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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.

Network101.32.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
101.32.0.0
Broadcast address
101.47.255.255
First usable
101.32.0.1
Last usable
101.47.255.254
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
Public public
Old class
A (default /8)
As numbers
Hex 65200000 · Integer 1696595968 to 1697644543
Reverse DNS zones
32.101.in-addr.arpa
33.101.in-addr.arpa
34.101.in-addr.arpa
35.101.in-addr.arpa
36.101.in-addr.arpa
37.101.in-addr.arpa
38.101.in-addr.arpa
39.101.in-addr.arpa
40.101.in-addr.arpa
41.101.in-addr.arpa
42.101.in-addr.arpa
43.101.in-addr.arpa
44.101.in-addr.arpa
45.101.in-addr.arpa
46.101.in-addr.arpa
47.101.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
Address01100101.00100000.00000000.00000000101.32.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network01100101.00100000.00000000.00000000101.32.0.0
Broadcast01100101.00101111.11111111.11111111101.47.255.255
Split into smaller subnets/21
/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)

101.32.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1101.32.0.0/21101.32.0.1 to 101.32.7.254101.32.7.2552,046
2101.32.8.0/21101.32.8.1 to 101.32.15.254101.32.15.2552,046
3101.32.16.0/21101.32.16.1 to 101.32.23.254101.32.23.2552,046
4101.32.24.0/21101.32.24.1 to 101.32.31.254101.32.31.2552,046
5101.32.32.0/21101.32.32.1 to 101.32.39.254101.32.39.2552,046
6101.32.40.0/21101.32.40.1 to 101.32.47.254101.32.47.2552,046
7101.32.48.0/21101.32.48.1 to 101.32.55.254101.32.55.2552,046
8101.32.56.0/21101.32.56.1 to 101.32.63.254101.32.63.2552,046
9101.32.64.0/21101.32.64.1 to 101.32.71.254101.32.71.2552,046
10101.32.72.0/21101.32.72.1 to 101.32.79.254101.32.79.2552,046
11101.32.80.0/21101.32.80.1 to 101.32.87.254101.32.87.2552,046
12101.32.88.0/21101.32.88.1 to 101.32.95.254101.32.95.2552,046
13101.32.96.0/21101.32.96.1 to 101.32.103.254101.32.103.2552,046
14101.32.104.0/21101.32.104.1 to 101.32.111.254101.32.111.2552,046
15101.32.112.0/21101.32.112.1 to 101.32.119.254101.32.119.2552,046
16101.32.120.0/21101.32.120.1 to 101.32.127.254101.32.127.2552,046
17101.32.128.0/21101.32.128.1 to 101.32.135.254101.32.135.2552,046
18101.32.136.0/21101.32.136.1 to 101.32.143.254101.32.143.2552,046
19101.32.144.0/21101.32.144.1 to 101.32.151.254101.32.151.2552,046
20101.32.152.0/21101.32.152.1 to 101.32.159.254101.32.159.2552,046
21101.32.160.0/21101.32.160.1 to 101.32.167.254101.32.167.2552,046
22101.32.168.0/21101.32.168.1 to 101.32.175.254101.32.175.2552,046
23101.32.176.0/21101.32.176.1 to 101.32.183.254101.32.183.2552,046
24101.32.184.0/21101.32.184.1 to 101.32.191.254101.32.191.2552,046
25101.32.192.0/21101.32.192.1 to 101.32.199.254101.32.199.2552,046
26101.32.200.0/21101.32.200.1 to 101.32.207.254101.32.207.2552,046
27101.32.208.0/21101.32.208.1 to 101.32.215.254101.32.215.2552,046
28101.32.216.0/21101.32.216.1 to 101.32.223.254101.32.223.2552,046
29101.32.224.0/21101.32.224.1 to 101.32.231.254101.32.231.2552,046
30101.32.232.0/21101.32.232.1 to 101.32.239.254101.32.239.2552,046
31101.32.240.0/21101.32.240.1 to 101.32.247.254101.32.247.2552,046
32101.32.248.0/21101.32.248.1 to 101.32.255.254101.32.255.2552,046
33101.33.0.0/21101.33.0.1 to 101.33.7.254101.33.7.2552,046
34101.33.8.0/21101.33.8.1 to 101.33.15.254101.33.15.2552,046
35101.33.16.0/21101.33.16.1 to 101.33.23.254101.33.23.2552,046
36101.33.24.0/21101.33.24.1 to 101.33.31.254101.33.31.2552,046
37101.33.32.0/21101.33.32.1 to 101.33.39.254101.33.39.2552,046
38101.33.40.0/21101.33.40.1 to 101.33.47.254101.33.47.2552,046
39101.33.48.0/21101.33.48.1 to 101.33.55.254101.33.55.2552,046
40101.33.56.0/21101.33.56.1 to 101.33.63.254101.33.63.2552,046
41101.33.64.0/21101.33.64.1 to 101.33.71.254101.33.71.2552,046
42101.33.72.0/21101.33.72.1 to 101.33.79.254101.33.79.2552,046
43101.33.80.0/21101.33.80.1 to 101.33.87.254101.33.87.2552,046
44101.33.88.0/21101.33.88.1 to 101.33.95.254101.33.95.2552,046
45101.33.96.0/21101.33.96.1 to 101.33.103.254101.33.103.2552,046
46101.33.104.0/21101.33.104.1 to 101.33.111.254101.33.111.2552,046
47101.33.112.0/21101.33.112.1 to 101.33.119.254101.33.119.2552,046
48101.33.120.0/21101.33.120.1 to 101.33.127.254101.33.127.2552,046
49101.33.128.0/21101.33.128.1 to 101.33.135.254101.33.135.2552,046
50101.33.136.0/21101.33.136.1 to 101.33.143.254101.33.143.2552,046
51101.33.144.0/21101.33.144.1 to 101.33.151.254101.33.151.2552,046
52101.33.152.0/21101.33.152.1 to 101.33.159.254101.33.159.2552,046
53101.33.160.0/21101.33.160.1 to 101.33.167.254101.33.167.2552,046
54101.33.168.0/21101.33.168.1 to 101.33.175.254101.33.175.2552,046
55101.33.176.0/21101.33.176.1 to 101.33.183.254101.33.183.2552,046
56101.33.184.0/21101.33.184.1 to 101.33.191.254101.33.191.2552,046
57101.33.192.0/21101.33.192.1 to 101.33.199.254101.33.199.2552,046
58101.33.200.0/21101.33.200.1 to 101.33.207.254101.33.207.2552,046
59101.33.208.0/21101.33.208.1 to 101.33.215.254101.33.215.2552,046
60101.33.216.0/21101.33.216.1 to 101.33.223.254101.33.223.2552,046
61101.33.224.0/21101.33.224.1 to 101.33.231.254101.33.231.2552,046
62101.33.232.0/21101.33.232.1 to 101.33.239.254101.33.239.2552,046
63101.33.240.0/21101.33.240.1 to 101.33.247.254101.33.247.2552,046
64101.33.248.0/21101.33.248.1 to 101.33.255.254101.33.255.2552,046
65101.34.0.0/21101.34.0.1 to 101.34.7.254101.34.7.2552,046
66101.34.8.0/21101.34.8.1 to 101.34.15.254101.34.15.2552,046
67101.34.16.0/21101.34.16.1 to 101.34.23.254101.34.23.2552,046
68101.34.24.0/21101.34.24.1 to 101.34.31.254101.34.31.2552,046
69101.34.32.0/21101.34.32.1 to 101.34.39.254101.34.39.2552,046
70101.34.40.0/21101.34.40.1 to 101.34.47.254101.34.47.2552,046
71101.34.48.0/21101.34.48.1 to 101.34.55.254101.34.55.2552,046
72101.34.56.0/21101.34.56.1 to 101.34.63.254101.34.63.2552,046
73101.34.64.0/21101.34.64.1 to 101.34.71.254101.34.71.2552,046
74101.34.72.0/21101.34.72.1 to 101.34.79.254101.34.79.2552,046
75101.34.80.0/21101.34.80.1 to 101.34.87.254101.34.87.2552,046
76101.34.88.0/21101.34.88.1 to 101.34.95.254101.34.95.2552,046
77101.34.96.0/21101.34.96.1 to 101.34.103.254101.34.103.2552,046
78101.34.104.0/21101.34.104.1 to 101.34.111.254101.34.111.2552,046
79101.34.112.0/21101.34.112.1 to 101.34.119.254101.34.119.2552,046
80101.34.120.0/21101.34.120.1 to 101.34.127.254101.34.127.2552,046
81101.34.128.0/21101.34.128.1 to 101.34.135.254101.34.135.2552,046
82101.34.136.0/21101.34.136.1 to 101.34.143.254101.34.143.2552,046
83101.34.144.0/21101.34.144.1 to 101.34.151.254101.34.151.2552,046
84101.34.152.0/21101.34.152.1 to 101.34.159.254101.34.159.2552,046
85101.34.160.0/21101.34.160.1 to 101.34.167.254101.34.167.2552,046
86101.34.168.0/21101.34.168.1 to 101.34.175.254101.34.175.2552,046
87101.34.176.0/21101.34.176.1 to 101.34.183.254101.34.183.2552,046
88101.34.184.0/21101.34.184.1 to 101.34.191.254101.34.191.2552,046
89101.34.192.0/21101.34.192.1 to 101.34.199.254101.34.199.2552,046
90101.34.200.0/21101.34.200.1 to 101.34.207.254101.34.207.2552,046
91101.34.208.0/21101.34.208.1 to 101.34.215.254101.34.215.2552,046
92101.34.216.0/21101.34.216.1 to 101.34.223.254101.34.223.2552,046
93101.34.224.0/21101.34.224.1 to 101.34.231.254101.34.231.2552,046
94101.34.232.0/21101.34.232.1 to 101.34.239.254101.34.239.2552,046
95101.34.240.0/21101.34.240.1 to 101.34.247.254101.34.247.2552,046
96101.34.248.0/21101.34.248.1 to 101.34.255.254101.34.255.2552,046
97101.35.0.0/21101.35.0.1 to 101.35.7.254101.35.7.2552,046
98101.35.8.0/21101.35.8.1 to 101.35.15.254101.35.15.2552,046
99101.35.16.0/21101.35.16.1 to 101.35.23.254101.35.23.2552,046
100101.35.24.0/21101.35.24.1 to 101.35.31.254101.35.31.2552,046
101101.35.32.0/21101.35.32.1 to 101.35.39.254101.35.39.2552,046
102101.35.40.0/21101.35.40.1 to 101.35.47.254101.35.47.2552,046
103101.35.48.0/21101.35.48.1 to 101.35.55.254101.35.55.2552,046
104101.35.56.0/21101.35.56.1 to 101.35.63.254101.35.63.2552,046
105101.35.64.0/21101.35.64.1 to 101.35.71.254101.35.71.2552,046
106101.35.72.0/21101.35.72.1 to 101.35.79.254101.35.79.2552,046
107101.35.80.0/21101.35.80.1 to 101.35.87.254101.35.87.2552,046
108101.35.88.0/21101.35.88.1 to 101.35.95.254101.35.95.2552,046
109101.35.96.0/21101.35.96.1 to 101.35.103.254101.35.103.2552,046
110101.35.104.0/21101.35.104.1 to 101.35.111.254101.35.111.2552,046
111101.35.112.0/21101.35.112.1 to 101.35.119.254101.35.119.2552,046
112101.35.120.0/21101.35.120.1 to 101.35.127.254101.35.127.2552,046
113101.35.128.0/21101.35.128.1 to 101.35.135.254101.35.135.2552,046
114101.35.136.0/21101.35.136.1 to 101.35.143.254101.35.143.2552,046
115101.35.144.0/21101.35.144.1 to 101.35.151.254101.35.151.2552,046
116101.35.152.0/21101.35.152.1 to 101.35.159.254101.35.159.2552,046
117101.35.160.0/21101.35.160.1 to 101.35.167.254101.35.167.2552,046
118101.35.168.0/21101.35.168.1 to 101.35.175.254101.35.175.2552,046
119101.35.176.0/21101.35.176.1 to 101.35.183.254101.35.183.2552,046
120101.35.184.0/21101.35.184.1 to 101.35.191.254101.35.191.2552,046
121101.35.192.0/21101.35.192.1 to 101.35.199.254101.35.199.2552,046
122101.35.200.0/21101.35.200.1 to 101.35.207.254101.35.207.2552,046
123101.35.208.0/21101.35.208.1 to 101.35.215.254101.35.215.2552,046
124101.35.216.0/21101.35.216.1 to 101.35.223.254101.35.223.2552,046
125101.35.224.0/21101.35.224.1 to 101.35.231.254101.35.231.2552,046
126101.35.232.0/21101.35.232.1 to 101.35.239.254101.35.239.2552,046
127101.35.240.0/21101.35.240.1 to 101.35.247.254101.35.247.2552,046
128101.35.248.0/21101.35.248.1 to 101.35.255.254101.35.255.2552,046
129101.36.0.0/21101.36.0.1 to 101.36.7.254101.36.7.2552,046
130101.36.8.0/21101.36.8.1 to 101.36.15.254101.36.15.2552,046
131101.36.16.0/21101.36.16.1 to 101.36.23.254101.36.23.2552,046
132101.36.24.0/21101.36.24.1 to 101.36.31.254101.36.31.2552,046
133101.36.32.0/21101.36.32.1 to 101.36.39.254101.36.39.2552,046
134101.36.40.0/21101.36.40.1 to 101.36.47.254101.36.47.2552,046
135101.36.48.0/21101.36.48.1 to 101.36.55.254101.36.55.2552,046
136101.36.56.0/21101.36.56.1 to 101.36.63.254101.36.63.2552,046
137101.36.64.0/21101.36.64.1 to 101.36.71.254101.36.71.2552,046
138101.36.72.0/21101.36.72.1 to 101.36.79.254101.36.79.2552,046
139101.36.80.0/21101.36.80.1 to 101.36.87.254101.36.87.2552,046
140101.36.88.0/21101.36.88.1 to 101.36.95.254101.36.95.2552,046
141101.36.96.0/21101.36.96.1 to 101.36.103.254101.36.103.2552,046
142101.36.104.0/21101.36.104.1 to 101.36.111.254101.36.111.2552,046
143101.36.112.0/21101.36.112.1 to 101.36.119.254101.36.119.2552,046
144101.36.120.0/21101.36.120.1 to 101.36.127.254101.36.127.2552,046
145101.36.128.0/21101.36.128.1 to 101.36.135.254101.36.135.2552,046
146101.36.136.0/21101.36.136.1 to 101.36.143.254101.36.143.2552,046
147101.36.144.0/21101.36.144.1 to 101.36.151.254101.36.151.2552,046
148101.36.152.0/21101.36.152.1 to 101.36.159.254101.36.159.2552,046
149101.36.160.0/21101.36.160.1 to 101.36.167.254101.36.167.2552,046
150101.36.168.0/21101.36.168.1 to 101.36.175.254101.36.175.2552,046
151101.36.176.0/21101.36.176.1 to 101.36.183.254101.36.183.2552,046
152101.36.184.0/21101.36.184.1 to 101.36.191.254101.36.191.2552,046
153101.36.192.0/21101.36.192.1 to 101.36.199.254101.36.199.2552,046
154101.36.200.0/21101.36.200.1 to 101.36.207.254101.36.207.2552,046
155101.36.208.0/21101.36.208.1 to 101.36.215.254101.36.215.2552,046
156101.36.216.0/21101.36.216.1 to 101.36.223.254101.36.223.2552,046
157101.36.224.0/21101.36.224.1 to 101.36.231.254101.36.231.2552,046
158101.36.232.0/21101.36.232.1 to 101.36.239.254101.36.239.2552,046
159101.36.240.0/21101.36.240.1 to 101.36.247.254101.36.247.2552,046
160101.36.248.0/21101.36.248.1 to 101.36.255.254101.36.255.2552,046
161101.37.0.0/21101.37.0.1 to 101.37.7.254101.37.7.2552,046
162101.37.8.0/21101.37.8.1 to 101.37.15.254101.37.15.2552,046
163101.37.16.0/21101.37.16.1 to 101.37.23.254101.37.23.2552,046
164101.37.24.0/21101.37.24.1 to 101.37.31.254101.37.31.2552,046
165101.37.32.0/21101.37.32.1 to 101.37.39.254101.37.39.2552,046
166101.37.40.0/21101.37.40.1 to 101.37.47.254101.37.47.2552,046
167101.37.48.0/21101.37.48.1 to 101.37.55.254101.37.55.2552,046
168101.37.56.0/21101.37.56.1 to 101.37.63.254101.37.63.2552,046
169101.37.64.0/21101.37.64.1 to 101.37.71.254101.37.71.2552,046
170101.37.72.0/21101.37.72.1 to 101.37.79.254101.37.79.2552,046
171101.37.80.0/21101.37.80.1 to 101.37.87.254101.37.87.2552,046
172101.37.88.0/21101.37.88.1 to 101.37.95.254101.37.95.2552,046
173101.37.96.0/21101.37.96.1 to 101.37.103.254101.37.103.2552,046
174101.37.104.0/21101.37.104.1 to 101.37.111.254101.37.111.2552,046
175101.37.112.0/21101.37.112.1 to 101.37.119.254101.37.119.2552,046
176101.37.120.0/21101.37.120.1 to 101.37.127.254101.37.127.2552,046
177101.37.128.0/21101.37.128.1 to 101.37.135.254101.37.135.2552,046
178101.37.136.0/21101.37.136.1 to 101.37.143.254101.37.143.2552,046
179101.37.144.0/21101.37.144.1 to 101.37.151.254101.37.151.2552,046
180101.37.152.0/21101.37.152.1 to 101.37.159.254101.37.159.2552,046
181101.37.160.0/21101.37.160.1 to 101.37.167.254101.37.167.2552,046
182101.37.168.0/21101.37.168.1 to 101.37.175.254101.37.175.2552,046
183101.37.176.0/21101.37.176.1 to 101.37.183.254101.37.183.2552,046
184101.37.184.0/21101.37.184.1 to 101.37.191.254101.37.191.2552,046
185101.37.192.0/21101.37.192.1 to 101.37.199.254101.37.199.2552,046
186101.37.200.0/21101.37.200.1 to 101.37.207.254101.37.207.2552,046
187101.37.208.0/21101.37.208.1 to 101.37.215.254101.37.215.2552,046
188101.37.216.0/21101.37.216.1 to 101.37.223.254101.37.223.2552,046
189101.37.224.0/21101.37.224.1 to 101.37.231.254101.37.231.2552,046
190101.37.232.0/21101.37.232.1 to 101.37.239.254101.37.239.2552,046
191101.37.240.0/21101.37.240.1 to 101.37.247.254101.37.247.2552,046
192101.37.248.0/21101.37.248.1 to 101.37.255.254101.37.255.2552,046
193101.38.0.0/21101.38.0.1 to 101.38.7.254101.38.7.2552,046
194101.38.8.0/21101.38.8.1 to 101.38.15.254101.38.15.2552,046
195101.38.16.0/21101.38.16.1 to 101.38.23.254101.38.23.2552,046
196101.38.24.0/21101.38.24.1 to 101.38.31.254101.38.31.2552,046
197101.38.32.0/21101.38.32.1 to 101.38.39.254101.38.39.2552,046
198101.38.40.0/21101.38.40.1 to 101.38.47.254101.38.47.2552,046
199101.38.48.0/21101.38.48.1 to 101.38.55.254101.38.55.2552,046
200101.38.56.0/21101.38.56.1 to 101.38.63.254101.38.63.2552,046
201101.38.64.0/21101.38.64.1 to 101.38.71.254101.38.71.2552,046
202101.38.72.0/21101.38.72.1 to 101.38.79.254101.38.79.2552,046
203101.38.80.0/21101.38.80.1 to 101.38.87.254101.38.87.2552,046
204101.38.88.0/21101.38.88.1 to 101.38.95.254101.38.95.2552,046
205101.38.96.0/21101.38.96.1 to 101.38.103.254101.38.103.2552,046
206101.38.104.0/21101.38.104.1 to 101.38.111.254101.38.111.2552,046
207101.38.112.0/21101.38.112.1 to 101.38.119.254101.38.119.2552,046
208101.38.120.0/21101.38.120.1 to 101.38.127.254101.38.127.2552,046
209101.38.128.0/21101.38.128.1 to 101.38.135.254101.38.135.2552,046
210101.38.136.0/21101.38.136.1 to 101.38.143.254101.38.143.2552,046
211101.38.144.0/21101.38.144.1 to 101.38.151.254101.38.151.2552,046
212101.38.152.0/21101.38.152.1 to 101.38.159.254101.38.159.2552,046
213101.38.160.0/21101.38.160.1 to 101.38.167.254101.38.167.2552,046
214101.38.168.0/21101.38.168.1 to 101.38.175.254101.38.175.2552,046
215101.38.176.0/21101.38.176.1 to 101.38.183.254101.38.183.2552,046
216101.38.184.0/21101.38.184.1 to 101.38.191.254101.38.191.2552,046
217101.38.192.0/21101.38.192.1 to 101.38.199.254101.38.199.2552,046
218101.38.200.0/21101.38.200.1 to 101.38.207.254101.38.207.2552,046
219101.38.208.0/21101.38.208.1 to 101.38.215.254101.38.215.2552,046
220101.38.216.0/21101.38.216.1 to 101.38.223.254101.38.223.2552,046
221101.38.224.0/21101.38.224.1 to 101.38.231.254101.38.231.2552,046
222101.38.232.0/21101.38.232.1 to 101.38.239.254101.38.239.2552,046
223101.38.240.0/21101.38.240.1 to 101.38.247.254101.38.247.2552,046
224101.38.248.0/21101.38.248.1 to 101.38.255.254101.38.255.2552,046
225101.39.0.0/21101.39.0.1 to 101.39.7.254101.39.7.2552,046
226101.39.8.0/21101.39.8.1 to 101.39.15.254101.39.15.2552,046
227101.39.16.0/21101.39.16.1 to 101.39.23.254101.39.23.2552,046
228101.39.24.0/21101.39.24.1 to 101.39.31.254101.39.31.2552,046
229101.39.32.0/21101.39.32.1 to 101.39.39.254101.39.39.2552,046
230101.39.40.0/21101.39.40.1 to 101.39.47.254101.39.47.2552,046
231101.39.48.0/21101.39.48.1 to 101.39.55.254101.39.55.2552,046
232101.39.56.0/21101.39.56.1 to 101.39.63.254101.39.63.2552,046
233101.39.64.0/21101.39.64.1 to 101.39.71.254101.39.71.2552,046
234101.39.72.0/21101.39.72.1 to 101.39.79.254101.39.79.2552,046
235101.39.80.0/21101.39.80.1 to 101.39.87.254101.39.87.2552,046
236101.39.88.0/21101.39.88.1 to 101.39.95.254101.39.95.2552,046
237101.39.96.0/21101.39.96.1 to 101.39.103.254101.39.103.2552,046
238101.39.104.0/21101.39.104.1 to 101.39.111.254101.39.111.2552,046
239101.39.112.0/21101.39.112.1 to 101.39.119.254101.39.119.2552,046
240101.39.120.0/21101.39.120.1 to 101.39.127.254101.39.127.2552,046
241101.39.128.0/21101.39.128.1 to 101.39.135.254101.39.135.2552,046
242101.39.136.0/21101.39.136.1 to 101.39.143.254101.39.143.2552,046
243101.39.144.0/21101.39.144.1 to 101.39.151.254101.39.151.2552,046
244101.39.152.0/21101.39.152.1 to 101.39.159.254101.39.159.2552,046
245101.39.160.0/21101.39.160.1 to 101.39.167.254101.39.167.2552,046
246101.39.168.0/21101.39.168.1 to 101.39.175.254101.39.175.2552,046
247101.39.176.0/21101.39.176.1 to 101.39.183.254101.39.183.2552,046
248101.39.184.0/21101.39.184.1 to 101.39.191.254101.39.191.2552,046
249101.39.192.0/21101.39.192.1 to 101.39.199.254101.39.199.2552,046
250101.39.200.0/21101.39.200.1 to 101.39.207.254101.39.207.2552,046
251101.39.208.0/21101.39.208.1 to 101.39.215.254101.39.215.2552,046
252101.39.216.0/21101.39.216.1 to 101.39.223.254101.39.223.2552,046
253101.39.224.0/21101.39.224.1 to 101.39.231.254101.39.231.2552,046
254101.39.232.0/21101.39.232.1 to 101.39.239.254101.39.239.2552,046
255101.39.240.0/21101.39.240.1 to 101.39.247.254101.39.247.2552,046
256101.39.248.0/21101.39.248.1 to 101.39.255.254101.39.255.2552,046

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.