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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.

Network187.3.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
187.3.0.0
Broadcast address
187.3.31.255
First usable
187.3.0.1
Last usable
187.3.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
B (default /16)
As numbers
Hex BB030000 · Integer 3137536000 to 3137544191
Reverse DNS zones
0.3.187.in-addr.arpa
1.3.187.in-addr.arpa
2.3.187.in-addr.arpa
3.3.187.in-addr.arpa
4.3.187.in-addr.arpa
5.3.187.in-addr.arpa
6.3.187.in-addr.arpa
7.3.187.in-addr.arpa
8.3.187.in-addr.arpa
9.3.187.in-addr.arpa
10.3.187.in-addr.arpa
11.3.187.in-addr.arpa
12.3.187.in-addr.arpa
13.3.187.in-addr.arpa
14.3.187.in-addr.arpa
15.3.187.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111011.00000011.00000000.00000000187.3.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10111011.00000011.00000000.00000000187.3.0.0
Broadcast10111011.00000011.00011111.11111111187.3.31.255
Split into smaller subnets/28
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

187.3.0.0/19 makes 512 subnets of /28; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.3.0.0/28187.3.0.1 to 187.3.0.14187.3.0.1514
2187.3.0.16/28187.3.0.17 to 187.3.0.30187.3.0.3114
3187.3.0.32/28187.3.0.33 to 187.3.0.46187.3.0.4714
4187.3.0.48/28187.3.0.49 to 187.3.0.62187.3.0.6314
5187.3.0.64/28187.3.0.65 to 187.3.0.78187.3.0.7914
6187.3.0.80/28187.3.0.81 to 187.3.0.94187.3.0.9514
7187.3.0.96/28187.3.0.97 to 187.3.0.110187.3.0.11114
8187.3.0.112/28187.3.0.113 to 187.3.0.126187.3.0.12714
9187.3.0.128/28187.3.0.129 to 187.3.0.142187.3.0.14314
10187.3.0.144/28187.3.0.145 to 187.3.0.158187.3.0.15914
11187.3.0.160/28187.3.0.161 to 187.3.0.174187.3.0.17514
12187.3.0.176/28187.3.0.177 to 187.3.0.190187.3.0.19114
13187.3.0.192/28187.3.0.193 to 187.3.0.206187.3.0.20714
14187.3.0.208/28187.3.0.209 to 187.3.0.222187.3.0.22314
15187.3.0.224/28187.3.0.225 to 187.3.0.238187.3.0.23914
16187.3.0.240/28187.3.0.241 to 187.3.0.254187.3.0.25514
17187.3.1.0/28187.3.1.1 to 187.3.1.14187.3.1.1514
18187.3.1.16/28187.3.1.17 to 187.3.1.30187.3.1.3114
19187.3.1.32/28187.3.1.33 to 187.3.1.46187.3.1.4714
20187.3.1.48/28187.3.1.49 to 187.3.1.62187.3.1.6314
21187.3.1.64/28187.3.1.65 to 187.3.1.78187.3.1.7914
22187.3.1.80/28187.3.1.81 to 187.3.1.94187.3.1.9514
23187.3.1.96/28187.3.1.97 to 187.3.1.110187.3.1.11114
24187.3.1.112/28187.3.1.113 to 187.3.1.126187.3.1.12714
25187.3.1.128/28187.3.1.129 to 187.3.1.142187.3.1.14314
26187.3.1.144/28187.3.1.145 to 187.3.1.158187.3.1.15914
27187.3.1.160/28187.3.1.161 to 187.3.1.174187.3.1.17514
28187.3.1.176/28187.3.1.177 to 187.3.1.190187.3.1.19114
29187.3.1.192/28187.3.1.193 to 187.3.1.206187.3.1.20714
30187.3.1.208/28187.3.1.209 to 187.3.1.222187.3.1.22314
31187.3.1.224/28187.3.1.225 to 187.3.1.238187.3.1.23914
32187.3.1.240/28187.3.1.241 to 187.3.1.254187.3.1.25514
33187.3.2.0/28187.3.2.1 to 187.3.2.14187.3.2.1514
34187.3.2.16/28187.3.2.17 to 187.3.2.30187.3.2.3114
35187.3.2.32/28187.3.2.33 to 187.3.2.46187.3.2.4714
36187.3.2.48/28187.3.2.49 to 187.3.2.62187.3.2.6314
37187.3.2.64/28187.3.2.65 to 187.3.2.78187.3.2.7914
38187.3.2.80/28187.3.2.81 to 187.3.2.94187.3.2.9514
39187.3.2.96/28187.3.2.97 to 187.3.2.110187.3.2.11114
40187.3.2.112/28187.3.2.113 to 187.3.2.126187.3.2.12714
41187.3.2.128/28187.3.2.129 to 187.3.2.142187.3.2.14314
42187.3.2.144/28187.3.2.145 to 187.3.2.158187.3.2.15914
43187.3.2.160/28187.3.2.161 to 187.3.2.174187.3.2.17514
44187.3.2.176/28187.3.2.177 to 187.3.2.190187.3.2.19114
45187.3.2.192/28187.3.2.193 to 187.3.2.206187.3.2.20714
46187.3.2.208/28187.3.2.209 to 187.3.2.222187.3.2.22314
47187.3.2.224/28187.3.2.225 to 187.3.2.238187.3.2.23914
48187.3.2.240/28187.3.2.241 to 187.3.2.254187.3.2.25514
49187.3.3.0/28187.3.3.1 to 187.3.3.14187.3.3.1514
50187.3.3.16/28187.3.3.17 to 187.3.3.30187.3.3.3114
51187.3.3.32/28187.3.3.33 to 187.3.3.46187.3.3.4714
52187.3.3.48/28187.3.3.49 to 187.3.3.62187.3.3.6314
53187.3.3.64/28187.3.3.65 to 187.3.3.78187.3.3.7914
54187.3.3.80/28187.3.3.81 to 187.3.3.94187.3.3.9514
55187.3.3.96/28187.3.3.97 to 187.3.3.110187.3.3.11114
56187.3.3.112/28187.3.3.113 to 187.3.3.126187.3.3.12714
57187.3.3.128/28187.3.3.129 to 187.3.3.142187.3.3.14314
58187.3.3.144/28187.3.3.145 to 187.3.3.158187.3.3.15914
59187.3.3.160/28187.3.3.161 to 187.3.3.174187.3.3.17514
60187.3.3.176/28187.3.3.177 to 187.3.3.190187.3.3.19114
61187.3.3.192/28187.3.3.193 to 187.3.3.206187.3.3.20714
62187.3.3.208/28187.3.3.209 to 187.3.3.222187.3.3.22314
63187.3.3.224/28187.3.3.225 to 187.3.3.238187.3.3.23914
64187.3.3.240/28187.3.3.241 to 187.3.3.254187.3.3.25514
65187.3.4.0/28187.3.4.1 to 187.3.4.14187.3.4.1514
66187.3.4.16/28187.3.4.17 to 187.3.4.30187.3.4.3114
67187.3.4.32/28187.3.4.33 to 187.3.4.46187.3.4.4714
68187.3.4.48/28187.3.4.49 to 187.3.4.62187.3.4.6314
69187.3.4.64/28187.3.4.65 to 187.3.4.78187.3.4.7914
70187.3.4.80/28187.3.4.81 to 187.3.4.94187.3.4.9514
71187.3.4.96/28187.3.4.97 to 187.3.4.110187.3.4.11114
72187.3.4.112/28187.3.4.113 to 187.3.4.126187.3.4.12714
73187.3.4.128/28187.3.4.129 to 187.3.4.142187.3.4.14314
74187.3.4.144/28187.3.4.145 to 187.3.4.158187.3.4.15914
75187.3.4.160/28187.3.4.161 to 187.3.4.174187.3.4.17514
76187.3.4.176/28187.3.4.177 to 187.3.4.190187.3.4.19114
77187.3.4.192/28187.3.4.193 to 187.3.4.206187.3.4.20714
78187.3.4.208/28187.3.4.209 to 187.3.4.222187.3.4.22314
79187.3.4.224/28187.3.4.225 to 187.3.4.238187.3.4.23914
80187.3.4.240/28187.3.4.241 to 187.3.4.254187.3.4.25514
81187.3.5.0/28187.3.5.1 to 187.3.5.14187.3.5.1514
82187.3.5.16/28187.3.5.17 to 187.3.5.30187.3.5.3114
83187.3.5.32/28187.3.5.33 to 187.3.5.46187.3.5.4714
84187.3.5.48/28187.3.5.49 to 187.3.5.62187.3.5.6314
85187.3.5.64/28187.3.5.65 to 187.3.5.78187.3.5.7914
86187.3.5.80/28187.3.5.81 to 187.3.5.94187.3.5.9514
87187.3.5.96/28187.3.5.97 to 187.3.5.110187.3.5.11114
88187.3.5.112/28187.3.5.113 to 187.3.5.126187.3.5.12714
89187.3.5.128/28187.3.5.129 to 187.3.5.142187.3.5.14314
90187.3.5.144/28187.3.5.145 to 187.3.5.158187.3.5.15914
91187.3.5.160/28187.3.5.161 to 187.3.5.174187.3.5.17514
92187.3.5.176/28187.3.5.177 to 187.3.5.190187.3.5.19114
93187.3.5.192/28187.3.5.193 to 187.3.5.206187.3.5.20714
94187.3.5.208/28187.3.5.209 to 187.3.5.222187.3.5.22314
95187.3.5.224/28187.3.5.225 to 187.3.5.238187.3.5.23914
96187.3.5.240/28187.3.5.241 to 187.3.5.254187.3.5.25514
97187.3.6.0/28187.3.6.1 to 187.3.6.14187.3.6.1514
98187.3.6.16/28187.3.6.17 to 187.3.6.30187.3.6.3114
99187.3.6.32/28187.3.6.33 to 187.3.6.46187.3.6.4714
100187.3.6.48/28187.3.6.49 to 187.3.6.62187.3.6.6314
101187.3.6.64/28187.3.6.65 to 187.3.6.78187.3.6.7914
102187.3.6.80/28187.3.6.81 to 187.3.6.94187.3.6.9514
103187.3.6.96/28187.3.6.97 to 187.3.6.110187.3.6.11114
104187.3.6.112/28187.3.6.113 to 187.3.6.126187.3.6.12714
105187.3.6.128/28187.3.6.129 to 187.3.6.142187.3.6.14314
106187.3.6.144/28187.3.6.145 to 187.3.6.158187.3.6.15914
107187.3.6.160/28187.3.6.161 to 187.3.6.174187.3.6.17514
108187.3.6.176/28187.3.6.177 to 187.3.6.190187.3.6.19114
109187.3.6.192/28187.3.6.193 to 187.3.6.206187.3.6.20714
110187.3.6.208/28187.3.6.209 to 187.3.6.222187.3.6.22314
111187.3.6.224/28187.3.6.225 to 187.3.6.238187.3.6.23914
112187.3.6.240/28187.3.6.241 to 187.3.6.254187.3.6.25514
113187.3.7.0/28187.3.7.1 to 187.3.7.14187.3.7.1514
114187.3.7.16/28187.3.7.17 to 187.3.7.30187.3.7.3114
115187.3.7.32/28187.3.7.33 to 187.3.7.46187.3.7.4714
116187.3.7.48/28187.3.7.49 to 187.3.7.62187.3.7.6314
117187.3.7.64/28187.3.7.65 to 187.3.7.78187.3.7.7914
118187.3.7.80/28187.3.7.81 to 187.3.7.94187.3.7.9514
119187.3.7.96/28187.3.7.97 to 187.3.7.110187.3.7.11114
120187.3.7.112/28187.3.7.113 to 187.3.7.126187.3.7.12714
121187.3.7.128/28187.3.7.129 to 187.3.7.142187.3.7.14314
122187.3.7.144/28187.3.7.145 to 187.3.7.158187.3.7.15914
123187.3.7.160/28187.3.7.161 to 187.3.7.174187.3.7.17514
124187.3.7.176/28187.3.7.177 to 187.3.7.190187.3.7.19114
125187.3.7.192/28187.3.7.193 to 187.3.7.206187.3.7.20714
126187.3.7.208/28187.3.7.209 to 187.3.7.222187.3.7.22314
127187.3.7.224/28187.3.7.225 to 187.3.7.238187.3.7.23914
128187.3.7.240/28187.3.7.241 to 187.3.7.254187.3.7.25514
129187.3.8.0/28187.3.8.1 to 187.3.8.14187.3.8.1514
130187.3.8.16/28187.3.8.17 to 187.3.8.30187.3.8.3114
131187.3.8.32/28187.3.8.33 to 187.3.8.46187.3.8.4714
132187.3.8.48/28187.3.8.49 to 187.3.8.62187.3.8.6314
133187.3.8.64/28187.3.8.65 to 187.3.8.78187.3.8.7914
134187.3.8.80/28187.3.8.81 to 187.3.8.94187.3.8.9514
135187.3.8.96/28187.3.8.97 to 187.3.8.110187.3.8.11114
136187.3.8.112/28187.3.8.113 to 187.3.8.126187.3.8.12714
137187.3.8.128/28187.3.8.129 to 187.3.8.142187.3.8.14314
138187.3.8.144/28187.3.8.145 to 187.3.8.158187.3.8.15914
139187.3.8.160/28187.3.8.161 to 187.3.8.174187.3.8.17514
140187.3.8.176/28187.3.8.177 to 187.3.8.190187.3.8.19114
141187.3.8.192/28187.3.8.193 to 187.3.8.206187.3.8.20714
142187.3.8.208/28187.3.8.209 to 187.3.8.222187.3.8.22314
143187.3.8.224/28187.3.8.225 to 187.3.8.238187.3.8.23914
144187.3.8.240/28187.3.8.241 to 187.3.8.254187.3.8.25514
145187.3.9.0/28187.3.9.1 to 187.3.9.14187.3.9.1514
146187.3.9.16/28187.3.9.17 to 187.3.9.30187.3.9.3114
147187.3.9.32/28187.3.9.33 to 187.3.9.46187.3.9.4714
148187.3.9.48/28187.3.9.49 to 187.3.9.62187.3.9.6314
149187.3.9.64/28187.3.9.65 to 187.3.9.78187.3.9.7914
150187.3.9.80/28187.3.9.81 to 187.3.9.94187.3.9.9514
151187.3.9.96/28187.3.9.97 to 187.3.9.110187.3.9.11114
152187.3.9.112/28187.3.9.113 to 187.3.9.126187.3.9.12714
153187.3.9.128/28187.3.9.129 to 187.3.9.142187.3.9.14314
154187.3.9.144/28187.3.9.145 to 187.3.9.158187.3.9.15914
155187.3.9.160/28187.3.9.161 to 187.3.9.174187.3.9.17514
156187.3.9.176/28187.3.9.177 to 187.3.9.190187.3.9.19114
157187.3.9.192/28187.3.9.193 to 187.3.9.206187.3.9.20714
158187.3.9.208/28187.3.9.209 to 187.3.9.222187.3.9.22314
159187.3.9.224/28187.3.9.225 to 187.3.9.238187.3.9.23914
160187.3.9.240/28187.3.9.241 to 187.3.9.254187.3.9.25514
161187.3.10.0/28187.3.10.1 to 187.3.10.14187.3.10.1514
162187.3.10.16/28187.3.10.17 to 187.3.10.30187.3.10.3114
163187.3.10.32/28187.3.10.33 to 187.3.10.46187.3.10.4714
164187.3.10.48/28187.3.10.49 to 187.3.10.62187.3.10.6314
165187.3.10.64/28187.3.10.65 to 187.3.10.78187.3.10.7914
166187.3.10.80/28187.3.10.81 to 187.3.10.94187.3.10.9514
167187.3.10.96/28187.3.10.97 to 187.3.10.110187.3.10.11114
168187.3.10.112/28187.3.10.113 to 187.3.10.126187.3.10.12714
169187.3.10.128/28187.3.10.129 to 187.3.10.142187.3.10.14314
170187.3.10.144/28187.3.10.145 to 187.3.10.158187.3.10.15914
171187.3.10.160/28187.3.10.161 to 187.3.10.174187.3.10.17514
172187.3.10.176/28187.3.10.177 to 187.3.10.190187.3.10.19114
173187.3.10.192/28187.3.10.193 to 187.3.10.206187.3.10.20714
174187.3.10.208/28187.3.10.209 to 187.3.10.222187.3.10.22314
175187.3.10.224/28187.3.10.225 to 187.3.10.238187.3.10.23914
176187.3.10.240/28187.3.10.241 to 187.3.10.254187.3.10.25514
177187.3.11.0/28187.3.11.1 to 187.3.11.14187.3.11.1514
178187.3.11.16/28187.3.11.17 to 187.3.11.30187.3.11.3114
179187.3.11.32/28187.3.11.33 to 187.3.11.46187.3.11.4714
180187.3.11.48/28187.3.11.49 to 187.3.11.62187.3.11.6314
181187.3.11.64/28187.3.11.65 to 187.3.11.78187.3.11.7914
182187.3.11.80/28187.3.11.81 to 187.3.11.94187.3.11.9514
183187.3.11.96/28187.3.11.97 to 187.3.11.110187.3.11.11114
184187.3.11.112/28187.3.11.113 to 187.3.11.126187.3.11.12714
185187.3.11.128/28187.3.11.129 to 187.3.11.142187.3.11.14314
186187.3.11.144/28187.3.11.145 to 187.3.11.158187.3.11.15914
187187.3.11.160/28187.3.11.161 to 187.3.11.174187.3.11.17514
188187.3.11.176/28187.3.11.177 to 187.3.11.190187.3.11.19114
189187.3.11.192/28187.3.11.193 to 187.3.11.206187.3.11.20714
190187.3.11.208/28187.3.11.209 to 187.3.11.222187.3.11.22314
191187.3.11.224/28187.3.11.225 to 187.3.11.238187.3.11.23914
192187.3.11.240/28187.3.11.241 to 187.3.11.254187.3.11.25514
193187.3.12.0/28187.3.12.1 to 187.3.12.14187.3.12.1514
194187.3.12.16/28187.3.12.17 to 187.3.12.30187.3.12.3114
195187.3.12.32/28187.3.12.33 to 187.3.12.46187.3.12.4714
196187.3.12.48/28187.3.12.49 to 187.3.12.62187.3.12.6314
197187.3.12.64/28187.3.12.65 to 187.3.12.78187.3.12.7914
198187.3.12.80/28187.3.12.81 to 187.3.12.94187.3.12.9514
199187.3.12.96/28187.3.12.97 to 187.3.12.110187.3.12.11114
200187.3.12.112/28187.3.12.113 to 187.3.12.126187.3.12.12714
201187.3.12.128/28187.3.12.129 to 187.3.12.142187.3.12.14314
202187.3.12.144/28187.3.12.145 to 187.3.12.158187.3.12.15914
203187.3.12.160/28187.3.12.161 to 187.3.12.174187.3.12.17514
204187.3.12.176/28187.3.12.177 to 187.3.12.190187.3.12.19114
205187.3.12.192/28187.3.12.193 to 187.3.12.206187.3.12.20714
206187.3.12.208/28187.3.12.209 to 187.3.12.222187.3.12.22314
207187.3.12.224/28187.3.12.225 to 187.3.12.238187.3.12.23914
208187.3.12.240/28187.3.12.241 to 187.3.12.254187.3.12.25514
209187.3.13.0/28187.3.13.1 to 187.3.13.14187.3.13.1514
210187.3.13.16/28187.3.13.17 to 187.3.13.30187.3.13.3114
211187.3.13.32/28187.3.13.33 to 187.3.13.46187.3.13.4714
212187.3.13.48/28187.3.13.49 to 187.3.13.62187.3.13.6314
213187.3.13.64/28187.3.13.65 to 187.3.13.78187.3.13.7914
214187.3.13.80/28187.3.13.81 to 187.3.13.94187.3.13.9514
215187.3.13.96/28187.3.13.97 to 187.3.13.110187.3.13.11114
216187.3.13.112/28187.3.13.113 to 187.3.13.126187.3.13.12714
217187.3.13.128/28187.3.13.129 to 187.3.13.142187.3.13.14314
218187.3.13.144/28187.3.13.145 to 187.3.13.158187.3.13.15914
219187.3.13.160/28187.3.13.161 to 187.3.13.174187.3.13.17514
220187.3.13.176/28187.3.13.177 to 187.3.13.190187.3.13.19114
221187.3.13.192/28187.3.13.193 to 187.3.13.206187.3.13.20714
222187.3.13.208/28187.3.13.209 to 187.3.13.222187.3.13.22314
223187.3.13.224/28187.3.13.225 to 187.3.13.238187.3.13.23914
224187.3.13.240/28187.3.13.241 to 187.3.13.254187.3.13.25514
225187.3.14.0/28187.3.14.1 to 187.3.14.14187.3.14.1514
226187.3.14.16/28187.3.14.17 to 187.3.14.30187.3.14.3114
227187.3.14.32/28187.3.14.33 to 187.3.14.46187.3.14.4714
228187.3.14.48/28187.3.14.49 to 187.3.14.62187.3.14.6314
229187.3.14.64/28187.3.14.65 to 187.3.14.78187.3.14.7914
230187.3.14.80/28187.3.14.81 to 187.3.14.94187.3.14.9514
231187.3.14.96/28187.3.14.97 to 187.3.14.110187.3.14.11114
232187.3.14.112/28187.3.14.113 to 187.3.14.126187.3.14.12714
233187.3.14.128/28187.3.14.129 to 187.3.14.142187.3.14.14314
234187.3.14.144/28187.3.14.145 to 187.3.14.158187.3.14.15914
235187.3.14.160/28187.3.14.161 to 187.3.14.174187.3.14.17514
236187.3.14.176/28187.3.14.177 to 187.3.14.190187.3.14.19114
237187.3.14.192/28187.3.14.193 to 187.3.14.206187.3.14.20714
238187.3.14.208/28187.3.14.209 to 187.3.14.222187.3.14.22314
239187.3.14.224/28187.3.14.225 to 187.3.14.238187.3.14.23914
240187.3.14.240/28187.3.14.241 to 187.3.14.254187.3.14.25514
241187.3.15.0/28187.3.15.1 to 187.3.15.14187.3.15.1514
242187.3.15.16/28187.3.15.17 to 187.3.15.30187.3.15.3114
243187.3.15.32/28187.3.15.33 to 187.3.15.46187.3.15.4714
244187.3.15.48/28187.3.15.49 to 187.3.15.62187.3.15.6314
245187.3.15.64/28187.3.15.65 to 187.3.15.78187.3.15.7914
246187.3.15.80/28187.3.15.81 to 187.3.15.94187.3.15.9514
247187.3.15.96/28187.3.15.97 to 187.3.15.110187.3.15.11114
248187.3.15.112/28187.3.15.113 to 187.3.15.126187.3.15.12714
249187.3.15.128/28187.3.15.129 to 187.3.15.142187.3.15.14314
250187.3.15.144/28187.3.15.145 to 187.3.15.158187.3.15.15914
251187.3.15.160/28187.3.15.161 to 187.3.15.174187.3.15.17514
252187.3.15.176/28187.3.15.177 to 187.3.15.190187.3.15.19114
253187.3.15.192/28187.3.15.193 to 187.3.15.206187.3.15.20714
254187.3.15.208/28187.3.15.209 to 187.3.15.222187.3.15.22314
255187.3.15.224/28187.3.15.225 to 187.3.15.238187.3.15.23914
256187.3.15.240/28187.3.15.241 to 187.3.15.254187.3.15.25514

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.