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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.

Network181.4.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
181.4.0.0
Broadcast address
181.4.127.255
First usable
181.4.0.1
Last usable
181.4.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex B5040000 · Integer 3036938240 to 3036971007
Reverse DNS zones
0.4.181.in-addr.arpa
1.4.181.in-addr.arpa
2.4.181.in-addr.arpa
3.4.181.in-addr.arpa
4.4.181.in-addr.arpa
5.4.181.in-addr.arpa
6.4.181.in-addr.arpa
7.4.181.in-addr.arpa
8.4.181.in-addr.arpa
9.4.181.in-addr.arpa
10.4.181.in-addr.arpa
11.4.181.in-addr.arpa
12.4.181.in-addr.arpa
13.4.181.in-addr.arpa
14.4.181.in-addr.arpa
15.4.181.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110101.00000100.00000000.00000000181.4.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10110101.00000100.00000000.00000000181.4.0.0
Broadcast10110101.00000100.01111111.11111111181.4.127.255
Split into smaller subnets/27
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

181.4.0.0/17 makes 1,024 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.4.0.0/27181.4.0.1 to 181.4.0.30181.4.0.3130
2181.4.0.32/27181.4.0.33 to 181.4.0.62181.4.0.6330
3181.4.0.64/27181.4.0.65 to 181.4.0.94181.4.0.9530
4181.4.0.96/27181.4.0.97 to 181.4.0.126181.4.0.12730
5181.4.0.128/27181.4.0.129 to 181.4.0.158181.4.0.15930
6181.4.0.160/27181.4.0.161 to 181.4.0.190181.4.0.19130
7181.4.0.192/27181.4.0.193 to 181.4.0.222181.4.0.22330
8181.4.0.224/27181.4.0.225 to 181.4.0.254181.4.0.25530
9181.4.1.0/27181.4.1.1 to 181.4.1.30181.4.1.3130
10181.4.1.32/27181.4.1.33 to 181.4.1.62181.4.1.6330
11181.4.1.64/27181.4.1.65 to 181.4.1.94181.4.1.9530
12181.4.1.96/27181.4.1.97 to 181.4.1.126181.4.1.12730
13181.4.1.128/27181.4.1.129 to 181.4.1.158181.4.1.15930
14181.4.1.160/27181.4.1.161 to 181.4.1.190181.4.1.19130
15181.4.1.192/27181.4.1.193 to 181.4.1.222181.4.1.22330
16181.4.1.224/27181.4.1.225 to 181.4.1.254181.4.1.25530
17181.4.2.0/27181.4.2.1 to 181.4.2.30181.4.2.3130
18181.4.2.32/27181.4.2.33 to 181.4.2.62181.4.2.6330
19181.4.2.64/27181.4.2.65 to 181.4.2.94181.4.2.9530
20181.4.2.96/27181.4.2.97 to 181.4.2.126181.4.2.12730
21181.4.2.128/27181.4.2.129 to 181.4.2.158181.4.2.15930
22181.4.2.160/27181.4.2.161 to 181.4.2.190181.4.2.19130
23181.4.2.192/27181.4.2.193 to 181.4.2.222181.4.2.22330
24181.4.2.224/27181.4.2.225 to 181.4.2.254181.4.2.25530
25181.4.3.0/27181.4.3.1 to 181.4.3.30181.4.3.3130
26181.4.3.32/27181.4.3.33 to 181.4.3.62181.4.3.6330
27181.4.3.64/27181.4.3.65 to 181.4.3.94181.4.3.9530
28181.4.3.96/27181.4.3.97 to 181.4.3.126181.4.3.12730
29181.4.3.128/27181.4.3.129 to 181.4.3.158181.4.3.15930
30181.4.3.160/27181.4.3.161 to 181.4.3.190181.4.3.19130
31181.4.3.192/27181.4.3.193 to 181.4.3.222181.4.3.22330
32181.4.3.224/27181.4.3.225 to 181.4.3.254181.4.3.25530
33181.4.4.0/27181.4.4.1 to 181.4.4.30181.4.4.3130
34181.4.4.32/27181.4.4.33 to 181.4.4.62181.4.4.6330
35181.4.4.64/27181.4.4.65 to 181.4.4.94181.4.4.9530
36181.4.4.96/27181.4.4.97 to 181.4.4.126181.4.4.12730
37181.4.4.128/27181.4.4.129 to 181.4.4.158181.4.4.15930
38181.4.4.160/27181.4.4.161 to 181.4.4.190181.4.4.19130
39181.4.4.192/27181.4.4.193 to 181.4.4.222181.4.4.22330
40181.4.4.224/27181.4.4.225 to 181.4.4.254181.4.4.25530
41181.4.5.0/27181.4.5.1 to 181.4.5.30181.4.5.3130
42181.4.5.32/27181.4.5.33 to 181.4.5.62181.4.5.6330
43181.4.5.64/27181.4.5.65 to 181.4.5.94181.4.5.9530
44181.4.5.96/27181.4.5.97 to 181.4.5.126181.4.5.12730
45181.4.5.128/27181.4.5.129 to 181.4.5.158181.4.5.15930
46181.4.5.160/27181.4.5.161 to 181.4.5.190181.4.5.19130
47181.4.5.192/27181.4.5.193 to 181.4.5.222181.4.5.22330
48181.4.5.224/27181.4.5.225 to 181.4.5.254181.4.5.25530
49181.4.6.0/27181.4.6.1 to 181.4.6.30181.4.6.3130
50181.4.6.32/27181.4.6.33 to 181.4.6.62181.4.6.6330
51181.4.6.64/27181.4.6.65 to 181.4.6.94181.4.6.9530
52181.4.6.96/27181.4.6.97 to 181.4.6.126181.4.6.12730
53181.4.6.128/27181.4.6.129 to 181.4.6.158181.4.6.15930
54181.4.6.160/27181.4.6.161 to 181.4.6.190181.4.6.19130
55181.4.6.192/27181.4.6.193 to 181.4.6.222181.4.6.22330
56181.4.6.224/27181.4.6.225 to 181.4.6.254181.4.6.25530
57181.4.7.0/27181.4.7.1 to 181.4.7.30181.4.7.3130
58181.4.7.32/27181.4.7.33 to 181.4.7.62181.4.7.6330
59181.4.7.64/27181.4.7.65 to 181.4.7.94181.4.7.9530
60181.4.7.96/27181.4.7.97 to 181.4.7.126181.4.7.12730
61181.4.7.128/27181.4.7.129 to 181.4.7.158181.4.7.15930
62181.4.7.160/27181.4.7.161 to 181.4.7.190181.4.7.19130
63181.4.7.192/27181.4.7.193 to 181.4.7.222181.4.7.22330
64181.4.7.224/27181.4.7.225 to 181.4.7.254181.4.7.25530
65181.4.8.0/27181.4.8.1 to 181.4.8.30181.4.8.3130
66181.4.8.32/27181.4.8.33 to 181.4.8.62181.4.8.6330
67181.4.8.64/27181.4.8.65 to 181.4.8.94181.4.8.9530
68181.4.8.96/27181.4.8.97 to 181.4.8.126181.4.8.12730
69181.4.8.128/27181.4.8.129 to 181.4.8.158181.4.8.15930
70181.4.8.160/27181.4.8.161 to 181.4.8.190181.4.8.19130
71181.4.8.192/27181.4.8.193 to 181.4.8.222181.4.8.22330
72181.4.8.224/27181.4.8.225 to 181.4.8.254181.4.8.25530
73181.4.9.0/27181.4.9.1 to 181.4.9.30181.4.9.3130
74181.4.9.32/27181.4.9.33 to 181.4.9.62181.4.9.6330
75181.4.9.64/27181.4.9.65 to 181.4.9.94181.4.9.9530
76181.4.9.96/27181.4.9.97 to 181.4.9.126181.4.9.12730
77181.4.9.128/27181.4.9.129 to 181.4.9.158181.4.9.15930
78181.4.9.160/27181.4.9.161 to 181.4.9.190181.4.9.19130
79181.4.9.192/27181.4.9.193 to 181.4.9.222181.4.9.22330
80181.4.9.224/27181.4.9.225 to 181.4.9.254181.4.9.25530
81181.4.10.0/27181.4.10.1 to 181.4.10.30181.4.10.3130
82181.4.10.32/27181.4.10.33 to 181.4.10.62181.4.10.6330
83181.4.10.64/27181.4.10.65 to 181.4.10.94181.4.10.9530
84181.4.10.96/27181.4.10.97 to 181.4.10.126181.4.10.12730
85181.4.10.128/27181.4.10.129 to 181.4.10.158181.4.10.15930
86181.4.10.160/27181.4.10.161 to 181.4.10.190181.4.10.19130
87181.4.10.192/27181.4.10.193 to 181.4.10.222181.4.10.22330
88181.4.10.224/27181.4.10.225 to 181.4.10.254181.4.10.25530
89181.4.11.0/27181.4.11.1 to 181.4.11.30181.4.11.3130
90181.4.11.32/27181.4.11.33 to 181.4.11.62181.4.11.6330
91181.4.11.64/27181.4.11.65 to 181.4.11.94181.4.11.9530
92181.4.11.96/27181.4.11.97 to 181.4.11.126181.4.11.12730
93181.4.11.128/27181.4.11.129 to 181.4.11.158181.4.11.15930
94181.4.11.160/27181.4.11.161 to 181.4.11.190181.4.11.19130
95181.4.11.192/27181.4.11.193 to 181.4.11.222181.4.11.22330
96181.4.11.224/27181.4.11.225 to 181.4.11.254181.4.11.25530
97181.4.12.0/27181.4.12.1 to 181.4.12.30181.4.12.3130
98181.4.12.32/27181.4.12.33 to 181.4.12.62181.4.12.6330
99181.4.12.64/27181.4.12.65 to 181.4.12.94181.4.12.9530
100181.4.12.96/27181.4.12.97 to 181.4.12.126181.4.12.12730
101181.4.12.128/27181.4.12.129 to 181.4.12.158181.4.12.15930
102181.4.12.160/27181.4.12.161 to 181.4.12.190181.4.12.19130
103181.4.12.192/27181.4.12.193 to 181.4.12.222181.4.12.22330
104181.4.12.224/27181.4.12.225 to 181.4.12.254181.4.12.25530
105181.4.13.0/27181.4.13.1 to 181.4.13.30181.4.13.3130
106181.4.13.32/27181.4.13.33 to 181.4.13.62181.4.13.6330
107181.4.13.64/27181.4.13.65 to 181.4.13.94181.4.13.9530
108181.4.13.96/27181.4.13.97 to 181.4.13.126181.4.13.12730
109181.4.13.128/27181.4.13.129 to 181.4.13.158181.4.13.15930
110181.4.13.160/27181.4.13.161 to 181.4.13.190181.4.13.19130
111181.4.13.192/27181.4.13.193 to 181.4.13.222181.4.13.22330
112181.4.13.224/27181.4.13.225 to 181.4.13.254181.4.13.25530
113181.4.14.0/27181.4.14.1 to 181.4.14.30181.4.14.3130
114181.4.14.32/27181.4.14.33 to 181.4.14.62181.4.14.6330
115181.4.14.64/27181.4.14.65 to 181.4.14.94181.4.14.9530
116181.4.14.96/27181.4.14.97 to 181.4.14.126181.4.14.12730
117181.4.14.128/27181.4.14.129 to 181.4.14.158181.4.14.15930
118181.4.14.160/27181.4.14.161 to 181.4.14.190181.4.14.19130
119181.4.14.192/27181.4.14.193 to 181.4.14.222181.4.14.22330
120181.4.14.224/27181.4.14.225 to 181.4.14.254181.4.14.25530
121181.4.15.0/27181.4.15.1 to 181.4.15.30181.4.15.3130
122181.4.15.32/27181.4.15.33 to 181.4.15.62181.4.15.6330
123181.4.15.64/27181.4.15.65 to 181.4.15.94181.4.15.9530
124181.4.15.96/27181.4.15.97 to 181.4.15.126181.4.15.12730
125181.4.15.128/27181.4.15.129 to 181.4.15.158181.4.15.15930
126181.4.15.160/27181.4.15.161 to 181.4.15.190181.4.15.19130
127181.4.15.192/27181.4.15.193 to 181.4.15.222181.4.15.22330
128181.4.15.224/27181.4.15.225 to 181.4.15.254181.4.15.25530
129181.4.16.0/27181.4.16.1 to 181.4.16.30181.4.16.3130
130181.4.16.32/27181.4.16.33 to 181.4.16.62181.4.16.6330
131181.4.16.64/27181.4.16.65 to 181.4.16.94181.4.16.9530
132181.4.16.96/27181.4.16.97 to 181.4.16.126181.4.16.12730
133181.4.16.128/27181.4.16.129 to 181.4.16.158181.4.16.15930
134181.4.16.160/27181.4.16.161 to 181.4.16.190181.4.16.19130
135181.4.16.192/27181.4.16.193 to 181.4.16.222181.4.16.22330
136181.4.16.224/27181.4.16.225 to 181.4.16.254181.4.16.25530
137181.4.17.0/27181.4.17.1 to 181.4.17.30181.4.17.3130
138181.4.17.32/27181.4.17.33 to 181.4.17.62181.4.17.6330
139181.4.17.64/27181.4.17.65 to 181.4.17.94181.4.17.9530
140181.4.17.96/27181.4.17.97 to 181.4.17.126181.4.17.12730
141181.4.17.128/27181.4.17.129 to 181.4.17.158181.4.17.15930
142181.4.17.160/27181.4.17.161 to 181.4.17.190181.4.17.19130
143181.4.17.192/27181.4.17.193 to 181.4.17.222181.4.17.22330
144181.4.17.224/27181.4.17.225 to 181.4.17.254181.4.17.25530
145181.4.18.0/27181.4.18.1 to 181.4.18.30181.4.18.3130
146181.4.18.32/27181.4.18.33 to 181.4.18.62181.4.18.6330
147181.4.18.64/27181.4.18.65 to 181.4.18.94181.4.18.9530
148181.4.18.96/27181.4.18.97 to 181.4.18.126181.4.18.12730
149181.4.18.128/27181.4.18.129 to 181.4.18.158181.4.18.15930
150181.4.18.160/27181.4.18.161 to 181.4.18.190181.4.18.19130
151181.4.18.192/27181.4.18.193 to 181.4.18.222181.4.18.22330
152181.4.18.224/27181.4.18.225 to 181.4.18.254181.4.18.25530
153181.4.19.0/27181.4.19.1 to 181.4.19.30181.4.19.3130
154181.4.19.32/27181.4.19.33 to 181.4.19.62181.4.19.6330
155181.4.19.64/27181.4.19.65 to 181.4.19.94181.4.19.9530
156181.4.19.96/27181.4.19.97 to 181.4.19.126181.4.19.12730
157181.4.19.128/27181.4.19.129 to 181.4.19.158181.4.19.15930
158181.4.19.160/27181.4.19.161 to 181.4.19.190181.4.19.19130
159181.4.19.192/27181.4.19.193 to 181.4.19.222181.4.19.22330
160181.4.19.224/27181.4.19.225 to 181.4.19.254181.4.19.25530
161181.4.20.0/27181.4.20.1 to 181.4.20.30181.4.20.3130
162181.4.20.32/27181.4.20.33 to 181.4.20.62181.4.20.6330
163181.4.20.64/27181.4.20.65 to 181.4.20.94181.4.20.9530
164181.4.20.96/27181.4.20.97 to 181.4.20.126181.4.20.12730
165181.4.20.128/27181.4.20.129 to 181.4.20.158181.4.20.15930
166181.4.20.160/27181.4.20.161 to 181.4.20.190181.4.20.19130
167181.4.20.192/27181.4.20.193 to 181.4.20.222181.4.20.22330
168181.4.20.224/27181.4.20.225 to 181.4.20.254181.4.20.25530
169181.4.21.0/27181.4.21.1 to 181.4.21.30181.4.21.3130
170181.4.21.32/27181.4.21.33 to 181.4.21.62181.4.21.6330
171181.4.21.64/27181.4.21.65 to 181.4.21.94181.4.21.9530
172181.4.21.96/27181.4.21.97 to 181.4.21.126181.4.21.12730
173181.4.21.128/27181.4.21.129 to 181.4.21.158181.4.21.15930
174181.4.21.160/27181.4.21.161 to 181.4.21.190181.4.21.19130
175181.4.21.192/27181.4.21.193 to 181.4.21.222181.4.21.22330
176181.4.21.224/27181.4.21.225 to 181.4.21.254181.4.21.25530
177181.4.22.0/27181.4.22.1 to 181.4.22.30181.4.22.3130
178181.4.22.32/27181.4.22.33 to 181.4.22.62181.4.22.6330
179181.4.22.64/27181.4.22.65 to 181.4.22.94181.4.22.9530
180181.4.22.96/27181.4.22.97 to 181.4.22.126181.4.22.12730
181181.4.22.128/27181.4.22.129 to 181.4.22.158181.4.22.15930
182181.4.22.160/27181.4.22.161 to 181.4.22.190181.4.22.19130
183181.4.22.192/27181.4.22.193 to 181.4.22.222181.4.22.22330
184181.4.22.224/27181.4.22.225 to 181.4.22.254181.4.22.25530
185181.4.23.0/27181.4.23.1 to 181.4.23.30181.4.23.3130
186181.4.23.32/27181.4.23.33 to 181.4.23.62181.4.23.6330
187181.4.23.64/27181.4.23.65 to 181.4.23.94181.4.23.9530
188181.4.23.96/27181.4.23.97 to 181.4.23.126181.4.23.12730
189181.4.23.128/27181.4.23.129 to 181.4.23.158181.4.23.15930
190181.4.23.160/27181.4.23.161 to 181.4.23.190181.4.23.19130
191181.4.23.192/27181.4.23.193 to 181.4.23.222181.4.23.22330
192181.4.23.224/27181.4.23.225 to 181.4.23.254181.4.23.25530
193181.4.24.0/27181.4.24.1 to 181.4.24.30181.4.24.3130
194181.4.24.32/27181.4.24.33 to 181.4.24.62181.4.24.6330
195181.4.24.64/27181.4.24.65 to 181.4.24.94181.4.24.9530
196181.4.24.96/27181.4.24.97 to 181.4.24.126181.4.24.12730
197181.4.24.128/27181.4.24.129 to 181.4.24.158181.4.24.15930
198181.4.24.160/27181.4.24.161 to 181.4.24.190181.4.24.19130
199181.4.24.192/27181.4.24.193 to 181.4.24.222181.4.24.22330
200181.4.24.224/27181.4.24.225 to 181.4.24.254181.4.24.25530
201181.4.25.0/27181.4.25.1 to 181.4.25.30181.4.25.3130
202181.4.25.32/27181.4.25.33 to 181.4.25.62181.4.25.6330
203181.4.25.64/27181.4.25.65 to 181.4.25.94181.4.25.9530
204181.4.25.96/27181.4.25.97 to 181.4.25.126181.4.25.12730
205181.4.25.128/27181.4.25.129 to 181.4.25.158181.4.25.15930
206181.4.25.160/27181.4.25.161 to 181.4.25.190181.4.25.19130
207181.4.25.192/27181.4.25.193 to 181.4.25.222181.4.25.22330
208181.4.25.224/27181.4.25.225 to 181.4.25.254181.4.25.25530
209181.4.26.0/27181.4.26.1 to 181.4.26.30181.4.26.3130
210181.4.26.32/27181.4.26.33 to 181.4.26.62181.4.26.6330
211181.4.26.64/27181.4.26.65 to 181.4.26.94181.4.26.9530
212181.4.26.96/27181.4.26.97 to 181.4.26.126181.4.26.12730
213181.4.26.128/27181.4.26.129 to 181.4.26.158181.4.26.15930
214181.4.26.160/27181.4.26.161 to 181.4.26.190181.4.26.19130
215181.4.26.192/27181.4.26.193 to 181.4.26.222181.4.26.22330
216181.4.26.224/27181.4.26.225 to 181.4.26.254181.4.26.25530
217181.4.27.0/27181.4.27.1 to 181.4.27.30181.4.27.3130
218181.4.27.32/27181.4.27.33 to 181.4.27.62181.4.27.6330
219181.4.27.64/27181.4.27.65 to 181.4.27.94181.4.27.9530
220181.4.27.96/27181.4.27.97 to 181.4.27.126181.4.27.12730
221181.4.27.128/27181.4.27.129 to 181.4.27.158181.4.27.15930
222181.4.27.160/27181.4.27.161 to 181.4.27.190181.4.27.19130
223181.4.27.192/27181.4.27.193 to 181.4.27.222181.4.27.22330
224181.4.27.224/27181.4.27.225 to 181.4.27.254181.4.27.25530
225181.4.28.0/27181.4.28.1 to 181.4.28.30181.4.28.3130
226181.4.28.32/27181.4.28.33 to 181.4.28.62181.4.28.6330
227181.4.28.64/27181.4.28.65 to 181.4.28.94181.4.28.9530
228181.4.28.96/27181.4.28.97 to 181.4.28.126181.4.28.12730
229181.4.28.128/27181.4.28.129 to 181.4.28.158181.4.28.15930
230181.4.28.160/27181.4.28.161 to 181.4.28.190181.4.28.19130
231181.4.28.192/27181.4.28.193 to 181.4.28.222181.4.28.22330
232181.4.28.224/27181.4.28.225 to 181.4.28.254181.4.28.25530
233181.4.29.0/27181.4.29.1 to 181.4.29.30181.4.29.3130
234181.4.29.32/27181.4.29.33 to 181.4.29.62181.4.29.6330
235181.4.29.64/27181.4.29.65 to 181.4.29.94181.4.29.9530
236181.4.29.96/27181.4.29.97 to 181.4.29.126181.4.29.12730
237181.4.29.128/27181.4.29.129 to 181.4.29.158181.4.29.15930
238181.4.29.160/27181.4.29.161 to 181.4.29.190181.4.29.19130
239181.4.29.192/27181.4.29.193 to 181.4.29.222181.4.29.22330
240181.4.29.224/27181.4.29.225 to 181.4.29.254181.4.29.25530
241181.4.30.0/27181.4.30.1 to 181.4.30.30181.4.30.3130
242181.4.30.32/27181.4.30.33 to 181.4.30.62181.4.30.6330
243181.4.30.64/27181.4.30.65 to 181.4.30.94181.4.30.9530
244181.4.30.96/27181.4.30.97 to 181.4.30.126181.4.30.12730
245181.4.30.128/27181.4.30.129 to 181.4.30.158181.4.30.15930
246181.4.30.160/27181.4.30.161 to 181.4.30.190181.4.30.19130
247181.4.30.192/27181.4.30.193 to 181.4.30.222181.4.30.22330
248181.4.30.224/27181.4.30.225 to 181.4.30.254181.4.30.25530
249181.4.31.0/27181.4.31.1 to 181.4.31.30181.4.31.3130
250181.4.31.32/27181.4.31.33 to 181.4.31.62181.4.31.6330
251181.4.31.64/27181.4.31.65 to 181.4.31.94181.4.31.9530
252181.4.31.96/27181.4.31.97 to 181.4.31.126181.4.31.12730
253181.4.31.128/27181.4.31.129 to 181.4.31.158181.4.31.15930
254181.4.31.160/27181.4.31.161 to 181.4.31.190181.4.31.19130
255181.4.31.192/27181.4.31.193 to 181.4.31.222181.4.31.22330
256181.4.31.224/27181.4.31.225 to 181.4.31.254181.4.31.25530

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.