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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.

Network221.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
221.0.0.0
Broadcast address
221.255.255.255
First usable
221.0.0.1
Last usable
221.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
C (default /24)
As numbers
Hex DD000000 · Integer 3707764736 to 3724541951
Reverse DNS zone
221.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011101..00000000.00000000.00000000221.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11011101..00000000.00000000.00000000221.0.0.0
Broadcast11011101..11111111.11111111.11111111221.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

221.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1221.0.0.0/19221.0.0.1 to 221.0.31.254221.0.31.2558,190
2221.0.32.0/19221.0.32.1 to 221.0.63.254221.0.63.2558,190
3221.0.64.0/19221.0.64.1 to 221.0.95.254221.0.95.2558,190
4221.0.96.0/19221.0.96.1 to 221.0.127.254221.0.127.2558,190
5221.0.128.0/19221.0.128.1 to 221.0.159.254221.0.159.2558,190
6221.0.160.0/19221.0.160.1 to 221.0.191.254221.0.191.2558,190
7221.0.192.0/19221.0.192.1 to 221.0.223.254221.0.223.2558,190
8221.0.224.0/19221.0.224.1 to 221.0.255.254221.0.255.2558,190
9221.1.0.0/19221.1.0.1 to 221.1.31.254221.1.31.2558,190
10221.1.32.0/19221.1.32.1 to 221.1.63.254221.1.63.2558,190
11221.1.64.0/19221.1.64.1 to 221.1.95.254221.1.95.2558,190
12221.1.96.0/19221.1.96.1 to 221.1.127.254221.1.127.2558,190
13221.1.128.0/19221.1.128.1 to 221.1.159.254221.1.159.2558,190
14221.1.160.0/19221.1.160.1 to 221.1.191.254221.1.191.2558,190
15221.1.192.0/19221.1.192.1 to 221.1.223.254221.1.223.2558,190
16221.1.224.0/19221.1.224.1 to 221.1.255.254221.1.255.2558,190
17221.2.0.0/19221.2.0.1 to 221.2.31.254221.2.31.2558,190
18221.2.32.0/19221.2.32.1 to 221.2.63.254221.2.63.2558,190
19221.2.64.0/19221.2.64.1 to 221.2.95.254221.2.95.2558,190
20221.2.96.0/19221.2.96.1 to 221.2.127.254221.2.127.2558,190
21221.2.128.0/19221.2.128.1 to 221.2.159.254221.2.159.2558,190
22221.2.160.0/19221.2.160.1 to 221.2.191.254221.2.191.2558,190
23221.2.192.0/19221.2.192.1 to 221.2.223.254221.2.223.2558,190
24221.2.224.0/19221.2.224.1 to 221.2.255.254221.2.255.2558,190
25221.3.0.0/19221.3.0.1 to 221.3.31.254221.3.31.2558,190
26221.3.32.0/19221.3.32.1 to 221.3.63.254221.3.63.2558,190
27221.3.64.0/19221.3.64.1 to 221.3.95.254221.3.95.2558,190
28221.3.96.0/19221.3.96.1 to 221.3.127.254221.3.127.2558,190
29221.3.128.0/19221.3.128.1 to 221.3.159.254221.3.159.2558,190
30221.3.160.0/19221.3.160.1 to 221.3.191.254221.3.191.2558,190
31221.3.192.0/19221.3.192.1 to 221.3.223.254221.3.223.2558,190
32221.3.224.0/19221.3.224.1 to 221.3.255.254221.3.255.2558,190
33221.4.0.0/19221.4.0.1 to 221.4.31.254221.4.31.2558,190
34221.4.32.0/19221.4.32.1 to 221.4.63.254221.4.63.2558,190
35221.4.64.0/19221.4.64.1 to 221.4.95.254221.4.95.2558,190
36221.4.96.0/19221.4.96.1 to 221.4.127.254221.4.127.2558,190
37221.4.128.0/19221.4.128.1 to 221.4.159.254221.4.159.2558,190
38221.4.160.0/19221.4.160.1 to 221.4.191.254221.4.191.2558,190
39221.4.192.0/19221.4.192.1 to 221.4.223.254221.4.223.2558,190
40221.4.224.0/19221.4.224.1 to 221.4.255.254221.4.255.2558,190
41221.5.0.0/19221.5.0.1 to 221.5.31.254221.5.31.2558,190
42221.5.32.0/19221.5.32.1 to 221.5.63.254221.5.63.2558,190
43221.5.64.0/19221.5.64.1 to 221.5.95.254221.5.95.2558,190
44221.5.96.0/19221.5.96.1 to 221.5.127.254221.5.127.2558,190
45221.5.128.0/19221.5.128.1 to 221.5.159.254221.5.159.2558,190
46221.5.160.0/19221.5.160.1 to 221.5.191.254221.5.191.2558,190
47221.5.192.0/19221.5.192.1 to 221.5.223.254221.5.223.2558,190
48221.5.224.0/19221.5.224.1 to 221.5.255.254221.5.255.2558,190
49221.6.0.0/19221.6.0.1 to 221.6.31.254221.6.31.2558,190
50221.6.32.0/19221.6.32.1 to 221.6.63.254221.6.63.2558,190
51221.6.64.0/19221.6.64.1 to 221.6.95.254221.6.95.2558,190
52221.6.96.0/19221.6.96.1 to 221.6.127.254221.6.127.2558,190
53221.6.128.0/19221.6.128.1 to 221.6.159.254221.6.159.2558,190
54221.6.160.0/19221.6.160.1 to 221.6.191.254221.6.191.2558,190
55221.6.192.0/19221.6.192.1 to 221.6.223.254221.6.223.2558,190
56221.6.224.0/19221.6.224.1 to 221.6.255.254221.6.255.2558,190
57221.7.0.0/19221.7.0.1 to 221.7.31.254221.7.31.2558,190
58221.7.32.0/19221.7.32.1 to 221.7.63.254221.7.63.2558,190
59221.7.64.0/19221.7.64.1 to 221.7.95.254221.7.95.2558,190
60221.7.96.0/19221.7.96.1 to 221.7.127.254221.7.127.2558,190
61221.7.128.0/19221.7.128.1 to 221.7.159.254221.7.159.2558,190
62221.7.160.0/19221.7.160.1 to 221.7.191.254221.7.191.2558,190
63221.7.192.0/19221.7.192.1 to 221.7.223.254221.7.223.2558,190
64221.7.224.0/19221.7.224.1 to 221.7.255.254221.7.255.2558,190
65221.8.0.0/19221.8.0.1 to 221.8.31.254221.8.31.2558,190
66221.8.32.0/19221.8.32.1 to 221.8.63.254221.8.63.2558,190
67221.8.64.0/19221.8.64.1 to 221.8.95.254221.8.95.2558,190
68221.8.96.0/19221.8.96.1 to 221.8.127.254221.8.127.2558,190
69221.8.128.0/19221.8.128.1 to 221.8.159.254221.8.159.2558,190
70221.8.160.0/19221.8.160.1 to 221.8.191.254221.8.191.2558,190
71221.8.192.0/19221.8.192.1 to 221.8.223.254221.8.223.2558,190
72221.8.224.0/19221.8.224.1 to 221.8.255.254221.8.255.2558,190
73221.9.0.0/19221.9.0.1 to 221.9.31.254221.9.31.2558,190
74221.9.32.0/19221.9.32.1 to 221.9.63.254221.9.63.2558,190
75221.9.64.0/19221.9.64.1 to 221.9.95.254221.9.95.2558,190
76221.9.96.0/19221.9.96.1 to 221.9.127.254221.9.127.2558,190
77221.9.128.0/19221.9.128.1 to 221.9.159.254221.9.159.2558,190
78221.9.160.0/19221.9.160.1 to 221.9.191.254221.9.191.2558,190
79221.9.192.0/19221.9.192.1 to 221.9.223.254221.9.223.2558,190
80221.9.224.0/19221.9.224.1 to 221.9.255.254221.9.255.2558,190
81221.10.0.0/19221.10.0.1 to 221.10.31.254221.10.31.2558,190
82221.10.32.0/19221.10.32.1 to 221.10.63.254221.10.63.2558,190
83221.10.64.0/19221.10.64.1 to 221.10.95.254221.10.95.2558,190
84221.10.96.0/19221.10.96.1 to 221.10.127.254221.10.127.2558,190
85221.10.128.0/19221.10.128.1 to 221.10.159.254221.10.159.2558,190
86221.10.160.0/19221.10.160.1 to 221.10.191.254221.10.191.2558,190
87221.10.192.0/19221.10.192.1 to 221.10.223.254221.10.223.2558,190
88221.10.224.0/19221.10.224.1 to 221.10.255.254221.10.255.2558,190
89221.11.0.0/19221.11.0.1 to 221.11.31.254221.11.31.2558,190
90221.11.32.0/19221.11.32.1 to 221.11.63.254221.11.63.2558,190
91221.11.64.0/19221.11.64.1 to 221.11.95.254221.11.95.2558,190
92221.11.96.0/19221.11.96.1 to 221.11.127.254221.11.127.2558,190
93221.11.128.0/19221.11.128.1 to 221.11.159.254221.11.159.2558,190
94221.11.160.0/19221.11.160.1 to 221.11.191.254221.11.191.2558,190
95221.11.192.0/19221.11.192.1 to 221.11.223.254221.11.223.2558,190
96221.11.224.0/19221.11.224.1 to 221.11.255.254221.11.255.2558,190
97221.12.0.0/19221.12.0.1 to 221.12.31.254221.12.31.2558,190
98221.12.32.0/19221.12.32.1 to 221.12.63.254221.12.63.2558,190
99221.12.64.0/19221.12.64.1 to 221.12.95.254221.12.95.2558,190
100221.12.96.0/19221.12.96.1 to 221.12.127.254221.12.127.2558,190
101221.12.128.0/19221.12.128.1 to 221.12.159.254221.12.159.2558,190
102221.12.160.0/19221.12.160.1 to 221.12.191.254221.12.191.2558,190
103221.12.192.0/19221.12.192.1 to 221.12.223.254221.12.223.2558,190
104221.12.224.0/19221.12.224.1 to 221.12.255.254221.12.255.2558,190
105221.13.0.0/19221.13.0.1 to 221.13.31.254221.13.31.2558,190
106221.13.32.0/19221.13.32.1 to 221.13.63.254221.13.63.2558,190
107221.13.64.0/19221.13.64.1 to 221.13.95.254221.13.95.2558,190
108221.13.96.0/19221.13.96.1 to 221.13.127.254221.13.127.2558,190
109221.13.128.0/19221.13.128.1 to 221.13.159.254221.13.159.2558,190
110221.13.160.0/19221.13.160.1 to 221.13.191.254221.13.191.2558,190
111221.13.192.0/19221.13.192.1 to 221.13.223.254221.13.223.2558,190
112221.13.224.0/19221.13.224.1 to 221.13.255.254221.13.255.2558,190
113221.14.0.0/19221.14.0.1 to 221.14.31.254221.14.31.2558,190
114221.14.32.0/19221.14.32.1 to 221.14.63.254221.14.63.2558,190
115221.14.64.0/19221.14.64.1 to 221.14.95.254221.14.95.2558,190
116221.14.96.0/19221.14.96.1 to 221.14.127.254221.14.127.2558,190
117221.14.128.0/19221.14.128.1 to 221.14.159.254221.14.159.2558,190
118221.14.160.0/19221.14.160.1 to 221.14.191.254221.14.191.2558,190
119221.14.192.0/19221.14.192.1 to 221.14.223.254221.14.223.2558,190
120221.14.224.0/19221.14.224.1 to 221.14.255.254221.14.255.2558,190
121221.15.0.0/19221.15.0.1 to 221.15.31.254221.15.31.2558,190
122221.15.32.0/19221.15.32.1 to 221.15.63.254221.15.63.2558,190
123221.15.64.0/19221.15.64.1 to 221.15.95.254221.15.95.2558,190
124221.15.96.0/19221.15.96.1 to 221.15.127.254221.15.127.2558,190
125221.15.128.0/19221.15.128.1 to 221.15.159.254221.15.159.2558,190
126221.15.160.0/19221.15.160.1 to 221.15.191.254221.15.191.2558,190
127221.15.192.0/19221.15.192.1 to 221.15.223.254221.15.223.2558,190
128221.15.224.0/19221.15.224.1 to 221.15.255.254221.15.255.2558,190
129221.16.0.0/19221.16.0.1 to 221.16.31.254221.16.31.2558,190
130221.16.32.0/19221.16.32.1 to 221.16.63.254221.16.63.2558,190
131221.16.64.0/19221.16.64.1 to 221.16.95.254221.16.95.2558,190
132221.16.96.0/19221.16.96.1 to 221.16.127.254221.16.127.2558,190
133221.16.128.0/19221.16.128.1 to 221.16.159.254221.16.159.2558,190
134221.16.160.0/19221.16.160.1 to 221.16.191.254221.16.191.2558,190
135221.16.192.0/19221.16.192.1 to 221.16.223.254221.16.223.2558,190
136221.16.224.0/19221.16.224.1 to 221.16.255.254221.16.255.2558,190
137221.17.0.0/19221.17.0.1 to 221.17.31.254221.17.31.2558,190
138221.17.32.0/19221.17.32.1 to 221.17.63.254221.17.63.2558,190
139221.17.64.0/19221.17.64.1 to 221.17.95.254221.17.95.2558,190
140221.17.96.0/19221.17.96.1 to 221.17.127.254221.17.127.2558,190
141221.17.128.0/19221.17.128.1 to 221.17.159.254221.17.159.2558,190
142221.17.160.0/19221.17.160.1 to 221.17.191.254221.17.191.2558,190
143221.17.192.0/19221.17.192.1 to 221.17.223.254221.17.223.2558,190
144221.17.224.0/19221.17.224.1 to 221.17.255.254221.17.255.2558,190
145221.18.0.0/19221.18.0.1 to 221.18.31.254221.18.31.2558,190
146221.18.32.0/19221.18.32.1 to 221.18.63.254221.18.63.2558,190
147221.18.64.0/19221.18.64.1 to 221.18.95.254221.18.95.2558,190
148221.18.96.0/19221.18.96.1 to 221.18.127.254221.18.127.2558,190
149221.18.128.0/19221.18.128.1 to 221.18.159.254221.18.159.2558,190
150221.18.160.0/19221.18.160.1 to 221.18.191.254221.18.191.2558,190
151221.18.192.0/19221.18.192.1 to 221.18.223.254221.18.223.2558,190
152221.18.224.0/19221.18.224.1 to 221.18.255.254221.18.255.2558,190
153221.19.0.0/19221.19.0.1 to 221.19.31.254221.19.31.2558,190
154221.19.32.0/19221.19.32.1 to 221.19.63.254221.19.63.2558,190
155221.19.64.0/19221.19.64.1 to 221.19.95.254221.19.95.2558,190
156221.19.96.0/19221.19.96.1 to 221.19.127.254221.19.127.2558,190
157221.19.128.0/19221.19.128.1 to 221.19.159.254221.19.159.2558,190
158221.19.160.0/19221.19.160.1 to 221.19.191.254221.19.191.2558,190
159221.19.192.0/19221.19.192.1 to 221.19.223.254221.19.223.2558,190
160221.19.224.0/19221.19.224.1 to 221.19.255.254221.19.255.2558,190
161221.20.0.0/19221.20.0.1 to 221.20.31.254221.20.31.2558,190
162221.20.32.0/19221.20.32.1 to 221.20.63.254221.20.63.2558,190
163221.20.64.0/19221.20.64.1 to 221.20.95.254221.20.95.2558,190
164221.20.96.0/19221.20.96.1 to 221.20.127.254221.20.127.2558,190
165221.20.128.0/19221.20.128.1 to 221.20.159.254221.20.159.2558,190
166221.20.160.0/19221.20.160.1 to 221.20.191.254221.20.191.2558,190
167221.20.192.0/19221.20.192.1 to 221.20.223.254221.20.223.2558,190
168221.20.224.0/19221.20.224.1 to 221.20.255.254221.20.255.2558,190
169221.21.0.0/19221.21.0.1 to 221.21.31.254221.21.31.2558,190
170221.21.32.0/19221.21.32.1 to 221.21.63.254221.21.63.2558,190
171221.21.64.0/19221.21.64.1 to 221.21.95.254221.21.95.2558,190
172221.21.96.0/19221.21.96.1 to 221.21.127.254221.21.127.2558,190
173221.21.128.0/19221.21.128.1 to 221.21.159.254221.21.159.2558,190
174221.21.160.0/19221.21.160.1 to 221.21.191.254221.21.191.2558,190
175221.21.192.0/19221.21.192.1 to 221.21.223.254221.21.223.2558,190
176221.21.224.0/19221.21.224.1 to 221.21.255.254221.21.255.2558,190
177221.22.0.0/19221.22.0.1 to 221.22.31.254221.22.31.2558,190
178221.22.32.0/19221.22.32.1 to 221.22.63.254221.22.63.2558,190
179221.22.64.0/19221.22.64.1 to 221.22.95.254221.22.95.2558,190
180221.22.96.0/19221.22.96.1 to 221.22.127.254221.22.127.2558,190
181221.22.128.0/19221.22.128.1 to 221.22.159.254221.22.159.2558,190
182221.22.160.0/19221.22.160.1 to 221.22.191.254221.22.191.2558,190
183221.22.192.0/19221.22.192.1 to 221.22.223.254221.22.223.2558,190
184221.22.224.0/19221.22.224.1 to 221.22.255.254221.22.255.2558,190
185221.23.0.0/19221.23.0.1 to 221.23.31.254221.23.31.2558,190
186221.23.32.0/19221.23.32.1 to 221.23.63.254221.23.63.2558,190
187221.23.64.0/19221.23.64.1 to 221.23.95.254221.23.95.2558,190
188221.23.96.0/19221.23.96.1 to 221.23.127.254221.23.127.2558,190
189221.23.128.0/19221.23.128.1 to 221.23.159.254221.23.159.2558,190
190221.23.160.0/19221.23.160.1 to 221.23.191.254221.23.191.2558,190
191221.23.192.0/19221.23.192.1 to 221.23.223.254221.23.223.2558,190
192221.23.224.0/19221.23.224.1 to 221.23.255.254221.23.255.2558,190
193221.24.0.0/19221.24.0.1 to 221.24.31.254221.24.31.2558,190
194221.24.32.0/19221.24.32.1 to 221.24.63.254221.24.63.2558,190
195221.24.64.0/19221.24.64.1 to 221.24.95.254221.24.95.2558,190
196221.24.96.0/19221.24.96.1 to 221.24.127.254221.24.127.2558,190
197221.24.128.0/19221.24.128.1 to 221.24.159.254221.24.159.2558,190
198221.24.160.0/19221.24.160.1 to 221.24.191.254221.24.191.2558,190
199221.24.192.0/19221.24.192.1 to 221.24.223.254221.24.223.2558,190
200221.24.224.0/19221.24.224.1 to 221.24.255.254221.24.255.2558,190
201221.25.0.0/19221.25.0.1 to 221.25.31.254221.25.31.2558,190
202221.25.32.0/19221.25.32.1 to 221.25.63.254221.25.63.2558,190
203221.25.64.0/19221.25.64.1 to 221.25.95.254221.25.95.2558,190
204221.25.96.0/19221.25.96.1 to 221.25.127.254221.25.127.2558,190
205221.25.128.0/19221.25.128.1 to 221.25.159.254221.25.159.2558,190
206221.25.160.0/19221.25.160.1 to 221.25.191.254221.25.191.2558,190
207221.25.192.0/19221.25.192.1 to 221.25.223.254221.25.223.2558,190
208221.25.224.0/19221.25.224.1 to 221.25.255.254221.25.255.2558,190
209221.26.0.0/19221.26.0.1 to 221.26.31.254221.26.31.2558,190
210221.26.32.0/19221.26.32.1 to 221.26.63.254221.26.63.2558,190
211221.26.64.0/19221.26.64.1 to 221.26.95.254221.26.95.2558,190
212221.26.96.0/19221.26.96.1 to 221.26.127.254221.26.127.2558,190
213221.26.128.0/19221.26.128.1 to 221.26.159.254221.26.159.2558,190
214221.26.160.0/19221.26.160.1 to 221.26.191.254221.26.191.2558,190
215221.26.192.0/19221.26.192.1 to 221.26.223.254221.26.223.2558,190
216221.26.224.0/19221.26.224.1 to 221.26.255.254221.26.255.2558,190
217221.27.0.0/19221.27.0.1 to 221.27.31.254221.27.31.2558,190
218221.27.32.0/19221.27.32.1 to 221.27.63.254221.27.63.2558,190
219221.27.64.0/19221.27.64.1 to 221.27.95.254221.27.95.2558,190
220221.27.96.0/19221.27.96.1 to 221.27.127.254221.27.127.2558,190
221221.27.128.0/19221.27.128.1 to 221.27.159.254221.27.159.2558,190
222221.27.160.0/19221.27.160.1 to 221.27.191.254221.27.191.2558,190
223221.27.192.0/19221.27.192.1 to 221.27.223.254221.27.223.2558,190
224221.27.224.0/19221.27.224.1 to 221.27.255.254221.27.255.2558,190
225221.28.0.0/19221.28.0.1 to 221.28.31.254221.28.31.2558,190
226221.28.32.0/19221.28.32.1 to 221.28.63.254221.28.63.2558,190
227221.28.64.0/19221.28.64.1 to 221.28.95.254221.28.95.2558,190
228221.28.96.0/19221.28.96.1 to 221.28.127.254221.28.127.2558,190
229221.28.128.0/19221.28.128.1 to 221.28.159.254221.28.159.2558,190
230221.28.160.0/19221.28.160.1 to 221.28.191.254221.28.191.2558,190
231221.28.192.0/19221.28.192.1 to 221.28.223.254221.28.223.2558,190
232221.28.224.0/19221.28.224.1 to 221.28.255.254221.28.255.2558,190
233221.29.0.0/19221.29.0.1 to 221.29.31.254221.29.31.2558,190
234221.29.32.0/19221.29.32.1 to 221.29.63.254221.29.63.2558,190
235221.29.64.0/19221.29.64.1 to 221.29.95.254221.29.95.2558,190
236221.29.96.0/19221.29.96.1 to 221.29.127.254221.29.127.2558,190
237221.29.128.0/19221.29.128.1 to 221.29.159.254221.29.159.2558,190
238221.29.160.0/19221.29.160.1 to 221.29.191.254221.29.191.2558,190
239221.29.192.0/19221.29.192.1 to 221.29.223.254221.29.223.2558,190
240221.29.224.0/19221.29.224.1 to 221.29.255.254221.29.255.2558,190
241221.30.0.0/19221.30.0.1 to 221.30.31.254221.30.31.2558,190
242221.30.32.0/19221.30.32.1 to 221.30.63.254221.30.63.2558,190
243221.30.64.0/19221.30.64.1 to 221.30.95.254221.30.95.2558,190
244221.30.96.0/19221.30.96.1 to 221.30.127.254221.30.127.2558,190
245221.30.128.0/19221.30.128.1 to 221.30.159.254221.30.159.2558,190
246221.30.160.0/19221.30.160.1 to 221.30.191.254221.30.191.2558,190
247221.30.192.0/19221.30.192.1 to 221.30.223.254221.30.223.2558,190
248221.30.224.0/19221.30.224.1 to 221.30.255.254221.30.255.2558,190
249221.31.0.0/19221.31.0.1 to 221.31.31.254221.31.31.2558,190
250221.31.32.0/19221.31.32.1 to 221.31.63.254221.31.63.2558,190
251221.31.64.0/19221.31.64.1 to 221.31.95.254221.31.95.2558,190
252221.31.96.0/19221.31.96.1 to 221.31.127.254221.31.127.2558,190
253221.31.128.0/19221.31.128.1 to 221.31.159.254221.31.159.2558,190
254221.31.160.0/19221.31.160.1 to 221.31.191.254221.31.191.2558,190
255221.31.192.0/19221.31.192.1 to 221.31.223.254221.31.223.2558,190
256221.31.224.0/19221.31.224.1 to 221.31.255.254221.31.255.2558,190

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.