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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.

Network124.7.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
124.7.80.0
Broadcast address
124.7.95.255
First usable
124.7.80.1
Last usable
124.7.95.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 7C075000 · Integer 2080854016 to 2080858111
Reverse DNS zones
80.7.124.in-addr.arpa
81.7.124.in-addr.arpa
82.7.124.in-addr.arpa
83.7.124.in-addr.arpa
84.7.124.in-addr.arpa
85.7.124.in-addr.arpa
86.7.124.in-addr.arpa
87.7.124.in-addr.arpa
88.7.124.in-addr.arpa
89.7.124.in-addr.arpa
90.7.124.in-addr.arpa
91.7.124.in-addr.arpa
92.7.124.in-addr.arpa
93.7.124.in-addr.arpa
94.7.124.in-addr.arpa
95.7.124.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111100.00000111.01010000.00000000124.7.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01111100.00000111.01010000.00000000124.7.80.0
Broadcast01111100.00000111.01011111.11111111124.7.95.255
Split into smaller subnets/30
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

124.7.80.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1124.7.80.0/30124.7.80.1 to 124.7.80.2124.7.80.32
2124.7.80.4/30124.7.80.5 to 124.7.80.6124.7.80.72
3124.7.80.8/30124.7.80.9 to 124.7.80.10124.7.80.112
4124.7.80.12/30124.7.80.13 to 124.7.80.14124.7.80.152
5124.7.80.16/30124.7.80.17 to 124.7.80.18124.7.80.192
6124.7.80.20/30124.7.80.21 to 124.7.80.22124.7.80.232
7124.7.80.24/30124.7.80.25 to 124.7.80.26124.7.80.272
8124.7.80.28/30124.7.80.29 to 124.7.80.30124.7.80.312
9124.7.80.32/30124.7.80.33 to 124.7.80.34124.7.80.352
10124.7.80.36/30124.7.80.37 to 124.7.80.38124.7.80.392
11124.7.80.40/30124.7.80.41 to 124.7.80.42124.7.80.432
12124.7.80.44/30124.7.80.45 to 124.7.80.46124.7.80.472
13124.7.80.48/30124.7.80.49 to 124.7.80.50124.7.80.512
14124.7.80.52/30124.7.80.53 to 124.7.80.54124.7.80.552
15124.7.80.56/30124.7.80.57 to 124.7.80.58124.7.80.592
16124.7.80.60/30124.7.80.61 to 124.7.80.62124.7.80.632
17124.7.80.64/30124.7.80.65 to 124.7.80.66124.7.80.672
18124.7.80.68/30124.7.80.69 to 124.7.80.70124.7.80.712
19124.7.80.72/30124.7.80.73 to 124.7.80.74124.7.80.752
20124.7.80.76/30124.7.80.77 to 124.7.80.78124.7.80.792
21124.7.80.80/30124.7.80.81 to 124.7.80.82124.7.80.832
22124.7.80.84/30124.7.80.85 to 124.7.80.86124.7.80.872
23124.7.80.88/30124.7.80.89 to 124.7.80.90124.7.80.912
24124.7.80.92/30124.7.80.93 to 124.7.80.94124.7.80.952
25124.7.80.96/30124.7.80.97 to 124.7.80.98124.7.80.992
26124.7.80.100/30124.7.80.101 to 124.7.80.102124.7.80.1032
27124.7.80.104/30124.7.80.105 to 124.7.80.106124.7.80.1072
28124.7.80.108/30124.7.80.109 to 124.7.80.110124.7.80.1112
29124.7.80.112/30124.7.80.113 to 124.7.80.114124.7.80.1152
30124.7.80.116/30124.7.80.117 to 124.7.80.118124.7.80.1192
31124.7.80.120/30124.7.80.121 to 124.7.80.122124.7.80.1232
32124.7.80.124/30124.7.80.125 to 124.7.80.126124.7.80.1272
33124.7.80.128/30124.7.80.129 to 124.7.80.130124.7.80.1312
34124.7.80.132/30124.7.80.133 to 124.7.80.134124.7.80.1352
35124.7.80.136/30124.7.80.137 to 124.7.80.138124.7.80.1392
36124.7.80.140/30124.7.80.141 to 124.7.80.142124.7.80.1432
37124.7.80.144/30124.7.80.145 to 124.7.80.146124.7.80.1472
38124.7.80.148/30124.7.80.149 to 124.7.80.150124.7.80.1512
39124.7.80.152/30124.7.80.153 to 124.7.80.154124.7.80.1552
40124.7.80.156/30124.7.80.157 to 124.7.80.158124.7.80.1592
41124.7.80.160/30124.7.80.161 to 124.7.80.162124.7.80.1632
42124.7.80.164/30124.7.80.165 to 124.7.80.166124.7.80.1672
43124.7.80.168/30124.7.80.169 to 124.7.80.170124.7.80.1712
44124.7.80.172/30124.7.80.173 to 124.7.80.174124.7.80.1752
45124.7.80.176/30124.7.80.177 to 124.7.80.178124.7.80.1792
46124.7.80.180/30124.7.80.181 to 124.7.80.182124.7.80.1832
47124.7.80.184/30124.7.80.185 to 124.7.80.186124.7.80.1872
48124.7.80.188/30124.7.80.189 to 124.7.80.190124.7.80.1912
49124.7.80.192/30124.7.80.193 to 124.7.80.194124.7.80.1952
50124.7.80.196/30124.7.80.197 to 124.7.80.198124.7.80.1992
51124.7.80.200/30124.7.80.201 to 124.7.80.202124.7.80.2032
52124.7.80.204/30124.7.80.205 to 124.7.80.206124.7.80.2072
53124.7.80.208/30124.7.80.209 to 124.7.80.210124.7.80.2112
54124.7.80.212/30124.7.80.213 to 124.7.80.214124.7.80.2152
55124.7.80.216/30124.7.80.217 to 124.7.80.218124.7.80.2192
56124.7.80.220/30124.7.80.221 to 124.7.80.222124.7.80.2232
57124.7.80.224/30124.7.80.225 to 124.7.80.226124.7.80.2272
58124.7.80.228/30124.7.80.229 to 124.7.80.230124.7.80.2312
59124.7.80.232/30124.7.80.233 to 124.7.80.234124.7.80.2352
60124.7.80.236/30124.7.80.237 to 124.7.80.238124.7.80.2392
61124.7.80.240/30124.7.80.241 to 124.7.80.242124.7.80.2432
62124.7.80.244/30124.7.80.245 to 124.7.80.246124.7.80.2472
63124.7.80.248/30124.7.80.249 to 124.7.80.250124.7.80.2512
64124.7.80.252/30124.7.80.253 to 124.7.80.254124.7.80.2552
65124.7.81.0/30124.7.81.1 to 124.7.81.2124.7.81.32
66124.7.81.4/30124.7.81.5 to 124.7.81.6124.7.81.72
67124.7.81.8/30124.7.81.9 to 124.7.81.10124.7.81.112
68124.7.81.12/30124.7.81.13 to 124.7.81.14124.7.81.152
69124.7.81.16/30124.7.81.17 to 124.7.81.18124.7.81.192
70124.7.81.20/30124.7.81.21 to 124.7.81.22124.7.81.232
71124.7.81.24/30124.7.81.25 to 124.7.81.26124.7.81.272
72124.7.81.28/30124.7.81.29 to 124.7.81.30124.7.81.312
73124.7.81.32/30124.7.81.33 to 124.7.81.34124.7.81.352
74124.7.81.36/30124.7.81.37 to 124.7.81.38124.7.81.392
75124.7.81.40/30124.7.81.41 to 124.7.81.42124.7.81.432
76124.7.81.44/30124.7.81.45 to 124.7.81.46124.7.81.472
77124.7.81.48/30124.7.81.49 to 124.7.81.50124.7.81.512
78124.7.81.52/30124.7.81.53 to 124.7.81.54124.7.81.552
79124.7.81.56/30124.7.81.57 to 124.7.81.58124.7.81.592
80124.7.81.60/30124.7.81.61 to 124.7.81.62124.7.81.632
81124.7.81.64/30124.7.81.65 to 124.7.81.66124.7.81.672
82124.7.81.68/30124.7.81.69 to 124.7.81.70124.7.81.712
83124.7.81.72/30124.7.81.73 to 124.7.81.74124.7.81.752
84124.7.81.76/30124.7.81.77 to 124.7.81.78124.7.81.792
85124.7.81.80/30124.7.81.81 to 124.7.81.82124.7.81.832
86124.7.81.84/30124.7.81.85 to 124.7.81.86124.7.81.872
87124.7.81.88/30124.7.81.89 to 124.7.81.90124.7.81.912
88124.7.81.92/30124.7.81.93 to 124.7.81.94124.7.81.952
89124.7.81.96/30124.7.81.97 to 124.7.81.98124.7.81.992
90124.7.81.100/30124.7.81.101 to 124.7.81.102124.7.81.1032
91124.7.81.104/30124.7.81.105 to 124.7.81.106124.7.81.1072
92124.7.81.108/30124.7.81.109 to 124.7.81.110124.7.81.1112
93124.7.81.112/30124.7.81.113 to 124.7.81.114124.7.81.1152
94124.7.81.116/30124.7.81.117 to 124.7.81.118124.7.81.1192
95124.7.81.120/30124.7.81.121 to 124.7.81.122124.7.81.1232
96124.7.81.124/30124.7.81.125 to 124.7.81.126124.7.81.1272
97124.7.81.128/30124.7.81.129 to 124.7.81.130124.7.81.1312
98124.7.81.132/30124.7.81.133 to 124.7.81.134124.7.81.1352
99124.7.81.136/30124.7.81.137 to 124.7.81.138124.7.81.1392
100124.7.81.140/30124.7.81.141 to 124.7.81.142124.7.81.1432
101124.7.81.144/30124.7.81.145 to 124.7.81.146124.7.81.1472
102124.7.81.148/30124.7.81.149 to 124.7.81.150124.7.81.1512
103124.7.81.152/30124.7.81.153 to 124.7.81.154124.7.81.1552
104124.7.81.156/30124.7.81.157 to 124.7.81.158124.7.81.1592
105124.7.81.160/30124.7.81.161 to 124.7.81.162124.7.81.1632
106124.7.81.164/30124.7.81.165 to 124.7.81.166124.7.81.1672
107124.7.81.168/30124.7.81.169 to 124.7.81.170124.7.81.1712
108124.7.81.172/30124.7.81.173 to 124.7.81.174124.7.81.1752
109124.7.81.176/30124.7.81.177 to 124.7.81.178124.7.81.1792
110124.7.81.180/30124.7.81.181 to 124.7.81.182124.7.81.1832
111124.7.81.184/30124.7.81.185 to 124.7.81.186124.7.81.1872
112124.7.81.188/30124.7.81.189 to 124.7.81.190124.7.81.1912
113124.7.81.192/30124.7.81.193 to 124.7.81.194124.7.81.1952
114124.7.81.196/30124.7.81.197 to 124.7.81.198124.7.81.1992
115124.7.81.200/30124.7.81.201 to 124.7.81.202124.7.81.2032
116124.7.81.204/30124.7.81.205 to 124.7.81.206124.7.81.2072
117124.7.81.208/30124.7.81.209 to 124.7.81.210124.7.81.2112
118124.7.81.212/30124.7.81.213 to 124.7.81.214124.7.81.2152
119124.7.81.216/30124.7.81.217 to 124.7.81.218124.7.81.2192
120124.7.81.220/30124.7.81.221 to 124.7.81.222124.7.81.2232
121124.7.81.224/30124.7.81.225 to 124.7.81.226124.7.81.2272
122124.7.81.228/30124.7.81.229 to 124.7.81.230124.7.81.2312
123124.7.81.232/30124.7.81.233 to 124.7.81.234124.7.81.2352
124124.7.81.236/30124.7.81.237 to 124.7.81.238124.7.81.2392
125124.7.81.240/30124.7.81.241 to 124.7.81.242124.7.81.2432
126124.7.81.244/30124.7.81.245 to 124.7.81.246124.7.81.2472
127124.7.81.248/30124.7.81.249 to 124.7.81.250124.7.81.2512
128124.7.81.252/30124.7.81.253 to 124.7.81.254124.7.81.2552
129124.7.82.0/30124.7.82.1 to 124.7.82.2124.7.82.32
130124.7.82.4/30124.7.82.5 to 124.7.82.6124.7.82.72
131124.7.82.8/30124.7.82.9 to 124.7.82.10124.7.82.112
132124.7.82.12/30124.7.82.13 to 124.7.82.14124.7.82.152
133124.7.82.16/30124.7.82.17 to 124.7.82.18124.7.82.192
134124.7.82.20/30124.7.82.21 to 124.7.82.22124.7.82.232
135124.7.82.24/30124.7.82.25 to 124.7.82.26124.7.82.272
136124.7.82.28/30124.7.82.29 to 124.7.82.30124.7.82.312
137124.7.82.32/30124.7.82.33 to 124.7.82.34124.7.82.352
138124.7.82.36/30124.7.82.37 to 124.7.82.38124.7.82.392
139124.7.82.40/30124.7.82.41 to 124.7.82.42124.7.82.432
140124.7.82.44/30124.7.82.45 to 124.7.82.46124.7.82.472
141124.7.82.48/30124.7.82.49 to 124.7.82.50124.7.82.512
142124.7.82.52/30124.7.82.53 to 124.7.82.54124.7.82.552
143124.7.82.56/30124.7.82.57 to 124.7.82.58124.7.82.592
144124.7.82.60/30124.7.82.61 to 124.7.82.62124.7.82.632
145124.7.82.64/30124.7.82.65 to 124.7.82.66124.7.82.672
146124.7.82.68/30124.7.82.69 to 124.7.82.70124.7.82.712
147124.7.82.72/30124.7.82.73 to 124.7.82.74124.7.82.752
148124.7.82.76/30124.7.82.77 to 124.7.82.78124.7.82.792
149124.7.82.80/30124.7.82.81 to 124.7.82.82124.7.82.832
150124.7.82.84/30124.7.82.85 to 124.7.82.86124.7.82.872
151124.7.82.88/30124.7.82.89 to 124.7.82.90124.7.82.912
152124.7.82.92/30124.7.82.93 to 124.7.82.94124.7.82.952
153124.7.82.96/30124.7.82.97 to 124.7.82.98124.7.82.992
154124.7.82.100/30124.7.82.101 to 124.7.82.102124.7.82.1032
155124.7.82.104/30124.7.82.105 to 124.7.82.106124.7.82.1072
156124.7.82.108/30124.7.82.109 to 124.7.82.110124.7.82.1112
157124.7.82.112/30124.7.82.113 to 124.7.82.114124.7.82.1152
158124.7.82.116/30124.7.82.117 to 124.7.82.118124.7.82.1192
159124.7.82.120/30124.7.82.121 to 124.7.82.122124.7.82.1232
160124.7.82.124/30124.7.82.125 to 124.7.82.126124.7.82.1272
161124.7.82.128/30124.7.82.129 to 124.7.82.130124.7.82.1312
162124.7.82.132/30124.7.82.133 to 124.7.82.134124.7.82.1352
163124.7.82.136/30124.7.82.137 to 124.7.82.138124.7.82.1392
164124.7.82.140/30124.7.82.141 to 124.7.82.142124.7.82.1432
165124.7.82.144/30124.7.82.145 to 124.7.82.146124.7.82.1472
166124.7.82.148/30124.7.82.149 to 124.7.82.150124.7.82.1512
167124.7.82.152/30124.7.82.153 to 124.7.82.154124.7.82.1552
168124.7.82.156/30124.7.82.157 to 124.7.82.158124.7.82.1592
169124.7.82.160/30124.7.82.161 to 124.7.82.162124.7.82.1632
170124.7.82.164/30124.7.82.165 to 124.7.82.166124.7.82.1672
171124.7.82.168/30124.7.82.169 to 124.7.82.170124.7.82.1712
172124.7.82.172/30124.7.82.173 to 124.7.82.174124.7.82.1752
173124.7.82.176/30124.7.82.177 to 124.7.82.178124.7.82.1792
174124.7.82.180/30124.7.82.181 to 124.7.82.182124.7.82.1832
175124.7.82.184/30124.7.82.185 to 124.7.82.186124.7.82.1872
176124.7.82.188/30124.7.82.189 to 124.7.82.190124.7.82.1912
177124.7.82.192/30124.7.82.193 to 124.7.82.194124.7.82.1952
178124.7.82.196/30124.7.82.197 to 124.7.82.198124.7.82.1992
179124.7.82.200/30124.7.82.201 to 124.7.82.202124.7.82.2032
180124.7.82.204/30124.7.82.205 to 124.7.82.206124.7.82.2072
181124.7.82.208/30124.7.82.209 to 124.7.82.210124.7.82.2112
182124.7.82.212/30124.7.82.213 to 124.7.82.214124.7.82.2152
183124.7.82.216/30124.7.82.217 to 124.7.82.218124.7.82.2192
184124.7.82.220/30124.7.82.221 to 124.7.82.222124.7.82.2232
185124.7.82.224/30124.7.82.225 to 124.7.82.226124.7.82.2272
186124.7.82.228/30124.7.82.229 to 124.7.82.230124.7.82.2312
187124.7.82.232/30124.7.82.233 to 124.7.82.234124.7.82.2352
188124.7.82.236/30124.7.82.237 to 124.7.82.238124.7.82.2392
189124.7.82.240/30124.7.82.241 to 124.7.82.242124.7.82.2432
190124.7.82.244/30124.7.82.245 to 124.7.82.246124.7.82.2472
191124.7.82.248/30124.7.82.249 to 124.7.82.250124.7.82.2512
192124.7.82.252/30124.7.82.253 to 124.7.82.254124.7.82.2552
193124.7.83.0/30124.7.83.1 to 124.7.83.2124.7.83.32
194124.7.83.4/30124.7.83.5 to 124.7.83.6124.7.83.72
195124.7.83.8/30124.7.83.9 to 124.7.83.10124.7.83.112
196124.7.83.12/30124.7.83.13 to 124.7.83.14124.7.83.152
197124.7.83.16/30124.7.83.17 to 124.7.83.18124.7.83.192
198124.7.83.20/30124.7.83.21 to 124.7.83.22124.7.83.232
199124.7.83.24/30124.7.83.25 to 124.7.83.26124.7.83.272
200124.7.83.28/30124.7.83.29 to 124.7.83.30124.7.83.312
201124.7.83.32/30124.7.83.33 to 124.7.83.34124.7.83.352
202124.7.83.36/30124.7.83.37 to 124.7.83.38124.7.83.392
203124.7.83.40/30124.7.83.41 to 124.7.83.42124.7.83.432
204124.7.83.44/30124.7.83.45 to 124.7.83.46124.7.83.472
205124.7.83.48/30124.7.83.49 to 124.7.83.50124.7.83.512
206124.7.83.52/30124.7.83.53 to 124.7.83.54124.7.83.552
207124.7.83.56/30124.7.83.57 to 124.7.83.58124.7.83.592
208124.7.83.60/30124.7.83.61 to 124.7.83.62124.7.83.632
209124.7.83.64/30124.7.83.65 to 124.7.83.66124.7.83.672
210124.7.83.68/30124.7.83.69 to 124.7.83.70124.7.83.712
211124.7.83.72/30124.7.83.73 to 124.7.83.74124.7.83.752
212124.7.83.76/30124.7.83.77 to 124.7.83.78124.7.83.792
213124.7.83.80/30124.7.83.81 to 124.7.83.82124.7.83.832
214124.7.83.84/30124.7.83.85 to 124.7.83.86124.7.83.872
215124.7.83.88/30124.7.83.89 to 124.7.83.90124.7.83.912
216124.7.83.92/30124.7.83.93 to 124.7.83.94124.7.83.952
217124.7.83.96/30124.7.83.97 to 124.7.83.98124.7.83.992
218124.7.83.100/30124.7.83.101 to 124.7.83.102124.7.83.1032
219124.7.83.104/30124.7.83.105 to 124.7.83.106124.7.83.1072
220124.7.83.108/30124.7.83.109 to 124.7.83.110124.7.83.1112
221124.7.83.112/30124.7.83.113 to 124.7.83.114124.7.83.1152
222124.7.83.116/30124.7.83.117 to 124.7.83.118124.7.83.1192
223124.7.83.120/30124.7.83.121 to 124.7.83.122124.7.83.1232
224124.7.83.124/30124.7.83.125 to 124.7.83.126124.7.83.1272
225124.7.83.128/30124.7.83.129 to 124.7.83.130124.7.83.1312
226124.7.83.132/30124.7.83.133 to 124.7.83.134124.7.83.1352
227124.7.83.136/30124.7.83.137 to 124.7.83.138124.7.83.1392
228124.7.83.140/30124.7.83.141 to 124.7.83.142124.7.83.1432
229124.7.83.144/30124.7.83.145 to 124.7.83.146124.7.83.1472
230124.7.83.148/30124.7.83.149 to 124.7.83.150124.7.83.1512
231124.7.83.152/30124.7.83.153 to 124.7.83.154124.7.83.1552
232124.7.83.156/30124.7.83.157 to 124.7.83.158124.7.83.1592
233124.7.83.160/30124.7.83.161 to 124.7.83.162124.7.83.1632
234124.7.83.164/30124.7.83.165 to 124.7.83.166124.7.83.1672
235124.7.83.168/30124.7.83.169 to 124.7.83.170124.7.83.1712
236124.7.83.172/30124.7.83.173 to 124.7.83.174124.7.83.1752
237124.7.83.176/30124.7.83.177 to 124.7.83.178124.7.83.1792
238124.7.83.180/30124.7.83.181 to 124.7.83.182124.7.83.1832
239124.7.83.184/30124.7.83.185 to 124.7.83.186124.7.83.1872
240124.7.83.188/30124.7.83.189 to 124.7.83.190124.7.83.1912
241124.7.83.192/30124.7.83.193 to 124.7.83.194124.7.83.1952
242124.7.83.196/30124.7.83.197 to 124.7.83.198124.7.83.1992
243124.7.83.200/30124.7.83.201 to 124.7.83.202124.7.83.2032
244124.7.83.204/30124.7.83.205 to 124.7.83.206124.7.83.2072
245124.7.83.208/30124.7.83.209 to 124.7.83.210124.7.83.2112
246124.7.83.212/30124.7.83.213 to 124.7.83.214124.7.83.2152
247124.7.83.216/30124.7.83.217 to 124.7.83.218124.7.83.2192
248124.7.83.220/30124.7.83.221 to 124.7.83.222124.7.83.2232
249124.7.83.224/30124.7.83.225 to 124.7.83.226124.7.83.2272
250124.7.83.228/30124.7.83.229 to 124.7.83.230124.7.83.2312
251124.7.83.232/30124.7.83.233 to 124.7.83.234124.7.83.2352
252124.7.83.236/30124.7.83.237 to 124.7.83.238124.7.83.2392
253124.7.83.240/30124.7.83.241 to 124.7.83.242124.7.83.2432
254124.7.83.244/30124.7.83.245 to 124.7.83.246124.7.83.2472
255124.7.83.248/30124.7.83.249 to 124.7.83.250124.7.83.2512
256124.7.83.252/30124.7.83.253 to 124.7.83.254124.7.83.2552

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.