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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.

Network220.91.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
220.91.0.0
Broadcast address
220.91.127.255
First usable
220.91.0.1
Last usable
220.91.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
C (default /24)
As numbers
Hex DC5B0000 · Integer 3696951296 to 3696984063
Reverse DNS zones
0.91.220.in-addr.arpa
1.91.220.in-addr.arpa
2.91.220.in-addr.arpa
3.91.220.in-addr.arpa
4.91.220.in-addr.arpa
5.91.220.in-addr.arpa
6.91.220.in-addr.arpa
7.91.220.in-addr.arpa
8.91.220.in-addr.arpa
9.91.220.in-addr.arpa
10.91.220.in-addr.arpa
11.91.220.in-addr.arpa
12.91.220.in-addr.arpa
13.91.220.in-addr.arpa
14.91.220.in-addr.arpa
15.91.220.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011100.01011011.00000000.00000000220.91.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11011100.01011011.00000000.00000000220.91.0.0
Broadcast11011100.01011011.01111111.11111111220.91.127.255
Split into smaller subnets/28
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

220.91.0.0/17 makes 2,048 subnets of /28; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1220.91.0.0/28220.91.0.1 to 220.91.0.14220.91.0.1514
2220.91.0.16/28220.91.0.17 to 220.91.0.30220.91.0.3114
3220.91.0.32/28220.91.0.33 to 220.91.0.46220.91.0.4714
4220.91.0.48/28220.91.0.49 to 220.91.0.62220.91.0.6314
5220.91.0.64/28220.91.0.65 to 220.91.0.78220.91.0.7914
6220.91.0.80/28220.91.0.81 to 220.91.0.94220.91.0.9514
7220.91.0.96/28220.91.0.97 to 220.91.0.110220.91.0.11114
8220.91.0.112/28220.91.0.113 to 220.91.0.126220.91.0.12714
9220.91.0.128/28220.91.0.129 to 220.91.0.142220.91.0.14314
10220.91.0.144/28220.91.0.145 to 220.91.0.158220.91.0.15914
11220.91.0.160/28220.91.0.161 to 220.91.0.174220.91.0.17514
12220.91.0.176/28220.91.0.177 to 220.91.0.190220.91.0.19114
13220.91.0.192/28220.91.0.193 to 220.91.0.206220.91.0.20714
14220.91.0.208/28220.91.0.209 to 220.91.0.222220.91.0.22314
15220.91.0.224/28220.91.0.225 to 220.91.0.238220.91.0.23914
16220.91.0.240/28220.91.0.241 to 220.91.0.254220.91.0.25514
17220.91.1.0/28220.91.1.1 to 220.91.1.14220.91.1.1514
18220.91.1.16/28220.91.1.17 to 220.91.1.30220.91.1.3114
19220.91.1.32/28220.91.1.33 to 220.91.1.46220.91.1.4714
20220.91.1.48/28220.91.1.49 to 220.91.1.62220.91.1.6314
21220.91.1.64/28220.91.1.65 to 220.91.1.78220.91.1.7914
22220.91.1.80/28220.91.1.81 to 220.91.1.94220.91.1.9514
23220.91.1.96/28220.91.1.97 to 220.91.1.110220.91.1.11114
24220.91.1.112/28220.91.1.113 to 220.91.1.126220.91.1.12714
25220.91.1.128/28220.91.1.129 to 220.91.1.142220.91.1.14314
26220.91.1.144/28220.91.1.145 to 220.91.1.158220.91.1.15914
27220.91.1.160/28220.91.1.161 to 220.91.1.174220.91.1.17514
28220.91.1.176/28220.91.1.177 to 220.91.1.190220.91.1.19114
29220.91.1.192/28220.91.1.193 to 220.91.1.206220.91.1.20714
30220.91.1.208/28220.91.1.209 to 220.91.1.222220.91.1.22314
31220.91.1.224/28220.91.1.225 to 220.91.1.238220.91.1.23914
32220.91.1.240/28220.91.1.241 to 220.91.1.254220.91.1.25514
33220.91.2.0/28220.91.2.1 to 220.91.2.14220.91.2.1514
34220.91.2.16/28220.91.2.17 to 220.91.2.30220.91.2.3114
35220.91.2.32/28220.91.2.33 to 220.91.2.46220.91.2.4714
36220.91.2.48/28220.91.2.49 to 220.91.2.62220.91.2.6314
37220.91.2.64/28220.91.2.65 to 220.91.2.78220.91.2.7914
38220.91.2.80/28220.91.2.81 to 220.91.2.94220.91.2.9514
39220.91.2.96/28220.91.2.97 to 220.91.2.110220.91.2.11114
40220.91.2.112/28220.91.2.113 to 220.91.2.126220.91.2.12714
41220.91.2.128/28220.91.2.129 to 220.91.2.142220.91.2.14314
42220.91.2.144/28220.91.2.145 to 220.91.2.158220.91.2.15914
43220.91.2.160/28220.91.2.161 to 220.91.2.174220.91.2.17514
44220.91.2.176/28220.91.2.177 to 220.91.2.190220.91.2.19114
45220.91.2.192/28220.91.2.193 to 220.91.2.206220.91.2.20714
46220.91.2.208/28220.91.2.209 to 220.91.2.222220.91.2.22314
47220.91.2.224/28220.91.2.225 to 220.91.2.238220.91.2.23914
48220.91.2.240/28220.91.2.241 to 220.91.2.254220.91.2.25514
49220.91.3.0/28220.91.3.1 to 220.91.3.14220.91.3.1514
50220.91.3.16/28220.91.3.17 to 220.91.3.30220.91.3.3114
51220.91.3.32/28220.91.3.33 to 220.91.3.46220.91.3.4714
52220.91.3.48/28220.91.3.49 to 220.91.3.62220.91.3.6314
53220.91.3.64/28220.91.3.65 to 220.91.3.78220.91.3.7914
54220.91.3.80/28220.91.3.81 to 220.91.3.94220.91.3.9514
55220.91.3.96/28220.91.3.97 to 220.91.3.110220.91.3.11114
56220.91.3.112/28220.91.3.113 to 220.91.3.126220.91.3.12714
57220.91.3.128/28220.91.3.129 to 220.91.3.142220.91.3.14314
58220.91.3.144/28220.91.3.145 to 220.91.3.158220.91.3.15914
59220.91.3.160/28220.91.3.161 to 220.91.3.174220.91.3.17514
60220.91.3.176/28220.91.3.177 to 220.91.3.190220.91.3.19114
61220.91.3.192/28220.91.3.193 to 220.91.3.206220.91.3.20714
62220.91.3.208/28220.91.3.209 to 220.91.3.222220.91.3.22314
63220.91.3.224/28220.91.3.225 to 220.91.3.238220.91.3.23914
64220.91.3.240/28220.91.3.241 to 220.91.3.254220.91.3.25514
65220.91.4.0/28220.91.4.1 to 220.91.4.14220.91.4.1514
66220.91.4.16/28220.91.4.17 to 220.91.4.30220.91.4.3114
67220.91.4.32/28220.91.4.33 to 220.91.4.46220.91.4.4714
68220.91.4.48/28220.91.4.49 to 220.91.4.62220.91.4.6314
69220.91.4.64/28220.91.4.65 to 220.91.4.78220.91.4.7914
70220.91.4.80/28220.91.4.81 to 220.91.4.94220.91.4.9514
71220.91.4.96/28220.91.4.97 to 220.91.4.110220.91.4.11114
72220.91.4.112/28220.91.4.113 to 220.91.4.126220.91.4.12714
73220.91.4.128/28220.91.4.129 to 220.91.4.142220.91.4.14314
74220.91.4.144/28220.91.4.145 to 220.91.4.158220.91.4.15914
75220.91.4.160/28220.91.4.161 to 220.91.4.174220.91.4.17514
76220.91.4.176/28220.91.4.177 to 220.91.4.190220.91.4.19114
77220.91.4.192/28220.91.4.193 to 220.91.4.206220.91.4.20714
78220.91.4.208/28220.91.4.209 to 220.91.4.222220.91.4.22314
79220.91.4.224/28220.91.4.225 to 220.91.4.238220.91.4.23914
80220.91.4.240/28220.91.4.241 to 220.91.4.254220.91.4.25514
81220.91.5.0/28220.91.5.1 to 220.91.5.14220.91.5.1514
82220.91.5.16/28220.91.5.17 to 220.91.5.30220.91.5.3114
83220.91.5.32/28220.91.5.33 to 220.91.5.46220.91.5.4714
84220.91.5.48/28220.91.5.49 to 220.91.5.62220.91.5.6314
85220.91.5.64/28220.91.5.65 to 220.91.5.78220.91.5.7914
86220.91.5.80/28220.91.5.81 to 220.91.5.94220.91.5.9514
87220.91.5.96/28220.91.5.97 to 220.91.5.110220.91.5.11114
88220.91.5.112/28220.91.5.113 to 220.91.5.126220.91.5.12714
89220.91.5.128/28220.91.5.129 to 220.91.5.142220.91.5.14314
90220.91.5.144/28220.91.5.145 to 220.91.5.158220.91.5.15914
91220.91.5.160/28220.91.5.161 to 220.91.5.174220.91.5.17514
92220.91.5.176/28220.91.5.177 to 220.91.5.190220.91.5.19114
93220.91.5.192/28220.91.5.193 to 220.91.5.206220.91.5.20714
94220.91.5.208/28220.91.5.209 to 220.91.5.222220.91.5.22314
95220.91.5.224/28220.91.5.225 to 220.91.5.238220.91.5.23914
96220.91.5.240/28220.91.5.241 to 220.91.5.254220.91.5.25514
97220.91.6.0/28220.91.6.1 to 220.91.6.14220.91.6.1514
98220.91.6.16/28220.91.6.17 to 220.91.6.30220.91.6.3114
99220.91.6.32/28220.91.6.33 to 220.91.6.46220.91.6.4714
100220.91.6.48/28220.91.6.49 to 220.91.6.62220.91.6.6314
101220.91.6.64/28220.91.6.65 to 220.91.6.78220.91.6.7914
102220.91.6.80/28220.91.6.81 to 220.91.6.94220.91.6.9514
103220.91.6.96/28220.91.6.97 to 220.91.6.110220.91.6.11114
104220.91.6.112/28220.91.6.113 to 220.91.6.126220.91.6.12714
105220.91.6.128/28220.91.6.129 to 220.91.6.142220.91.6.14314
106220.91.6.144/28220.91.6.145 to 220.91.6.158220.91.6.15914
107220.91.6.160/28220.91.6.161 to 220.91.6.174220.91.6.17514
108220.91.6.176/28220.91.6.177 to 220.91.6.190220.91.6.19114
109220.91.6.192/28220.91.6.193 to 220.91.6.206220.91.6.20714
110220.91.6.208/28220.91.6.209 to 220.91.6.222220.91.6.22314
111220.91.6.224/28220.91.6.225 to 220.91.6.238220.91.6.23914
112220.91.6.240/28220.91.6.241 to 220.91.6.254220.91.6.25514
113220.91.7.0/28220.91.7.1 to 220.91.7.14220.91.7.1514
114220.91.7.16/28220.91.7.17 to 220.91.7.30220.91.7.3114
115220.91.7.32/28220.91.7.33 to 220.91.7.46220.91.7.4714
116220.91.7.48/28220.91.7.49 to 220.91.7.62220.91.7.6314
117220.91.7.64/28220.91.7.65 to 220.91.7.78220.91.7.7914
118220.91.7.80/28220.91.7.81 to 220.91.7.94220.91.7.9514
119220.91.7.96/28220.91.7.97 to 220.91.7.110220.91.7.11114
120220.91.7.112/28220.91.7.113 to 220.91.7.126220.91.7.12714
121220.91.7.128/28220.91.7.129 to 220.91.7.142220.91.7.14314
122220.91.7.144/28220.91.7.145 to 220.91.7.158220.91.7.15914
123220.91.7.160/28220.91.7.161 to 220.91.7.174220.91.7.17514
124220.91.7.176/28220.91.7.177 to 220.91.7.190220.91.7.19114
125220.91.7.192/28220.91.7.193 to 220.91.7.206220.91.7.20714
126220.91.7.208/28220.91.7.209 to 220.91.7.222220.91.7.22314
127220.91.7.224/28220.91.7.225 to 220.91.7.238220.91.7.23914
128220.91.7.240/28220.91.7.241 to 220.91.7.254220.91.7.25514
129220.91.8.0/28220.91.8.1 to 220.91.8.14220.91.8.1514
130220.91.8.16/28220.91.8.17 to 220.91.8.30220.91.8.3114
131220.91.8.32/28220.91.8.33 to 220.91.8.46220.91.8.4714
132220.91.8.48/28220.91.8.49 to 220.91.8.62220.91.8.6314
133220.91.8.64/28220.91.8.65 to 220.91.8.78220.91.8.7914
134220.91.8.80/28220.91.8.81 to 220.91.8.94220.91.8.9514
135220.91.8.96/28220.91.8.97 to 220.91.8.110220.91.8.11114
136220.91.8.112/28220.91.8.113 to 220.91.8.126220.91.8.12714
137220.91.8.128/28220.91.8.129 to 220.91.8.142220.91.8.14314
138220.91.8.144/28220.91.8.145 to 220.91.8.158220.91.8.15914
139220.91.8.160/28220.91.8.161 to 220.91.8.174220.91.8.17514
140220.91.8.176/28220.91.8.177 to 220.91.8.190220.91.8.19114
141220.91.8.192/28220.91.8.193 to 220.91.8.206220.91.8.20714
142220.91.8.208/28220.91.8.209 to 220.91.8.222220.91.8.22314
143220.91.8.224/28220.91.8.225 to 220.91.8.238220.91.8.23914
144220.91.8.240/28220.91.8.241 to 220.91.8.254220.91.8.25514
145220.91.9.0/28220.91.9.1 to 220.91.9.14220.91.9.1514
146220.91.9.16/28220.91.9.17 to 220.91.9.30220.91.9.3114
147220.91.9.32/28220.91.9.33 to 220.91.9.46220.91.9.4714
148220.91.9.48/28220.91.9.49 to 220.91.9.62220.91.9.6314
149220.91.9.64/28220.91.9.65 to 220.91.9.78220.91.9.7914
150220.91.9.80/28220.91.9.81 to 220.91.9.94220.91.9.9514
151220.91.9.96/28220.91.9.97 to 220.91.9.110220.91.9.11114
152220.91.9.112/28220.91.9.113 to 220.91.9.126220.91.9.12714
153220.91.9.128/28220.91.9.129 to 220.91.9.142220.91.9.14314
154220.91.9.144/28220.91.9.145 to 220.91.9.158220.91.9.15914
155220.91.9.160/28220.91.9.161 to 220.91.9.174220.91.9.17514
156220.91.9.176/28220.91.9.177 to 220.91.9.190220.91.9.19114
157220.91.9.192/28220.91.9.193 to 220.91.9.206220.91.9.20714
158220.91.9.208/28220.91.9.209 to 220.91.9.222220.91.9.22314
159220.91.9.224/28220.91.9.225 to 220.91.9.238220.91.9.23914
160220.91.9.240/28220.91.9.241 to 220.91.9.254220.91.9.25514
161220.91.10.0/28220.91.10.1 to 220.91.10.14220.91.10.1514
162220.91.10.16/28220.91.10.17 to 220.91.10.30220.91.10.3114
163220.91.10.32/28220.91.10.33 to 220.91.10.46220.91.10.4714
164220.91.10.48/28220.91.10.49 to 220.91.10.62220.91.10.6314
165220.91.10.64/28220.91.10.65 to 220.91.10.78220.91.10.7914
166220.91.10.80/28220.91.10.81 to 220.91.10.94220.91.10.9514
167220.91.10.96/28220.91.10.97 to 220.91.10.110220.91.10.11114
168220.91.10.112/28220.91.10.113 to 220.91.10.126220.91.10.12714
169220.91.10.128/28220.91.10.129 to 220.91.10.142220.91.10.14314
170220.91.10.144/28220.91.10.145 to 220.91.10.158220.91.10.15914
171220.91.10.160/28220.91.10.161 to 220.91.10.174220.91.10.17514
172220.91.10.176/28220.91.10.177 to 220.91.10.190220.91.10.19114
173220.91.10.192/28220.91.10.193 to 220.91.10.206220.91.10.20714
174220.91.10.208/28220.91.10.209 to 220.91.10.222220.91.10.22314
175220.91.10.224/28220.91.10.225 to 220.91.10.238220.91.10.23914
176220.91.10.240/28220.91.10.241 to 220.91.10.254220.91.10.25514
177220.91.11.0/28220.91.11.1 to 220.91.11.14220.91.11.1514
178220.91.11.16/28220.91.11.17 to 220.91.11.30220.91.11.3114
179220.91.11.32/28220.91.11.33 to 220.91.11.46220.91.11.4714
180220.91.11.48/28220.91.11.49 to 220.91.11.62220.91.11.6314
181220.91.11.64/28220.91.11.65 to 220.91.11.78220.91.11.7914
182220.91.11.80/28220.91.11.81 to 220.91.11.94220.91.11.9514
183220.91.11.96/28220.91.11.97 to 220.91.11.110220.91.11.11114
184220.91.11.112/28220.91.11.113 to 220.91.11.126220.91.11.12714
185220.91.11.128/28220.91.11.129 to 220.91.11.142220.91.11.14314
186220.91.11.144/28220.91.11.145 to 220.91.11.158220.91.11.15914
187220.91.11.160/28220.91.11.161 to 220.91.11.174220.91.11.17514
188220.91.11.176/28220.91.11.177 to 220.91.11.190220.91.11.19114
189220.91.11.192/28220.91.11.193 to 220.91.11.206220.91.11.20714
190220.91.11.208/28220.91.11.209 to 220.91.11.222220.91.11.22314
191220.91.11.224/28220.91.11.225 to 220.91.11.238220.91.11.23914
192220.91.11.240/28220.91.11.241 to 220.91.11.254220.91.11.25514
193220.91.12.0/28220.91.12.1 to 220.91.12.14220.91.12.1514
194220.91.12.16/28220.91.12.17 to 220.91.12.30220.91.12.3114
195220.91.12.32/28220.91.12.33 to 220.91.12.46220.91.12.4714
196220.91.12.48/28220.91.12.49 to 220.91.12.62220.91.12.6314
197220.91.12.64/28220.91.12.65 to 220.91.12.78220.91.12.7914
198220.91.12.80/28220.91.12.81 to 220.91.12.94220.91.12.9514
199220.91.12.96/28220.91.12.97 to 220.91.12.110220.91.12.11114
200220.91.12.112/28220.91.12.113 to 220.91.12.126220.91.12.12714
201220.91.12.128/28220.91.12.129 to 220.91.12.142220.91.12.14314
202220.91.12.144/28220.91.12.145 to 220.91.12.158220.91.12.15914
203220.91.12.160/28220.91.12.161 to 220.91.12.174220.91.12.17514
204220.91.12.176/28220.91.12.177 to 220.91.12.190220.91.12.19114
205220.91.12.192/28220.91.12.193 to 220.91.12.206220.91.12.20714
206220.91.12.208/28220.91.12.209 to 220.91.12.222220.91.12.22314
207220.91.12.224/28220.91.12.225 to 220.91.12.238220.91.12.23914
208220.91.12.240/28220.91.12.241 to 220.91.12.254220.91.12.25514
209220.91.13.0/28220.91.13.1 to 220.91.13.14220.91.13.1514
210220.91.13.16/28220.91.13.17 to 220.91.13.30220.91.13.3114
211220.91.13.32/28220.91.13.33 to 220.91.13.46220.91.13.4714
212220.91.13.48/28220.91.13.49 to 220.91.13.62220.91.13.6314
213220.91.13.64/28220.91.13.65 to 220.91.13.78220.91.13.7914
214220.91.13.80/28220.91.13.81 to 220.91.13.94220.91.13.9514
215220.91.13.96/28220.91.13.97 to 220.91.13.110220.91.13.11114
216220.91.13.112/28220.91.13.113 to 220.91.13.126220.91.13.12714
217220.91.13.128/28220.91.13.129 to 220.91.13.142220.91.13.14314
218220.91.13.144/28220.91.13.145 to 220.91.13.158220.91.13.15914
219220.91.13.160/28220.91.13.161 to 220.91.13.174220.91.13.17514
220220.91.13.176/28220.91.13.177 to 220.91.13.190220.91.13.19114
221220.91.13.192/28220.91.13.193 to 220.91.13.206220.91.13.20714
222220.91.13.208/28220.91.13.209 to 220.91.13.222220.91.13.22314
223220.91.13.224/28220.91.13.225 to 220.91.13.238220.91.13.23914
224220.91.13.240/28220.91.13.241 to 220.91.13.254220.91.13.25514
225220.91.14.0/28220.91.14.1 to 220.91.14.14220.91.14.1514
226220.91.14.16/28220.91.14.17 to 220.91.14.30220.91.14.3114
227220.91.14.32/28220.91.14.33 to 220.91.14.46220.91.14.4714
228220.91.14.48/28220.91.14.49 to 220.91.14.62220.91.14.6314
229220.91.14.64/28220.91.14.65 to 220.91.14.78220.91.14.7914
230220.91.14.80/28220.91.14.81 to 220.91.14.94220.91.14.9514
231220.91.14.96/28220.91.14.97 to 220.91.14.110220.91.14.11114
232220.91.14.112/28220.91.14.113 to 220.91.14.126220.91.14.12714
233220.91.14.128/28220.91.14.129 to 220.91.14.142220.91.14.14314
234220.91.14.144/28220.91.14.145 to 220.91.14.158220.91.14.15914
235220.91.14.160/28220.91.14.161 to 220.91.14.174220.91.14.17514
236220.91.14.176/28220.91.14.177 to 220.91.14.190220.91.14.19114
237220.91.14.192/28220.91.14.193 to 220.91.14.206220.91.14.20714
238220.91.14.208/28220.91.14.209 to 220.91.14.222220.91.14.22314
239220.91.14.224/28220.91.14.225 to 220.91.14.238220.91.14.23914
240220.91.14.240/28220.91.14.241 to 220.91.14.254220.91.14.25514
241220.91.15.0/28220.91.15.1 to 220.91.15.14220.91.15.1514
242220.91.15.16/28220.91.15.17 to 220.91.15.30220.91.15.3114
243220.91.15.32/28220.91.15.33 to 220.91.15.46220.91.15.4714
244220.91.15.48/28220.91.15.49 to 220.91.15.62220.91.15.6314
245220.91.15.64/28220.91.15.65 to 220.91.15.78220.91.15.7914
246220.91.15.80/28220.91.15.81 to 220.91.15.94220.91.15.9514
247220.91.15.96/28220.91.15.97 to 220.91.15.110220.91.15.11114
248220.91.15.112/28220.91.15.113 to 220.91.15.126220.91.15.12714
249220.91.15.128/28220.91.15.129 to 220.91.15.142220.91.15.14314
250220.91.15.144/28220.91.15.145 to 220.91.15.158220.91.15.15914
251220.91.15.160/28220.91.15.161 to 220.91.15.174220.91.15.17514
252220.91.15.176/28220.91.15.177 to 220.91.15.190220.91.15.19114
253220.91.15.192/28220.91.15.193 to 220.91.15.206220.91.15.20714
254220.91.15.208/28220.91.15.209 to 220.91.15.222220.91.15.22314
255220.91.15.224/28220.91.15.225 to 220.91.15.238220.91.15.23914
256220.91.15.240/28220.91.15.241 to 220.91.15.254220.91.15.25514

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.