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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.

Network187.4.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
187.4.64.0
Broadcast address
187.4.127.255
First usable
187.4.64.1
Last usable
187.4.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
B (default /16)
As numbers
Hex BB044000 · Integer 3137617920 to 3137634303
Reverse DNS zones
64.4.187.in-addr.arpa
65.4.187.in-addr.arpa
66.4.187.in-addr.arpa
67.4.187.in-addr.arpa
68.4.187.in-addr.arpa
69.4.187.in-addr.arpa
70.4.187.in-addr.arpa
71.4.187.in-addr.arpa
72.4.187.in-addr.arpa
73.4.187.in-addr.arpa
74.4.187.in-addr.arpa
75.4.187.in-addr.arpa
76.4.187.in-addr.arpa
77.4.187.in-addr.arpa
78.4.187.in-addr.arpa
79.4.187.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111011.00000100.01000000.00000000187.4.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network10111011.00000100.01000000.00000000187.4.64.0
Broadcast10111011.00000100.01111111.11111111187.4.127.255
Split into smaller subnets/26
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

187.4.64.0/18 makes 256 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.4.64.0/26187.4.64.1 to 187.4.64.62187.4.64.6362
2187.4.64.64/26187.4.64.65 to 187.4.64.126187.4.64.12762
3187.4.64.128/26187.4.64.129 to 187.4.64.190187.4.64.19162
4187.4.64.192/26187.4.64.193 to 187.4.64.254187.4.64.25562
5187.4.65.0/26187.4.65.1 to 187.4.65.62187.4.65.6362
6187.4.65.64/26187.4.65.65 to 187.4.65.126187.4.65.12762
7187.4.65.128/26187.4.65.129 to 187.4.65.190187.4.65.19162
8187.4.65.192/26187.4.65.193 to 187.4.65.254187.4.65.25562
9187.4.66.0/26187.4.66.1 to 187.4.66.62187.4.66.6362
10187.4.66.64/26187.4.66.65 to 187.4.66.126187.4.66.12762
11187.4.66.128/26187.4.66.129 to 187.4.66.190187.4.66.19162
12187.4.66.192/26187.4.66.193 to 187.4.66.254187.4.66.25562
13187.4.67.0/26187.4.67.1 to 187.4.67.62187.4.67.6362
14187.4.67.64/26187.4.67.65 to 187.4.67.126187.4.67.12762
15187.4.67.128/26187.4.67.129 to 187.4.67.190187.4.67.19162
16187.4.67.192/26187.4.67.193 to 187.4.67.254187.4.67.25562
17187.4.68.0/26187.4.68.1 to 187.4.68.62187.4.68.6362
18187.4.68.64/26187.4.68.65 to 187.4.68.126187.4.68.12762
19187.4.68.128/26187.4.68.129 to 187.4.68.190187.4.68.19162
20187.4.68.192/26187.4.68.193 to 187.4.68.254187.4.68.25562
21187.4.69.0/26187.4.69.1 to 187.4.69.62187.4.69.6362
22187.4.69.64/26187.4.69.65 to 187.4.69.126187.4.69.12762
23187.4.69.128/26187.4.69.129 to 187.4.69.190187.4.69.19162
24187.4.69.192/26187.4.69.193 to 187.4.69.254187.4.69.25562
25187.4.70.0/26187.4.70.1 to 187.4.70.62187.4.70.6362
26187.4.70.64/26187.4.70.65 to 187.4.70.126187.4.70.12762
27187.4.70.128/26187.4.70.129 to 187.4.70.190187.4.70.19162
28187.4.70.192/26187.4.70.193 to 187.4.70.254187.4.70.25562
29187.4.71.0/26187.4.71.1 to 187.4.71.62187.4.71.6362
30187.4.71.64/26187.4.71.65 to 187.4.71.126187.4.71.12762
31187.4.71.128/26187.4.71.129 to 187.4.71.190187.4.71.19162
32187.4.71.192/26187.4.71.193 to 187.4.71.254187.4.71.25562
33187.4.72.0/26187.4.72.1 to 187.4.72.62187.4.72.6362
34187.4.72.64/26187.4.72.65 to 187.4.72.126187.4.72.12762
35187.4.72.128/26187.4.72.129 to 187.4.72.190187.4.72.19162
36187.4.72.192/26187.4.72.193 to 187.4.72.254187.4.72.25562
37187.4.73.0/26187.4.73.1 to 187.4.73.62187.4.73.6362
38187.4.73.64/26187.4.73.65 to 187.4.73.126187.4.73.12762
39187.4.73.128/26187.4.73.129 to 187.4.73.190187.4.73.19162
40187.4.73.192/26187.4.73.193 to 187.4.73.254187.4.73.25562
41187.4.74.0/26187.4.74.1 to 187.4.74.62187.4.74.6362
42187.4.74.64/26187.4.74.65 to 187.4.74.126187.4.74.12762
43187.4.74.128/26187.4.74.129 to 187.4.74.190187.4.74.19162
44187.4.74.192/26187.4.74.193 to 187.4.74.254187.4.74.25562
45187.4.75.0/26187.4.75.1 to 187.4.75.62187.4.75.6362
46187.4.75.64/26187.4.75.65 to 187.4.75.126187.4.75.12762
47187.4.75.128/26187.4.75.129 to 187.4.75.190187.4.75.19162
48187.4.75.192/26187.4.75.193 to 187.4.75.254187.4.75.25562
49187.4.76.0/26187.4.76.1 to 187.4.76.62187.4.76.6362
50187.4.76.64/26187.4.76.65 to 187.4.76.126187.4.76.12762
51187.4.76.128/26187.4.76.129 to 187.4.76.190187.4.76.19162
52187.4.76.192/26187.4.76.193 to 187.4.76.254187.4.76.25562
53187.4.77.0/26187.4.77.1 to 187.4.77.62187.4.77.6362
54187.4.77.64/26187.4.77.65 to 187.4.77.126187.4.77.12762
55187.4.77.128/26187.4.77.129 to 187.4.77.190187.4.77.19162
56187.4.77.192/26187.4.77.193 to 187.4.77.254187.4.77.25562
57187.4.78.0/26187.4.78.1 to 187.4.78.62187.4.78.6362
58187.4.78.64/26187.4.78.65 to 187.4.78.126187.4.78.12762
59187.4.78.128/26187.4.78.129 to 187.4.78.190187.4.78.19162
60187.4.78.192/26187.4.78.193 to 187.4.78.254187.4.78.25562
61187.4.79.0/26187.4.79.1 to 187.4.79.62187.4.79.6362
62187.4.79.64/26187.4.79.65 to 187.4.79.126187.4.79.12762
63187.4.79.128/26187.4.79.129 to 187.4.79.190187.4.79.19162
64187.4.79.192/26187.4.79.193 to 187.4.79.254187.4.79.25562
65187.4.80.0/26187.4.80.1 to 187.4.80.62187.4.80.6362
66187.4.80.64/26187.4.80.65 to 187.4.80.126187.4.80.12762
67187.4.80.128/26187.4.80.129 to 187.4.80.190187.4.80.19162
68187.4.80.192/26187.4.80.193 to 187.4.80.254187.4.80.25562
69187.4.81.0/26187.4.81.1 to 187.4.81.62187.4.81.6362
70187.4.81.64/26187.4.81.65 to 187.4.81.126187.4.81.12762
71187.4.81.128/26187.4.81.129 to 187.4.81.190187.4.81.19162
72187.4.81.192/26187.4.81.193 to 187.4.81.254187.4.81.25562
73187.4.82.0/26187.4.82.1 to 187.4.82.62187.4.82.6362
74187.4.82.64/26187.4.82.65 to 187.4.82.126187.4.82.12762
75187.4.82.128/26187.4.82.129 to 187.4.82.190187.4.82.19162
76187.4.82.192/26187.4.82.193 to 187.4.82.254187.4.82.25562
77187.4.83.0/26187.4.83.1 to 187.4.83.62187.4.83.6362
78187.4.83.64/26187.4.83.65 to 187.4.83.126187.4.83.12762
79187.4.83.128/26187.4.83.129 to 187.4.83.190187.4.83.19162
80187.4.83.192/26187.4.83.193 to 187.4.83.254187.4.83.25562
81187.4.84.0/26187.4.84.1 to 187.4.84.62187.4.84.6362
82187.4.84.64/26187.4.84.65 to 187.4.84.126187.4.84.12762
83187.4.84.128/26187.4.84.129 to 187.4.84.190187.4.84.19162
84187.4.84.192/26187.4.84.193 to 187.4.84.254187.4.84.25562
85187.4.85.0/26187.4.85.1 to 187.4.85.62187.4.85.6362
86187.4.85.64/26187.4.85.65 to 187.4.85.126187.4.85.12762
87187.4.85.128/26187.4.85.129 to 187.4.85.190187.4.85.19162
88187.4.85.192/26187.4.85.193 to 187.4.85.254187.4.85.25562
89187.4.86.0/26187.4.86.1 to 187.4.86.62187.4.86.6362
90187.4.86.64/26187.4.86.65 to 187.4.86.126187.4.86.12762
91187.4.86.128/26187.4.86.129 to 187.4.86.190187.4.86.19162
92187.4.86.192/26187.4.86.193 to 187.4.86.254187.4.86.25562
93187.4.87.0/26187.4.87.1 to 187.4.87.62187.4.87.6362
94187.4.87.64/26187.4.87.65 to 187.4.87.126187.4.87.12762
95187.4.87.128/26187.4.87.129 to 187.4.87.190187.4.87.19162
96187.4.87.192/26187.4.87.193 to 187.4.87.254187.4.87.25562
97187.4.88.0/26187.4.88.1 to 187.4.88.62187.4.88.6362
98187.4.88.64/26187.4.88.65 to 187.4.88.126187.4.88.12762
99187.4.88.128/26187.4.88.129 to 187.4.88.190187.4.88.19162
100187.4.88.192/26187.4.88.193 to 187.4.88.254187.4.88.25562
101187.4.89.0/26187.4.89.1 to 187.4.89.62187.4.89.6362
102187.4.89.64/26187.4.89.65 to 187.4.89.126187.4.89.12762
103187.4.89.128/26187.4.89.129 to 187.4.89.190187.4.89.19162
104187.4.89.192/26187.4.89.193 to 187.4.89.254187.4.89.25562
105187.4.90.0/26187.4.90.1 to 187.4.90.62187.4.90.6362
106187.4.90.64/26187.4.90.65 to 187.4.90.126187.4.90.12762
107187.4.90.128/26187.4.90.129 to 187.4.90.190187.4.90.19162
108187.4.90.192/26187.4.90.193 to 187.4.90.254187.4.90.25562
109187.4.91.0/26187.4.91.1 to 187.4.91.62187.4.91.6362
110187.4.91.64/26187.4.91.65 to 187.4.91.126187.4.91.12762
111187.4.91.128/26187.4.91.129 to 187.4.91.190187.4.91.19162
112187.4.91.192/26187.4.91.193 to 187.4.91.254187.4.91.25562
113187.4.92.0/26187.4.92.1 to 187.4.92.62187.4.92.6362
114187.4.92.64/26187.4.92.65 to 187.4.92.126187.4.92.12762
115187.4.92.128/26187.4.92.129 to 187.4.92.190187.4.92.19162
116187.4.92.192/26187.4.92.193 to 187.4.92.254187.4.92.25562
117187.4.93.0/26187.4.93.1 to 187.4.93.62187.4.93.6362
118187.4.93.64/26187.4.93.65 to 187.4.93.126187.4.93.12762
119187.4.93.128/26187.4.93.129 to 187.4.93.190187.4.93.19162
120187.4.93.192/26187.4.93.193 to 187.4.93.254187.4.93.25562
121187.4.94.0/26187.4.94.1 to 187.4.94.62187.4.94.6362
122187.4.94.64/26187.4.94.65 to 187.4.94.126187.4.94.12762
123187.4.94.128/26187.4.94.129 to 187.4.94.190187.4.94.19162
124187.4.94.192/26187.4.94.193 to 187.4.94.254187.4.94.25562
125187.4.95.0/26187.4.95.1 to 187.4.95.62187.4.95.6362
126187.4.95.64/26187.4.95.65 to 187.4.95.126187.4.95.12762
127187.4.95.128/26187.4.95.129 to 187.4.95.190187.4.95.19162
128187.4.95.192/26187.4.95.193 to 187.4.95.254187.4.95.25562
129187.4.96.0/26187.4.96.1 to 187.4.96.62187.4.96.6362
130187.4.96.64/26187.4.96.65 to 187.4.96.126187.4.96.12762
131187.4.96.128/26187.4.96.129 to 187.4.96.190187.4.96.19162
132187.4.96.192/26187.4.96.193 to 187.4.96.254187.4.96.25562
133187.4.97.0/26187.4.97.1 to 187.4.97.62187.4.97.6362
134187.4.97.64/26187.4.97.65 to 187.4.97.126187.4.97.12762
135187.4.97.128/26187.4.97.129 to 187.4.97.190187.4.97.19162
136187.4.97.192/26187.4.97.193 to 187.4.97.254187.4.97.25562
137187.4.98.0/26187.4.98.1 to 187.4.98.62187.4.98.6362
138187.4.98.64/26187.4.98.65 to 187.4.98.126187.4.98.12762
139187.4.98.128/26187.4.98.129 to 187.4.98.190187.4.98.19162
140187.4.98.192/26187.4.98.193 to 187.4.98.254187.4.98.25562
141187.4.99.0/26187.4.99.1 to 187.4.99.62187.4.99.6362
142187.4.99.64/26187.4.99.65 to 187.4.99.126187.4.99.12762
143187.4.99.128/26187.4.99.129 to 187.4.99.190187.4.99.19162
144187.4.99.192/26187.4.99.193 to 187.4.99.254187.4.99.25562
145187.4.100.0/26187.4.100.1 to 187.4.100.62187.4.100.6362
146187.4.100.64/26187.4.100.65 to 187.4.100.126187.4.100.12762
147187.4.100.128/26187.4.100.129 to 187.4.100.190187.4.100.19162
148187.4.100.192/26187.4.100.193 to 187.4.100.254187.4.100.25562
149187.4.101.0/26187.4.101.1 to 187.4.101.62187.4.101.6362
150187.4.101.64/26187.4.101.65 to 187.4.101.126187.4.101.12762
151187.4.101.128/26187.4.101.129 to 187.4.101.190187.4.101.19162
152187.4.101.192/26187.4.101.193 to 187.4.101.254187.4.101.25562
153187.4.102.0/26187.4.102.1 to 187.4.102.62187.4.102.6362
154187.4.102.64/26187.4.102.65 to 187.4.102.126187.4.102.12762
155187.4.102.128/26187.4.102.129 to 187.4.102.190187.4.102.19162
156187.4.102.192/26187.4.102.193 to 187.4.102.254187.4.102.25562
157187.4.103.0/26187.4.103.1 to 187.4.103.62187.4.103.6362
158187.4.103.64/26187.4.103.65 to 187.4.103.126187.4.103.12762
159187.4.103.128/26187.4.103.129 to 187.4.103.190187.4.103.19162
160187.4.103.192/26187.4.103.193 to 187.4.103.254187.4.103.25562
161187.4.104.0/26187.4.104.1 to 187.4.104.62187.4.104.6362
162187.4.104.64/26187.4.104.65 to 187.4.104.126187.4.104.12762
163187.4.104.128/26187.4.104.129 to 187.4.104.190187.4.104.19162
164187.4.104.192/26187.4.104.193 to 187.4.104.254187.4.104.25562
165187.4.105.0/26187.4.105.1 to 187.4.105.62187.4.105.6362
166187.4.105.64/26187.4.105.65 to 187.4.105.126187.4.105.12762
167187.4.105.128/26187.4.105.129 to 187.4.105.190187.4.105.19162
168187.4.105.192/26187.4.105.193 to 187.4.105.254187.4.105.25562
169187.4.106.0/26187.4.106.1 to 187.4.106.62187.4.106.6362
170187.4.106.64/26187.4.106.65 to 187.4.106.126187.4.106.12762
171187.4.106.128/26187.4.106.129 to 187.4.106.190187.4.106.19162
172187.4.106.192/26187.4.106.193 to 187.4.106.254187.4.106.25562
173187.4.107.0/26187.4.107.1 to 187.4.107.62187.4.107.6362
174187.4.107.64/26187.4.107.65 to 187.4.107.126187.4.107.12762
175187.4.107.128/26187.4.107.129 to 187.4.107.190187.4.107.19162
176187.4.107.192/26187.4.107.193 to 187.4.107.254187.4.107.25562
177187.4.108.0/26187.4.108.1 to 187.4.108.62187.4.108.6362
178187.4.108.64/26187.4.108.65 to 187.4.108.126187.4.108.12762
179187.4.108.128/26187.4.108.129 to 187.4.108.190187.4.108.19162
180187.4.108.192/26187.4.108.193 to 187.4.108.254187.4.108.25562
181187.4.109.0/26187.4.109.1 to 187.4.109.62187.4.109.6362
182187.4.109.64/26187.4.109.65 to 187.4.109.126187.4.109.12762
183187.4.109.128/26187.4.109.129 to 187.4.109.190187.4.109.19162
184187.4.109.192/26187.4.109.193 to 187.4.109.254187.4.109.25562
185187.4.110.0/26187.4.110.1 to 187.4.110.62187.4.110.6362
186187.4.110.64/26187.4.110.65 to 187.4.110.126187.4.110.12762
187187.4.110.128/26187.4.110.129 to 187.4.110.190187.4.110.19162
188187.4.110.192/26187.4.110.193 to 187.4.110.254187.4.110.25562
189187.4.111.0/26187.4.111.1 to 187.4.111.62187.4.111.6362
190187.4.111.64/26187.4.111.65 to 187.4.111.126187.4.111.12762
191187.4.111.128/26187.4.111.129 to 187.4.111.190187.4.111.19162
192187.4.111.192/26187.4.111.193 to 187.4.111.254187.4.111.25562
193187.4.112.0/26187.4.112.1 to 187.4.112.62187.4.112.6362
194187.4.112.64/26187.4.112.65 to 187.4.112.126187.4.112.12762
195187.4.112.128/26187.4.112.129 to 187.4.112.190187.4.112.19162
196187.4.112.192/26187.4.112.193 to 187.4.112.254187.4.112.25562
197187.4.113.0/26187.4.113.1 to 187.4.113.62187.4.113.6362
198187.4.113.64/26187.4.113.65 to 187.4.113.126187.4.113.12762
199187.4.113.128/26187.4.113.129 to 187.4.113.190187.4.113.19162
200187.4.113.192/26187.4.113.193 to 187.4.113.254187.4.113.25562
201187.4.114.0/26187.4.114.1 to 187.4.114.62187.4.114.6362
202187.4.114.64/26187.4.114.65 to 187.4.114.126187.4.114.12762
203187.4.114.128/26187.4.114.129 to 187.4.114.190187.4.114.19162
204187.4.114.192/26187.4.114.193 to 187.4.114.254187.4.114.25562
205187.4.115.0/26187.4.115.1 to 187.4.115.62187.4.115.6362
206187.4.115.64/26187.4.115.65 to 187.4.115.126187.4.115.12762
207187.4.115.128/26187.4.115.129 to 187.4.115.190187.4.115.19162
208187.4.115.192/26187.4.115.193 to 187.4.115.254187.4.115.25562
209187.4.116.0/26187.4.116.1 to 187.4.116.62187.4.116.6362
210187.4.116.64/26187.4.116.65 to 187.4.116.126187.4.116.12762
211187.4.116.128/26187.4.116.129 to 187.4.116.190187.4.116.19162
212187.4.116.192/26187.4.116.193 to 187.4.116.254187.4.116.25562
213187.4.117.0/26187.4.117.1 to 187.4.117.62187.4.117.6362
214187.4.117.64/26187.4.117.65 to 187.4.117.126187.4.117.12762
215187.4.117.128/26187.4.117.129 to 187.4.117.190187.4.117.19162
216187.4.117.192/26187.4.117.193 to 187.4.117.254187.4.117.25562
217187.4.118.0/26187.4.118.1 to 187.4.118.62187.4.118.6362
218187.4.118.64/26187.4.118.65 to 187.4.118.126187.4.118.12762
219187.4.118.128/26187.4.118.129 to 187.4.118.190187.4.118.19162
220187.4.118.192/26187.4.118.193 to 187.4.118.254187.4.118.25562
221187.4.119.0/26187.4.119.1 to 187.4.119.62187.4.119.6362
222187.4.119.64/26187.4.119.65 to 187.4.119.126187.4.119.12762
223187.4.119.128/26187.4.119.129 to 187.4.119.190187.4.119.19162
224187.4.119.192/26187.4.119.193 to 187.4.119.254187.4.119.25562
225187.4.120.0/26187.4.120.1 to 187.4.120.62187.4.120.6362
226187.4.120.64/26187.4.120.65 to 187.4.120.126187.4.120.12762
227187.4.120.128/26187.4.120.129 to 187.4.120.190187.4.120.19162
228187.4.120.192/26187.4.120.193 to 187.4.120.254187.4.120.25562
229187.4.121.0/26187.4.121.1 to 187.4.121.62187.4.121.6362
230187.4.121.64/26187.4.121.65 to 187.4.121.126187.4.121.12762
231187.4.121.128/26187.4.121.129 to 187.4.121.190187.4.121.19162
232187.4.121.192/26187.4.121.193 to 187.4.121.254187.4.121.25562
233187.4.122.0/26187.4.122.1 to 187.4.122.62187.4.122.6362
234187.4.122.64/26187.4.122.65 to 187.4.122.126187.4.122.12762
235187.4.122.128/26187.4.122.129 to 187.4.122.190187.4.122.19162
236187.4.122.192/26187.4.122.193 to 187.4.122.254187.4.122.25562
237187.4.123.0/26187.4.123.1 to 187.4.123.62187.4.123.6362
238187.4.123.64/26187.4.123.65 to 187.4.123.126187.4.123.12762
239187.4.123.128/26187.4.123.129 to 187.4.123.190187.4.123.19162
240187.4.123.192/26187.4.123.193 to 187.4.123.254187.4.123.25562
241187.4.124.0/26187.4.124.1 to 187.4.124.62187.4.124.6362
242187.4.124.64/26187.4.124.65 to 187.4.124.126187.4.124.12762
243187.4.124.128/26187.4.124.129 to 187.4.124.190187.4.124.19162
244187.4.124.192/26187.4.124.193 to 187.4.124.254187.4.124.25562
245187.4.125.0/26187.4.125.1 to 187.4.125.62187.4.125.6362
246187.4.125.64/26187.4.125.65 to 187.4.125.126187.4.125.12762
247187.4.125.128/26187.4.125.129 to 187.4.125.190187.4.125.19162
248187.4.125.192/26187.4.125.193 to 187.4.125.254187.4.125.25562
249187.4.126.0/26187.4.126.1 to 187.4.126.62187.4.126.6362
250187.4.126.64/26187.4.126.65 to 187.4.126.126187.4.126.12762
251187.4.126.128/26187.4.126.129 to 187.4.126.190187.4.126.19162
252187.4.126.192/26187.4.126.193 to 187.4.126.254187.4.126.25562
253187.4.127.0/26187.4.127.1 to 187.4.127.62187.4.127.6362
254187.4.127.64/26187.4.127.65 to 187.4.127.126187.4.127.12762
255187.4.127.128/26187.4.127.129 to 187.4.127.190187.4.127.19162
256187.4.127.192/26187.4.127.193 to 187.4.127.254187.4.127.25562

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.