67.140.1 to 251.67.143.254251.67.143.2551,022
229251.67.144.0/22251.67.144.1 to 251.67.147.254251.67.147.2551,022
230251.67.148.0/22251.67.148.1 to 251.67.151.254251.67.151.2551,022
231251.67.152.0/22251.67.152.1 to 251.67.155.254251.67.155.2551,022
232251.67.156.0/22251.67.156.1 to 251.67.159.254251.67.159.2551,022
233251.67.160.0/22251.67.160.1 to 251.67.163.254251.67.163.2551,022
234251.67.164.0/22251.67.164.1 to 251.67.167.254251.67.167.2551,022
235251.67.168.0/22251.67.168.1 to 251.67.171.254251.67.171.2551,022
236251.67.172.0/22251.67.172.1 to 251.67.175.254251.67.175.2551,022
237251.67.176.0/22251.67.176.1 to 251.67.179.254251.67.179.2551,022
238251.67.180.0/22251.67.180.1 to 251.67.183.254251.67.183.2551,022
239251.67.184.0/22251.67.184.1 to 251.67.187.254251.67.187.2551,022
240251.67.188.0/22251.67.188.1 to 251.67.191.254251.67.191.2551,022
241251.67.192.0/22251.67.192.1 to 251.67.195.254251.67.195.2551,022
242251.67.196.0/22251.67.196.1 to 251.67.199.254251.67.199.2551,022
243251.67.200.0/22251.67.200.1 to 251.67.203.254251.67.203.2551,022
244251.67.204.0/22251.67.204.1 to 251.67.207.254251.67.207.2551,022
245251.67.208.0/22251.67.208.1 to 251.67.211.254251.67.211.2551,022
246251.67.212.0/22251.67.212.1 to 251.67.215.254251.67.215.2551,022
247251.67.216.0/22251.67.216.1 to 251.67.219.254251.67.219.2551,022
248251.67.220.0/22251.67.220.1 to 251.67.223.254251.67.223.2551,022
249251.67.224.0/22251.67.224.1 to 251.67.227.254251.67.227.2551,022
250251.67.228.0/22251.67.228.1 to 251.67.231.254251.67.231.2551,022
251251.67.232.0/22251.67.232.1 to 251.67.235.254251.67.235.2551,022
252251.67.236.0/22251.67.236.1 to 251.67.239.254251.67.239.2551,022
253251.67.240.0/22251.67.240.1 to 251.67.243.254251.67.243.2551,022
254251.67.244.0/22251.67.244.1 to 251.67.247.254251.67.247.2551,022
255251.67.248.0/22251.67.248.1 to 251.67.251.254251.67.251.2551,022
256251.67.252.0/22251.67.252.1 to 251.67.255.254251.67.255.2551,022

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.