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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.

Network205.30.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
205.30.0.0
Broadcast address
205.30.31.255
First usable
205.30.0.1
Last usable
205.30.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
C (default /24)
As numbers
Hex CD1E0000 · Integer 3441295360 to 3441303551
Reverse DNS zones
0.30.205.in-addr.arpa
1.30.205.in-addr.arpa
2.30.205.in-addr.arpa
3.30.205.in-addr.arpa
4.30.205.in-addr.arpa
5.30.205.in-addr.arpa
6.30.205.in-addr.arpa
7.30.205.in-addr.arpa
8.30.205.in-addr.arpa
9.30.205.in-addr.arpa
10.30.205.in-addr.arpa
11.30.205.in-addr.arpa
12.30.205.in-addr.arpa
13.30.205.in-addr.arpa
14.30.205.in-addr.arpa
15.30.205.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001101.00011110.00000000.00000000205.30.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network11001101.00011110.00000000.00000000205.30.0.0
Broadcast11001101.00011110.00011111.11111111205.30.31.255
Split into smaller subnets/29
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

205.30.0.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1205.30.0.0/29205.30.0.1 to 205.30.0.6205.30.0.76
2205.30.0.8/29205.30.0.9 to 205.30.0.14205.30.0.156
3205.30.0.16/29205.30.0.17 to 205.30.0.22205.30.0.236
4205.30.0.24/29205.30.0.25 to 205.30.0.30205.30.0.316
5205.30.0.32/29205.30.0.33 to 205.30.0.38205.30.0.396
6205.30.0.40/29205.30.0.41 to 205.30.0.46205.30.0.476
7205.30.0.48/29205.30.0.49 to 205.30.0.54205.30.0.556
8205.30.0.56/29205.30.0.57 to 205.30.0.62205.30.0.636
9205.30.0.64/29205.30.0.65 to 205.30.0.70205.30.0.716
10205.30.0.72/29205.30.0.73 to 205.30.0.78205.30.0.796
11205.30.0.80/29205.30.0.81 to 205.30.0.86205.30.0.876
12205.30.0.88/29205.30.0.89 to 205.30.0.94205.30.0.956
13205.30.0.96/29205.30.0.97 to 205.30.0.102205.30.0.1036
14205.30.0.104/29205.30.0.105 to 205.30.0.110205.30.0.1116
15205.30.0.112/29205.30.0.113 to 205.30.0.118205.30.0.1196
16205.30.0.120/29205.30.0.121 to 205.30.0.126205.30.0.1276
17205.30.0.128/29205.30.0.129 to 205.30.0.134205.30.0.1356
18205.30.0.136/29205.30.0.137 to 205.30.0.142205.30.0.1436
19205.30.0.144/29205.30.0.145 to 205.30.0.150205.30.0.1516
20205.30.0.152/29205.30.0.153 to 205.30.0.158205.30.0.1596
21205.30.0.160/29205.30.0.161 to 205.30.0.166205.30.0.1676
22205.30.0.168/29205.30.0.169 to 205.30.0.174205.30.0.1756
23205.30.0.176/29205.30.0.177 to 205.30.0.182205.30.0.1836
24205.30.0.184/29205.30.0.185 to 205.30.0.190205.30.0.1916
25205.30.0.192/29205.30.0.193 to 205.30.0.198205.30.0.1996
26205.30.0.200/29205.30.0.201 to 205.30.0.206205.30.0.2076
27205.30.0.208/29205.30.0.209 to 205.30.0.214205.30.0.2156
28205.30.0.216/29205.30.0.217 to 205.30.0.222205.30.0.2236
29205.30.0.224/29205.30.0.225 to 205.30.0.230205.30.0.2316
30205.30.0.232/29205.30.0.233 to 205.30.0.238205.30.0.2396
31205.30.0.240/29205.30.0.241 to 205.30.0.246205.30.0.2476
32205.30.0.248/29205.30.0.249 to 205.30.0.254205.30.0.2556
33205.30.1.0/29205.30.1.1 to 205.30.1.6205.30.1.76
34205.30.1.8/29205.30.1.9 to 205.30.1.14205.30.1.156
35205.30.1.16/29205.30.1.17 to 205.30.1.22205.30.1.236
36205.30.1.24/29205.30.1.25 to 205.30.1.30205.30.1.316
37205.30.1.32/29205.30.1.33 to 205.30.1.38205.30.1.396
38205.30.1.40/29205.30.1.41 to 205.30.1.46205.30.1.476
39205.30.1.48/29205.30.1.49 to 205.30.1.54205.30.1.556
40205.30.1.56/29205.30.1.57 to 205.30.1.62205.30.1.636
41205.30.1.64/29205.30.1.65 to 205.30.1.70205.30.1.716
42205.30.1.72/29205.30.1.73 to 205.30.1.78205.30.1.796
43205.30.1.80/29205.30.1.81 to 205.30.1.86205.30.1.876
44205.30.1.88/29205.30.1.89 to 205.30.1.94205.30.1.956
45205.30.1.96/29205.30.1.97 to 205.30.1.102205.30.1.1036
46205.30.1.104/29205.30.1.105 to 205.30.1.110205.30.1.1116
47205.30.1.112/29205.30.1.113 to 205.30.1.118205.30.1.1196
48205.30.1.120/29205.30.1.121 to 205.30.1.126205.30.1.1276
49205.30.1.128/29205.30.1.129 to 205.30.1.134205.30.1.1356
50205.30.1.136/29205.30.1.137 to 205.30.1.142205.30.1.1436
51205.30.1.144/29205.30.1.145 to 205.30.1.150205.30.1.1516
52205.30.1.152/29205.30.1.153 to 205.30.1.158205.30.1.1596
53205.30.1.160/29205.30.1.161 to 205.30.1.166205.30.1.1676
54205.30.1.168/29205.30.1.169 to 205.30.1.174205.30.1.1756
55205.30.1.176/29205.30.1.177 to 205.30.1.182205.30.1.1836
56205.30.1.184/29205.30.1.185 to 205.30.1.190205.30.1.1916
57205.30.1.192/29205.30.1.193 to 205.30.1.198205.30.1.1996
58205.30.1.200/29205.30.1.201 to 205.30.1.206205.30.1.2076
59205.30.1.208/29205.30.1.209 to 205.30.1.214205.30.1.2156
60205.30.1.216/29205.30.1.217 to 205.30.1.222205.30.1.2236
61205.30.1.224/29205.30.1.225 to 205.30.1.230205.30.1.2316
62205.30.1.232/29205.30.1.233 to 205.30.1.238205.30.1.2396
63205.30.1.240/29205.30.1.241 to 205.30.1.246205.30.1.2476
64205.30.1.248/29205.30.1.249 to 205.30.1.254205.30.1.2556
65205.30.2.0/29205.30.2.1 to 205.30.2.6205.30.2.76
66205.30.2.8/29205.30.2.9 to 205.30.2.14205.30.2.156
67205.30.2.16/29205.30.2.17 to 205.30.2.22205.30.2.236
68205.30.2.24/29205.30.2.25 to 205.30.2.30205.30.2.316
69205.30.2.32/29205.30.2.33 to 205.30.2.38205.30.2.396
70205.30.2.40/29205.30.2.41 to 205.30.2.46205.30.2.476
71205.30.2.48/29205.30.2.49 to 205.30.2.54205.30.2.556
72205.30.2.56/29205.30.2.57 to 205.30.2.62205.30.2.636
73205.30.2.64/29205.30.2.65 to 205.30.2.70205.30.2.716
74205.30.2.72/29205.30.2.73 to 205.30.2.78205.30.2.796
75205.30.2.80/29205.30.2.81 to 205.30.2.86205.30.2.876
76205.30.2.88/29205.30.2.89 to 205.30.2.94205.30.2.956
77205.30.2.96/29205.30.2.97 to 205.30.2.102205.30.2.1036
78205.30.2.104/29205.30.2.105 to 205.30.2.110205.30.2.1116
79205.30.2.112/29205.30.2.113 to 205.30.2.118205.30.2.1196
80205.30.2.120/29205.30.2.121 to 205.30.2.126205.30.2.1276
81205.30.2.128/29205.30.2.129 to 205.30.2.134205.30.2.1356
82205.30.2.136/29205.30.2.137 to 205.30.2.142205.30.2.1436
83205.30.2.144/29205.30.2.145 to 205.30.2.150205.30.2.1516
84205.30.2.152/29205.30.2.153 to 205.30.2.158205.30.2.1596
85205.30.2.160/29205.30.2.161 to 205.30.2.166205.30.2.1676
86205.30.2.168/29205.30.2.169 to 205.30.2.174205.30.2.1756
87205.30.2.176/29205.30.2.177 to 205.30.2.182205.30.2.1836
88205.30.2.184/29205.30.2.185 to 205.30.2.190205.30.2.1916
89205.30.2.192/29205.30.2.193 to 205.30.2.198205.30.2.1996
90205.30.2.200/29205.30.2.201 to 205.30.2.206205.30.2.2076
91205.30.2.208/29205.30.2.209 to 205.30.2.214205.30.2.2156
92205.30.2.216/29205.30.2.217 to 205.30.2.222205.30.2.2236
93205.30.2.224/29205.30.2.225 to 205.30.2.230205.30.2.2316
94205.30.2.232/29205.30.2.233 to 205.30.2.238205.30.2.2396
95205.30.2.240/29205.30.2.241 to 205.30.2.246205.30.2.2476
96205.30.2.248/29205.30.2.249 to 205.30.2.254205.30.2.2556
97205.30.3.0/29205.30.3.1 to 205.30.3.6205.30.3.76
98205.30.3.8/29205.30.3.9 to 205.30.3.14205.30.3.156
99205.30.3.16/29205.30.3.17 to 205.30.3.22205.30.3.236
100205.30.3.24/29205.30.3.25 to 205.30.3.30205.30.3.316
101205.30.3.32/29205.30.3.33 to 205.30.3.38205.30.3.396
102205.30.3.40/29205.30.3.41 to 205.30.3.46205.30.3.476
103205.30.3.48/29205.30.3.49 to 205.30.3.54205.30.3.556
104205.30.3.56/29205.30.3.57 to 205.30.3.62205.30.3.636
105205.30.3.64/29205.30.3.65 to 205.30.3.70205.30.3.716
106205.30.3.72/29205.30.3.73 to 205.30.3.78205.30.3.796
107205.30.3.80/29205.30.3.81 to 205.30.3.86205.30.3.876
108205.30.3.88/29205.30.3.89 to 205.30.3.94205.30.3.956
109205.30.3.96/29205.30.3.97 to 205.30.3.102205.30.3.1036
110205.30.3.104/29205.30.3.105 to 205.30.3.110205.30.3.1116
111205.30.3.112/29205.30.3.113 to 205.30.3.118205.30.3.1196
112205.30.3.120/29205.30.3.121 to 205.30.3.126205.30.3.1276
113205.30.3.128/29205.30.3.129 to 205.30.3.134205.30.3.1356
114205.30.3.136/29205.30.3.137 to 205.30.3.142205.30.3.1436
115205.30.3.144/29205.30.3.145 to 205.30.3.150205.30.3.1516
116205.30.3.152/29205.30.3.153 to 205.30.3.158205.30.3.1596
117205.30.3.160/29205.30.3.161 to 205.30.3.166205.30.3.1676
118205.30.3.168/29205.30.3.169 to 205.30.3.174205.30.3.1756
119205.30.3.176/29205.30.3.177 to 205.30.3.182205.30.3.1836
120205.30.3.184/29205.30.3.185 to 205.30.3.190205.30.3.1916
121205.30.3.192/29205.30.3.193 to 205.30.3.198205.30.3.1996
122205.30.3.200/29205.30.3.201 to 205.30.3.206205.30.3.2076
123205.30.3.208/29205.30.3.209 to 205.30.3.214205.30.3.2156
124205.30.3.216/29205.30.3.217 to 205.30.3.222205.30.3.2236
125205.30.3.224/29205.30.3.225 to 205.30.3.230205.30.3.2316
126205.30.3.232/29205.30.3.233 to 205.30.3.238205.30.3.2396
127205.30.3.240/29205.30.3.241 to 205.30.3.246205.30.3.2476
128205.30.3.248/29205.30.3.249 to 205.30.3.254205.30.3.2556
129205.30.4.0/29205.30.4.1 to 205.30.4.6205.30.4.76
130205.30.4.8/29205.30.4.9 to 205.30.4.14205.30.4.156
131205.30.4.16/29205.30.4.17 to 205.30.4.22205.30.4.236
132205.30.4.24/29205.30.4.25 to 205.30.4.30205.30.4.316
133205.30.4.32/29205.30.4.33 to 205.30.4.38205.30.4.396
134205.30.4.40/29205.30.4.41 to 205.30.4.46205.30.4.476
135205.30.4.48/29205.30.4.49 to 205.30.4.54205.30.4.556
136205.30.4.56/29205.30.4.57 to 205.30.4.62205.30.4.636
137205.30.4.64/29205.30.4.65 to 205.30.4.70205.30.4.716
138205.30.4.72/29205.30.4.73 to 205.30.4.78205.30.4.796
139205.30.4.80/29205.30.4.81 to 205.30.4.86205.30.4.876
140205.30.4.88/29205.30.4.89 to 205.30.4.94205.30.4.956
141205.30.4.96/29205.30.4.97 to 205.30.4.102205.30.4.1036
142205.30.4.104/29205.30.4.105 to 205.30.4.110205.30.4.1116
143205.30.4.112/29205.30.4.113 to 205.30.4.118205.30.4.1196
144205.30.4.120/29205.30.4.121 to 205.30.4.126205.30.4.1276
145205.30.4.128/29205.30.4.129 to 205.30.4.134205.30.4.1356
146205.30.4.136/29205.30.4.137 to 205.30.4.142205.30.4.1436
147205.30.4.144/29205.30.4.145 to 205.30.4.150205.30.4.1516
148205.30.4.152/29205.30.4.153 to 205.30.4.158205.30.4.1596
149205.30.4.160/29205.30.4.161 to 205.30.4.166205.30.4.1676
150205.30.4.168/29205.30.4.169 to 205.30.4.174205.30.4.1756
151205.30.4.176/29205.30.4.177 to 205.30.4.182205.30.4.1836
152205.30.4.184/29205.30.4.185 to 205.30.4.190205.30.4.1916
153205.30.4.192/29205.30.4.193 to 205.30.4.198205.30.4.1996
154205.30.4.200/29205.30.4.201 to 205.30.4.206205.30.4.2076
155205.30.4.208/29205.30.4.209 to 205.30.4.214205.30.4.2156
156205.30.4.216/29205.30.4.217 to 205.30.4.222205.30.4.2236
157205.30.4.224/29205.30.4.225 to 205.30.4.230205.30.4.2316
158205.30.4.232/29205.30.4.233 to 205.30.4.238205.30.4.2396
159205.30.4.240/29205.30.4.241 to 205.30.4.246205.30.4.2476
160205.30.4.248/29205.30.4.249 to 205.30.4.254205.30.4.2556
161205.30.5.0/29205.30.5.1 to 205.30.5.6205.30.5.76
162205.30.5.8/29205.30.5.9 to 205.30.5.14205.30.5.156
163205.30.5.16/29205.30.5.17 to 205.30.5.22205.30.5.236
164205.30.5.24/29205.30.5.25 to 205.30.5.30205.30.5.316
165205.30.5.32/29205.30.5.33 to 205.30.5.38205.30.5.396
166205.30.5.40/29205.30.5.41 to 205.30.5.46205.30.5.476
167205.30.5.48/29205.30.5.49 to 205.30.5.54205.30.5.556
168205.30.5.56/29205.30.5.57 to 205.30.5.62205.30.5.636
169205.30.5.64/29205.30.5.65 to 205.30.5.70205.30.5.716
170205.30.5.72/29205.30.5.73 to 205.30.5.78205.30.5.796
171205.30.5.80/29205.30.5.81 to 205.30.5.86205.30.5.876
172205.30.5.88/29205.30.5.89 to 205.30.5.94205.30.5.956
173205.30.5.96/29205.30.5.97 to 205.30.5.102205.30.5.1036
174205.30.5.104/29205.30.5.105 to 205.30.5.110205.30.5.1116
175205.30.5.112/29205.30.5.113 to 205.30.5.118205.30.5.1196
176205.30.5.120/29205.30.5.121 to 205.30.5.126205.30.5.1276
177205.30.5.128/29205.30.5.129 to 205.30.5.134205.30.5.1356
178205.30.5.136/29205.30.5.137 to 205.30.5.142205.30.5.1436
179205.30.5.144/29205.30.5.145 to 205.30.5.150205.30.5.1516
180205.30.5.152/29205.30.5.153 to 205.30.5.158205.30.5.1596
181205.30.5.160/29205.30.5.161 to 205.30.5.166205.30.5.1676
182205.30.5.168/29205.30.5.169 to 205.30.5.174205.30.5.1756
183205.30.5.176/29205.30.5.177 to 205.30.5.182205.30.5.1836
184205.30.5.184/29205.30.5.185 to 205.30.5.190205.30.5.1916
185205.30.5.192/29205.30.5.193 to 205.30.5.198205.30.5.1996
186205.30.5.200/29205.30.5.201 to 205.30.5.206205.30.5.2076
187205.30.5.208/29205.30.5.209 to 205.30.5.214205.30.5.2156
188205.30.5.216/29205.30.5.217 to 205.30.5.222205.30.5.2236
189205.30.5.224/29205.30.5.225 to 205.30.5.230205.30.5.2316
190205.30.5.232/29205.30.5.233 to 205.30.5.238205.30.5.2396
191205.30.5.240/29205.30.5.241 to 205.30.5.246205.30.5.2476
192205.30.5.248/29205.30.5.249 to 205.30.5.254205.30.5.2556
193205.30.6.0/29205.30.6.1 to 205.30.6.6205.30.6.76
194205.30.6.8/29205.30.6.9 to 205.30.6.14205.30.6.156
195205.30.6.16/29205.30.6.17 to 205.30.6.22205.30.6.236
196205.30.6.24/29205.30.6.25 to 205.30.6.30205.30.6.316
197205.30.6.32/29205.30.6.33 to 205.30.6.38205.30.6.396
198205.30.6.40/29205.30.6.41 to 205.30.6.46205.30.6.476
199205.30.6.48/29205.30.6.49 to 205.30.6.54205.30.6.556
200205.30.6.56/29205.30.6.57 to 205.30.6.62205.30.6.636
201205.30.6.64/29205.30.6.65 to 205.30.6.70205.30.6.716
202205.30.6.72/29205.30.6.73 to 205.30.6.78205.30.6.796
203205.30.6.80/29205.30.6.81 to 205.30.6.86205.30.6.876
204205.30.6.88/29205.30.6.89 to 205.30.6.94205.30.6.956
205205.30.6.96/29205.30.6.97 to 205.30.6.102205.30.6.1036
206205.30.6.104/29205.30.6.105 to 205.30.6.110205.30.6.1116
207205.30.6.112/29205.30.6.113 to 205.30.6.118205.30.6.1196
208205.30.6.120/29205.30.6.121 to 205.30.6.126205.30.6.1276
209205.30.6.128/29205.30.6.129 to 205.30.6.134205.30.6.1356
210205.30.6.136/29205.30.6.137 to 205.30.6.142205.30.6.1436
211205.30.6.144/29205.30.6.145 to 205.30.6.150205.30.6.1516
212205.30.6.152/29205.30.6.153 to 205.30.6.158205.30.6.1596
213205.30.6.160/29205.30.6.161 to 205.30.6.166205.30.6.1676
214205.30.6.168/29205.30.6.169 to 205.30.6.174205.30.6.1756
215205.30.6.176/29205.30.6.177 to 205.30.6.182205.30.6.1836
216205.30.6.184/29205.30.6.185 to 205.30.6.190205.30.6.1916
217205.30.6.192/29205.30.6.193 to 205.30.6.198205.30.6.1996
218205.30.6.200/29205.30.6.201 to 205.30.6.206205.30.6.2076
219205.30.6.208/29205.30.6.209 to 205.30.6.214205.30.6.2156
220205.30.6.216/29205.30.6.217 to 205.30.6.222205.30.6.2236
221205.30.6.224/29205.30.6.225 to 205.30.6.230205.30.6.2316
222205.30.6.232/29205.30.6.233 to 205.30.6.238205.30.6.2396
223205.30.6.240/29205.30.6.241 to 205.30.6.246205.30.6.2476
224205.30.6.248/29205.30.6.249 to 205.30.6.254205.30.6.2556
225205.30.7.0/29205.30.7.1 to 205.30.7.6205.30.7.76
226205.30.7.8/29205.30.7.9 to 205.30.7.14205.30.7.156
227205.30.7.16/29205.30.7.17 to 205.30.7.22205.30.7.236
228205.30.7.24/29205.30.7.25 to 205.30.7.30205.30.7.316
229205.30.7.32/29205.30.7.33 to 205.30.7.38205.30.7.396
230205.30.7.40/29205.30.7.41 to 205.30.7.46205.30.7.476
231205.30.7.48/29205.30.7.49 to 205.30.7.54205.30.7.556
232205.30.7.56/29205.30.7.57 to 205.30.7.62205.30.7.636
233205.30.7.64/29205.30.7.65 to 205.30.7.70205.30.7.716
234205.30.7.72/29205.30.7.73 to 205.30.7.78205.30.7.796
235205.30.7.80/29205.30.7.81 to 205.30.7.86205.30.7.876
236205.30.7.88/29205.30.7.89 to 205.30.7.94205.30.7.956
237205.30.7.96/29205.30.7.97 to 205.30.7.102205.30.7.1036
238205.30.7.104/29205.30.7.105 to 205.30.7.110205.30.7.1116
239205.30.7.112/29205.30.7.113 to 205.30.7.118205.30.7.1196
240205.30.7.120/29205.30.7.121 to 205.30.7.126205.30.7.1276
241205.30.7.128/29205.30.7.129 to 205.30.7.134205.30.7.1356
242205.30.7.136/29205.30.7.137 to 205.30.7.142205.30.7.1436
243205.30.7.144/29205.30.7.145 to 205.30.7.150205.30.7.1516
244205.30.7.152/29205.30.7.153 to 205.30.7.158205.30.7.1596
245205.30.7.160/29205.30.7.161 to 205.30.7.166205.30.7.1676
246205.30.7.168/29205.30.7.169 to 205.30.7.174205.30.7.1756
247205.30.7.176/29205.30.7.177 to 205.30.7.182205.30.7.1836
248205.30.7.184/29205.30.7.185 to 205.30.7.190205.30.7.1916
249205.30.7.192/29205.30.7.193 to 205.30.7.198205.30.7.1996
250205.30.7.200/29205.30.7.201 to 205.30.7.206205.30.7.2076
251205.30.7.208/29205.30.7.209 to 205.30.7.214205.30.7.2156
252205.30.7.216/29205.30.7.217 to 205.30.7.222205.30.7.2236
253205.30.7.224/29205.30.7.225 to 205.30.7.230205.30.7.2316
254205.30.7.232/29205.30.7.233 to 205.30.7.238205.30.7.2396
255205.30.7.240/29205.30.7.241 to 205.30.7.246205.30.7.2476
256205.30.7.248/29205.30.7.249 to 205.30.7.254205.30.7.2556

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.