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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.

Network243.78.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
243.78.0.0
Broadcast address
243.78.63.255
First usable
243.78.0.1
Last usable
243.78.63.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F34E0000 · Integer 4081975296 to 4081991679
Reverse DNS zones
0.78.243.in-addr.arpa
1.78.243.in-addr.arpa
2.78.243.in-addr.arpa
3.78.243.in-addr.arpa
4.78.243.in-addr.arpa
5.78.243.in-addr.arpa
6.78.243.in-addr.arpa
7.78.243.in-addr.arpa
8.78.243.in-addr.arpa
9.78.243.in-addr.arpa
10.78.243.in-addr.arpa
11.78.243.in-addr.arpa
12.78.243.in-addr.arpa
13.78.243.in-addr.arpa
14.78.243.in-addr.arpa
15.78.243.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
Address11110011.01001110.00000000.00000000243.78.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11110011.01001110.00000000.00000000243.78.0.0
Broadcast11110011.01001110.00111111.11111111243.78.63.255
Split into smaller subnets/29
/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)

243.78.0.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1243.78.0.0/29243.78.0.1 to 243.78.0.6243.78.0.76
2243.78.0.8/29243.78.0.9 to 243.78.0.14243.78.0.156
3243.78.0.16/29243.78.0.17 to 243.78.0.22243.78.0.236
4243.78.0.24/29243.78.0.25 to 243.78.0.30243.78.0.316
5243.78.0.32/29243.78.0.33 to 243.78.0.38243.78.0.396
6243.78.0.40/29243.78.0.41 to 243.78.0.46243.78.0.476
7243.78.0.48/29243.78.0.49 to 243.78.0.54243.78.0.556
8243.78.0.56/29243.78.0.57 to 243.78.0.62243.78.0.636
9243.78.0.64/29243.78.0.65 to 243.78.0.70243.78.0.716
10243.78.0.72/29243.78.0.73 to 243.78.0.78243.78.0.796
11243.78.0.80/29243.78.0.81 to 243.78.0.86243.78.0.876
12243.78.0.88/29243.78.0.89 to 243.78.0.94243.78.0.956
13243.78.0.96/29243.78.0.97 to 243.78.0.102243.78.0.1036
14243.78.0.104/29243.78.0.105 to 243.78.0.110243.78.0.1116
15243.78.0.112/29243.78.0.113 to 243.78.0.118243.78.0.1196
16243.78.0.120/29243.78.0.121 to 243.78.0.126243.78.0.1276
17243.78.0.128/29243.78.0.129 to 243.78.0.134243.78.0.1356
18243.78.0.136/29243.78.0.137 to 243.78.0.142243.78.0.1436
19243.78.0.144/29243.78.0.145 to 243.78.0.150243.78.0.1516
20243.78.0.152/29243.78.0.153 to 243.78.0.158243.78.0.1596
21243.78.0.160/29243.78.0.161 to 243.78.0.166243.78.0.1676
22243.78.0.168/29243.78.0.169 to 243.78.0.174243.78.0.1756
23243.78.0.176/29243.78.0.177 to 243.78.0.182243.78.0.1836
24243.78.0.184/29243.78.0.185 to 243.78.0.190243.78.0.1916
25243.78.0.192/29243.78.0.193 to 243.78.0.198243.78.0.1996
26243.78.0.200/29243.78.0.201 to 243.78.0.206243.78.0.2076
27243.78.0.208/29243.78.0.209 to 243.78.0.214243.78.0.2156
28243.78.0.216/29243.78.0.217 to 243.78.0.222243.78.0.2236
29243.78.0.224/29243.78.0.225 to 243.78.0.230243.78.0.2316
30243.78.0.232/29243.78.0.233 to 243.78.0.238243.78.0.2396
31243.78.0.240/29243.78.0.241 to 243.78.0.246243.78.0.2476
32243.78.0.248/29243.78.0.249 to 243.78.0.254243.78.0.2556
33243.78.1.0/29243.78.1.1 to 243.78.1.6243.78.1.76
34243.78.1.8/29243.78.1.9 to 243.78.1.14243.78.1.156
35243.78.1.16/29243.78.1.17 to 243.78.1.22243.78.1.236
36243.78.1.24/29243.78.1.25 to 243.78.1.30243.78.1.316
37243.78.1.32/29243.78.1.33 to 243.78.1.38243.78.1.396
38243.78.1.40/29243.78.1.41 to 243.78.1.46243.78.1.476
39243.78.1.48/29243.78.1.49 to 243.78.1.54243.78.1.556
40243.78.1.56/29243.78.1.57 to 243.78.1.62243.78.1.636
41243.78.1.64/29243.78.1.65 to 243.78.1.70243.78.1.716
42243.78.1.72/29243.78.1.73 to 243.78.1.78243.78.1.796
43243.78.1.80/29243.78.1.81 to 243.78.1.86243.78.1.876
44243.78.1.88/29243.78.1.89 to 243.78.1.94243.78.1.956
45243.78.1.96/29243.78.1.97 to 243.78.1.102243.78.1.1036
46243.78.1.104/29243.78.1.105 to 243.78.1.110243.78.1.1116
47243.78.1.112/29243.78.1.113 to 243.78.1.118243.78.1.1196
48243.78.1.120/29243.78.1.121 to 243.78.1.126243.78.1.1276
49243.78.1.128/29243.78.1.129 to 243.78.1.134243.78.1.1356
50243.78.1.136/29243.78.1.137 to 243.78.1.142243.78.1.1436
51243.78.1.144/29243.78.1.145 to 243.78.1.150243.78.1.1516
52243.78.1.152/29243.78.1.153 to 243.78.1.158243.78.1.1596
53243.78.1.160/29243.78.1.161 to 243.78.1.166243.78.1.1676
54243.78.1.168/29243.78.1.169 to 243.78.1.174243.78.1.1756
55243.78.1.176/29243.78.1.177 to 243.78.1.182243.78.1.1836
56243.78.1.184/29243.78.1.185 to 243.78.1.190243.78.1.1916
57243.78.1.192/29243.78.1.193 to 243.78.1.198243.78.1.1996
58243.78.1.200/29243.78.1.201 to 243.78.1.206243.78.1.2076
59243.78.1.208/29243.78.1.209 to 243.78.1.214243.78.1.2156
60243.78.1.216/29243.78.1.217 to 243.78.1.222243.78.1.2236
61243.78.1.224/29243.78.1.225 to 243.78.1.230243.78.1.2316
62243.78.1.232/29243.78.1.233 to 243.78.1.238243.78.1.2396
63243.78.1.240/29243.78.1.241 to 243.78.1.246243.78.1.2476
64243.78.1.248/29243.78.1.249 to 243.78.1.254243.78.1.2556
65243.78.2.0/29243.78.2.1 to 243.78.2.6243.78.2.76
66243.78.2.8/29243.78.2.9 to 243.78.2.14243.78.2.156
67243.78.2.16/29243.78.2.17 to 243.78.2.22243.78.2.236
68243.78.2.24/29243.78.2.25 to 243.78.2.30243.78.2.316
69243.78.2.32/29243.78.2.33 to 243.78.2.38243.78.2.396
70243.78.2.40/29243.78.2.41 to 243.78.2.46243.78.2.476
71243.78.2.48/29243.78.2.49 to 243.78.2.54243.78.2.556
72243.78.2.56/29243.78.2.57 to 243.78.2.62243.78.2.636
73243.78.2.64/29243.78.2.65 to 243.78.2.70243.78.2.716
74243.78.2.72/29243.78.2.73 to 243.78.2.78243.78.2.796
75243.78.2.80/29243.78.2.81 to 243.78.2.86243.78.2.876
76243.78.2.88/29243.78.2.89 to 243.78.2.94243.78.2.956
77243.78.2.96/29243.78.2.97 to 243.78.2.102243.78.2.1036
78243.78.2.104/29243.78.2.105 to 243.78.2.110243.78.2.1116
79243.78.2.112/29243.78.2.113 to 243.78.2.118243.78.2.1196
80243.78.2.120/29243.78.2.121 to 243.78.2.126243.78.2.1276
81243.78.2.128/29243.78.2.129 to 243.78.2.134243.78.2.1356
82243.78.2.136/29243.78.2.137 to 243.78.2.142243.78.2.1436
83243.78.2.144/29243.78.2.145 to 243.78.2.150243.78.2.1516
84243.78.2.152/29243.78.2.153 to 243.78.2.158243.78.2.1596
85243.78.2.160/29243.78.2.161 to 243.78.2.166243.78.2.1676
86243.78.2.168/29243.78.2.169 to 243.78.2.174243.78.2.1756
87243.78.2.176/29243.78.2.177 to 243.78.2.182243.78.2.1836
88243.78.2.184/29243.78.2.185 to 243.78.2.190243.78.2.1916
89243.78.2.192/29243.78.2.193 to 243.78.2.198243.78.2.1996
90243.78.2.200/29243.78.2.201 to 243.78.2.206243.78.2.2076
91243.78.2.208/29243.78.2.209 to 243.78.2.214243.78.2.2156
92243.78.2.216/29243.78.2.217 to 243.78.2.222243.78.2.2236
93243.78.2.224/29243.78.2.225 to 243.78.2.230243.78.2.2316
94243.78.2.232/29243.78.2.233 to 243.78.2.238243.78.2.2396
95243.78.2.240/29243.78.2.241 to 243.78.2.246243.78.2.2476
96243.78.2.248/29243.78.2.249 to 243.78.2.254243.78.2.2556
97243.78.3.0/29243.78.3.1 to 243.78.3.6243.78.3.76
98243.78.3.8/29243.78.3.9 to 243.78.3.14243.78.3.156
99243.78.3.16/29243.78.3.17 to 243.78.3.22243.78.3.236
100243.78.3.24/29243.78.3.25 to 243.78.3.30243.78.3.316
101243.78.3.32/29243.78.3.33 to 243.78.3.38243.78.3.396
102243.78.3.40/29243.78.3.41 to 243.78.3.46243.78.3.476
103243.78.3.48/29243.78.3.49 to 243.78.3.54243.78.3.556
104243.78.3.56/29243.78.3.57 to 243.78.3.62243.78.3.636
105243.78.3.64/29243.78.3.65 to 243.78.3.70243.78.3.716
106243.78.3.72/29243.78.3.73 to 243.78.3.78243.78.3.796
107243.78.3.80/29243.78.3.81 to 243.78.3.86243.78.3.876
108243.78.3.88/29243.78.3.89 to 243.78.3.94243.78.3.956
109243.78.3.96/29243.78.3.97 to 243.78.3.102243.78.3.1036
110243.78.3.104/29243.78.3.105 to 243.78.3.110243.78.3.1116
111243.78.3.112/29243.78.3.113 to 243.78.3.118243.78.3.1196
112243.78.3.120/29243.78.3.121 to 243.78.3.126243.78.3.1276
113243.78.3.128/29243.78.3.129 to 243.78.3.134243.78.3.1356
114243.78.3.136/29243.78.3.137 to 243.78.3.142243.78.3.1436
115243.78.3.144/29243.78.3.145 to 243.78.3.150243.78.3.1516
116243.78.3.152/29243.78.3.153 to 243.78.3.158243.78.3.1596
117243.78.3.160/29243.78.3.161 to 243.78.3.166243.78.3.1676
118243.78.3.168/29243.78.3.169 to 243.78.3.174243.78.3.1756
119243.78.3.176/29243.78.3.177 to 243.78.3.182243.78.3.1836
120243.78.3.184/29243.78.3.185 to 243.78.3.190243.78.3.1916
121243.78.3.192/29243.78.3.193 to 243.78.3.198243.78.3.1996
122243.78.3.200/29243.78.3.201 to 243.78.3.206243.78.3.2076
123243.78.3.208/29243.78.3.209 to 243.78.3.214243.78.3.2156
124243.78.3.216/29243.78.3.217 to 243.78.3.222243.78.3.2236
125243.78.3.224/29243.78.3.225 to 243.78.3.230243.78.3.2316
126243.78.3.232/29243.78.3.233 to 243.78.3.238243.78.3.2396
127243.78.3.240/29243.78.3.241 to 243.78.3.246243.78.3.2476
128243.78.3.248/29243.78.3.249 to 243.78.3.254243.78.3.2556
129243.78.4.0/29243.78.4.1 to 243.78.4.6243.78.4.76
130243.78.4.8/29243.78.4.9 to 243.78.4.14243.78.4.156
131243.78.4.16/29243.78.4.17 to 243.78.4.22243.78.4.236
132243.78.4.24/29243.78.4.25 to 243.78.4.30243.78.4.316
133243.78.4.32/29243.78.4.33 to 243.78.4.38243.78.4.396
134243.78.4.40/29243.78.4.41 to 243.78.4.46243.78.4.476
135243.78.4.48/29243.78.4.49 to 243.78.4.54243.78.4.556
136243.78.4.56/29243.78.4.57 to 243.78.4.62243.78.4.636
137243.78.4.64/29243.78.4.65 to 243.78.4.70243.78.4.716
138243.78.4.72/29243.78.4.73 to 243.78.4.78243.78.4.796
139243.78.4.80/29243.78.4.81 to 243.78.4.86243.78.4.876
140243.78.4.88/29243.78.4.89 to 243.78.4.94243.78.4.956
141243.78.4.96/29243.78.4.97 to 243.78.4.102243.78.4.1036
142243.78.4.104/29243.78.4.105 to 243.78.4.110243.78.4.1116
143243.78.4.112/29243.78.4.113 to 243.78.4.118243.78.4.1196
144243.78.4.120/29243.78.4.121 to 243.78.4.126243.78.4.1276
145243.78.4.128/29243.78.4.129 to 243.78.4.134243.78.4.1356
146243.78.4.136/29243.78.4.137 to 243.78.4.142243.78.4.1436
147243.78.4.144/29243.78.4.145 to 243.78.4.150243.78.4.1516
148243.78.4.152/29243.78.4.153 to 243.78.4.158243.78.4.1596
149243.78.4.160/29243.78.4.161 to 243.78.4.166243.78.4.1676
150243.78.4.168/29243.78.4.169 to 243.78.4.174243.78.4.1756
151243.78.4.176/29243.78.4.177 to 243.78.4.182243.78.4.1836
152243.78.4.184/29243.78.4.185 to 243.78.4.190243.78.4.1916
153243.78.4.192/29243.78.4.193 to 243.78.4.198243.78.4.1996
154243.78.4.200/29243.78.4.201 to 243.78.4.206243.78.4.2076
155243.78.4.208/29243.78.4.209 to 243.78.4.214243.78.4.2156
156243.78.4.216/29243.78.4.217 to 243.78.4.222243.78.4.2236
157243.78.4.224/29243.78.4.225 to 243.78.4.230243.78.4.2316
158243.78.4.232/29243.78.4.233 to 243.78.4.238243.78.4.2396
159243.78.4.240/29243.78.4.241 to 243.78.4.246243.78.4.2476
160243.78.4.248/29243.78.4.249 to 243.78.4.254243.78.4.2556
161243.78.5.0/29243.78.5.1 to 243.78.5.6243.78.5.76
162243.78.5.8/29243.78.5.9 to 243.78.5.14243.78.5.156
163243.78.5.16/29243.78.5.17 to 243.78.5.22243.78.5.236
164243.78.5.24/29243.78.5.25 to 243.78.5.30243.78.5.316
165243.78.5.32/29243.78.5.33 to 243.78.5.38243.78.5.396
166243.78.5.40/29243.78.5.41 to 243.78.5.46243.78.5.476
167243.78.5.48/29243.78.5.49 to 243.78.5.54243.78.5.556
168243.78.5.56/29243.78.5.57 to 243.78.5.62243.78.5.636
169243.78.5.64/29243.78.5.65 to 243.78.5.70243.78.5.716
170243.78.5.72/29243.78.5.73 to 243.78.5.78243.78.5.796
171243.78.5.80/29243.78.5.81 to 243.78.5.86243.78.5.876
172243.78.5.88/29243.78.5.89 to 243.78.5.94243.78.5.956
173243.78.5.96/29243.78.5.97 to 243.78.5.102243.78.5.1036
174243.78.5.104/29243.78.5.105 to 243.78.5.110243.78.5.1116
175243.78.5.112/29243.78.5.113 to 243.78.5.118243.78.5.1196
176243.78.5.120/29243.78.5.121 to 243.78.5.126243.78.5.1276
177243.78.5.128/29243.78.5.129 to 243.78.5.134243.78.5.1356
178243.78.5.136/29243.78.5.137 to 243.78.5.142243.78.5.1436
179243.78.5.144/29243.78.5.145 to 243.78.5.150243.78.5.1516
180243.78.5.152/29243.78.5.153 to 243.78.5.158243.78.5.1596
181243.78.5.160/29243.78.5.161 to 243.78.5.166243.78.5.1676
182243.78.5.168/29243.78.5.169 to 243.78.5.174243.78.5.1756
183243.78.5.176/29243.78.5.177 to 243.78.5.182243.78.5.1836
184243.78.5.184/29243.78.5.185 to 243.78.5.190243.78.5.1916
185243.78.5.192/29243.78.5.193 to 243.78.5.198243.78.5.1996
186243.78.5.200/29243.78.5.201 to 243.78.5.206243.78.5.2076
187243.78.5.208/29243.78.5.209 to 243.78.5.214243.78.5.2156
188243.78.5.216/29243.78.5.217 to 243.78.5.222243.78.5.2236
189243.78.5.224/29243.78.5.225 to 243.78.5.230243.78.5.2316
190243.78.5.232/29243.78.5.233 to 243.78.5.238243.78.5.2396
191243.78.5.240/29243.78.5.241 to 243.78.5.246243.78.5.2476
192243.78.5.248/29243.78.5.249 to 243.78.5.254243.78.5.2556
193243.78.6.0/29243.78.6.1 to 243.78.6.6243.78.6.76
194243.78.6.8/29243.78.6.9 to 243.78.6.14243.78.6.156
195243.78.6.16/29243.78.6.17 to 243.78.6.22243.78.6.236
196243.78.6.24/29243.78.6.25 to 243.78.6.30243.78.6.316
197243.78.6.32/29243.78.6.33 to 243.78.6.38243.78.6.396
198243.78.6.40/29243.78.6.41 to 243.78.6.46243.78.6.476
199243.78.6.48/29243.78.6.49 to 243.78.6.54243.78.6.556
200243.78.6.56/29243.78.6.57 to 243.78.6.62243.78.6.636
201243.78.6.64/29243.78.6.65 to 243.78.6.70243.78.6.716
202243.78.6.72/29243.78.6.73 to 243.78.6.78243.78.6.796
203243.78.6.80/29243.78.6.81 to 243.78.6.86243.78.6.876
204243.78.6.88/29243.78.6.89 to 243.78.6.94243.78.6.956
205243.78.6.96/29243.78.6.97 to 243.78.6.102243.78.6.1036
206243.78.6.104/29243.78.6.105 to 243.78.6.110243.78.6.1116
207243.78.6.112/29243.78.6.113 to 243.78.6.118243.78.6.1196
208243.78.6.120/29243.78.6.121 to 243.78.6.126243.78.6.1276
209243.78.6.128/29243.78.6.129 to 243.78.6.134243.78.6.1356
210243.78.6.136/29243.78.6.137 to 243.78.6.142243.78.6.1436
211243.78.6.144/29243.78.6.145 to 243.78.6.150243.78.6.1516
212243.78.6.152/29243.78.6.153 to 243.78.6.158243.78.6.1596
213243.78.6.160/29243.78.6.161 to 243.78.6.166243.78.6.1676
214243.78.6.168/29243.78.6.169 to 243.78.6.174243.78.6.1756
215243.78.6.176/29243.78.6.177 to 243.78.6.182243.78.6.1836
216243.78.6.184/29243.78.6.185 to 243.78.6.190243.78.6.1916
217243.78.6.192/29243.78.6.193 to 243.78.6.198243.78.6.1996
218243.78.6.200/29243.78.6.201 to 243.78.6.206243.78.6.2076
219243.78.6.208/29243.78.6.209 to 243.78.6.214243.78.6.2156
220243.78.6.216/29243.78.6.217 to 243.78.6.222243.78.6.2236
221243.78.6.224/29243.78.6.225 to 243.78.6.230243.78.6.2316
222243.78.6.232/29243.78.6.233 to 243.78.6.238243.78.6.2396
223243.78.6.240/29243.78.6.241 to 243.78.6.246243.78.6.2476
224243.78.6.248/29243.78.6.249 to 243.78.6.254243.78.6.2556
225243.78.7.0/29243.78.7.1 to 243.78.7.6243.78.7.76
226243.78.7.8/29243.78.7.9 to 243.78.7.14243.78.7.156
227243.78.7.16/29243.78.7.17 to 243.78.7.22243.78.7.236
228243.78.7.24/29243.78.7.25 to 243.78.7.30243.78.7.316
229243.78.7.32/29243.78.7.33 to 243.78.7.38243.78.7.396
230243.78.7.40/29243.78.7.41 to 243.78.7.46243.78.7.476
231243.78.7.48/29243.78.7.49 to 243.78.7.54243.78.7.556
232243.78.7.56/29243.78.7.57 to 243.78.7.62243.78.7.636
233243.78.7.64/29243.78.7.65 to 243.78.7.70243.78.7.716
234243.78.7.72/29243.78.7.73 to 243.78.7.78243.78.7.796
235243.78.7.80/29243.78.7.81 to 243.78.7.86243.78.7.876
236243.78.7.88/29243.78.7.89 to 243.78.7.94243.78.7.956
237243.78.7.96/29243.78.7.97 to 243.78.7.102243.78.7.1036
238243.78.7.104/29243.78.7.105 to 243.78.7.110243.78.7.1116
239243.78.7.112/29243.78.7.113 to 243.78.7.118243.78.7.1196
240243.78.7.120/29243.78.7.121 to 243.78.7.126243.78.7.1276
241243.78.7.128/29243.78.7.129 to 243.78.7.134243.78.7.1356
242243.78.7.136/29243.78.7.137 to 243.78.7.142243.78.7.1436
243243.78.7.144/29243.78.7.145 to 243.78.7.150243.78.7.1516
244243.78.7.152/29243.78.7.153 to 243.78.7.158243.78.7.1596
245243.78.7.160/29243.78.7.161 to 243.78.7.166243.78.7.1676
246243.78.7.168/29243.78.7.169 to 243.78.7.174243.78.7.1756
247243.78.7.176/29243.78.7.177 to 243.78.7.182243.78.7.1836
248243.78.7.184/29243.78.7.185 to 243.78.7.190243.78.7.1916
249243.78.7.192/29243.78.7.193 to 243.78.7.198243.78.7.1996
250243.78.7.200/29243.78.7.201 to 243.78.7.206243.78.7.2076
251243.78.7.208/29243.78.7.209 to 243.78.7.214243.78.7.2156
252243.78.7.216/29243.78.7.217 to 243.78.7.222243.78.7.2236
253243.78.7.224/29243.78.7.225 to 243.78.7.230243.78.7.2316
254243.78.7.232/29243.78.7.233 to 243.78.7.238243.78.7.2396
255243.78.7.240/29243.78.7.241 to 243.78.7.246243.78.7.2476
256243.78.7.248/29243.78.7.249 to 243.78.7.254243.78.7.2556

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.