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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.

Network187.0.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
187.0.0.0
Broadcast address
187.0.31.255
First usable
187.0.0.1
Last usable
187.0.31.254
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 BB000000 · Integer 3137339392 to 3137347583
Reverse DNS zones
0.0.187.in-addr.arpa
1.0.187.in-addr.arpa
2.0.187.in-addr.arpa
3.0.187.in-addr.arpa
4.0.187.in-addr.arpa
5.0.187.in-addr.arpa
6.0.187.in-addr.arpa
7.0.187.in-addr.arpa
8.0.187.in-addr.arpa
9.0.187.in-addr.arpa
10.0.187.in-addr.arpa
11.0.187.in-addr.arpa
12.0.187.in-addr.arpa
13.0.187.in-addr.arpa
14.0.187.in-addr.arpa
15.0.187.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
Address10111011.00000000.00000000.00000000187.0.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10111011.00000000.00000000.00000000187.0.0.0
Broadcast10111011.00000000.00011111.11111111187.0.31.255
Split into smaller subnets/29
/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)

187.0.0.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.0.0.0/29187.0.0.1 to 187.0.0.6187.0.0.76
2187.0.0.8/29187.0.0.9 to 187.0.0.14187.0.0.156
3187.0.0.16/29187.0.0.17 to 187.0.0.22187.0.0.236
4187.0.0.24/29187.0.0.25 to 187.0.0.30187.0.0.316
5187.0.0.32/29187.0.0.33 to 187.0.0.38187.0.0.396
6187.0.0.40/29187.0.0.41 to 187.0.0.46187.0.0.476
7187.0.0.48/29187.0.0.49 to 187.0.0.54187.0.0.556
8187.0.0.56/29187.0.0.57 to 187.0.0.62187.0.0.636
9187.0.0.64/29187.0.0.65 to 187.0.0.70187.0.0.716
10187.0.0.72/29187.0.0.73 to 187.0.0.78187.0.0.796
11187.0.0.80/29187.0.0.81 to 187.0.0.86187.0.0.876
12187.0.0.88/29187.0.0.89 to 187.0.0.94187.0.0.956
13187.0.0.96/29187.0.0.97 to 187.0.0.102187.0.0.1036
14187.0.0.104/29187.0.0.105 to 187.0.0.110187.0.0.1116
15187.0.0.112/29187.0.0.113 to 187.0.0.118187.0.0.1196
16187.0.0.120/29187.0.0.121 to 187.0.0.126187.0.0.1276
17187.0.0.128/29187.0.0.129 to 187.0.0.134187.0.0.1356
18187.0.0.136/29187.0.0.137 to 187.0.0.142187.0.0.1436
19187.0.0.144/29187.0.0.145 to 187.0.0.150187.0.0.1516
20187.0.0.152/29187.0.0.153 to 187.0.0.158187.0.0.1596
21187.0.0.160/29187.0.0.161 to 187.0.0.166187.0.0.1676
22187.0.0.168/29187.0.0.169 to 187.0.0.174187.0.0.1756
23187.0.0.176/29187.0.0.177 to 187.0.0.182187.0.0.1836
24187.0.0.184/29187.0.0.185 to 187.0.0.190187.0.0.1916
25187.0.0.192/29187.0.0.193 to 187.0.0.198187.0.0.1996
26187.0.0.200/29187.0.0.201 to 187.0.0.206187.0.0.2076
27187.0.0.208/29187.0.0.209 to 187.0.0.214187.0.0.2156
28187.0.0.216/29187.0.0.217 to 187.0.0.222187.0.0.2236
29187.0.0.224/29187.0.0.225 to 187.0.0.230187.0.0.2316
30187.0.0.232/29187.0.0.233 to 187.0.0.238187.0.0.2396
31187.0.0.240/29187.0.0.241 to 187.0.0.246187.0.0.2476
32187.0.0.248/29187.0.0.249 to 187.0.0.254187.0.0.2556
33187.0.1.0/29187.0.1.1 to 187.0.1.6187.0.1.76
34187.0.1.8/29187.0.1.9 to 187.0.1.14187.0.1.156
35187.0.1.16/29187.0.1.17 to 187.0.1.22187.0.1.236
36187.0.1.24/29187.0.1.25 to 187.0.1.30187.0.1.316
37187.0.1.32/29187.0.1.33 to 187.0.1.38187.0.1.396
38187.0.1.40/29187.0.1.41 to 187.0.1.46187.0.1.476
39187.0.1.48/29187.0.1.49 to 187.0.1.54187.0.1.556
40187.0.1.56/29187.0.1.57 to 187.0.1.62187.0.1.636
41187.0.1.64/29187.0.1.65 to 187.0.1.70187.0.1.716
42187.0.1.72/29187.0.1.73 to 187.0.1.78187.0.1.796
43187.0.1.80/29187.0.1.81 to 187.0.1.86187.0.1.876
44187.0.1.88/29187.0.1.89 to 187.0.1.94187.0.1.956
45187.0.1.96/29187.0.1.97 to 187.0.1.102187.0.1.1036
46187.0.1.104/29187.0.1.105 to 187.0.1.110187.0.1.1116
47187.0.1.112/29187.0.1.113 to 187.0.1.118187.0.1.1196
48187.0.1.120/29187.0.1.121 to 187.0.1.126187.0.1.1276
49187.0.1.128/29187.0.1.129 to 187.0.1.134187.0.1.1356
50187.0.1.136/29187.0.1.137 to 187.0.1.142187.0.1.1436
51187.0.1.144/29187.0.1.145 to 187.0.1.150187.0.1.1516
52187.0.1.152/29187.0.1.153 to 187.0.1.158187.0.1.1596
53187.0.1.160/29187.0.1.161 to 187.0.1.166187.0.1.1676
54187.0.1.168/29187.0.1.169 to 187.0.1.174187.0.1.1756
55187.0.1.176/29187.0.1.177 to 187.0.1.182187.0.1.1836
56187.0.1.184/29187.0.1.185 to 187.0.1.190187.0.1.1916
57187.0.1.192/29187.0.1.193 to 187.0.1.198187.0.1.1996
58187.0.1.200/29187.0.1.201 to 187.0.1.206187.0.1.2076
59187.0.1.208/29187.0.1.209 to 187.0.1.214187.0.1.2156
60187.0.1.216/29187.0.1.217 to 187.0.1.222187.0.1.2236
61187.0.1.224/29187.0.1.225 to 187.0.1.230187.0.1.2316
62187.0.1.232/29187.0.1.233 to 187.0.1.238187.0.1.2396
63187.0.1.240/29187.0.1.241 to 187.0.1.246187.0.1.2476
64187.0.1.248/29187.0.1.249 to 187.0.1.254187.0.1.2556
65187.0.2.0/29187.0.2.1 to 187.0.2.6187.0.2.76
66187.0.2.8/29187.0.2.9 to 187.0.2.14187.0.2.156
67187.0.2.16/29187.0.2.17 to 187.0.2.22187.0.2.236
68187.0.2.24/29187.0.2.25 to 187.0.2.30187.0.2.316
69187.0.2.32/29187.0.2.33 to 187.0.2.38187.0.2.396
70187.0.2.40/29187.0.2.41 to 187.0.2.46187.0.2.476
71187.0.2.48/29187.0.2.49 to 187.0.2.54187.0.2.556
72187.0.2.56/29187.0.2.57 to 187.0.2.62187.0.2.636
73187.0.2.64/29187.0.2.65 to 187.0.2.70187.0.2.716
74187.0.2.72/29187.0.2.73 to 187.0.2.78187.0.2.796
75187.0.2.80/29187.0.2.81 to 187.0.2.86187.0.2.876
76187.0.2.88/29187.0.2.89 to 187.0.2.94187.0.2.956
77187.0.2.96/29187.0.2.97 to 187.0.2.102187.0.2.1036
78187.0.2.104/29187.0.2.105 to 187.0.2.110187.0.2.1116
79187.0.2.112/29187.0.2.113 to 187.0.2.118187.0.2.1196
80187.0.2.120/29187.0.2.121 to 187.0.2.126187.0.2.1276
81187.0.2.128/29187.0.2.129 to 187.0.2.134187.0.2.1356
82187.0.2.136/29187.0.2.137 to 187.0.2.142187.0.2.1436
83187.0.2.144/29187.0.2.145 to 187.0.2.150187.0.2.1516
84187.0.2.152/29187.0.2.153 to 187.0.2.158187.0.2.1596
85187.0.2.160/29187.0.2.161 to 187.0.2.166187.0.2.1676
86187.0.2.168/29187.0.2.169 to 187.0.2.174187.0.2.1756
87187.0.2.176/29187.0.2.177 to 187.0.2.182187.0.2.1836
88187.0.2.184/29187.0.2.185 to 187.0.2.190187.0.2.1916
89187.0.2.192/29187.0.2.193 to 187.0.2.198187.0.2.1996
90187.0.2.200/29187.0.2.201 to 187.0.2.206187.0.2.2076
91187.0.2.208/29187.0.2.209 to 187.0.2.214187.0.2.2156
92187.0.2.216/29187.0.2.217 to 187.0.2.222187.0.2.2236
93187.0.2.224/29187.0.2.225 to 187.0.2.230187.0.2.2316
94187.0.2.232/29187.0.2.233 to 187.0.2.238187.0.2.2396
95187.0.2.240/29187.0.2.241 to 187.0.2.246187.0.2.2476
96187.0.2.248/29187.0.2.249 to 187.0.2.254187.0.2.2556
97187.0.3.0/29187.0.3.1 to 187.0.3.6187.0.3.76
98187.0.3.8/29187.0.3.9 to 187.0.3.14187.0.3.156
99187.0.3.16/29187.0.3.17 to 187.0.3.22187.0.3.236
100187.0.3.24/29187.0.3.25 to 187.0.3.30187.0.3.316
101187.0.3.32/29187.0.3.33 to 187.0.3.38187.0.3.396
102187.0.3.40/29187.0.3.41 to 187.0.3.46187.0.3.476
103187.0.3.48/29187.0.3.49 to 187.0.3.54187.0.3.556
104187.0.3.56/29187.0.3.57 to 187.0.3.62187.0.3.636
105187.0.3.64/29187.0.3.65 to 187.0.3.70187.0.3.716
106187.0.3.72/29187.0.3.73 to 187.0.3.78187.0.3.796
107187.0.3.80/29187.0.3.81 to 187.0.3.86187.0.3.876
108187.0.3.88/29187.0.3.89 to 187.0.3.94187.0.3.956
109187.0.3.96/29187.0.3.97 to 187.0.3.102187.0.3.1036
110187.0.3.104/29187.0.3.105 to 187.0.3.110187.0.3.1116
111187.0.3.112/29187.0.3.113 to 187.0.3.118187.0.3.1196
112187.0.3.120/29187.0.3.121 to 187.0.3.126187.0.3.1276
113187.0.3.128/29187.0.3.129 to 187.0.3.134187.0.3.1356
114187.0.3.136/29187.0.3.137 to 187.0.3.142187.0.3.1436
115187.0.3.144/29187.0.3.145 to 187.0.3.150187.0.3.1516
116187.0.3.152/29187.0.3.153 to 187.0.3.158187.0.3.1596
117187.0.3.160/29187.0.3.161 to 187.0.3.166187.0.3.1676
118187.0.3.168/29187.0.3.169 to 187.0.3.174187.0.3.1756
119187.0.3.176/29187.0.3.177 to 187.0.3.182187.0.3.1836
120187.0.3.184/29187.0.3.185 to 187.0.3.190187.0.3.1916
121187.0.3.192/29187.0.3.193 to 187.0.3.198187.0.3.1996
122187.0.3.200/29187.0.3.201 to 187.0.3.206187.0.3.2076
123187.0.3.208/29187.0.3.209 to 187.0.3.214187.0.3.2156
124187.0.3.216/29187.0.3.217 to 187.0.3.222187.0.3.2236
125187.0.3.224/29187.0.3.225 to 187.0.3.230187.0.3.2316
126187.0.3.232/29187.0.3.233 to 187.0.3.238187.0.3.2396
127187.0.3.240/29187.0.3.241 to 187.0.3.246187.0.3.2476
128187.0.3.248/29187.0.3.249 to 187.0.3.254187.0.3.2556
129187.0.4.0/29187.0.4.1 to 187.0.4.6187.0.4.76
130187.0.4.8/29187.0.4.9 to 187.0.4.14187.0.4.156
131187.0.4.16/29187.0.4.17 to 187.0.4.22187.0.4.236
132187.0.4.24/29187.0.4.25 to 187.0.4.30187.0.4.316
133187.0.4.32/29187.0.4.33 to 187.0.4.38187.0.4.396
134187.0.4.40/29187.0.4.41 to 187.0.4.46187.0.4.476
135187.0.4.48/29187.0.4.49 to 187.0.4.54187.0.4.556
136187.0.4.56/29187.0.4.57 to 187.0.4.62187.0.4.636
137187.0.4.64/29187.0.4.65 to 187.0.4.70187.0.4.716
138187.0.4.72/29187.0.4.73 to 187.0.4.78187.0.4.796
139187.0.4.80/29187.0.4.81 to 187.0.4.86187.0.4.876
140187.0.4.88/29187.0.4.89 to 187.0.4.94187.0.4.956
141187.0.4.96/29187.0.4.97 to 187.0.4.102187.0.4.1036
142187.0.4.104/29187.0.4.105 to 187.0.4.110187.0.4.1116
143187.0.4.112/29187.0.4.113 to 187.0.4.118187.0.4.1196
144187.0.4.120/29187.0.4.121 to 187.0.4.126187.0.4.1276
145187.0.4.128/29187.0.4.129 to 187.0.4.134187.0.4.1356
146187.0.4.136/29187.0.4.137 to 187.0.4.142187.0.4.1436
147187.0.4.144/29187.0.4.145 to 187.0.4.150187.0.4.1516
148187.0.4.152/29187.0.4.153 to 187.0.4.158187.0.4.1596
149187.0.4.160/29187.0.4.161 to 187.0.4.166187.0.4.1676
150187.0.4.168/29187.0.4.169 to 187.0.4.174187.0.4.1756
151187.0.4.176/29187.0.4.177 to 187.0.4.182187.0.4.1836
152187.0.4.184/29187.0.4.185 to 187.0.4.190187.0.4.1916
153187.0.4.192/29187.0.4.193 to 187.0.4.198187.0.4.1996
154187.0.4.200/29187.0.4.201 to 187.0.4.206187.0.4.2076
155187.0.4.208/29187.0.4.209 to 187.0.4.214187.0.4.2156
156187.0.4.216/29187.0.4.217 to 187.0.4.222187.0.4.2236
157187.0.4.224/29187.0.4.225 to 187.0.4.230187.0.4.2316
158187.0.4.232/29187.0.4.233 to 187.0.4.238187.0.4.2396
159187.0.4.240/29187.0.4.241 to 187.0.4.246187.0.4.2476
160187.0.4.248/29187.0.4.249 to 187.0.4.254187.0.4.2556
161187.0.5.0/29187.0.5.1 to 187.0.5.6187.0.5.76
162187.0.5.8/29187.0.5.9 to 187.0.5.14187.0.5.156
163187.0.5.16/29187.0.5.17 to 187.0.5.22187.0.5.236
164187.0.5.24/29187.0.5.25 to 187.0.5.30187.0.5.316
165187.0.5.32/29187.0.5.33 to 187.0.5.38187.0.5.396
166187.0.5.40/29187.0.5.41 to 187.0.5.46187.0.5.476
167187.0.5.48/29187.0.5.49 to 187.0.5.54187.0.5.556
168187.0.5.56/29187.0.5.57 to 187.0.5.62187.0.5.636
169187.0.5.64/29187.0.5.65 to 187.0.5.70187.0.5.716
170187.0.5.72/29187.0.5.73 to 187.0.5.78187.0.5.796
171187.0.5.80/29187.0.5.81 to 187.0.5.86187.0.5.876
172187.0.5.88/29187.0.5.89 to 187.0.5.94187.0.5.956
173187.0.5.96/29187.0.5.97 to 187.0.5.102187.0.5.1036
174187.0.5.104/29187.0.5.105 to 187.0.5.110187.0.5.1116
175187.0.5.112/29187.0.5.113 to 187.0.5.118187.0.5.1196
176187.0.5.120/29187.0.5.121 to 187.0.5.126187.0.5.1276
177187.0.5.128/29187.0.5.129 to 187.0.5.134187.0.5.1356
178187.0.5.136/29187.0.5.137 to 187.0.5.142187.0.5.1436
179187.0.5.144/29187.0.5.145 to 187.0.5.150187.0.5.1516
180187.0.5.152/29187.0.5.153 to 187.0.5.158187.0.5.1596
181187.0.5.160/29187.0.5.161 to 187.0.5.166187.0.5.1676
182187.0.5.168/29187.0.5.169 to 187.0.5.174187.0.5.1756
183187.0.5.176/29187.0.5.177 to 187.0.5.182187.0.5.1836
184187.0.5.184/29187.0.5.185 to 187.0.5.190187.0.5.1916
185187.0.5.192/29187.0.5.193 to 187.0.5.198187.0.5.1996
186187.0.5.200/29187.0.5.201 to 187.0.5.206187.0.5.2076
187187.0.5.208/29187.0.5.209 to 187.0.5.214187.0.5.2156
188187.0.5.216/29187.0.5.217 to 187.0.5.222187.0.5.2236
189187.0.5.224/29187.0.5.225 to 187.0.5.230187.0.5.2316
190187.0.5.232/29187.0.5.233 to 187.0.5.238187.0.5.2396
191187.0.5.240/29187.0.5.241 to 187.0.5.246187.0.5.2476
192187.0.5.248/29187.0.5.249 to 187.0.5.254187.0.5.2556
193187.0.6.0/29187.0.6.1 to 187.0.6.6187.0.6.76
194187.0.6.8/29187.0.6.9 to 187.0.6.14187.0.6.156
195187.0.6.16/29187.0.6.17 to 187.0.6.22187.0.6.236
196187.0.6.24/29187.0.6.25 to 187.0.6.30187.0.6.316
197187.0.6.32/29187.0.6.33 to 187.0.6.38187.0.6.396
198187.0.6.40/29187.0.6.41 to 187.0.6.46187.0.6.476
199187.0.6.48/29187.0.6.49 to 187.0.6.54187.0.6.556
200187.0.6.56/29187.0.6.57 to 187.0.6.62187.0.6.636
201187.0.6.64/29187.0.6.65 to 187.0.6.70187.0.6.716
202187.0.6.72/29187.0.6.73 to 187.0.6.78187.0.6.796
203187.0.6.80/29187.0.6.81 to 187.0.6.86187.0.6.876
204187.0.6.88/29187.0.6.89 to 187.0.6.94187.0.6.956
205187.0.6.96/29187.0.6.97 to 187.0.6.102187.0.6.1036
206187.0.6.104/29187.0.6.105 to 187.0.6.110187.0.6.1116
207187.0.6.112/29187.0.6.113 to 187.0.6.118187.0.6.1196
208187.0.6.120/29187.0.6.121 to 187.0.6.126187.0.6.1276
209187.0.6.128/29187.0.6.129 to 187.0.6.134187.0.6.1356
210187.0.6.136/29187.0.6.137 to 187.0.6.142187.0.6.1436
211187.0.6.144/29187.0.6.145 to 187.0.6.150187.0.6.1516
212187.0.6.152/29187.0.6.153 to 187.0.6.158187.0.6.1596
213187.0.6.160/29187.0.6.161 to 187.0.6.166187.0.6.1676
214187.0.6.168/29187.0.6.169 to 187.0.6.174187.0.6.1756
215187.0.6.176/29187.0.6.177 to 187.0.6.182187.0.6.1836
216187.0.6.184/29187.0.6.185 to 187.0.6.190187.0.6.1916
217187.0.6.192/29187.0.6.193 to 187.0.6.198187.0.6.1996
218187.0.6.200/29187.0.6.201 to 187.0.6.206187.0.6.2076
219187.0.6.208/29187.0.6.209 to 187.0.6.214187.0.6.2156
220187.0.6.216/29187.0.6.217 to 187.0.6.222187.0.6.2236
221187.0.6.224/29187.0.6.225 to 187.0.6.230187.0.6.2316
222187.0.6.232/29187.0.6.233 to 187.0.6.238187.0.6.2396
223187.0.6.240/29187.0.6.241 to 187.0.6.246187.0.6.2476
224187.0.6.248/29187.0.6.249 to 187.0.6.254187.0.6.2556
225187.0.7.0/29187.0.7.1 to 187.0.7.6187.0.7.76
226187.0.7.8/29187.0.7.9 to 187.0.7.14187.0.7.156
227187.0.7.16/29187.0.7.17 to 187.0.7.22187.0.7.236
228187.0.7.24/29187.0.7.25 to 187.0.7.30187.0.7.316
229187.0.7.32/29187.0.7.33 to 187.0.7.38187.0.7.396
230187.0.7.40/29187.0.7.41 to 187.0.7.46187.0.7.476
231187.0.7.48/29187.0.7.49 to 187.0.7.54187.0.7.556
232187.0.7.56/29187.0.7.57 to 187.0.7.62187.0.7.636
233187.0.7.64/29187.0.7.65 to 187.0.7.70187.0.7.716
234187.0.7.72/29187.0.7.73 to 187.0.7.78187.0.7.796
235187.0.7.80/29187.0.7.81 to 187.0.7.86187.0.7.876
236187.0.7.88/29187.0.7.89 to 187.0.7.94187.0.7.956
237187.0.7.96/29187.0.7.97 to 187.0.7.102187.0.7.1036
238187.0.7.104/29187.0.7.105 to 187.0.7.110187.0.7.1116
239187.0.7.112/29187.0.7.113 to 187.0.7.118187.0.7.1196
240187.0.7.120/29187.0.7.121 to 187.0.7.126187.0.7.1276
241187.0.7.128/29187.0.7.129 to 187.0.7.134187.0.7.1356
242187.0.7.136/29187.0.7.137 to 187.0.7.142187.0.7.1436
243187.0.7.144/29187.0.7.145 to 187.0.7.150187.0.7.1516
244187.0.7.152/29187.0.7.153 to 187.0.7.158187.0.7.1596
245187.0.7.160/29187.0.7.161 to 187.0.7.166187.0.7.1676
246187.0.7.168/29187.0.7.169 to 187.0.7.174187.0.7.1756
247187.0.7.176/29187.0.7.177 to 187.0.7.182187.0.7.1836
248187.0.7.184/29187.0.7.185 to 187.0.7.190187.0.7.1916
249187.0.7.192/29187.0.7.193 to 187.0.7.198187.0.7.1996
250187.0.7.200/29187.0.7.201 to 187.0.7.206187.0.7.2076
251187.0.7.208/29187.0.7.209 to 187.0.7.214187.0.7.2156
252187.0.7.216/29187.0.7.217 to 187.0.7.222187.0.7.2236
253187.0.7.224/29187.0.7.225 to 187.0.7.230187.0.7.2316
254187.0.7.232/29187.0.7.233 to 187.0.7.238187.0.7.2396
255187.0.7.240/29187.0.7.241 to 187.0.7.246187.0.7.2476
256187.0.7.248/29187.0.7.249 to 187.0.7.254187.0.7.2556

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.