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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.

Network185.78.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
185.78.0.0
Broadcast address
185.78.127.255
First usable
185.78.0.1
Last usable
185.78.127.254
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
B (default /16)
As numbers
Hex B94E0000 · Integer 3108896768 to 3108929535
Reverse DNS zones
0.78.185.in-addr.arpa
1.78.185.in-addr.arpa
2.78.185.in-addr.arpa
3.78.185.in-addr.arpa
4.78.185.in-addr.arpa
5.78.185.in-addr.arpa
6.78.185.in-addr.arpa
7.78.185.in-addr.arpa
8.78.185.in-addr.arpa
9.78.185.in-addr.arpa
10.78.185.in-addr.arpa
11.78.185.in-addr.arpa
12.78.185.in-addr.arpa
13.78.185.in-addr.arpa
14.78.185.in-addr.arpa
15.78.185.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
Address10111001.01001110.00000000.00000000185.78.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10111001.01001110.00000000.00000000185.78.0.0
Broadcast10111001.01001110.01111111.11111111185.78.127.255
Split into smaller subnets/29
/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)

185.78.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1185.78.0.0/29185.78.0.1 to 185.78.0.6185.78.0.76
2185.78.0.8/29185.78.0.9 to 185.78.0.14185.78.0.156
3185.78.0.16/29185.78.0.17 to 185.78.0.22185.78.0.236
4185.78.0.24/29185.78.0.25 to 185.78.0.30185.78.0.316
5185.78.0.32/29185.78.0.33 to 185.78.0.38185.78.0.396
6185.78.0.40/29185.78.0.41 to 185.78.0.46185.78.0.476
7185.78.0.48/29185.78.0.49 to 185.78.0.54185.78.0.556
8185.78.0.56/29185.78.0.57 to 185.78.0.62185.78.0.636
9185.78.0.64/29185.78.0.65 to 185.78.0.70185.78.0.716
10185.78.0.72/29185.78.0.73 to 185.78.0.78185.78.0.796
11185.78.0.80/29185.78.0.81 to 185.78.0.86185.78.0.876
12185.78.0.88/29185.78.0.89 to 185.78.0.94185.78.0.956
13185.78.0.96/29185.78.0.97 to 185.78.0.102185.78.0.1036
14185.78.0.104/29185.78.0.105 to 185.78.0.110185.78.0.1116
15185.78.0.112/29185.78.0.113 to 185.78.0.118185.78.0.1196
16185.78.0.120/29185.78.0.121 to 185.78.0.126185.78.0.1276
17185.78.0.128/29185.78.0.129 to 185.78.0.134185.78.0.1356
18185.78.0.136/29185.78.0.137 to 185.78.0.142185.78.0.1436
19185.78.0.144/29185.78.0.145 to 185.78.0.150185.78.0.1516
20185.78.0.152/29185.78.0.153 to 185.78.0.158185.78.0.1596
21185.78.0.160/29185.78.0.161 to 185.78.0.166185.78.0.1676
22185.78.0.168/29185.78.0.169 to 185.78.0.174185.78.0.1756
23185.78.0.176/29185.78.0.177 to 185.78.0.182185.78.0.1836
24185.78.0.184/29185.78.0.185 to 185.78.0.190185.78.0.1916
25185.78.0.192/29185.78.0.193 to 185.78.0.198185.78.0.1996
26185.78.0.200/29185.78.0.201 to 185.78.0.206185.78.0.2076
27185.78.0.208/29185.78.0.209 to 185.78.0.214185.78.0.2156
28185.78.0.216/29185.78.0.217 to 185.78.0.222185.78.0.2236
29185.78.0.224/29185.78.0.225 to 185.78.0.230185.78.0.2316
30185.78.0.232/29185.78.0.233 to 185.78.0.238185.78.0.2396
31185.78.0.240/29185.78.0.241 to 185.78.0.246185.78.0.2476
32185.78.0.248/29185.78.0.249 to 185.78.0.254185.78.0.2556
33185.78.1.0/29185.78.1.1 to 185.78.1.6185.78.1.76
34185.78.1.8/29185.78.1.9 to 185.78.1.14185.78.1.156
35185.78.1.16/29185.78.1.17 to 185.78.1.22185.78.1.236
36185.78.1.24/29185.78.1.25 to 185.78.1.30185.78.1.316
37185.78.1.32/29185.78.1.33 to 185.78.1.38185.78.1.396
38185.78.1.40/29185.78.1.41 to 185.78.1.46185.78.1.476
39185.78.1.48/29185.78.1.49 to 185.78.1.54185.78.1.556
40185.78.1.56/29185.78.1.57 to 185.78.1.62185.78.1.636
41185.78.1.64/29185.78.1.65 to 185.78.1.70185.78.1.716
42185.78.1.72/29185.78.1.73 to 185.78.1.78185.78.1.796
43185.78.1.80/29185.78.1.81 to 185.78.1.86185.78.1.876
44185.78.1.88/29185.78.1.89 to 185.78.1.94185.78.1.956
45185.78.1.96/29185.78.1.97 to 185.78.1.102185.78.1.1036
46185.78.1.104/29185.78.1.105 to 185.78.1.110185.78.1.1116
47185.78.1.112/29185.78.1.113 to 185.78.1.118185.78.1.1196
48185.78.1.120/29185.78.1.121 to 185.78.1.126185.78.1.1276
49185.78.1.128/29185.78.1.129 to 185.78.1.134185.78.1.1356
50185.78.1.136/29185.78.1.137 to 185.78.1.142185.78.1.1436
51185.78.1.144/29185.78.1.145 to 185.78.1.150185.78.1.1516
52185.78.1.152/29185.78.1.153 to 185.78.1.158185.78.1.1596
53185.78.1.160/29185.78.1.161 to 185.78.1.166185.78.1.1676
54185.78.1.168/29185.78.1.169 to 185.78.1.174185.78.1.1756
55185.78.1.176/29185.78.1.177 to 185.78.1.182185.78.1.1836
56185.78.1.184/29185.78.1.185 to 185.78.1.190185.78.1.1916
57185.78.1.192/29185.78.1.193 to 185.78.1.198185.78.1.1996
58185.78.1.200/29185.78.1.201 to 185.78.1.206185.78.1.2076
59185.78.1.208/29185.78.1.209 to 185.78.1.214185.78.1.2156
60185.78.1.216/29185.78.1.217 to 185.78.1.222185.78.1.2236
61185.78.1.224/29185.78.1.225 to 185.78.1.230185.78.1.2316
62185.78.1.232/29185.78.1.233 to 185.78.1.238185.78.1.2396
63185.78.1.240/29185.78.1.241 to 185.78.1.246185.78.1.2476
64185.78.1.248/29185.78.1.249 to 185.78.1.254185.78.1.2556
65185.78.2.0/29185.78.2.1 to 185.78.2.6185.78.2.76
66185.78.2.8/29185.78.2.9 to 185.78.2.14185.78.2.156
67185.78.2.16/29185.78.2.17 to 185.78.2.22185.78.2.236
68185.78.2.24/29185.78.2.25 to 185.78.2.30185.78.2.316
69185.78.2.32/29185.78.2.33 to 185.78.2.38185.78.2.396
70185.78.2.40/29185.78.2.41 to 185.78.2.46185.78.2.476
71185.78.2.48/29185.78.2.49 to 185.78.2.54185.78.2.556
72185.78.2.56/29185.78.2.57 to 185.78.2.62185.78.2.636
73185.78.2.64/29185.78.2.65 to 185.78.2.70185.78.2.716
74185.78.2.72/29185.78.2.73 to 185.78.2.78185.78.2.796
75185.78.2.80/29185.78.2.81 to 185.78.2.86185.78.2.876
76185.78.2.88/29185.78.2.89 to 185.78.2.94185.78.2.956
77185.78.2.96/29185.78.2.97 to 185.78.2.102185.78.2.1036
78185.78.2.104/29185.78.2.105 to 185.78.2.110185.78.2.1116
79185.78.2.112/29185.78.2.113 to 185.78.2.118185.78.2.1196
80185.78.2.120/29185.78.2.121 to 185.78.2.126185.78.2.1276
81185.78.2.128/29185.78.2.129 to 185.78.2.134185.78.2.1356
82185.78.2.136/29185.78.2.137 to 185.78.2.142185.78.2.1436
83185.78.2.144/29185.78.2.145 to 185.78.2.150185.78.2.1516
84185.78.2.152/29185.78.2.153 to 185.78.2.158185.78.2.1596
85185.78.2.160/29185.78.2.161 to 185.78.2.166185.78.2.1676
86185.78.2.168/29185.78.2.169 to 185.78.2.174185.78.2.1756
87185.78.2.176/29185.78.2.177 to 185.78.2.182185.78.2.1836
88185.78.2.184/29185.78.2.185 to 185.78.2.190185.78.2.1916
89185.78.2.192/29185.78.2.193 to 185.78.2.198185.78.2.1996
90185.78.2.200/29185.78.2.201 to 185.78.2.206185.78.2.2076
91185.78.2.208/29185.78.2.209 to 185.78.2.214185.78.2.2156
92185.78.2.216/29185.78.2.217 to 185.78.2.222185.78.2.2236
93185.78.2.224/29185.78.2.225 to 185.78.2.230185.78.2.2316
94185.78.2.232/29185.78.2.233 to 185.78.2.238185.78.2.2396
95185.78.2.240/29185.78.2.241 to 185.78.2.246185.78.2.2476
96185.78.2.248/29185.78.2.249 to 185.78.2.254185.78.2.2556
97185.78.3.0/29185.78.3.1 to 185.78.3.6185.78.3.76
98185.78.3.8/29185.78.3.9 to 185.78.3.14185.78.3.156
99185.78.3.16/29185.78.3.17 to 185.78.3.22185.78.3.236
100185.78.3.24/29185.78.3.25 to 185.78.3.30185.78.3.316
101185.78.3.32/29185.78.3.33 to 185.78.3.38185.78.3.396
102185.78.3.40/29185.78.3.41 to 185.78.3.46185.78.3.476
103185.78.3.48/29185.78.3.49 to 185.78.3.54185.78.3.556
104185.78.3.56/29185.78.3.57 to 185.78.3.62185.78.3.636
105185.78.3.64/29185.78.3.65 to 185.78.3.70185.78.3.716
106185.78.3.72/29185.78.3.73 to 185.78.3.78185.78.3.796
107185.78.3.80/29185.78.3.81 to 185.78.3.86185.78.3.876
108185.78.3.88/29185.78.3.89 to 185.78.3.94185.78.3.956
109185.78.3.96/29185.78.3.97 to 185.78.3.102185.78.3.1036
110185.78.3.104/29185.78.3.105 to 185.78.3.110185.78.3.1116
111185.78.3.112/29185.78.3.113 to 185.78.3.118185.78.3.1196
112185.78.3.120/29185.78.3.121 to 185.78.3.126185.78.3.1276
113185.78.3.128/29185.78.3.129 to 185.78.3.134185.78.3.1356
114185.78.3.136/29185.78.3.137 to 185.78.3.142185.78.3.1436
115185.78.3.144/29185.78.3.145 to 185.78.3.150185.78.3.1516
116185.78.3.152/29185.78.3.153 to 185.78.3.158185.78.3.1596
117185.78.3.160/29185.78.3.161 to 185.78.3.166185.78.3.1676
118185.78.3.168/29185.78.3.169 to 185.78.3.174185.78.3.1756
119185.78.3.176/29185.78.3.177 to 185.78.3.182185.78.3.1836
120185.78.3.184/29185.78.3.185 to 185.78.3.190185.78.3.1916
121185.78.3.192/29185.78.3.193 to 185.78.3.198185.78.3.1996
122185.78.3.200/29185.78.3.201 to 185.78.3.206185.78.3.2076
123185.78.3.208/29185.78.3.209 to 185.78.3.214185.78.3.2156
124185.78.3.216/29185.78.3.217 to 185.78.3.222185.78.3.2236
125185.78.3.224/29185.78.3.225 to 185.78.3.230185.78.3.2316
126185.78.3.232/29185.78.3.233 to 185.78.3.238185.78.3.2396
127185.78.3.240/29185.78.3.241 to 185.78.3.246185.78.3.2476
128185.78.3.248/29185.78.3.249 to 185.78.3.254185.78.3.2556
129185.78.4.0/29185.78.4.1 to 185.78.4.6185.78.4.76
130185.78.4.8/29185.78.4.9 to 185.78.4.14185.78.4.156
131185.78.4.16/29185.78.4.17 to 185.78.4.22185.78.4.236
132185.78.4.24/29185.78.4.25 to 185.78.4.30185.78.4.316
133185.78.4.32/29185.78.4.33 to 185.78.4.38185.78.4.396
134185.78.4.40/29185.78.4.41 to 185.78.4.46185.78.4.476
135185.78.4.48/29185.78.4.49 to 185.78.4.54185.78.4.556
136185.78.4.56/29185.78.4.57 to 185.78.4.62185.78.4.636
137185.78.4.64/29185.78.4.65 to 185.78.4.70185.78.4.716
138185.78.4.72/29185.78.4.73 to 185.78.4.78185.78.4.796
139185.78.4.80/29185.78.4.81 to 185.78.4.86185.78.4.876
140185.78.4.88/29185.78.4.89 to 185.78.4.94185.78.4.956
141185.78.4.96/29185.78.4.97 to 185.78.4.102185.78.4.1036
142185.78.4.104/29185.78.4.105 to 185.78.4.110185.78.4.1116
143185.78.4.112/29185.78.4.113 to 185.78.4.118185.78.4.1196
144185.78.4.120/29185.78.4.121 to 185.78.4.126185.78.4.1276
145185.78.4.128/29185.78.4.129 to 185.78.4.134185.78.4.1356
146185.78.4.136/29185.78.4.137 to 185.78.4.142185.78.4.1436
147185.78.4.144/29185.78.4.145 to 185.78.4.150185.78.4.1516
148185.78.4.152/29185.78.4.153 to 185.78.4.158185.78.4.1596
149185.78.4.160/29185.78.4.161 to 185.78.4.166185.78.4.1676
150185.78.4.168/29185.78.4.169 to 185.78.4.174185.78.4.1756
151185.78.4.176/29185.78.4.177 to 185.78.4.182185.78.4.1836
152185.78.4.184/29185.78.4.185 to 185.78.4.190185.78.4.1916
153185.78.4.192/29185.78.4.193 to 185.78.4.198185.78.4.1996
154185.78.4.200/29185.78.4.201 to 185.78.4.206185.78.4.2076
155185.78.4.208/29185.78.4.209 to 185.78.4.214185.78.4.2156
156185.78.4.216/29185.78.4.217 to 185.78.4.222185.78.4.2236
157185.78.4.224/29185.78.4.225 to 185.78.4.230185.78.4.2316
158185.78.4.232/29185.78.4.233 to 185.78.4.238185.78.4.2396
159185.78.4.240/29185.78.4.241 to 185.78.4.246185.78.4.2476
160185.78.4.248/29185.78.4.249 to 185.78.4.254185.78.4.2556
161185.78.5.0/29185.78.5.1 to 185.78.5.6185.78.5.76
162185.78.5.8/29185.78.5.9 to 185.78.5.14185.78.5.156
163185.78.5.16/29185.78.5.17 to 185.78.5.22185.78.5.236
164185.78.5.24/29185.78.5.25 to 185.78.5.30185.78.5.316
165185.78.5.32/29185.78.5.33 to 185.78.5.38185.78.5.396
166185.78.5.40/29185.78.5.41 to 185.78.5.46185.78.5.476
167185.78.5.48/29185.78.5.49 to 185.78.5.54185.78.5.556
168185.78.5.56/29185.78.5.57 to 185.78.5.62185.78.5.636
169185.78.5.64/29185.78.5.65 to 185.78.5.70185.78.5.716
170185.78.5.72/29185.78.5.73 to 185.78.5.78185.78.5.796
171185.78.5.80/29185.78.5.81 to 185.78.5.86185.78.5.876
172185.78.5.88/29185.78.5.89 to 185.78.5.94185.78.5.956
173185.78.5.96/29185.78.5.97 to 185.78.5.102185.78.5.1036
174185.78.5.104/29185.78.5.105 to 185.78.5.110185.78.5.1116
175185.78.5.112/29185.78.5.113 to 185.78.5.118185.78.5.1196
176185.78.5.120/29185.78.5.121 to 185.78.5.126185.78.5.1276
177185.78.5.128/29185.78.5.129 to 185.78.5.134185.78.5.1356
178185.78.5.136/29185.78.5.137 to 185.78.5.142185.78.5.1436
179185.78.5.144/29185.78.5.145 to 185.78.5.150185.78.5.1516
180185.78.5.152/29185.78.5.153 to 185.78.5.158185.78.5.1596
181185.78.5.160/29185.78.5.161 to 185.78.5.166185.78.5.1676
182185.78.5.168/29185.78.5.169 to 185.78.5.174185.78.5.1756
183185.78.5.176/29185.78.5.177 to 185.78.5.182185.78.5.1836
184185.78.5.184/29185.78.5.185 to 185.78.5.190185.78.5.1916
185185.78.5.192/29185.78.5.193 to 185.78.5.198185.78.5.1996
186185.78.5.200/29185.78.5.201 to 185.78.5.206185.78.5.2076
187185.78.5.208/29185.78.5.209 to 185.78.5.214185.78.5.2156
188185.78.5.216/29185.78.5.217 to 185.78.5.222185.78.5.2236
189185.78.5.224/29185.78.5.225 to 185.78.5.230185.78.5.2316
190185.78.5.232/29185.78.5.233 to 185.78.5.238185.78.5.2396
191185.78.5.240/29185.78.5.241 to 185.78.5.246185.78.5.2476
192185.78.5.248/29185.78.5.249 to 185.78.5.254185.78.5.2556
193185.78.6.0/29185.78.6.1 to 185.78.6.6185.78.6.76
194185.78.6.8/29185.78.6.9 to 185.78.6.14185.78.6.156
195185.78.6.16/29185.78.6.17 to 185.78.6.22185.78.6.236
196185.78.6.24/29185.78.6.25 to 185.78.6.30185.78.6.316
197185.78.6.32/29185.78.6.33 to 185.78.6.38185.78.6.396
198185.78.6.40/29185.78.6.41 to 185.78.6.46185.78.6.476
199185.78.6.48/29185.78.6.49 to 185.78.6.54185.78.6.556
200185.78.6.56/29185.78.6.57 to 185.78.6.62185.78.6.636
201185.78.6.64/29185.78.6.65 to 185.78.6.70185.78.6.716
202185.78.6.72/29185.78.6.73 to 185.78.6.78185.78.6.796
203185.78.6.80/29185.78.6.81 to 185.78.6.86185.78.6.876
204185.78.6.88/29185.78.6.89 to 185.78.6.94185.78.6.956
205185.78.6.96/29185.78.6.97 to 185.78.6.102185.78.6.1036
206185.78.6.104/29185.78.6.105 to 185.78.6.110185.78.6.1116
207185.78.6.112/29185.78.6.113 to 185.78.6.118185.78.6.1196
208185.78.6.120/29185.78.6.121 to 185.78.6.126185.78.6.1276
209185.78.6.128/29185.78.6.129 to 185.78.6.134185.78.6.1356
210185.78.6.136/29185.78.6.137 to 185.78.6.142185.78.6.1436
211185.78.6.144/29185.78.6.145 to 185.78.6.150185.78.6.1516
212185.78.6.152/29185.78.6.153 to 185.78.6.158185.78.6.1596
213185.78.6.160/29185.78.6.161 to 185.78.6.166185.78.6.1676
214185.78.6.168/29185.78.6.169 to 185.78.6.174185.78.6.1756
215185.78.6.176/29185.78.6.177 to 185.78.6.182185.78.6.1836
216185.78.6.184/29185.78.6.185 to 185.78.6.190185.78.6.1916
217185.78.6.192/29185.78.6.193 to 185.78.6.198185.78.6.1996
218185.78.6.200/29185.78.6.201 to 185.78.6.206185.78.6.2076
219185.78.6.208/29185.78.6.209 to 185.78.6.214185.78.6.2156
220185.78.6.216/29185.78.6.217 to 185.78.6.222185.78.6.2236
221185.78.6.224/29185.78.6.225 to 185.78.6.230185.78.6.2316
222185.78.6.232/29185.78.6.233 to 185.78.6.238185.78.6.2396
223185.78.6.240/29185.78.6.241 to 185.78.6.246185.78.6.2476
224185.78.6.248/29185.78.6.249 to 185.78.6.254185.78.6.2556
225185.78.7.0/29185.78.7.1 to 185.78.7.6185.78.7.76
226185.78.7.8/29185.78.7.9 to 185.78.7.14185.78.7.156
227185.78.7.16/29185.78.7.17 to 185.78.7.22185.78.7.236
228185.78.7.24/29185.78.7.25 to 185.78.7.30185.78.7.316
229185.78.7.32/29185.78.7.33 to 185.78.7.38185.78.7.396
230185.78.7.40/29185.78.7.41 to 185.78.7.46185.78.7.476
231185.78.7.48/29185.78.7.49 to 185.78.7.54185.78.7.556
232185.78.7.56/29185.78.7.57 to 185.78.7.62185.78.7.636
233185.78.7.64/29185.78.7.65 to 185.78.7.70185.78.7.716
234185.78.7.72/29185.78.7.73 to 185.78.7.78185.78.7.796
235185.78.7.80/29185.78.7.81 to 185.78.7.86185.78.7.876
236185.78.7.88/29185.78.7.89 to 185.78.7.94185.78.7.956
237185.78.7.96/29185.78.7.97 to 185.78.7.102185.78.7.1036
238185.78.7.104/29185.78.7.105 to 185.78.7.110185.78.7.1116
239185.78.7.112/29185.78.7.113 to 185.78.7.118185.78.7.1196
240185.78.7.120/29185.78.7.121 to 185.78.7.126185.78.7.1276
241185.78.7.128/29185.78.7.129 to 185.78.7.134185.78.7.1356
242185.78.7.136/29185.78.7.137 to 185.78.7.142185.78.7.1436
243185.78.7.144/29185.78.7.145 to 185.78.7.150185.78.7.1516
244185.78.7.152/29185.78.7.153 to 185.78.7.158185.78.7.1596
245185.78.7.160/29185.78.7.161 to 185.78.7.166185.78.7.1676
246185.78.7.168/29185.78.7.169 to 185.78.7.174185.78.7.1756
247185.78.7.176/29185.78.7.177 to 185.78.7.182185.78.7.1836
248185.78.7.184/29185.78.7.185 to 185.78.7.190185.78.7.1916
249185.78.7.192/29185.78.7.193 to 185.78.7.198185.78.7.1996
250185.78.7.200/29185.78.7.201 to 185.78.7.206185.78.7.2076
251185.78.7.208/29185.78.7.209 to 185.78.7.214185.78.7.2156
252185.78.7.216/29185.78.7.217 to 185.78.7.222185.78.7.2236
253185.78.7.224/29185.78.7.225 to 185.78.7.230185.78.7.2316
254185.78.7.232/29185.78.7.233 to 185.78.7.238185.78.7.2396
255185.78.7.240/29185.78.7.241 to 185.78.7.246185.78.7.2476
256185.78.7.248/29185.78.7.249 to 185.78.7.254185.78.7.2556

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.