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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.

Network229.7.136.0/21
Usable hosts2,046
Subnet mask255.255.248.0
Addresses2,048
Network address
229.7.136.0
Broadcast address
229.7.143.255
First usable
229.7.136.1
Last usable
229.7.143.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E5078800 · Integer 3842476032 to 3842478079
Reverse DNS zones
136.7.229.in-addr.arpa
137.7.229.in-addr.arpa
138.7.229.in-addr.arpa
139.7.229.in-addr.arpa
140.7.229.in-addr.arpa
141.7.229.in-addr.arpa
142.7.229.in-addr.arpa
143.7.229.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
Address11100101.00000111.10001000.00000000229.7.136.0
Subnet mask11111111.11111111.11111000.00000000255.255.248.0
Network11100101.00000111.10001000.00000000229.7.136.0
Broadcast11100101.00000111.10001111.11111111229.7.143.255
Split into smaller subnets/30
/22 (2)/23 (4)/24 (8)/25 (16)/26 (32)/27 (64)/28 (128)/29 (256)/30 (512)/31 (1,024)/32 (2,048)

229.7.136.0/21 makes 512 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1229.7.136.0/30229.7.136.1 to 229.7.136.2229.7.136.32
2229.7.136.4/30229.7.136.5 to 229.7.136.6229.7.136.72
3229.7.136.8/30229.7.136.9 to 229.7.136.10229.7.136.112
4229.7.136.12/30229.7.136.13 to 229.7.136.14229.7.136.152
5229.7.136.16/30229.7.136.17 to 229.7.136.18229.7.136.192
6229.7.136.20/30229.7.136.21 to 229.7.136.22229.7.136.232
7229.7.136.24/30229.7.136.25 to 229.7.136.26229.7.136.272
8229.7.136.28/30229.7.136.29 to 229.7.136.30229.7.136.312
9229.7.136.32/30229.7.136.33 to 229.7.136.34229.7.136.352
10229.7.136.36/30229.7.136.37 to 229.7.136.38229.7.136.392
11229.7.136.40/30229.7.136.41 to 229.7.136.42229.7.136.432
12229.7.136.44/30229.7.136.45 to 229.7.136.46229.7.136.472
13229.7.136.48/30229.7.136.49 to 229.7.136.50229.7.136.512
14229.7.136.52/30229.7.136.53 to 229.7.136.54229.7.136.552
15229.7.136.56/30229.7.136.57 to 229.7.136.58229.7.136.592
16229.7.136.60/30229.7.136.61 to 229.7.136.62229.7.136.632
17229.7.136.64/30229.7.136.65 to 229.7.136.66229.7.136.672
18229.7.136.68/30229.7.136.69 to 229.7.136.70229.7.136.712
19229.7.136.72/30229.7.136.73 to 229.7.136.74229.7.136.752
20229.7.136.76/30229.7.136.77 to 229.7.136.78229.7.136.792
21229.7.136.80/30229.7.136.81 to 229.7.136.82229.7.136.832
22229.7.136.84/30229.7.136.85 to 229.7.136.86229.7.136.872
23229.7.136.88/30229.7.136.89 to 229.7.136.90229.7.136.912
24229.7.136.92/30229.7.136.93 to 229.7.136.94229.7.136.952
25229.7.136.96/30229.7.136.97 to 229.7.136.98229.7.136.992
26229.7.136.100/30229.7.136.101 to 229.7.136.102229.7.136.1032
27229.7.136.104/30229.7.136.105 to 229.7.136.106229.7.136.1072
28229.7.136.108/30229.7.136.109 to 229.7.136.110229.7.136.1112
29229.7.136.112/30229.7.136.113 to 229.7.136.114229.7.136.1152
30229.7.136.116/30229.7.136.117 to 229.7.136.118229.7.136.1192
31229.7.136.120/30229.7.136.121 to 229.7.136.122229.7.136.1232
32229.7.136.124/30229.7.136.125 to 229.7.136.126229.7.136.1272
33229.7.136.128/30229.7.136.129 to 229.7.136.130229.7.136.1312
34229.7.136.132/30229.7.136.133 to 229.7.136.134229.7.136.1352
35229.7.136.136/30229.7.136.137 to 229.7.136.138229.7.136.1392
36229.7.136.140/30229.7.136.141 to 229.7.136.142229.7.136.1432
37229.7.136.144/30229.7.136.145 to 229.7.136.146229.7.136.1472
38229.7.136.148/30229.7.136.149 to 229.7.136.150229.7.136.1512
39229.7.136.152/30229.7.136.153 to 229.7.136.154229.7.136.1552
40229.7.136.156/30229.7.136.157 to 229.7.136.158229.7.136.1592
41229.7.136.160/30229.7.136.161 to 229.7.136.162229.7.136.1632
42229.7.136.164/30229.7.136.165 to 229.7.136.166229.7.136.1672
43229.7.136.168/30229.7.136.169 to 229.7.136.170229.7.136.1712
44229.7.136.172/30229.7.136.173 to 229.7.136.174229.7.136.1752
45229.7.136.176/30229.7.136.177 to 229.7.136.178229.7.136.1792
46229.7.136.180/30229.7.136.181 to 229.7.136.182229.7.136.1832
47229.7.136.184/30229.7.136.185 to 229.7.136.186229.7.136.1872
48229.7.136.188/30229.7.136.189 to 229.7.136.190229.7.136.1912
49229.7.136.192/30229.7.136.193 to 229.7.136.194229.7.136.1952
50229.7.136.196/30229.7.136.197 to 229.7.136.198229.7.136.1992
51229.7.136.200/30229.7.136.201 to 229.7.136.202229.7.136.2032
52229.7.136.204/30229.7.136.205 to 229.7.136.206229.7.136.2072
53229.7.136.208/30229.7.136.209 to 229.7.136.210229.7.136.2112
54229.7.136.212/30229.7.136.213 to 229.7.136.214229.7.136.2152
55229.7.136.216/30229.7.136.217 to 229.7.136.218229.7.136.2192
56229.7.136.220/30229.7.136.221 to 229.7.136.222229.7.136.2232
57229.7.136.224/30229.7.136.225 to 229.7.136.226229.7.136.2272
58229.7.136.228/30229.7.136.229 to 229.7.136.230229.7.136.2312
59229.7.136.232/30229.7.136.233 to 229.7.136.234229.7.136.2352
60229.7.136.236/30229.7.136.237 to 229.7.136.238229.7.136.2392
61229.7.136.240/30229.7.136.241 to 229.7.136.242229.7.136.2432
62229.7.136.244/30229.7.136.245 to 229.7.136.246229.7.136.2472
63229.7.136.248/30229.7.136.249 to 229.7.136.250229.7.136.2512
64229.7.136.252/30229.7.136.253 to 229.7.136.254229.7.136.2552
65229.7.137.0/30229.7.137.1 to 229.7.137.2229.7.137.32
66229.7.137.4/30229.7.137.5 to 229.7.137.6229.7.137.72
67229.7.137.8/30229.7.137.9 to 229.7.137.10229.7.137.112
68229.7.137.12/30229.7.137.13 to 229.7.137.14229.7.137.152
69229.7.137.16/30229.7.137.17 to 229.7.137.18229.7.137.192
70229.7.137.20/30229.7.137.21 to 229.7.137.22229.7.137.232
71229.7.137.24/30229.7.137.25 to 229.7.137.26229.7.137.272
72229.7.137.28/30229.7.137.29 to 229.7.137.30229.7.137.312
73229.7.137.32/30229.7.137.33 to 229.7.137.34229.7.137.352
74229.7.137.36/30229.7.137.37 to 229.7.137.38229.7.137.392
75229.7.137.40/30229.7.137.41 to 229.7.137.42229.7.137.432
76229.7.137.44/30229.7.137.45 to 229.7.137.46229.7.137.472
77229.7.137.48/30229.7.137.49 to 229.7.137.50229.7.137.512
78229.7.137.52/30229.7.137.53 to 229.7.137.54229.7.137.552
79229.7.137.56/30229.7.137.57 to 229.7.137.58229.7.137.592
80229.7.137.60/30229.7.137.61 to 229.7.137.62229.7.137.632
81229.7.137.64/30229.7.137.65 to 229.7.137.66229.7.137.672
82229.7.137.68/30229.7.137.69 to 229.7.137.70229.7.137.712
83229.7.137.72/30229.7.137.73 to 229.7.137.74229.7.137.752
84229.7.137.76/30229.7.137.77 to 229.7.137.78229.7.137.792
85229.7.137.80/30229.7.137.81 to 229.7.137.82229.7.137.832
86229.7.137.84/30229.7.137.85 to 229.7.137.86229.7.137.872
87229.7.137.88/30229.7.137.89 to 229.7.137.90229.7.137.912
88229.7.137.92/30229.7.137.93 to 229.7.137.94229.7.137.952
89229.7.137.96/30229.7.137.97 to 229.7.137.98229.7.137.992
90229.7.137.100/30229.7.137.101 to 229.7.137.102229.7.137.1032
91229.7.137.104/30229.7.137.105 to 229.7.137.106229.7.137.1072
92229.7.137.108/30229.7.137.109 to 229.7.137.110229.7.137.1112
93229.7.137.112/30229.7.137.113 to 229.7.137.114229.7.137.1152
94229.7.137.116/30229.7.137.117 to 229.7.137.118229.7.137.1192
95229.7.137.120/30229.7.137.121 to 229.7.137.122229.7.137.1232
96229.7.137.124/30229.7.137.125 to 229.7.137.126229.7.137.1272
97229.7.137.128/30229.7.137.129 to 229.7.137.130229.7.137.1312
98229.7.137.132/30229.7.137.133 to 229.7.137.134229.7.137.1352
99229.7.137.136/30229.7.137.137 to 229.7.137.138229.7.137.1392
100229.7.137.140/30229.7.137.141 to 229.7.137.142229.7.137.1432
101229.7.137.144/30229.7.137.145 to 229.7.137.146229.7.137.1472
102229.7.137.148/30229.7.137.149 to 229.7.137.150229.7.137.1512
103229.7.137.152/30229.7.137.153 to 229.7.137.154229.7.137.1552
104229.7.137.156/30229.7.137.157 to 229.7.137.158229.7.137.1592
105229.7.137.160/30229.7.137.161 to 229.7.137.162229.7.137.1632
106229.7.137.164/30229.7.137.165 to 229.7.137.166229.7.137.1672
107229.7.137.168/30229.7.137.169 to 229.7.137.170229.7.137.1712
108229.7.137.172/30229.7.137.173 to 229.7.137.174229.7.137.1752
109229.7.137.176/30229.7.137.177 to 229.7.137.178229.7.137.1792
110229.7.137.180/30229.7.137.181 to 229.7.137.182229.7.137.1832
111229.7.137.184/30229.7.137.185 to 229.7.137.186229.7.137.1872
112229.7.137.188/30229.7.137.189 to 229.7.137.190229.7.137.1912
113229.7.137.192/30229.7.137.193 to 229.7.137.194229.7.137.1952
114229.7.137.196/30229.7.137.197 to 229.7.137.198229.7.137.1992
115229.7.137.200/30229.7.137.201 to 229.7.137.202229.7.137.2032
116229.7.137.204/30229.7.137.205 to 229.7.137.206229.7.137.2072
117229.7.137.208/30229.7.137.209 to 229.7.137.210229.7.137.2112
118229.7.137.212/30229.7.137.213 to 229.7.137.214229.7.137.2152
119229.7.137.216/30229.7.137.217 to 229.7.137.218229.7.137.2192
120229.7.137.220/30229.7.137.221 to 229.7.137.222229.7.137.2232
121229.7.137.224/30229.7.137.225 to 229.7.137.226229.7.137.2272
122229.7.137.228/30229.7.137.229 to 229.7.137.230229.7.137.2312
123229.7.137.232/30229.7.137.233 to 229.7.137.234229.7.137.2352
124229.7.137.236/30229.7.137.237 to 229.7.137.238229.7.137.2392
125229.7.137.240/30229.7.137.241 to 229.7.137.242229.7.137.2432
126229.7.137.244/30229.7.137.245 to 229.7.137.246229.7.137.2472
127229.7.137.248/30229.7.137.249 to 229.7.137.250229.7.137.2512
128229.7.137.252/30229.7.137.253 to 229.7.137.254229.7.137.2552
129229.7.138.0/30229.7.138.1 to 229.7.138.2229.7.138.32
130229.7.138.4/30229.7.138.5 to 229.7.138.6229.7.138.72
131229.7.138.8/30229.7.138.9 to 229.7.138.10229.7.138.112
132229.7.138.12/30229.7.138.13 to 229.7.138.14229.7.138.152
133229.7.138.16/30229.7.138.17 to 229.7.138.18229.7.138.192
134229.7.138.20/30229.7.138.21 to 229.7.138.22229.7.138.232
135229.7.138.24/30229.7.138.25 to 229.7.138.26229.7.138.272
136229.7.138.28/30229.7.138.29 to 229.7.138.30229.7.138.312
137229.7.138.32/30229.7.138.33 to 229.7.138.34229.7.138.352
138229.7.138.36/30229.7.138.37 to 229.7.138.38229.7.138.392
139229.7.138.40/30229.7.138.41 to 229.7.138.42229.7.138.432
140229.7.138.44/30229.7.138.45 to 229.7.138.46229.7.138.472
141229.7.138.48/30229.7.138.49 to 229.7.138.50229.7.138.512
142229.7.138.52/30229.7.138.53 to 229.7.138.54229.7.138.552
143229.7.138.56/30229.7.138.57 to 229.7.138.58229.7.138.592
144229.7.138.60/30229.7.138.61 to 229.7.138.62229.7.138.632
145229.7.138.64/30229.7.138.65 to 229.7.138.66229.7.138.672
146229.7.138.68/30229.7.138.69 to 229.7.138.70229.7.138.712
147229.7.138.72/30229.7.138.73 to 229.7.138.74229.7.138.752
148229.7.138.76/30229.7.138.77 to 229.7.138.78229.7.138.792
149229.7.138.80/30229.7.138.81 to 229.7.138.82229.7.138.832
150229.7.138.84/30229.7.138.85 to 229.7.138.86229.7.138.872
151229.7.138.88/30229.7.138.89 to 229.7.138.90229.7.138.912
152229.7.138.92/30229.7.138.93 to 229.7.138.94229.7.138.952
153229.7.138.96/30229.7.138.97 to 229.7.138.98229.7.138.992
154229.7.138.100/30229.7.138.101 to 229.7.138.102229.7.138.1032
155229.7.138.104/30229.7.138.105 to 229.7.138.106229.7.138.1072
156229.7.138.108/30229.7.138.109 to 229.7.138.110229.7.138.1112
157229.7.138.112/30229.7.138.113 to 229.7.138.114229.7.138.1152
158229.7.138.116/30229.7.138.117 to 229.7.138.118229.7.138.1192
159229.7.138.120/30229.7.138.121 to 229.7.138.122229.7.138.1232
160229.7.138.124/30229.7.138.125 to 229.7.138.126229.7.138.1272
161229.7.138.128/30229.7.138.129 to 229.7.138.130229.7.138.1312
162229.7.138.132/30229.7.138.133 to 229.7.138.134229.7.138.1352
163229.7.138.136/30229.7.138.137 to 229.7.138.138229.7.138.1392
164229.7.138.140/30229.7.138.141 to 229.7.138.142229.7.138.1432
165229.7.138.144/30229.7.138.145 to 229.7.138.146229.7.138.1472
166229.7.138.148/30229.7.138.149 to 229.7.138.150229.7.138.1512
167229.7.138.152/30229.7.138.153 to 229.7.138.154229.7.138.1552
168229.7.138.156/30229.7.138.157 to 229.7.138.158229.7.138.1592
169229.7.138.160/30229.7.138.161 to 229.7.138.162229.7.138.1632
170229.7.138.164/30229.7.138.165 to 229.7.138.166229.7.138.1672
171229.7.138.168/30229.7.138.169 to 229.7.138.170229.7.138.1712
172229.7.138.172/30229.7.138.173 to 229.7.138.174229.7.138.1752
173229.7.138.176/30229.7.138.177 to 229.7.138.178229.7.138.1792
174229.7.138.180/30229.7.138.181 to 229.7.138.182229.7.138.1832
175229.7.138.184/30229.7.138.185 to 229.7.138.186229.7.138.1872
176229.7.138.188/30229.7.138.189 to 229.7.138.190229.7.138.1912
177229.7.138.192/30229.7.138.193 to 229.7.138.194229.7.138.1952
178229.7.138.196/30229.7.138.197 to 229.7.138.198229.7.138.1992
179229.7.138.200/30229.7.138.201 to 229.7.138.202229.7.138.2032
180229.7.138.204/30229.7.138.205 to 229.7.138.206229.7.138.2072
181229.7.138.208/30229.7.138.209 to 229.7.138.210229.7.138.2112
182229.7.138.212/30229.7.138.213 to 229.7.138.214229.7.138.2152
183229.7.138.216/30229.7.138.217 to 229.7.138.218229.7.138.2192
184229.7.138.220/30229.7.138.221 to 229.7.138.222229.7.138.2232
185229.7.138.224/30229.7.138.225 to 229.7.138.226229.7.138.2272
186229.7.138.228/30229.7.138.229 to 229.7.138.230229.7.138.2312
187229.7.138.232/30229.7.138.233 to 229.7.138.234229.7.138.2352
188229.7.138.236/30229.7.138.237 to 229.7.138.238229.7.138.2392
189229.7.138.240/30229.7.138.241 to 229.7.138.242229.7.138.2432
190229.7.138.244/30229.7.138.245 to 229.7.138.246229.7.138.2472
191229.7.138.248/30229.7.138.249 to 229.7.138.250229.7.138.2512
192229.7.138.252/30229.7.138.253 to 229.7.138.254229.7.138.2552
193229.7.139.0/30229.7.139.1 to 229.7.139.2229.7.139.32
194229.7.139.4/30229.7.139.5 to 229.7.139.6229.7.139.72
195229.7.139.8/30229.7.139.9 to 229.7.139.10229.7.139.112
196229.7.139.12/30229.7.139.13 to 229.7.139.14229.7.139.152
197229.7.139.16/30229.7.139.17 to 229.7.139.18229.7.139.192
198229.7.139.20/30229.7.139.21 to 229.7.139.22229.7.139.232
199229.7.139.24/30229.7.139.25 to 229.7.139.26229.7.139.272
200229.7.139.28/30229.7.139.29 to 229.7.139.30229.7.139.312
201229.7.139.32/30229.7.139.33 to 229.7.139.34229.7.139.352
202229.7.139.36/30229.7.139.37 to 229.7.139.38229.7.139.392
203229.7.139.40/30229.7.139.41 to 229.7.139.42229.7.139.432
204229.7.139.44/30229.7.139.45 to 229.7.139.46229.7.139.472
205229.7.139.48/30229.7.139.49 to 229.7.139.50229.7.139.512
206229.7.139.52/30229.7.139.53 to 229.7.139.54229.7.139.552
207229.7.139.56/30229.7.139.57 to 229.7.139.58229.7.139.592
208229.7.139.60/30229.7.139.61 to 229.7.139.62229.7.139.632
209229.7.139.64/30229.7.139.65 to 229.7.139.66229.7.139.672
210229.7.139.68/30229.7.139.69 to 229.7.139.70229.7.139.712
211229.7.139.72/30229.7.139.73 to 229.7.139.74229.7.139.752
212229.7.139.76/30229.7.139.77 to 229.7.139.78229.7.139.792
213229.7.139.80/30229.7.139.81 to 229.7.139.82229.7.139.832
214229.7.139.84/30229.7.139.85 to 229.7.139.86229.7.139.872
215229.7.139.88/30229.7.139.89 to 229.7.139.90229.7.139.912
216229.7.139.92/30229.7.139.93 to 229.7.139.94229.7.139.952
217229.7.139.96/30229.7.139.97 to 229.7.139.98229.7.139.992
218229.7.139.100/30229.7.139.101 to 229.7.139.102229.7.139.1032
219229.7.139.104/30229.7.139.105 to 229.7.139.106229.7.139.1072
220229.7.139.108/30229.7.139.109 to 229.7.139.110229.7.139.1112
221229.7.139.112/30229.7.139.113 to 229.7.139.114229.7.139.1152
222229.7.139.116/30229.7.139.117 to 229.7.139.118229.7.139.1192
223229.7.139.120/30229.7.139.121 to 229.7.139.122229.7.139.1232
224229.7.139.124/30229.7.139.125 to 229.7.139.126229.7.139.1272
225229.7.139.128/30229.7.139.129 to 229.7.139.130229.7.139.1312
226229.7.139.132/30229.7.139.133 to 229.7.139.134229.7.139.1352
227229.7.139.136/30229.7.139.137 to 229.7.139.138229.7.139.1392
228229.7.139.140/30229.7.139.141 to 229.7.139.142229.7.139.1432
229229.7.139.144/30229.7.139.145 to 229.7.139.146229.7.139.1472
230229.7.139.148/30229.7.139.149 to 229.7.139.150229.7.139.1512
231229.7.139.152/30229.7.139.153 to 229.7.139.154229.7.139.1552
232229.7.139.156/30229.7.139.157 to 229.7.139.158229.7.139.1592
233229.7.139.160/30229.7.139.161 to 229.7.139.162229.7.139.1632
234229.7.139.164/30229.7.139.165 to 229.7.139.166229.7.139.1672
235229.7.139.168/30229.7.139.169 to 229.7.139.170229.7.139.1712
236229.7.139.172/30229.7.139.173 to 229.7.139.174229.7.139.1752
237229.7.139.176/30229.7.139.177 to 229.7.139.178229.7.139.1792
238229.7.139.180/30229.7.139.181 to 229.7.139.182229.7.139.1832
239229.7.139.184/30229.7.139.185 to 229.7.139.186229.7.139.1872
240229.7.139.188/30229.7.139.189 to 229.7.139.190229.7.139.1912
241229.7.139.192/30229.7.139.193 to 229.7.139.194229.7.139.1952
242229.7.139.196/30229.7.139.197 to 229.7.139.198229.7.139.1992
243229.7.139.200/30229.7.139.201 to 229.7.139.202229.7.139.2032
244229.7.139.204/30229.7.139.205 to 229.7.139.206229.7.139.2072
245229.7.139.208/30229.7.139.209 to 229.7.139.210229.7.139.2112
246229.7.139.212/30229.7.139.213 to 229.7.139.214229.7.139.2152
247229.7.139.216/30229.7.139.217 to 229.7.139.218229.7.139.2192
248229.7.139.220/30229.7.139.221 to 229.7.139.222229.7.139.2232
249229.7.139.224/30229.7.139.225 to 229.7.139.226229.7.139.2272
250229.7.139.228/30229.7.139.229 to 229.7.139.230229.7.139.2312
251229.7.139.232/30229.7.139.233 to 229.7.139.234229.7.139.2352
252229.7.139.236/30229.7.139.237 to 229.7.139.238229.7.139.2392
253229.7.139.240/30229.7.139.241 to 229.7.139.242229.7.139.2432
254229.7.139.244/30229.7.139.245 to 229.7.139.246229.7.139.2472
255229.7.139.248/30229.7.139.249 to 229.7.139.250229.7.139.2512
256229.7.139.252/30229.7.139.253 to 229.7.139.254229.7.139.2552

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.