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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.

Network205.97.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
205.97.0.0
Broadcast address
205.97.255.255
First usable
205.97.0.1
Last usable
205.97.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
C (default /24)
As numbers
Hex CD610000 · Integer 3445686272 to 3445751807
Reverse DNS zone
97.205.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001101.01100001..00000000.00000000205.97.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11001101.01100001..00000000.00000000205.97.0.0
Broadcast11001101.01100001..11111111.11111111205.97.255.255
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

205.97.0.0/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1205.97.0.0/28205.97.0.1 to 205.97.0.14205.97.0.1514
2205.97.0.16/28205.97.0.17 to 205.97.0.30205.97.0.3114
3205.97.0.32/28205.97.0.33 to 205.97.0.46205.97.0.4714
4205.97.0.48/28205.97.0.49 to 205.97.0.62205.97.0.6314
5205.97.0.64/28205.97.0.65 to 205.97.0.78205.97.0.7914
6205.97.0.80/28205.97.0.81 to 205.97.0.94205.97.0.9514
7205.97.0.96/28205.97.0.97 to 205.97.0.110205.97.0.11114
8205.97.0.112/28205.97.0.113 to 205.97.0.126205.97.0.12714
9205.97.0.128/28205.97.0.129 to 205.97.0.142205.97.0.14314
10205.97.0.144/28205.97.0.145 to 205.97.0.158205.97.0.15914
11205.97.0.160/28205.97.0.161 to 205.97.0.174205.97.0.17514
12205.97.0.176/28205.97.0.177 to 205.97.0.190205.97.0.19114
13205.97.0.192/28205.97.0.193 to 205.97.0.206205.97.0.20714
14205.97.0.208/28205.97.0.209 to 205.97.0.222205.97.0.22314
15205.97.0.224/28205.97.0.225 to 205.97.0.238205.97.0.23914
16205.97.0.240/28205.97.0.241 to 205.97.0.254205.97.0.25514
17205.97.1.0/28205.97.1.1 to 205.97.1.14205.97.1.1514
18205.97.1.16/28205.97.1.17 to 205.97.1.30205.97.1.3114
19205.97.1.32/28205.97.1.33 to 205.97.1.46205.97.1.4714
20205.97.1.48/28205.97.1.49 to 205.97.1.62205.97.1.6314
21205.97.1.64/28205.97.1.65 to 205.97.1.78205.97.1.7914
22205.97.1.80/28205.97.1.81 to 205.97.1.94205.97.1.9514
23205.97.1.96/28205.97.1.97 to 205.97.1.110205.97.1.11114
24205.97.1.112/28205.97.1.113 to 205.97.1.126205.97.1.12714
25205.97.1.128/28205.97.1.129 to 205.97.1.142205.97.1.14314
26205.97.1.144/28205.97.1.145 to 205.97.1.158205.97.1.15914
27205.97.1.160/28205.97.1.161 to 205.97.1.174205.97.1.17514
28205.97.1.176/28205.97.1.177 to 205.97.1.190205.97.1.19114
29205.97.1.192/28205.97.1.193 to 205.97.1.206205.97.1.20714
30205.97.1.208/28205.97.1.209 to 205.97.1.222205.97.1.22314
31205.97.1.224/28205.97.1.225 to 205.97.1.238205.97.1.23914
32205.97.1.240/28205.97.1.241 to 205.97.1.254205.97.1.25514
33205.97.2.0/28205.97.2.1 to 205.97.2.14205.97.2.1514
34205.97.2.16/28205.97.2.17 to 205.97.2.30205.97.2.3114
35205.97.2.32/28205.97.2.33 to 205.97.2.46205.97.2.4714
36205.97.2.48/28205.97.2.49 to 205.97.2.62205.97.2.6314
37205.97.2.64/28205.97.2.65 to 205.97.2.78205.97.2.7914
38205.97.2.80/28205.97.2.81 to 205.97.2.94205.97.2.9514
39205.97.2.96/28205.97.2.97 to 205.97.2.110205.97.2.11114
40205.97.2.112/28205.97.2.113 to 205.97.2.126205.97.2.12714
41205.97.2.128/28205.97.2.129 to 205.97.2.142205.97.2.14314
42205.97.2.144/28205.97.2.145 to 205.97.2.158205.97.2.15914
43205.97.2.160/28205.97.2.161 to 205.97.2.174205.97.2.17514
44205.97.2.176/28205.97.2.177 to 205.97.2.190205.97.2.19114
45205.97.2.192/28205.97.2.193 to 205.97.2.206205.97.2.20714
46205.97.2.208/28205.97.2.209 to 205.97.2.222205.97.2.22314
47205.97.2.224/28205.97.2.225 to 205.97.2.238205.97.2.23914
48205.97.2.240/28205.97.2.241 to 205.97.2.254205.97.2.25514
49205.97.3.0/28205.97.3.1 to 205.97.3.14205.97.3.1514
50205.97.3.16/28205.97.3.17 to 205.97.3.30205.97.3.3114
51205.97.3.32/28205.97.3.33 to 205.97.3.46205.97.3.4714
52205.97.3.48/28205.97.3.49 to 205.97.3.62205.97.3.6314
53205.97.3.64/28205.97.3.65 to 205.97.3.78205.97.3.7914
54205.97.3.80/28205.97.3.81 to 205.97.3.94205.97.3.9514
55205.97.3.96/28205.97.3.97 to 205.97.3.110205.97.3.11114
56205.97.3.112/28205.97.3.113 to 205.97.3.126205.97.3.12714
57205.97.3.128/28205.97.3.129 to 205.97.3.142205.97.3.14314
58205.97.3.144/28205.97.3.145 to 205.97.3.158205.97.3.15914
59205.97.3.160/28205.97.3.161 to 205.97.3.174205.97.3.17514
60205.97.3.176/28205.97.3.177 to 205.97.3.190205.97.3.19114
61205.97.3.192/28205.97.3.193 to 205.97.3.206205.97.3.20714
62205.97.3.208/28205.97.3.209 to 205.97.3.222205.97.3.22314
63205.97.3.224/28205.97.3.225 to 205.97.3.238205.97.3.23914
64205.97.3.240/28205.97.3.241 to 205.97.3.254205.97.3.25514
65205.97.4.0/28205.97.4.1 to 205.97.4.14205.97.4.1514
66205.97.4.16/28205.97.4.17 to 205.97.4.30205.97.4.3114
67205.97.4.32/28205.97.4.33 to 205.97.4.46205.97.4.4714
68205.97.4.48/28205.97.4.49 to 205.97.4.62205.97.4.6314
69205.97.4.64/28205.97.4.65 to 205.97.4.78205.97.4.7914
70205.97.4.80/28205.97.4.81 to 205.97.4.94205.97.4.9514
71205.97.4.96/28205.97.4.97 to 205.97.4.110205.97.4.11114
72205.97.4.112/28205.97.4.113 to 205.97.4.126205.97.4.12714
73205.97.4.128/28205.97.4.129 to 205.97.4.142205.97.4.14314
74205.97.4.144/28205.97.4.145 to 205.97.4.158205.97.4.15914
75205.97.4.160/28205.97.4.161 to 205.97.4.174205.97.4.17514
76205.97.4.176/28205.97.4.177 to 205.97.4.190205.97.4.19114
77205.97.4.192/28205.97.4.193 to 205.97.4.206205.97.4.20714
78205.97.4.208/28205.97.4.209 to 205.97.4.222205.97.4.22314
79205.97.4.224/28205.97.4.225 to 205.97.4.238205.97.4.23914
80205.97.4.240/28205.97.4.241 to 205.97.4.254205.97.4.25514
81205.97.5.0/28205.97.5.1 to 205.97.5.14205.97.5.1514
82205.97.5.16/28205.97.5.17 to 205.97.5.30205.97.5.3114
83205.97.5.32/28205.97.5.33 to 205.97.5.46205.97.5.4714
84205.97.5.48/28205.97.5.49 to 205.97.5.62205.97.5.6314
85205.97.5.64/28205.97.5.65 to 205.97.5.78205.97.5.7914
86205.97.5.80/28205.97.5.81 to 205.97.5.94205.97.5.9514
87205.97.5.96/28205.97.5.97 to 205.97.5.110205.97.5.11114
88205.97.5.112/28205.97.5.113 to 205.97.5.126205.97.5.12714
89205.97.5.128/28205.97.5.129 to 205.97.5.142205.97.5.14314
90205.97.5.144/28205.97.5.145 to 205.97.5.158205.97.5.15914
91205.97.5.160/28205.97.5.161 to 205.97.5.174205.97.5.17514
92205.97.5.176/28205.97.5.177 to 205.97.5.190205.97.5.19114
93205.97.5.192/28205.97.5.193 to 205.97.5.206205.97.5.20714
94205.97.5.208/28205.97.5.209 to 205.97.5.222205.97.5.22314
95205.97.5.224/28205.97.5.225 to 205.97.5.238205.97.5.23914
96205.97.5.240/28205.97.5.241 to 205.97.5.254205.97.5.25514
97205.97.6.0/28205.97.6.1 to 205.97.6.14205.97.6.1514
98205.97.6.16/28205.97.6.17 to 205.97.6.30205.97.6.3114
99205.97.6.32/28205.97.6.33 to 205.97.6.46205.97.6.4714
100205.97.6.48/28205.97.6.49 to 205.97.6.62205.97.6.6314
101205.97.6.64/28205.97.6.65 to 205.97.6.78205.97.6.7914
102205.97.6.80/28205.97.6.81 to 205.97.6.94205.97.6.9514
103205.97.6.96/28205.97.6.97 to 205.97.6.110205.97.6.11114
104205.97.6.112/28205.97.6.113 to 205.97.6.126205.97.6.12714
105205.97.6.128/28205.97.6.129 to 205.97.6.142205.97.6.14314
106205.97.6.144/28205.97.6.145 to 205.97.6.158205.97.6.15914
107205.97.6.160/28205.97.6.161 to 205.97.6.174205.97.6.17514
108205.97.6.176/28205.97.6.177 to 205.97.6.190205.97.6.19114
109205.97.6.192/28205.97.6.193 to 205.97.6.206205.97.6.20714
110205.97.6.208/28205.97.6.209 to 205.97.6.222205.97.6.22314
111205.97.6.224/28205.97.6.225 to 205.97.6.238205.97.6.23914
112205.97.6.240/28205.97.6.241 to 205.97.6.254205.97.6.25514
113205.97.7.0/28205.97.7.1 to 205.97.7.14205.97.7.1514
114205.97.7.16/28205.97.7.17 to 205.97.7.30205.97.7.3114
115205.97.7.32/28205.97.7.33 to 205.97.7.46205.97.7.4714
116205.97.7.48/28205.97.7.49 to 205.97.7.62205.97.7.6314
117205.97.7.64/28205.97.7.65 to 205.97.7.78205.97.7.7914
118205.97.7.80/28205.97.7.81 to 205.97.7.94205.97.7.9514
119205.97.7.96/28205.97.7.97 to 205.97.7.110205.97.7.11114
120205.97.7.112/28205.97.7.113 to 205.97.7.126205.97.7.12714
121205.97.7.128/28205.97.7.129 to 205.97.7.142205.97.7.14314
122205.97.7.144/28205.97.7.145 to 205.97.7.158205.97.7.15914
123205.97.7.160/28205.97.7.161 to 205.97.7.174205.97.7.17514
124205.97.7.176/28205.97.7.177 to 205.97.7.190205.97.7.19114
125205.97.7.192/28205.97.7.193 to 205.97.7.206205.97.7.20714
126205.97.7.208/28205.97.7.209 to 205.97.7.222205.97.7.22314
127205.97.7.224/28205.97.7.225 to 205.97.7.238205.97.7.23914
128205.97.7.240/28205.97.7.241 to 205.97.7.254205.97.7.25514
129205.97.8.0/28205.97.8.1 to 205.97.8.14205.97.8.1514
130205.97.8.16/28205.97.8.17 to 205.97.8.30205.97.8.3114
131205.97.8.32/28205.97.8.33 to 205.97.8.46205.97.8.4714
132205.97.8.48/28205.97.8.49 to 205.97.8.62205.97.8.6314
133205.97.8.64/28205.97.8.65 to 205.97.8.78205.97.8.7914
134205.97.8.80/28205.97.8.81 to 205.97.8.94205.97.8.9514
135205.97.8.96/28205.97.8.97 to 205.97.8.110205.97.8.11114
136205.97.8.112/28205.97.8.113 to 205.97.8.126205.97.8.12714
137205.97.8.128/28205.97.8.129 to 205.97.8.142205.97.8.14314
138205.97.8.144/28205.97.8.145 to 205.97.8.158205.97.8.15914
139205.97.8.160/28205.97.8.161 to 205.97.8.174205.97.8.17514
140205.97.8.176/28205.97.8.177 to 205.97.8.190205.97.8.19114
141205.97.8.192/28205.97.8.193 to 205.97.8.206205.97.8.20714
142205.97.8.208/28205.97.8.209 to 205.97.8.222205.97.8.22314
143205.97.8.224/28205.97.8.225 to 205.97.8.238205.97.8.23914
144205.97.8.240/28205.97.8.241 to 205.97.8.254205.97.8.25514
145205.97.9.0/28205.97.9.1 to 205.97.9.14205.97.9.1514
146205.97.9.16/28205.97.9.17 to 205.97.9.30205.97.9.3114
147205.97.9.32/28205.97.9.33 to 205.97.9.46205.97.9.4714
148205.97.9.48/28205.97.9.49 to 205.97.9.62205.97.9.6314
149205.97.9.64/28205.97.9.65 to 205.97.9.78205.97.9.7914
150205.97.9.80/28205.97.9.81 to 205.97.9.94205.97.9.9514
151205.97.9.96/28205.97.9.97 to 205.97.9.110205.97.9.11114
152205.97.9.112/28205.97.9.113 to 205.97.9.126205.97.9.12714
153205.97.9.128/28205.97.9.129 to 205.97.9.142205.97.9.14314
154205.97.9.144/28205.97.9.145 to 205.97.9.158205.97.9.15914
155205.97.9.160/28205.97.9.161 to 205.97.9.174205.97.9.17514
156205.97.9.176/28205.97.9.177 to 205.97.9.190205.97.9.19114
157205.97.9.192/28205.97.9.193 to 205.97.9.206205.97.9.20714
158205.97.9.208/28205.97.9.209 to 205.97.9.222205.97.9.22314
159205.97.9.224/28205.97.9.225 to 205.97.9.238205.97.9.23914
160205.97.9.240/28205.97.9.241 to 205.97.9.254205.97.9.25514
161205.97.10.0/28205.97.10.1 to 205.97.10.14205.97.10.1514
162205.97.10.16/28205.97.10.17 to 205.97.10.30205.97.10.3114
163205.97.10.32/28205.97.10.33 to 205.97.10.46205.97.10.4714
164205.97.10.48/28205.97.10.49 to 205.97.10.62205.97.10.6314
165205.97.10.64/28205.97.10.65 to 205.97.10.78205.97.10.7914
166205.97.10.80/28205.97.10.81 to 205.97.10.94205.97.10.9514
167205.97.10.96/28205.97.10.97 to 205.97.10.110205.97.10.11114
168205.97.10.112/28205.97.10.113 to 205.97.10.126205.97.10.12714
169205.97.10.128/28205.97.10.129 to 205.97.10.142205.97.10.14314
170205.97.10.144/28205.97.10.145 to 205.97.10.158205.97.10.15914
171205.97.10.160/28205.97.10.161 to 205.97.10.174205.97.10.17514
172205.97.10.176/28205.97.10.177 to 205.97.10.190205.97.10.19114
173205.97.10.192/28205.97.10.193 to 205.97.10.206205.97.10.20714
174205.97.10.208/28205.97.10.209 to 205.97.10.222205.97.10.22314
175205.97.10.224/28205.97.10.225 to 205.97.10.238205.97.10.23914
176205.97.10.240/28205.97.10.241 to 205.97.10.254205.97.10.25514
177205.97.11.0/28205.97.11.1 to 205.97.11.14205.97.11.1514
178205.97.11.16/28205.97.11.17 to 205.97.11.30205.97.11.3114
179205.97.11.32/28205.97.11.33 to 205.97.11.46205.97.11.4714
180205.97.11.48/28205.97.11.49 to 205.97.11.62205.97.11.6314
181205.97.11.64/28205.97.11.65 to 205.97.11.78205.97.11.7914
182205.97.11.80/28205.97.11.81 to 205.97.11.94205.97.11.9514
183205.97.11.96/28205.97.11.97 to 205.97.11.110205.97.11.11114
184205.97.11.112/28205.97.11.113 to 205.97.11.126205.97.11.12714
185205.97.11.128/28205.97.11.129 to 205.97.11.142205.97.11.14314
186205.97.11.144/28205.97.11.145 to 205.97.11.158205.97.11.15914
187205.97.11.160/28205.97.11.161 to 205.97.11.174205.97.11.17514
188205.97.11.176/28205.97.11.177 to 205.97.11.190205.97.11.19114
189205.97.11.192/28205.97.11.193 to 205.97.11.206205.97.11.20714
190205.97.11.208/28205.97.11.209 to 205.97.11.222205.97.11.22314
191205.97.11.224/28205.97.11.225 to 205.97.11.238205.97.11.23914
192205.97.11.240/28205.97.11.241 to 205.97.11.254205.97.11.25514
193205.97.12.0/28205.97.12.1 to 205.97.12.14205.97.12.1514
194205.97.12.16/28205.97.12.17 to 205.97.12.30205.97.12.3114
195205.97.12.32/28205.97.12.33 to 205.97.12.46205.97.12.4714
196205.97.12.48/28205.97.12.49 to 205.97.12.62205.97.12.6314
197205.97.12.64/28205.97.12.65 to 205.97.12.78205.97.12.7914
198205.97.12.80/28205.97.12.81 to 205.97.12.94205.97.12.9514
199205.97.12.96/28205.97.12.97 to 205.97.12.110205.97.12.11114
200205.97.12.112/28205.97.12.113 to 205.97.12.126205.97.12.12714
201205.97.12.128/28205.97.12.129 to 205.97.12.142205.97.12.14314
202205.97.12.144/28205.97.12.145 to 205.97.12.158205.97.12.15914
203205.97.12.160/28205.97.12.161 to 205.97.12.174205.97.12.17514
204205.97.12.176/28205.97.12.177 to 205.97.12.190205.97.12.19114
205205.97.12.192/28205.97.12.193 to 205.97.12.206205.97.12.20714
206205.97.12.208/28205.97.12.209 to 205.97.12.222205.97.12.22314
207205.97.12.224/28205.97.12.225 to 205.97.12.238205.97.12.23914
208205.97.12.240/28205.97.12.241 to 205.97.12.254205.97.12.25514
209205.97.13.0/28205.97.13.1 to 205.97.13.14205.97.13.1514
210205.97.13.16/28205.97.13.17 to 205.97.13.30205.97.13.3114
211205.97.13.32/28205.97.13.33 to 205.97.13.46205.97.13.4714
212205.97.13.48/28205.97.13.49 to 205.97.13.62205.97.13.6314
213205.97.13.64/28205.97.13.65 to 205.97.13.78205.97.13.7914
214205.97.13.80/28205.97.13.81 to 205.97.13.94205.97.13.9514
215205.97.13.96/28205.97.13.97 to 205.97.13.110205.97.13.11114
216205.97.13.112/28205.97.13.113 to 205.97.13.126205.97.13.12714
217205.97.13.128/28205.97.13.129 to 205.97.13.142205.97.13.14314
218205.97.13.144/28205.97.13.145 to 205.97.13.158205.97.13.15914
219205.97.13.160/28205.97.13.161 to 205.97.13.174205.97.13.17514
220205.97.13.176/28205.97.13.177 to 205.97.13.190205.97.13.19114
221205.97.13.192/28205.97.13.193 to 205.97.13.206205.97.13.20714
222205.97.13.208/28205.97.13.209 to 205.97.13.222205.97.13.22314
223205.97.13.224/28205.97.13.225 to 205.97.13.238205.97.13.23914
224205.97.13.240/28205.97.13.241 to 205.97.13.254205.97.13.25514
225205.97.14.0/28205.97.14.1 to 205.97.14.14205.97.14.1514
226205.97.14.16/28205.97.14.17 to 205.97.14.30205.97.14.3114
227205.97.14.32/28205.97.14.33 to 205.97.14.46205.97.14.4714
228205.97.14.48/28205.97.14.49 to 205.97.14.62205.97.14.6314
229205.97.14.64/28205.97.14.65 to 205.97.14.78205.97.14.7914
230205.97.14.80/28205.97.14.81 to 205.97.14.94205.97.14.9514
231205.97.14.96/28205.97.14.97 to 205.97.14.110205.97.14.11114
232205.97.14.112/28205.97.14.113 to 205.97.14.126205.97.14.12714
233205.97.14.128/28205.97.14.129 to 205.97.14.142205.97.14.14314
234205.97.14.144/28205.97.14.145 to 205.97.14.158205.97.14.15914
235205.97.14.160/28205.97.14.161 to 205.97.14.174205.97.14.17514
236205.97.14.176/28205.97.14.177 to 205.97.14.190205.97.14.19114
237205.97.14.192/28205.97.14.193 to 205.97.14.206205.97.14.20714
238205.97.14.208/28205.97.14.209 to 205.97.14.222205.97.14.22314
239205.97.14.224/28205.97.14.225 to 205.97.14.238205.97.14.23914
240205.97.14.240/28205.97.14.241 to 205.97.14.254205.97.14.25514
241205.97.15.0/28205.97.15.1 to 205.97.15.14205.97.15.1514
242205.97.15.16/28205.97.15.17 to 205.97.15.30205.97.15.3114
243205.97.15.32/28205.97.15.33 to 205.97.15.46205.97.15.4714
244205.97.15.48/28205.97.15.49 to 205.97.15.62205.97.15.6314
245205.97.15.64/28205.97.15.65 to 205.97.15.78205.97.15.7914
246205.97.15.80/28205.97.15.81 to 205.97.15.94205.97.15.9514
247205.97.15.96/28205.97.15.97 to 205.97.15.110205.97.15.11114
248205.97.15.112/28205.97.15.113 to 205.97.15.126205.97.15.12714
249205.97.15.128/28205.97.15.129 to 205.97.15.142205.97.15.14314
250205.97.15.144/28205.97.15.145 to 205.97.15.158205.97.15.15914
251205.97.15.160/28205.97.15.161 to 205.97.15.174205.97.15.17514
252205.97.15.176/28205.97.15.177 to 205.97.15.190205.97.15.19114
253205.97.15.192/28205.97.15.193 to 205.97.15.206205.97.15.20714
254205.97.15.208/28205.97.15.209 to 205.97.15.222205.97.15.22314
255205.97.15.224/28205.97.15.225 to 205.97.15.238205.97.15.23914
256205.97.15.240/28205.97.15.241 to 205.97.15.254205.97.15.25514

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.