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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.

Network205.3.96.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
205.3.96.0
Broadcast address
205.3.111.255
First usable
205.3.96.1
Last usable
205.3.111.254
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
C (default /24)
As numbers
Hex CD036000 · Integer 3439550464 to 3439554559
Reverse DNS zones
96.3.205.in-addr.arpa
97.3.205.in-addr.arpa
98.3.205.in-addr.arpa
99.3.205.in-addr.arpa
100.3.205.in-addr.arpa
101.3.205.in-addr.arpa
102.3.205.in-addr.arpa
103.3.205.in-addr.arpa
104.3.205.in-addr.arpa
105.3.205.in-addr.arpa
106.3.205.in-addr.arpa
107.3.205.in-addr.arpa
108.3.205.in-addr.arpa
109.3.205.in-addr.arpa
110.3.205.in-addr.arpa
111.3.205.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
Address11001101.00000011.01100000.00000000205.3.96.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11001101.00000011.01100000.00000000205.3.96.0
Broadcast11001101.00000011.01101111.11111111205.3.111.255
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)

205.3.96.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1205.3.96.0/30205.3.96.1 to 205.3.96.2205.3.96.32
2205.3.96.4/30205.3.96.5 to 205.3.96.6205.3.96.72
3205.3.96.8/30205.3.96.9 to 205.3.96.10205.3.96.112
4205.3.96.12/30205.3.96.13 to 205.3.96.14205.3.96.152
5205.3.96.16/30205.3.96.17 to 205.3.96.18205.3.96.192
6205.3.96.20/30205.3.96.21 to 205.3.96.22205.3.96.232
7205.3.96.24/30205.3.96.25 to 205.3.96.26205.3.96.272
8205.3.96.28/30205.3.96.29 to 205.3.96.30205.3.96.312
9205.3.96.32/30205.3.96.33 to 205.3.96.34205.3.96.352
10205.3.96.36/30205.3.96.37 to 205.3.96.38205.3.96.392
11205.3.96.40/30205.3.96.41 to 205.3.96.42205.3.96.432
12205.3.96.44/30205.3.96.45 to 205.3.96.46205.3.96.472
13205.3.96.48/30205.3.96.49 to 205.3.96.50205.3.96.512
14205.3.96.52/30205.3.96.53 to 205.3.96.54205.3.96.552
15205.3.96.56/30205.3.96.57 to 205.3.96.58205.3.96.592
16205.3.96.60/30205.3.96.61 to 205.3.96.62205.3.96.632
17205.3.96.64/30205.3.96.65 to 205.3.96.66205.3.96.672
18205.3.96.68/30205.3.96.69 to 205.3.96.70205.3.96.712
19205.3.96.72/30205.3.96.73 to 205.3.96.74205.3.96.752
20205.3.96.76/30205.3.96.77 to 205.3.96.78205.3.96.792
21205.3.96.80/30205.3.96.81 to 205.3.96.82205.3.96.832
22205.3.96.84/30205.3.96.85 to 205.3.96.86205.3.96.872
23205.3.96.88/30205.3.96.89 to 205.3.96.90205.3.96.912
24205.3.96.92/30205.3.96.93 to 205.3.96.94205.3.96.952
25205.3.96.96/30205.3.96.97 to 205.3.96.98205.3.96.992
26205.3.96.100/30205.3.96.101 to 205.3.96.102205.3.96.1032
27205.3.96.104/30205.3.96.105 to 205.3.96.106205.3.96.1072
28205.3.96.108/30205.3.96.109 to 205.3.96.110205.3.96.1112
29205.3.96.112/30205.3.96.113 to 205.3.96.114205.3.96.1152
30205.3.96.116/30205.3.96.117 to 205.3.96.118205.3.96.1192
31205.3.96.120/30205.3.96.121 to 205.3.96.122205.3.96.1232
32205.3.96.124/30205.3.96.125 to 205.3.96.126205.3.96.1272
33205.3.96.128/30205.3.96.129 to 205.3.96.130205.3.96.1312
34205.3.96.132/30205.3.96.133 to 205.3.96.134205.3.96.1352
35205.3.96.136/30205.3.96.137 to 205.3.96.138205.3.96.1392
36205.3.96.140/30205.3.96.141 to 205.3.96.142205.3.96.1432
37205.3.96.144/30205.3.96.145 to 205.3.96.146205.3.96.1472
38205.3.96.148/30205.3.96.149 to 205.3.96.150205.3.96.1512
39205.3.96.152/30205.3.96.153 to 205.3.96.154205.3.96.1552
40205.3.96.156/30205.3.96.157 to 205.3.96.158205.3.96.1592
41205.3.96.160/30205.3.96.161 to 205.3.96.162205.3.96.1632
42205.3.96.164/30205.3.96.165 to 205.3.96.166205.3.96.1672
43205.3.96.168/30205.3.96.169 to 205.3.96.170205.3.96.1712
44205.3.96.172/30205.3.96.173 to 205.3.96.174205.3.96.1752
45205.3.96.176/30205.3.96.177 to 205.3.96.178205.3.96.1792
46205.3.96.180/30205.3.96.181 to 205.3.96.182205.3.96.1832
47205.3.96.184/30205.3.96.185 to 205.3.96.186205.3.96.1872
48205.3.96.188/30205.3.96.189 to 205.3.96.190205.3.96.1912
49205.3.96.192/30205.3.96.193 to 205.3.96.194205.3.96.1952
50205.3.96.196/30205.3.96.197 to 205.3.96.198205.3.96.1992
51205.3.96.200/30205.3.96.201 to 205.3.96.202205.3.96.2032
52205.3.96.204/30205.3.96.205 to 205.3.96.206205.3.96.2072
53205.3.96.208/30205.3.96.209 to 205.3.96.210205.3.96.2112
54205.3.96.212/30205.3.96.213 to 205.3.96.214205.3.96.2152
55205.3.96.216/30205.3.96.217 to 205.3.96.218205.3.96.2192
56205.3.96.220/30205.3.96.221 to 205.3.96.222205.3.96.2232
57205.3.96.224/30205.3.96.225 to 205.3.96.226205.3.96.2272
58205.3.96.228/30205.3.96.229 to 205.3.96.230205.3.96.2312
59205.3.96.232/30205.3.96.233 to 205.3.96.234205.3.96.2352
60205.3.96.236/30205.3.96.237 to 205.3.96.238205.3.96.2392
61205.3.96.240/30205.3.96.241 to 205.3.96.242205.3.96.2432
62205.3.96.244/30205.3.96.245 to 205.3.96.246205.3.96.2472
63205.3.96.248/30205.3.96.249 to 205.3.96.250205.3.96.2512
64205.3.96.252/30205.3.96.253 to 205.3.96.254205.3.96.2552
65205.3.97.0/30205.3.97.1 to 205.3.97.2205.3.97.32
66205.3.97.4/30205.3.97.5 to 205.3.97.6205.3.97.72
67205.3.97.8/30205.3.97.9 to 205.3.97.10205.3.97.112
68205.3.97.12/30205.3.97.13 to 205.3.97.14205.3.97.152
69205.3.97.16/30205.3.97.17 to 205.3.97.18205.3.97.192
70205.3.97.20/30205.3.97.21 to 205.3.97.22205.3.97.232
71205.3.97.24/30205.3.97.25 to 205.3.97.26205.3.97.272
72205.3.97.28/30205.3.97.29 to 205.3.97.30205.3.97.312
73205.3.97.32/30205.3.97.33 to 205.3.97.34205.3.97.352
74205.3.97.36/30205.3.97.37 to 205.3.97.38205.3.97.392
75205.3.97.40/30205.3.97.41 to 205.3.97.42205.3.97.432
76205.3.97.44/30205.3.97.45 to 205.3.97.46205.3.97.472
77205.3.97.48/30205.3.97.49 to 205.3.97.50205.3.97.512
78205.3.97.52/30205.3.97.53 to 205.3.97.54205.3.97.552
79205.3.97.56/30205.3.97.57 to 205.3.97.58205.3.97.592
80205.3.97.60/30205.3.97.61 to 205.3.97.62205.3.97.632
81205.3.97.64/30205.3.97.65 to 205.3.97.66205.3.97.672
82205.3.97.68/30205.3.97.69 to 205.3.97.70205.3.97.712
83205.3.97.72/30205.3.97.73 to 205.3.97.74205.3.97.752
84205.3.97.76/30205.3.97.77 to 205.3.97.78205.3.97.792
85205.3.97.80/30205.3.97.81 to 205.3.97.82205.3.97.832
86205.3.97.84/30205.3.97.85 to 205.3.97.86205.3.97.872
87205.3.97.88/30205.3.97.89 to 205.3.97.90205.3.97.912
88205.3.97.92/30205.3.97.93 to 205.3.97.94205.3.97.952
89205.3.97.96/30205.3.97.97 to 205.3.97.98205.3.97.992
90205.3.97.100/30205.3.97.101 to 205.3.97.102205.3.97.1032
91205.3.97.104/30205.3.97.105 to 205.3.97.106205.3.97.1072
92205.3.97.108/30205.3.97.109 to 205.3.97.110205.3.97.1112
93205.3.97.112/30205.3.97.113 to 205.3.97.114205.3.97.1152
94205.3.97.116/30205.3.97.117 to 205.3.97.118205.3.97.1192
95205.3.97.120/30205.3.97.121 to 205.3.97.122205.3.97.1232
96205.3.97.124/30205.3.97.125 to 205.3.97.126205.3.97.1272
97205.3.97.128/30205.3.97.129 to 205.3.97.130205.3.97.1312
98205.3.97.132/30205.3.97.133 to 205.3.97.134205.3.97.1352
99205.3.97.136/30205.3.97.137 to 205.3.97.138205.3.97.1392
100205.3.97.140/30205.3.97.141 to 205.3.97.142205.3.97.1432
101205.3.97.144/30205.3.97.145 to 205.3.97.146205.3.97.1472
102205.3.97.148/30205.3.97.149 to 205.3.97.150205.3.97.1512
103205.3.97.152/30205.3.97.153 to 205.3.97.154205.3.97.1552
104205.3.97.156/30205.3.97.157 to 205.3.97.158205.3.97.1592
105205.3.97.160/30205.3.97.161 to 205.3.97.162205.3.97.1632
106205.3.97.164/30205.3.97.165 to 205.3.97.166205.3.97.1672
107205.3.97.168/30205.3.97.169 to 205.3.97.170205.3.97.1712
108205.3.97.172/30205.3.97.173 to 205.3.97.174205.3.97.1752
109205.3.97.176/30205.3.97.177 to 205.3.97.178205.3.97.1792
110205.3.97.180/30205.3.97.181 to 205.3.97.182205.3.97.1832
111205.3.97.184/30205.3.97.185 to 205.3.97.186205.3.97.1872
112205.3.97.188/30205.3.97.189 to 205.3.97.190205.3.97.1912
113205.3.97.192/30205.3.97.193 to 205.3.97.194205.3.97.1952
114205.3.97.196/30205.3.97.197 to 205.3.97.198205.3.97.1992
115205.3.97.200/30205.3.97.201 to 205.3.97.202205.3.97.2032
116205.3.97.204/30205.3.97.205 to 205.3.97.206205.3.97.2072
117205.3.97.208/30205.3.97.209 to 205.3.97.210205.3.97.2112
118205.3.97.212/30205.3.97.213 to 205.3.97.214205.3.97.2152
119205.3.97.216/30205.3.97.217 to 205.3.97.218205.3.97.2192
120205.3.97.220/30205.3.97.221 to 205.3.97.222205.3.97.2232
121205.3.97.224/30205.3.97.225 to 205.3.97.226205.3.97.2272
122205.3.97.228/30205.3.97.229 to 205.3.97.230205.3.97.2312
123205.3.97.232/30205.3.97.233 to 205.3.97.234205.3.97.2352
124205.3.97.236/30205.3.97.237 to 205.3.97.238205.3.97.2392
125205.3.97.240/30205.3.97.241 to 205.3.97.242205.3.97.2432
126205.3.97.244/30205.3.97.245 to 205.3.97.246205.3.97.2472
127205.3.97.248/30205.3.97.249 to 205.3.97.250205.3.97.2512
128205.3.97.252/30205.3.97.253 to 205.3.97.254205.3.97.2552
129205.3.98.0/30205.3.98.1 to 205.3.98.2205.3.98.32
130205.3.98.4/30205.3.98.5 to 205.3.98.6205.3.98.72
131205.3.98.8/30205.3.98.9 to 205.3.98.10205.3.98.112
132205.3.98.12/30205.3.98.13 to 205.3.98.14205.3.98.152
133205.3.98.16/30205.3.98.17 to 205.3.98.18205.3.98.192
134205.3.98.20/30205.3.98.21 to 205.3.98.22205.3.98.232
135205.3.98.24/30205.3.98.25 to 205.3.98.26205.3.98.272
136205.3.98.28/30205.3.98.29 to 205.3.98.30205.3.98.312
137205.3.98.32/30205.3.98.33 to 205.3.98.34205.3.98.352
138205.3.98.36/30205.3.98.37 to 205.3.98.38205.3.98.392
139205.3.98.40/30205.3.98.41 to 205.3.98.42205.3.98.432
140205.3.98.44/30205.3.98.45 to 205.3.98.46205.3.98.472
141205.3.98.48/30205.3.98.49 to 205.3.98.50205.3.98.512
142205.3.98.52/30205.3.98.53 to 205.3.98.54205.3.98.552
143205.3.98.56/30205.3.98.57 to 205.3.98.58205.3.98.592
144205.3.98.60/30205.3.98.61 to 205.3.98.62205.3.98.632
145205.3.98.64/30205.3.98.65 to 205.3.98.66205.3.98.672
146205.3.98.68/30205.3.98.69 to 205.3.98.70205.3.98.712
147205.3.98.72/30205.3.98.73 to 205.3.98.74205.3.98.752
148205.3.98.76/30205.3.98.77 to 205.3.98.78205.3.98.792
149205.3.98.80/30205.3.98.81 to 205.3.98.82205.3.98.832
150205.3.98.84/30205.3.98.85 to 205.3.98.86205.3.98.872
151205.3.98.88/30205.3.98.89 to 205.3.98.90205.3.98.912
152205.3.98.92/30205.3.98.93 to 205.3.98.94205.3.98.952
153205.3.98.96/30205.3.98.97 to 205.3.98.98205.3.98.992
154205.3.98.100/30205.3.98.101 to 205.3.98.102205.3.98.1032
155205.3.98.104/30205.3.98.105 to 205.3.98.106205.3.98.1072
156205.3.98.108/30205.3.98.109 to 205.3.98.110205.3.98.1112
157205.3.98.112/30205.3.98.113 to 205.3.98.114205.3.98.1152
158205.3.98.116/30205.3.98.117 to 205.3.98.118205.3.98.1192
159205.3.98.120/30205.3.98.121 to 205.3.98.122205.3.98.1232
160205.3.98.124/30205.3.98.125 to 205.3.98.126205.3.98.1272
161205.3.98.128/30205.3.98.129 to 205.3.98.130205.3.98.1312
162205.3.98.132/30205.3.98.133 to 205.3.98.134205.3.98.1352
163205.3.98.136/30205.3.98.137 to 205.3.98.138205.3.98.1392
164205.3.98.140/30205.3.98.141 to 205.3.98.142205.3.98.1432
165205.3.98.144/30205.3.98.145 to 205.3.98.146205.3.98.1472
166205.3.98.148/30205.3.98.149 to 205.3.98.150205.3.98.1512
167205.3.98.152/30205.3.98.153 to 205.3.98.154205.3.98.1552
168205.3.98.156/30205.3.98.157 to 205.3.98.158205.3.98.1592
169205.3.98.160/30205.3.98.161 to 205.3.98.162205.3.98.1632
170205.3.98.164/30205.3.98.165 to 205.3.98.166205.3.98.1672
171205.3.98.168/30205.3.98.169 to 205.3.98.170205.3.98.1712
172205.3.98.172/30205.3.98.173 to 205.3.98.174205.3.98.1752
173205.3.98.176/30205.3.98.177 to 205.3.98.178205.3.98.1792
174205.3.98.180/30205.3.98.181 to 205.3.98.182205.3.98.1832
175205.3.98.184/30205.3.98.185 to 205.3.98.186205.3.98.1872
176205.3.98.188/30205.3.98.189 to 205.3.98.190205.3.98.1912
177205.3.98.192/30205.3.98.193 to 205.3.98.194205.3.98.1952
178205.3.98.196/30205.3.98.197 to 205.3.98.198205.3.98.1992
179205.3.98.200/30205.3.98.201 to 205.3.98.202205.3.98.2032
180205.3.98.204/30205.3.98.205 to 205.3.98.206205.3.98.2072
181205.3.98.208/30205.3.98.209 to 205.3.98.210205.3.98.2112
182205.3.98.212/30205.3.98.213 to 205.3.98.214205.3.98.2152
183205.3.98.216/30205.3.98.217 to 205.3.98.218205.3.98.2192
184205.3.98.220/30205.3.98.221 to 205.3.98.222205.3.98.2232
185205.3.98.224/30205.3.98.225 to 205.3.98.226205.3.98.2272
186205.3.98.228/30205.3.98.229 to 205.3.98.230205.3.98.2312
187205.3.98.232/30205.3.98.233 to 205.3.98.234205.3.98.2352
188205.3.98.236/30205.3.98.237 to 205.3.98.238205.3.98.2392
189205.3.98.240/30205.3.98.241 to 205.3.98.242205.3.98.2432
190205.3.98.244/30205.3.98.245 to 205.3.98.246205.3.98.2472
191205.3.98.248/30205.3.98.249 to 205.3.98.250205.3.98.2512
192205.3.98.252/30205.3.98.253 to 205.3.98.254205.3.98.2552
193205.3.99.0/30205.3.99.1 to 205.3.99.2205.3.99.32
194205.3.99.4/30205.3.99.5 to 205.3.99.6205.3.99.72
195205.3.99.8/30205.3.99.9 to 205.3.99.10205.3.99.112
196205.3.99.12/30205.3.99.13 to 205.3.99.14205.3.99.152
197205.3.99.16/30205.3.99.17 to 205.3.99.18205.3.99.192
198205.3.99.20/30205.3.99.21 to 205.3.99.22205.3.99.232
199205.3.99.24/30205.3.99.25 to 205.3.99.26205.3.99.272
200205.3.99.28/30205.3.99.29 to 205.3.99.30205.3.99.312
201205.3.99.32/30205.3.99.33 to 205.3.99.34205.3.99.352
202205.3.99.36/30205.3.99.37 to 205.3.99.38205.3.99.392
203205.3.99.40/30205.3.99.41 to 205.3.99.42205.3.99.432
204205.3.99.44/30205.3.99.45 to 205.3.99.46205.3.99.472
205205.3.99.48/30205.3.99.49 to 205.3.99.50205.3.99.512
206205.3.99.52/30205.3.99.53 to 205.3.99.54205.3.99.552
207205.3.99.56/30205.3.99.57 to 205.3.99.58205.3.99.592
208205.3.99.60/30205.3.99.61 to 205.3.99.62205.3.99.632
209205.3.99.64/30205.3.99.65 to 205.3.99.66205.3.99.672
210205.3.99.68/30205.3.99.69 to 205.3.99.70205.3.99.712
211205.3.99.72/30205.3.99.73 to 205.3.99.74205.3.99.752
212205.3.99.76/30205.3.99.77 to 205.3.99.78205.3.99.792
213205.3.99.80/30205.3.99.81 to 205.3.99.82205.3.99.832
214205.3.99.84/30205.3.99.85 to 205.3.99.86205.3.99.872
215205.3.99.88/30205.3.99.89 to 205.3.99.90205.3.99.912
216205.3.99.92/30205.3.99.93 to 205.3.99.94205.3.99.952
217205.3.99.96/30205.3.99.97 to 205.3.99.98205.3.99.992
218205.3.99.100/30205.3.99.101 to 205.3.99.102205.3.99.1032
219205.3.99.104/30205.3.99.105 to 205.3.99.106205.3.99.1072
220205.3.99.108/30205.3.99.109 to 205.3.99.110205.3.99.1112
221205.3.99.112/30205.3.99.113 to 205.3.99.114205.3.99.1152
222205.3.99.116/30205.3.99.117 to 205.3.99.118205.3.99.1192
223205.3.99.120/30205.3.99.121 to 205.3.99.122205.3.99.1232
224205.3.99.124/30205.3.99.125 to 205.3.99.126205.3.99.1272
225205.3.99.128/30205.3.99.129 to 205.3.99.130205.3.99.1312
226205.3.99.132/30205.3.99.133 to 205.3.99.134205.3.99.1352
227205.3.99.136/30205.3.99.137 to 205.3.99.138205.3.99.1392
228205.3.99.140/30205.3.99.141 to 205.3.99.142205.3.99.1432
229205.3.99.144/30205.3.99.145 to 205.3.99.146205.3.99.1472
230205.3.99.148/30205.3.99.149 to 205.3.99.150205.3.99.1512
231205.3.99.152/30205.3.99.153 to 205.3.99.154205.3.99.1552
232205.3.99.156/30205.3.99.157 to 205.3.99.158205.3.99.1592
233205.3.99.160/30205.3.99.161 to 205.3.99.162205.3.99.1632
234205.3.99.164/30205.3.99.165 to 205.3.99.166205.3.99.1672
235205.3.99.168/30205.3.99.169 to 205.3.99.170205.3.99.1712
236205.3.99.172/30205.3.99.173 to 205.3.99.174205.3.99.1752
237205.3.99.176/30205.3.99.177 to 205.3.99.178205.3.99.1792
238205.3.99.180/30205.3.99.181 to 205.3.99.182205.3.99.1832
239205.3.99.184/30205.3.99.185 to 205.3.99.186205.3.99.1872
240205.3.99.188/30205.3.99.189 to 205.3.99.190205.3.99.1912
241205.3.99.192/30205.3.99.193 to 205.3.99.194205.3.99.1952
242205.3.99.196/30205.3.99.197 to 205.3.99.198205.3.99.1992
243205.3.99.200/30205.3.99.201 to 205.3.99.202205.3.99.2032
244205.3.99.204/30205.3.99.205 to 205.3.99.206205.3.99.2072
245205.3.99.208/30205.3.99.209 to 205.3.99.210205.3.99.2112
246205.3.99.212/30205.3.99.213 to 205.3.99.214205.3.99.2152
247205.3.99.216/30205.3.99.217 to 205.3.99.218205.3.99.2192
248205.3.99.220/30205.3.99.221 to 205.3.99.222205.3.99.2232
249205.3.99.224/30205.3.99.225 to 205.3.99.226205.3.99.2272
250205.3.99.228/30205.3.99.229 to 205.3.99.230205.3.99.2312
251205.3.99.232/30205.3.99.233 to 205.3.99.234205.3.99.2352
252205.3.99.236/30205.3.99.237 to 205.3.99.238205.3.99.2392
253205.3.99.240/30205.3.99.241 to 205.3.99.242205.3.99.2432
254205.3.99.244/30205.3.99.245 to 205.3.99.246205.3.99.2472
255205.3.99.248/30205.3.99.249 to 205.3.99.250205.3.99.2512
256205.3.99.252/30205.3.99.253 to 205.3.99.254205.3.99.2552

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.