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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.

Network167.167.48.0/21
Usable hosts2,046
Subnet mask255.255.248.0
Addresses2,048
Network address
167.167.48.0
Broadcast address
167.167.55.255
First usable
167.167.48.1
Last usable
167.167.55.254
Usable hosts
2,046 (2,048 less the network and broadcast addresses)
Subnet mask
255.255.248.0
Wildcard mask
0.0.7.255 (Cisco ACLs, OSPF)
Prefix length
/21
Type
Public public
Old class
B (default /16)
As numbers
Hex A7A73000 · Integer 2812751872 to 2812753919
Reverse DNS zones
48.167.167.in-addr.arpa
49.167.167.in-addr.arpa
50.167.167.in-addr.arpa
51.167.167.in-addr.arpa
52.167.167.in-addr.arpa
53.167.167.in-addr.arpa
54.167.167.in-addr.arpa
55.167.167.in-addr.arpa
/21 is not on a 8-bit boundary, so it takes 8 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100111.10100111.00110000.00000000167.167.48.0
Subnet mask11111111.11111111.11111000.00000000255.255.248.0
Network10100111.10100111.00110000.00000000167.167.48.0
Broadcast10100111.10100111.00110111.11111111167.167.55.255
Split into smaller subnets/29
/22 (2)/23 (4)/24 (8)/25 (16)/26 (32)/27 (64)/28 (128)/29 (256)/30 (512)/31 (1,024)/32 (2,048)

167.167.48.0/21 makes 256 subnets of /29.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1167.167.48.0/29167.167.48.1 to 167.167.48.6167.167.48.76
2167.167.48.8/29167.167.48.9 to 167.167.48.14167.167.48.156
3167.167.48.16/29167.167.48.17 to 167.167.48.22167.167.48.236
4167.167.48.24/29167.167.48.25 to 167.167.48.30167.167.48.316
5167.167.48.32/29167.167.48.33 to 167.167.48.38167.167.48.396
6167.167.48.40/29167.167.48.41 to 167.167.48.46167.167.48.476
7167.167.48.48/29167.167.48.49 to 167.167.48.54167.167.48.556
8167.167.48.56/29167.167.48.57 to 167.167.48.62167.167.48.636
9167.167.48.64/29167.167.48.65 to 167.167.48.70167.167.48.716
10167.167.48.72/29167.167.48.73 to 167.167.48.78167.167.48.796
11167.167.48.80/29167.167.48.81 to 167.167.48.86167.167.48.876
12167.167.48.88/29167.167.48.89 to 167.167.48.94167.167.48.956
13167.167.48.96/29167.167.48.97 to 167.167.48.102167.167.48.1036
14167.167.48.104/29167.167.48.105 to 167.167.48.110167.167.48.1116
15167.167.48.112/29167.167.48.113 to 167.167.48.118167.167.48.1196
16167.167.48.120/29167.167.48.121 to 167.167.48.126167.167.48.1276
17167.167.48.128/29167.167.48.129 to 167.167.48.134167.167.48.1356
18167.167.48.136/29167.167.48.137 to 167.167.48.142167.167.48.1436
19167.167.48.144/29167.167.48.145 to 167.167.48.150167.167.48.1516
20167.167.48.152/29167.167.48.153 to 167.167.48.158167.167.48.1596
21167.167.48.160/29167.167.48.161 to 167.167.48.166167.167.48.1676
22167.167.48.168/29167.167.48.169 to 167.167.48.174167.167.48.1756
23167.167.48.176/29167.167.48.177 to 167.167.48.182167.167.48.1836
24167.167.48.184/29167.167.48.185 to 167.167.48.190167.167.48.1916
25167.167.48.192/29167.167.48.193 to 167.167.48.198167.167.48.1996
26167.167.48.200/29167.167.48.201 to 167.167.48.206167.167.48.2076
27167.167.48.208/29167.167.48.209 to 167.167.48.214167.167.48.2156
28167.167.48.216/29167.167.48.217 to 167.167.48.222167.167.48.2236
29167.167.48.224/29167.167.48.225 to 167.167.48.230167.167.48.2316
30167.167.48.232/29167.167.48.233 to 167.167.48.238167.167.48.2396
31167.167.48.240/29167.167.48.241 to 167.167.48.246167.167.48.2476
32167.167.48.248/29167.167.48.249 to 167.167.48.254167.167.48.2556
33167.167.49.0/29167.167.49.1 to 167.167.49.6167.167.49.76
34167.167.49.8/29167.167.49.9 to 167.167.49.14167.167.49.156
35167.167.49.16/29167.167.49.17 to 167.167.49.22167.167.49.236
36167.167.49.24/29167.167.49.25 to 167.167.49.30167.167.49.316
37167.167.49.32/29167.167.49.33 to 167.167.49.38167.167.49.396
38167.167.49.40/29167.167.49.41 to 167.167.49.46167.167.49.476
39167.167.49.48/29167.167.49.49 to 167.167.49.54167.167.49.556
40167.167.49.56/29167.167.49.57 to 167.167.49.62167.167.49.636
41167.167.49.64/29167.167.49.65 to 167.167.49.70167.167.49.716
42167.167.49.72/29167.167.49.73 to 167.167.49.78167.167.49.796
43167.167.49.80/29167.167.49.81 to 167.167.49.86167.167.49.876
44167.167.49.88/29167.167.49.89 to 167.167.49.94167.167.49.956
45167.167.49.96/29167.167.49.97 to 167.167.49.102167.167.49.1036
46167.167.49.104/29167.167.49.105 to 167.167.49.110167.167.49.1116
47167.167.49.112/29167.167.49.113 to 167.167.49.118167.167.49.1196
48167.167.49.120/29167.167.49.121 to 167.167.49.126167.167.49.1276
49167.167.49.128/29167.167.49.129 to 167.167.49.134167.167.49.1356
50167.167.49.136/29167.167.49.137 to 167.167.49.142167.167.49.1436
51167.167.49.144/29167.167.49.145 to 167.167.49.150167.167.49.1516
52167.167.49.152/29167.167.49.153 to 167.167.49.158167.167.49.1596
53167.167.49.160/29167.167.49.161 to 167.167.49.166167.167.49.1676
54167.167.49.168/29167.167.49.169 to 167.167.49.174167.167.49.1756
55167.167.49.176/29167.167.49.177 to 167.167.49.182167.167.49.1836
56167.167.49.184/29167.167.49.185 to 167.167.49.190167.167.49.1916
57167.167.49.192/29167.167.49.193 to 167.167.49.198167.167.49.1996
58167.167.49.200/29167.167.49.201 to 167.167.49.206167.167.49.2076
59167.167.49.208/29167.167.49.209 to 167.167.49.214167.167.49.2156
60167.167.49.216/29167.167.49.217 to 167.167.49.222167.167.49.2236
61167.167.49.224/29167.167.49.225 to 167.167.49.230167.167.49.2316
62167.167.49.232/29167.167.49.233 to 167.167.49.238167.167.49.2396
63167.167.49.240/29167.167.49.241 to 167.167.49.246167.167.49.2476
64167.167.49.248/29167.167.49.249 to 167.167.49.254167.167.49.2556
65167.167.50.0/29167.167.50.1 to 167.167.50.6167.167.50.76
66167.167.50.8/29167.167.50.9 to 167.167.50.14167.167.50.156
67167.167.50.16/29167.167.50.17 to 167.167.50.22167.167.50.236
68167.167.50.24/29167.167.50.25 to 167.167.50.30167.167.50.316
69167.167.50.32/29167.167.50.33 to 167.167.50.38167.167.50.396
70167.167.50.40/29167.167.50.41 to 167.167.50.46167.167.50.476
71167.167.50.48/29167.167.50.49 to 167.167.50.54167.167.50.556
72167.167.50.56/29167.167.50.57 to 167.167.50.62167.167.50.636
73167.167.50.64/29167.167.50.65 to 167.167.50.70167.167.50.716
74167.167.50.72/29167.167.50.73 to 167.167.50.78167.167.50.796
75167.167.50.80/29167.167.50.81 to 167.167.50.86167.167.50.876
76167.167.50.88/29167.167.50.89 to 167.167.50.94167.167.50.956
77167.167.50.96/29167.167.50.97 to 167.167.50.102167.167.50.1036
78167.167.50.104/29167.167.50.105 to 167.167.50.110167.167.50.1116
79167.167.50.112/29167.167.50.113 to 167.167.50.118167.167.50.1196
80167.167.50.120/29167.167.50.121 to 167.167.50.126167.167.50.1276
81167.167.50.128/29167.167.50.129 to 167.167.50.134167.167.50.1356
82167.167.50.136/29167.167.50.137 to 167.167.50.142167.167.50.1436
83167.167.50.144/29167.167.50.145 to 167.167.50.150167.167.50.1516
84167.167.50.152/29167.167.50.153 to 167.167.50.158167.167.50.1596
85167.167.50.160/29167.167.50.161 to 167.167.50.166167.167.50.1676
86167.167.50.168/29167.167.50.169 to 167.167.50.174167.167.50.1756
87167.167.50.176/29167.167.50.177 to 167.167.50.182167.167.50.1836
88167.167.50.184/29167.167.50.185 to 167.167.50.190167.167.50.1916
89167.167.50.192/29167.167.50.193 to 167.167.50.198167.167.50.1996
90167.167.50.200/29167.167.50.201 to 167.167.50.206167.167.50.2076
91167.167.50.208/29167.167.50.209 to 167.167.50.214167.167.50.2156
92167.167.50.216/29167.167.50.217 to 167.167.50.222167.167.50.2236
93167.167.50.224/29167.167.50.225 to 167.167.50.230167.167.50.2316
94167.167.50.232/29167.167.50.233 to 167.167.50.238167.167.50.2396
95167.167.50.240/29167.167.50.241 to 167.167.50.246167.167.50.2476
96167.167.50.248/29167.167.50.249 to 167.167.50.254167.167.50.2556
97167.167.51.0/29167.167.51.1 to 167.167.51.6167.167.51.76
98167.167.51.8/29167.167.51.9 to 167.167.51.14167.167.51.156
99167.167.51.16/29167.167.51.17 to 167.167.51.22167.167.51.236
100167.167.51.24/29167.167.51.25 to 167.167.51.30167.167.51.316
101167.167.51.32/29167.167.51.33 to 167.167.51.38167.167.51.396
102167.167.51.40/29167.167.51.41 to 167.167.51.46167.167.51.476
103167.167.51.48/29167.167.51.49 to 167.167.51.54167.167.51.556
104167.167.51.56/29167.167.51.57 to 167.167.51.62167.167.51.636
105167.167.51.64/29167.167.51.65 to 167.167.51.70167.167.51.716
106167.167.51.72/29167.167.51.73 to 167.167.51.78167.167.51.796
107167.167.51.80/29167.167.51.81 to 167.167.51.86167.167.51.876
108167.167.51.88/29167.167.51.89 to 167.167.51.94167.167.51.956
109167.167.51.96/29167.167.51.97 to 167.167.51.102167.167.51.1036
110167.167.51.104/29167.167.51.105 to 167.167.51.110167.167.51.1116
111167.167.51.112/29167.167.51.113 to 167.167.51.118167.167.51.1196
112167.167.51.120/29167.167.51.121 to 167.167.51.126167.167.51.1276
113167.167.51.128/29167.167.51.129 to 167.167.51.134167.167.51.1356
114167.167.51.136/29167.167.51.137 to 167.167.51.142167.167.51.1436
115167.167.51.144/29167.167.51.145 to 167.167.51.150167.167.51.1516
116167.167.51.152/29167.167.51.153 to 167.167.51.158167.167.51.1596
117167.167.51.160/29167.167.51.161 to 167.167.51.166167.167.51.1676
118167.167.51.168/29167.167.51.169 to 167.167.51.174167.167.51.1756
119167.167.51.176/29167.167.51.177 to 167.167.51.182167.167.51.1836
120167.167.51.184/29167.167.51.185 to 167.167.51.190167.167.51.1916
121167.167.51.192/29167.167.51.193 to 167.167.51.198167.167.51.1996
122167.167.51.200/29167.167.51.201 to 167.167.51.206167.167.51.2076
123167.167.51.208/29167.167.51.209 to 167.167.51.214167.167.51.2156
124167.167.51.216/29167.167.51.217 to 167.167.51.222167.167.51.2236
125167.167.51.224/29167.167.51.225 to 167.167.51.230167.167.51.2316
126167.167.51.232/29167.167.51.233 to 167.167.51.238167.167.51.2396
127167.167.51.240/29167.167.51.241 to 167.167.51.246167.167.51.2476
128167.167.51.248/29167.167.51.249 to 167.167.51.254167.167.51.2556
129167.167.52.0/29167.167.52.1 to 167.167.52.6167.167.52.76
130167.167.52.8/29167.167.52.9 to 167.167.52.14167.167.52.156
131167.167.52.16/29167.167.52.17 to 167.167.52.22167.167.52.236
132167.167.52.24/29167.167.52.25 to 167.167.52.30167.167.52.316
133167.167.52.32/29167.167.52.33 to 167.167.52.38167.167.52.396
134167.167.52.40/29167.167.52.41 to 167.167.52.46167.167.52.476
135167.167.52.48/29167.167.52.49 to 167.167.52.54167.167.52.556
136167.167.52.56/29167.167.52.57 to 167.167.52.62167.167.52.636
137167.167.52.64/29167.167.52.65 to 167.167.52.70167.167.52.716
138167.167.52.72/29167.167.52.73 to 167.167.52.78167.167.52.796
139167.167.52.80/29167.167.52.81 to 167.167.52.86167.167.52.876
140167.167.52.88/29167.167.52.89 to 167.167.52.94167.167.52.956
141167.167.52.96/29167.167.52.97 to 167.167.52.102167.167.52.1036
142167.167.52.104/29167.167.52.105 to 167.167.52.110167.167.52.1116
143167.167.52.112/29167.167.52.113 to 167.167.52.118167.167.52.1196
144167.167.52.120/29167.167.52.121 to 167.167.52.126167.167.52.1276
145167.167.52.128/29167.167.52.129 to 167.167.52.134167.167.52.1356
146167.167.52.136/29167.167.52.137 to 167.167.52.142167.167.52.1436
147167.167.52.144/29167.167.52.145 to 167.167.52.150167.167.52.1516
148167.167.52.152/29167.167.52.153 to 167.167.52.158167.167.52.1596
149167.167.52.160/29167.167.52.161 to 167.167.52.166167.167.52.1676
150167.167.52.168/29167.167.52.169 to 167.167.52.174167.167.52.1756
151167.167.52.176/29167.167.52.177 to 167.167.52.182167.167.52.1836
152167.167.52.184/29167.167.52.185 to 167.167.52.190167.167.52.1916
153167.167.52.192/29167.167.52.193 to 167.167.52.198167.167.52.1996
154167.167.52.200/29167.167.52.201 to 167.167.52.206167.167.52.2076
155167.167.52.208/29167.167.52.209 to 167.167.52.214167.167.52.2156
156167.167.52.216/29167.167.52.217 to 167.167.52.222167.167.52.2236
157167.167.52.224/29167.167.52.225 to 167.167.52.230167.167.52.2316
158167.167.52.232/29167.167.52.233 to 167.167.52.238167.167.52.2396
159167.167.52.240/29167.167.52.241 to 167.167.52.246167.167.52.2476
160167.167.52.248/29167.167.52.249 to 167.167.52.254167.167.52.2556
161167.167.53.0/29167.167.53.1 to 167.167.53.6167.167.53.76
162167.167.53.8/29167.167.53.9 to 167.167.53.14167.167.53.156
163167.167.53.16/29167.167.53.17 to 167.167.53.22167.167.53.236
164167.167.53.24/29167.167.53.25 to 167.167.53.30167.167.53.316
165167.167.53.32/29167.167.53.33 to 167.167.53.38167.167.53.396
166167.167.53.40/29167.167.53.41 to 167.167.53.46167.167.53.476
167167.167.53.48/29167.167.53.49 to 167.167.53.54167.167.53.556
168167.167.53.56/29167.167.53.57 to 167.167.53.62167.167.53.636
169167.167.53.64/29167.167.53.65 to 167.167.53.70167.167.53.716
170167.167.53.72/29167.167.53.73 to 167.167.53.78167.167.53.796
171167.167.53.80/29167.167.53.81 to 167.167.53.86167.167.53.876
172167.167.53.88/29167.167.53.89 to 167.167.53.94167.167.53.956
173167.167.53.96/29167.167.53.97 to 167.167.53.102167.167.53.1036
174167.167.53.104/29167.167.53.105 to 167.167.53.110167.167.53.1116
175167.167.53.112/29167.167.53.113 to 167.167.53.118167.167.53.1196
176167.167.53.120/29167.167.53.121 to 167.167.53.126167.167.53.1276
177167.167.53.128/29167.167.53.129 to 167.167.53.134167.167.53.1356
178167.167.53.136/29167.167.53.137 to 167.167.53.142167.167.53.1436
179167.167.53.144/29167.167.53.145 to 167.167.53.150167.167.53.1516
180167.167.53.152/29167.167.53.153 to 167.167.53.158167.167.53.1596
181167.167.53.160/29167.167.53.161 to 167.167.53.166167.167.53.1676
182167.167.53.168/29167.167.53.169 to 167.167.53.174167.167.53.1756
183167.167.53.176/29167.167.53.177 to 167.167.53.182167.167.53.1836
184167.167.53.184/29167.167.53.185 to 167.167.53.190167.167.53.1916
185167.167.53.192/29167.167.53.193 to 167.167.53.198167.167.53.1996
186167.167.53.200/29167.167.53.201 to 167.167.53.206167.167.53.2076
187167.167.53.208/29167.167.53.209 to 167.167.53.214167.167.53.2156
188167.167.53.216/29167.167.53.217 to 167.167.53.222167.167.53.2236
189167.167.53.224/29167.167.53.225 to 167.167.53.230167.167.53.2316
190167.167.53.232/29167.167.53.233 to 167.167.53.238167.167.53.2396
191167.167.53.240/29167.167.53.241 to 167.167.53.246167.167.53.2476
192167.167.53.248/29167.167.53.249 to 167.167.53.254167.167.53.2556
193167.167.54.0/29167.167.54.1 to 167.167.54.6167.167.54.76
194167.167.54.8/29167.167.54.9 to 167.167.54.14167.167.54.156
195167.167.54.16/29167.167.54.17 to 167.167.54.22167.167.54.236
196167.167.54.24/29167.167.54.25 to 167.167.54.30167.167.54.316
197167.167.54.32/29167.167.54.33 to 167.167.54.38167.167.54.396
198167.167.54.40/29167.167.54.41 to 167.167.54.46167.167.54.476
199167.167.54.48/29167.167.54.49 to 167.167.54.54167.167.54.556
200167.167.54.56/29167.167.54.57 to 167.167.54.62167.167.54.636
201167.167.54.64/29167.167.54.65 to 167.167.54.70167.167.54.716
202167.167.54.72/29167.167.54.73 to 167.167.54.78167.167.54.796
203167.167.54.80/29167.167.54.81 to 167.167.54.86167.167.54.876
204167.167.54.88/29167.167.54.89 to 167.167.54.94167.167.54.956
205167.167.54.96/29167.167.54.97 to 167.167.54.102167.167.54.1036
206167.167.54.104/29167.167.54.105 to 167.167.54.110167.167.54.1116
207167.167.54.112/29167.167.54.113 to 167.167.54.118167.167.54.1196
208167.167.54.120/29167.167.54.121 to 167.167.54.126167.167.54.1276
209167.167.54.128/29167.167.54.129 to 167.167.54.134167.167.54.1356
210167.167.54.136/29167.167.54.137 to 167.167.54.142167.167.54.1436
211167.167.54.144/29167.167.54.145 to 167.167.54.150167.167.54.1516
212167.167.54.152/29167.167.54.153 to 167.167.54.158167.167.54.1596
213167.167.54.160/29167.167.54.161 to 167.167.54.166167.167.54.1676
214167.167.54.168/29167.167.54.169 to 167.167.54.174167.167.54.1756
215167.167.54.176/29167.167.54.177 to 167.167.54.182167.167.54.1836
216167.167.54.184/29167.167.54.185 to 167.167.54.190167.167.54.1916
217167.167.54.192/29167.167.54.193 to 167.167.54.198167.167.54.1996
218167.167.54.200/29167.167.54.201 to 167.167.54.206167.167.54.2076
219167.167.54.208/29167.167.54.209 to 167.167.54.214167.167.54.2156
220167.167.54.216/29167.167.54.217 to 167.167.54.222167.167.54.2236
221167.167.54.224/29167.167.54.225 to 167.167.54.230167.167.54.2316
222167.167.54.232/29167.167.54.233 to 167.167.54.238167.167.54.2396
223167.167.54.240/29167.167.54.241 to 167.167.54.246167.167.54.2476
224167.167.54.248/29167.167.54.249 to 167.167.54.254167.167.54.2556
225167.167.55.0/29167.167.55.1 to 167.167.55.6167.167.55.76
226167.167.55.8/29167.167.55.9 to 167.167.55.14167.167.55.156
227167.167.55.16/29167.167.55.17 to 167.167.55.22167.167.55.236
228167.167.55.24/29167.167.55.25 to 167.167.55.30167.167.55.316
229167.167.55.32/29167.167.55.33 to 167.167.55.38167.167.55.396
230167.167.55.40/29167.167.55.41 to 167.167.55.46167.167.55.476
231167.167.55.48/29167.167.55.49 to 167.167.55.54167.167.55.556
232167.167.55.56/29167.167.55.57 to 167.167.55.62167.167.55.636
233167.167.55.64/29167.167.55.65 to 167.167.55.70167.167.55.716
234167.167.55.72/29167.167.55.73 to 167.167.55.78167.167.55.796
235167.167.55.80/29167.167.55.81 to 167.167.55.86167.167.55.876
236167.167.55.88/29167.167.55.89 to 167.167.55.94167.167.55.956
237167.167.55.96/29167.167.55.97 to 167.167.55.102167.167.55.1036
238167.167.55.104/29167.167.55.105 to 167.167.55.110167.167.55.1116
239167.167.55.112/29167.167.55.113 to 167.167.55.118167.167.55.1196
240167.167.55.120/29167.167.55.121 to 167.167.55.126167.167.55.1276
241167.167.55.128/29167.167.55.129 to 167.167.55.134167.167.55.1356
242167.167.55.136/29167.167.55.137 to 167.167.55.142167.167.55.1436
243167.167.55.144/29167.167.55.145 to 167.167.55.150167.167.55.1516
244167.167.55.152/29167.167.55.153 to 167.167.55.158167.167.55.1596
245167.167.55.160/29167.167.55.161 to 167.167.55.166167.167.55.1676
246167.167.55.168/29167.167.55.169 to 167.167.55.174167.167.55.1756
247167.167.55.176/29167.167.55.177 to 167.167.55.182167.167.55.1836
248167.167.55.184/29167.167.55.185 to 167.167.55.190167.167.55.1916
249167.167.55.192/29167.167.55.193 to 167.167.55.198167.167.55.1996
250167.167.55.200/29167.167.55.201 to 167.167.55.206167.167.55.2076
251167.167.55.208/29167.167.55.209 to 167.167.55.214167.167.55.2156
252167.167.55.216/29167.167.55.217 to 167.167.55.222167.167.55.2236
253167.167.55.224/29167.167.55.225 to 167.167.55.230167.167.55.2316
254167.167.55.232/29167.167.55.233 to 167.167.55.238167.167.55.2396
255167.167.55.240/29167.167.55.241 to 167.167.55.246167.167.55.2476
256167.167.55.248/29167.167.55.249 to 167.167.55.254167.167.55.2556

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.