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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.

Network145.7.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
145.7.64.0
Broadcast address
145.7.79.255
First usable
145.7.64.1
Last usable
145.7.79.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
B (default /16)
As numbers
Hex 91074000 · Integer 2433171456 to 2433175551
Reverse DNS zones
64.7.145.in-addr.arpa
65.7.145.in-addr.arpa
66.7.145.in-addr.arpa
67.7.145.in-addr.arpa
68.7.145.in-addr.arpa
69.7.145.in-addr.arpa
70.7.145.in-addr.arpa
71.7.145.in-addr.arpa
72.7.145.in-addr.arpa
73.7.145.in-addr.arpa
74.7.145.in-addr.arpa
75.7.145.in-addr.arpa
76.7.145.in-addr.arpa
77.7.145.in-addr.arpa
78.7.145.in-addr.arpa
79.7.145.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010001.00000111.01000000.00000000145.7.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10010001.00000111.01000000.00000000145.7.64.0
Broadcast10010001.00000111.01001111.11111111145.7.79.255
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

145.7.64.0/20 makes 256 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.7.64.0/28145.7.64.1 to 145.7.64.14145.7.64.1514
2145.7.64.16/28145.7.64.17 to 145.7.64.30145.7.64.3114
3145.7.64.32/28145.7.64.33 to 145.7.64.46145.7.64.4714
4145.7.64.48/28145.7.64.49 to 145.7.64.62145.7.64.6314
5145.7.64.64/28145.7.64.65 to 145.7.64.78145.7.64.7914
6145.7.64.80/28145.7.64.81 to 145.7.64.94145.7.64.9514
7145.7.64.96/28145.7.64.97 to 145.7.64.110145.7.64.11114
8145.7.64.112/28145.7.64.113 to 145.7.64.126145.7.64.12714
9145.7.64.128/28145.7.64.129 to 145.7.64.142145.7.64.14314
10145.7.64.144/28145.7.64.145 to 145.7.64.158145.7.64.15914
11145.7.64.160/28145.7.64.161 to 145.7.64.174145.7.64.17514
12145.7.64.176/28145.7.64.177 to 145.7.64.190145.7.64.19114
13145.7.64.192/28145.7.64.193 to 145.7.64.206145.7.64.20714
14145.7.64.208/28145.7.64.209 to 145.7.64.222145.7.64.22314
15145.7.64.224/28145.7.64.225 to 145.7.64.238145.7.64.23914
16145.7.64.240/28145.7.64.241 to 145.7.64.254145.7.64.25514
17145.7.65.0/28145.7.65.1 to 145.7.65.14145.7.65.1514
18145.7.65.16/28145.7.65.17 to 145.7.65.30145.7.65.3114
19145.7.65.32/28145.7.65.33 to 145.7.65.46145.7.65.4714
20145.7.65.48/28145.7.65.49 to 145.7.65.62145.7.65.6314
21145.7.65.64/28145.7.65.65 to 145.7.65.78145.7.65.7914
22145.7.65.80/28145.7.65.81 to 145.7.65.94145.7.65.9514
23145.7.65.96/28145.7.65.97 to 145.7.65.110145.7.65.11114
24145.7.65.112/28145.7.65.113 to 145.7.65.126145.7.65.12714
25145.7.65.128/28145.7.65.129 to 145.7.65.142145.7.65.14314
26145.7.65.144/28145.7.65.145 to 145.7.65.158145.7.65.15914
27145.7.65.160/28145.7.65.161 to 145.7.65.174145.7.65.17514
28145.7.65.176/28145.7.65.177 to 145.7.65.190145.7.65.19114
29145.7.65.192/28145.7.65.193 to 145.7.65.206145.7.65.20714
30145.7.65.208/28145.7.65.209 to 145.7.65.222145.7.65.22314
31145.7.65.224/28145.7.65.225 to 145.7.65.238145.7.65.23914
32145.7.65.240/28145.7.65.241 to 145.7.65.254145.7.65.25514
33145.7.66.0/28145.7.66.1 to 145.7.66.14145.7.66.1514
34145.7.66.16/28145.7.66.17 to 145.7.66.30145.7.66.3114
35145.7.66.32/28145.7.66.33 to 145.7.66.46145.7.66.4714
36145.7.66.48/28145.7.66.49 to 145.7.66.62145.7.66.6314
37145.7.66.64/28145.7.66.65 to 145.7.66.78145.7.66.7914
38145.7.66.80/28145.7.66.81 to 145.7.66.94145.7.66.9514
39145.7.66.96/28145.7.66.97 to 145.7.66.110145.7.66.11114
40145.7.66.112/28145.7.66.113 to 145.7.66.126145.7.66.12714
41145.7.66.128/28145.7.66.129 to 145.7.66.142145.7.66.14314
42145.7.66.144/28145.7.66.145 to 145.7.66.158145.7.66.15914
43145.7.66.160/28145.7.66.161 to 145.7.66.174145.7.66.17514
44145.7.66.176/28145.7.66.177 to 145.7.66.190145.7.66.19114
45145.7.66.192/28145.7.66.193 to 145.7.66.206145.7.66.20714
46145.7.66.208/28145.7.66.209 to 145.7.66.222145.7.66.22314
47145.7.66.224/28145.7.66.225 to 145.7.66.238145.7.66.23914
48145.7.66.240/28145.7.66.241 to 145.7.66.254145.7.66.25514
49145.7.67.0/28145.7.67.1 to 145.7.67.14145.7.67.1514
50145.7.67.16/28145.7.67.17 to 145.7.67.30145.7.67.3114
51145.7.67.32/28145.7.67.33 to 145.7.67.46145.7.67.4714
52145.7.67.48/28145.7.67.49 to 145.7.67.62145.7.67.6314
53145.7.67.64/28145.7.67.65 to 145.7.67.78145.7.67.7914
54145.7.67.80/28145.7.67.81 to 145.7.67.94145.7.67.9514
55145.7.67.96/28145.7.67.97 to 145.7.67.110145.7.67.11114
56145.7.67.112/28145.7.67.113 to 145.7.67.126145.7.67.12714
57145.7.67.128/28145.7.67.129 to 145.7.67.142145.7.67.14314
58145.7.67.144/28145.7.67.145 to 145.7.67.158145.7.67.15914
59145.7.67.160/28145.7.67.161 to 145.7.67.174145.7.67.17514
60145.7.67.176/28145.7.67.177 to 145.7.67.190145.7.67.19114
61145.7.67.192/28145.7.67.193 to 145.7.67.206145.7.67.20714
62145.7.67.208/28145.7.67.209 to 145.7.67.222145.7.67.22314
63145.7.67.224/28145.7.67.225 to 145.7.67.238145.7.67.23914
64145.7.67.240/28145.7.67.241 to 145.7.67.254145.7.67.25514
65145.7.68.0/28145.7.68.1 to 145.7.68.14145.7.68.1514
66145.7.68.16/28145.7.68.17 to 145.7.68.30145.7.68.3114
67145.7.68.32/28145.7.68.33 to 145.7.68.46145.7.68.4714
68145.7.68.48/28145.7.68.49 to 145.7.68.62145.7.68.6314
69145.7.68.64/28145.7.68.65 to 145.7.68.78145.7.68.7914
70145.7.68.80/28145.7.68.81 to 145.7.68.94145.7.68.9514
71145.7.68.96/28145.7.68.97 to 145.7.68.110145.7.68.11114
72145.7.68.112/28145.7.68.113 to 145.7.68.126145.7.68.12714
73145.7.68.128/28145.7.68.129 to 145.7.68.142145.7.68.14314
74145.7.68.144/28145.7.68.145 to 145.7.68.158145.7.68.15914
75145.7.68.160/28145.7.68.161 to 145.7.68.174145.7.68.17514
76145.7.68.176/28145.7.68.177 to 145.7.68.190145.7.68.19114
77145.7.68.192/28145.7.68.193 to 145.7.68.206145.7.68.20714
78145.7.68.208/28145.7.68.209 to 145.7.68.222145.7.68.22314
79145.7.68.224/28145.7.68.225 to 145.7.68.238145.7.68.23914
80145.7.68.240/28145.7.68.241 to 145.7.68.254145.7.68.25514
81145.7.69.0/28145.7.69.1 to 145.7.69.14145.7.69.1514
82145.7.69.16/28145.7.69.17 to 145.7.69.30145.7.69.3114
83145.7.69.32/28145.7.69.33 to 145.7.69.46145.7.69.4714
84145.7.69.48/28145.7.69.49 to 145.7.69.62145.7.69.6314
85145.7.69.64/28145.7.69.65 to 145.7.69.78145.7.69.7914
86145.7.69.80/28145.7.69.81 to 145.7.69.94145.7.69.9514
87145.7.69.96/28145.7.69.97 to 145.7.69.110145.7.69.11114
88145.7.69.112/28145.7.69.113 to 145.7.69.126145.7.69.12714
89145.7.69.128/28145.7.69.129 to 145.7.69.142145.7.69.14314
90145.7.69.144/28145.7.69.145 to 145.7.69.158145.7.69.15914
91145.7.69.160/28145.7.69.161 to 145.7.69.174145.7.69.17514
92145.7.69.176/28145.7.69.177 to 145.7.69.190145.7.69.19114
93145.7.69.192/28145.7.69.193 to 145.7.69.206145.7.69.20714
94145.7.69.208/28145.7.69.209 to 145.7.69.222145.7.69.22314
95145.7.69.224/28145.7.69.225 to 145.7.69.238145.7.69.23914
96145.7.69.240/28145.7.69.241 to 145.7.69.254145.7.69.25514
97145.7.70.0/28145.7.70.1 to 145.7.70.14145.7.70.1514
98145.7.70.16/28145.7.70.17 to 145.7.70.30145.7.70.3114
99145.7.70.32/28145.7.70.33 to 145.7.70.46145.7.70.4714
100145.7.70.48/28145.7.70.49 to 145.7.70.62145.7.70.6314
101145.7.70.64/28145.7.70.65 to 145.7.70.78145.7.70.7914
102145.7.70.80/28145.7.70.81 to 145.7.70.94145.7.70.9514
103145.7.70.96/28145.7.70.97 to 145.7.70.110145.7.70.11114
104145.7.70.112/28145.7.70.113 to 145.7.70.126145.7.70.12714
105145.7.70.128/28145.7.70.129 to 145.7.70.142145.7.70.14314
106145.7.70.144/28145.7.70.145 to 145.7.70.158145.7.70.15914
107145.7.70.160/28145.7.70.161 to 145.7.70.174145.7.70.17514
108145.7.70.176/28145.7.70.177 to 145.7.70.190145.7.70.19114
109145.7.70.192/28145.7.70.193 to 145.7.70.206145.7.70.20714
110145.7.70.208/28145.7.70.209 to 145.7.70.222145.7.70.22314
111145.7.70.224/28145.7.70.225 to 145.7.70.238145.7.70.23914
112145.7.70.240/28145.7.70.241 to 145.7.70.254145.7.70.25514
113145.7.71.0/28145.7.71.1 to 145.7.71.14145.7.71.1514
114145.7.71.16/28145.7.71.17 to 145.7.71.30145.7.71.3114
115145.7.71.32/28145.7.71.33 to 145.7.71.46145.7.71.4714
116145.7.71.48/28145.7.71.49 to 145.7.71.62145.7.71.6314
117145.7.71.64/28145.7.71.65 to 145.7.71.78145.7.71.7914
118145.7.71.80/28145.7.71.81 to 145.7.71.94145.7.71.9514
119145.7.71.96/28145.7.71.97 to 145.7.71.110145.7.71.11114
120145.7.71.112/28145.7.71.113 to 145.7.71.126145.7.71.12714
121145.7.71.128/28145.7.71.129 to 145.7.71.142145.7.71.14314
122145.7.71.144/28145.7.71.145 to 145.7.71.158145.7.71.15914
123145.7.71.160/28145.7.71.161 to 145.7.71.174145.7.71.17514
124145.7.71.176/28145.7.71.177 to 145.7.71.190145.7.71.19114
125145.7.71.192/28145.7.71.193 to 145.7.71.206145.7.71.20714
126145.7.71.208/28145.7.71.209 to 145.7.71.222145.7.71.22314
127145.7.71.224/28145.7.71.225 to 145.7.71.238145.7.71.23914
128145.7.71.240/28145.7.71.241 to 145.7.71.254145.7.71.25514
129145.7.72.0/28145.7.72.1 to 145.7.72.14145.7.72.1514
130145.7.72.16/28145.7.72.17 to 145.7.72.30145.7.72.3114
131145.7.72.32/28145.7.72.33 to 145.7.72.46145.7.72.4714
132145.7.72.48/28145.7.72.49 to 145.7.72.62145.7.72.6314
133145.7.72.64/28145.7.72.65 to 145.7.72.78145.7.72.7914
134145.7.72.80/28145.7.72.81 to 145.7.72.94145.7.72.9514
135145.7.72.96/28145.7.72.97 to 145.7.72.110145.7.72.11114
136145.7.72.112/28145.7.72.113 to 145.7.72.126145.7.72.12714
137145.7.72.128/28145.7.72.129 to 145.7.72.142145.7.72.14314
138145.7.72.144/28145.7.72.145 to 145.7.72.158145.7.72.15914
139145.7.72.160/28145.7.72.161 to 145.7.72.174145.7.72.17514
140145.7.72.176/28145.7.72.177 to 145.7.72.190145.7.72.19114
141145.7.72.192/28145.7.72.193 to 145.7.72.206145.7.72.20714
142145.7.72.208/28145.7.72.209 to 145.7.72.222145.7.72.22314
143145.7.72.224/28145.7.72.225 to 145.7.72.238145.7.72.23914
144145.7.72.240/28145.7.72.241 to 145.7.72.254145.7.72.25514
145145.7.73.0/28145.7.73.1 to 145.7.73.14145.7.73.1514
146145.7.73.16/28145.7.73.17 to 145.7.73.30145.7.73.3114
147145.7.73.32/28145.7.73.33 to 145.7.73.46145.7.73.4714
148145.7.73.48/28145.7.73.49 to 145.7.73.62145.7.73.6314
149145.7.73.64/28145.7.73.65 to 145.7.73.78145.7.73.7914
150145.7.73.80/28145.7.73.81 to 145.7.73.94145.7.73.9514
151145.7.73.96/28145.7.73.97 to 145.7.73.110145.7.73.11114
152145.7.73.112/28145.7.73.113 to 145.7.73.126145.7.73.12714
153145.7.73.128/28145.7.73.129 to 145.7.73.142145.7.73.14314
154145.7.73.144/28145.7.73.145 to 145.7.73.158145.7.73.15914
155145.7.73.160/28145.7.73.161 to 145.7.73.174145.7.73.17514
156145.7.73.176/28145.7.73.177 to 145.7.73.190145.7.73.19114
157145.7.73.192/28145.7.73.193 to 145.7.73.206145.7.73.20714
158145.7.73.208/28145.7.73.209 to 145.7.73.222145.7.73.22314
159145.7.73.224/28145.7.73.225 to 145.7.73.238145.7.73.23914
160145.7.73.240/28145.7.73.241 to 145.7.73.254145.7.73.25514
161145.7.74.0/28145.7.74.1 to 145.7.74.14145.7.74.1514
162145.7.74.16/28145.7.74.17 to 145.7.74.30145.7.74.3114
163145.7.74.32/28145.7.74.33 to 145.7.74.46145.7.74.4714
164145.7.74.48/28145.7.74.49 to 145.7.74.62145.7.74.6314
165145.7.74.64/28145.7.74.65 to 145.7.74.78145.7.74.7914
166145.7.74.80/28145.7.74.81 to 145.7.74.94145.7.74.9514
167145.7.74.96/28145.7.74.97 to 145.7.74.110145.7.74.11114
168145.7.74.112/28145.7.74.113 to 145.7.74.126145.7.74.12714
169145.7.74.128/28145.7.74.129 to 145.7.74.142145.7.74.14314
170145.7.74.144/28145.7.74.145 to 145.7.74.158145.7.74.15914
171145.7.74.160/28145.7.74.161 to 145.7.74.174145.7.74.17514
172145.7.74.176/28145.7.74.177 to 145.7.74.190145.7.74.19114
173145.7.74.192/28145.7.74.193 to 145.7.74.206145.7.74.20714
174145.7.74.208/28145.7.74.209 to 145.7.74.222145.7.74.22314
175145.7.74.224/28145.7.74.225 to 145.7.74.238145.7.74.23914
176145.7.74.240/28145.7.74.241 to 145.7.74.254145.7.74.25514
177145.7.75.0/28145.7.75.1 to 145.7.75.14145.7.75.1514
178145.7.75.16/28145.7.75.17 to 145.7.75.30145.7.75.3114
179145.7.75.32/28145.7.75.33 to 145.7.75.46145.7.75.4714
180145.7.75.48/28145.7.75.49 to 145.7.75.62145.7.75.6314
181145.7.75.64/28145.7.75.65 to 145.7.75.78145.7.75.7914
182145.7.75.80/28145.7.75.81 to 145.7.75.94145.7.75.9514
183145.7.75.96/28145.7.75.97 to 145.7.75.110145.7.75.11114
184145.7.75.112/28145.7.75.113 to 145.7.75.126145.7.75.12714
185145.7.75.128/28145.7.75.129 to 145.7.75.142145.7.75.14314
186145.7.75.144/28145.7.75.145 to 145.7.75.158145.7.75.15914
187145.7.75.160/28145.7.75.161 to 145.7.75.174145.7.75.17514
188145.7.75.176/28145.7.75.177 to 145.7.75.190145.7.75.19114
189145.7.75.192/28145.7.75.193 to 145.7.75.206145.7.75.20714
190145.7.75.208/28145.7.75.209 to 145.7.75.222145.7.75.22314
191145.7.75.224/28145.7.75.225 to 145.7.75.238145.7.75.23914
192145.7.75.240/28145.7.75.241 to 145.7.75.254145.7.75.25514
193145.7.76.0/28145.7.76.1 to 145.7.76.14145.7.76.1514
194145.7.76.16/28145.7.76.17 to 145.7.76.30145.7.76.3114
195145.7.76.32/28145.7.76.33 to 145.7.76.46145.7.76.4714
196145.7.76.48/28145.7.76.49 to 145.7.76.62145.7.76.6314
197145.7.76.64/28145.7.76.65 to 145.7.76.78145.7.76.7914
198145.7.76.80/28145.7.76.81 to 145.7.76.94145.7.76.9514
199145.7.76.96/28145.7.76.97 to 145.7.76.110145.7.76.11114
200145.7.76.112/28145.7.76.113 to 145.7.76.126145.7.76.12714
201145.7.76.128/28145.7.76.129 to 145.7.76.142145.7.76.14314
202145.7.76.144/28145.7.76.145 to 145.7.76.158145.7.76.15914
203145.7.76.160/28145.7.76.161 to 145.7.76.174145.7.76.17514
204145.7.76.176/28145.7.76.177 to 145.7.76.190145.7.76.19114
205145.7.76.192/28145.7.76.193 to 145.7.76.206145.7.76.20714
206145.7.76.208/28145.7.76.209 to 145.7.76.222145.7.76.22314
207145.7.76.224/28145.7.76.225 to 145.7.76.238145.7.76.23914
208145.7.76.240/28145.7.76.241 to 145.7.76.254145.7.76.25514
209145.7.77.0/28145.7.77.1 to 145.7.77.14145.7.77.1514
210145.7.77.16/28145.7.77.17 to 145.7.77.30145.7.77.3114
211145.7.77.32/28145.7.77.33 to 145.7.77.46145.7.77.4714
212145.7.77.48/28145.7.77.49 to 145.7.77.62145.7.77.6314
213145.7.77.64/28145.7.77.65 to 145.7.77.78145.7.77.7914
214145.7.77.80/28145.7.77.81 to 145.7.77.94145.7.77.9514
215145.7.77.96/28145.7.77.97 to 145.7.77.110145.7.77.11114
216145.7.77.112/28145.7.77.113 to 145.7.77.126145.7.77.12714
217145.7.77.128/28145.7.77.129 to 145.7.77.142145.7.77.14314
218145.7.77.144/28145.7.77.145 to 145.7.77.158145.7.77.15914
219145.7.77.160/28145.7.77.161 to 145.7.77.174145.7.77.17514
220145.7.77.176/28145.7.77.177 to 145.7.77.190145.7.77.19114
221145.7.77.192/28145.7.77.193 to 145.7.77.206145.7.77.20714
222145.7.77.208/28145.7.77.209 to 145.7.77.222145.7.77.22314
223145.7.77.224/28145.7.77.225 to 145.7.77.238145.7.77.23914
224145.7.77.240/28145.7.77.241 to 145.7.77.254145.7.77.25514
225145.7.78.0/28145.7.78.1 to 145.7.78.14145.7.78.1514
226145.7.78.16/28145.7.78.17 to 145.7.78.30145.7.78.3114
227145.7.78.32/28145.7.78.33 to 145.7.78.46145.7.78.4714
228145.7.78.48/28145.7.78.49 to 145.7.78.62145.7.78.6314
229145.7.78.64/28145.7.78.65 to 145.7.78.78145.7.78.7914
230145.7.78.80/28145.7.78.81 to 145.7.78.94145.7.78.9514
231145.7.78.96/28145.7.78.97 to 145.7.78.110145.7.78.11114
232145.7.78.112/28145.7.78.113 to 145.7.78.126145.7.78.12714
233145.7.78.128/28145.7.78.129 to 145.7.78.142145.7.78.14314
234145.7.78.144/28145.7.78.145 to 145.7.78.158145.7.78.15914
235145.7.78.160/28145.7.78.161 to 145.7.78.174145.7.78.17514
236145.7.78.176/28145.7.78.177 to 145.7.78.190145.7.78.19114
237145.7.78.192/28145.7.78.193 to 145.7.78.206145.7.78.20714
238145.7.78.208/28145.7.78.209 to 145.7.78.222145.7.78.22314
239145.7.78.224/28145.7.78.225 to 145.7.78.238145.7.78.23914
240145.7.78.240/28145.7.78.241 to 145.7.78.254145.7.78.25514
241145.7.79.0/28145.7.79.1 to 145.7.79.14145.7.79.1514
242145.7.79.16/28145.7.79.17 to 145.7.79.30145.7.79.3114
243145.7.79.32/28145.7.79.33 to 145.7.79.46145.7.79.4714
244145.7.79.48/28145.7.79.49 to 145.7.79.62145.7.79.6314
245145.7.79.64/28145.7.79.65 to 145.7.79.78145.7.79.7914
246145.7.79.80/28145.7.79.81 to 145.7.79.94145.7.79.9514
247145.7.79.96/28145.7.79.97 to 145.7.79.110145.7.79.11114
248145.7.79.112/28145.7.79.113 to 145.7.79.126145.7.79.12714
249145.7.79.128/28145.7.79.129 to 145.7.79.142145.7.79.14314
250145.7.79.144/28145.7.79.145 to 145.7.79.158145.7.79.15914
251145.7.79.160/28145.7.79.161 to 145.7.79.174145.7.79.17514
252145.7.79.176/28145.7.79.177 to 145.7.79.190145.7.79.19114
253145.7.79.192/28145.7.79.193 to 145.7.79.206145.7.79.20714
254145.7.79.208/28145.7.79.209 to 145.7.79.222145.7.79.22314
255145.7.79.224/28145.7.79.225 to 145.7.79.238145.7.79.23914
256145.7.79.240/28145.7.79.241 to 145.7.79.254145.7.79.25514

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.