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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.

Network204.2.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
204.2.0.0
Broadcast address
204.2.127.255
First usable
204.2.0.1
Last usable
204.2.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
C (default /24)
As numbers
Hex CC020000 · Integer 3422683136 to 3422715903
Reverse DNS zones
0.2.204.in-addr.arpa
1.2.204.in-addr.arpa
2.2.204.in-addr.arpa
3.2.204.in-addr.arpa
4.2.204.in-addr.arpa
5.2.204.in-addr.arpa
6.2.204.in-addr.arpa
7.2.204.in-addr.arpa
8.2.204.in-addr.arpa
9.2.204.in-addr.arpa
10.2.204.in-addr.arpa
11.2.204.in-addr.arpa
12.2.204.in-addr.arpa
13.2.204.in-addr.arpa
14.2.204.in-addr.arpa
15.2.204.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001100.00000010.00000000.00000000204.2.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11001100.00000010.00000000.00000000204.2.0.0
Broadcast11001100.00000010.01111111.11111111204.2.127.255
Split into smaller subnets/29
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

204.2.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.2.0.0/29204.2.0.1 to 204.2.0.6204.2.0.76
2204.2.0.8/29204.2.0.9 to 204.2.0.14204.2.0.156
3204.2.0.16/29204.2.0.17 to 204.2.0.22204.2.0.236
4204.2.0.24/29204.2.0.25 to 204.2.0.30204.2.0.316
5204.2.0.32/29204.2.0.33 to 204.2.0.38204.2.0.396
6204.2.0.40/29204.2.0.41 to 204.2.0.46204.2.0.476
7204.2.0.48/29204.2.0.49 to 204.2.0.54204.2.0.556
8204.2.0.56/29204.2.0.57 to 204.2.0.62204.2.0.636
9204.2.0.64/29204.2.0.65 to 204.2.0.70204.2.0.716
10204.2.0.72/29204.2.0.73 to 204.2.0.78204.2.0.796
11204.2.0.80/29204.2.0.81 to 204.2.0.86204.2.0.876
12204.2.0.88/29204.2.0.89 to 204.2.0.94204.2.0.956
13204.2.0.96/29204.2.0.97 to 204.2.0.102204.2.0.1036
14204.2.0.104/29204.2.0.105 to 204.2.0.110204.2.0.1116
15204.2.0.112/29204.2.0.113 to 204.2.0.118204.2.0.1196
16204.2.0.120/29204.2.0.121 to 204.2.0.126204.2.0.1276
17204.2.0.128/29204.2.0.129 to 204.2.0.134204.2.0.1356
18204.2.0.136/29204.2.0.137 to 204.2.0.142204.2.0.1436
19204.2.0.144/29204.2.0.145 to 204.2.0.150204.2.0.1516
20204.2.0.152/29204.2.0.153 to 204.2.0.158204.2.0.1596
21204.2.0.160/29204.2.0.161 to 204.2.0.166204.2.0.1676
22204.2.0.168/29204.2.0.169 to 204.2.0.174204.2.0.1756
23204.2.0.176/29204.2.0.177 to 204.2.0.182204.2.0.1836
24204.2.0.184/29204.2.0.185 to 204.2.0.190204.2.0.1916
25204.2.0.192/29204.2.0.193 to 204.2.0.198204.2.0.1996
26204.2.0.200/29204.2.0.201 to 204.2.0.206204.2.0.2076
27204.2.0.208/29204.2.0.209 to 204.2.0.214204.2.0.2156
28204.2.0.216/29204.2.0.217 to 204.2.0.222204.2.0.2236
29204.2.0.224/29204.2.0.225 to 204.2.0.230204.2.0.2316
30204.2.0.232/29204.2.0.233 to 204.2.0.238204.2.0.2396
31204.2.0.240/29204.2.0.241 to 204.2.0.246204.2.0.2476
32204.2.0.248/29204.2.0.249 to 204.2.0.254204.2.0.2556
33204.2.1.0/29204.2.1.1 to 204.2.1.6204.2.1.76
34204.2.1.8/29204.2.1.9 to 204.2.1.14204.2.1.156
35204.2.1.16/29204.2.1.17 to 204.2.1.22204.2.1.236
36204.2.1.24/29204.2.1.25 to 204.2.1.30204.2.1.316
37204.2.1.32/29204.2.1.33 to 204.2.1.38204.2.1.396
38204.2.1.40/29204.2.1.41 to 204.2.1.46204.2.1.476
39204.2.1.48/29204.2.1.49 to 204.2.1.54204.2.1.556
40204.2.1.56/29204.2.1.57 to 204.2.1.62204.2.1.636
41204.2.1.64/29204.2.1.65 to 204.2.1.70204.2.1.716
42204.2.1.72/29204.2.1.73 to 204.2.1.78204.2.1.796
43204.2.1.80/29204.2.1.81 to 204.2.1.86204.2.1.876
44204.2.1.88/29204.2.1.89 to 204.2.1.94204.2.1.956
45204.2.1.96/29204.2.1.97 to 204.2.1.102204.2.1.1036
46204.2.1.104/29204.2.1.105 to 204.2.1.110204.2.1.1116
47204.2.1.112/29204.2.1.113 to 204.2.1.118204.2.1.1196
48204.2.1.120/29204.2.1.121 to 204.2.1.126204.2.1.1276
49204.2.1.128/29204.2.1.129 to 204.2.1.134204.2.1.1356
50204.2.1.136/29204.2.1.137 to 204.2.1.142204.2.1.1436
51204.2.1.144/29204.2.1.145 to 204.2.1.150204.2.1.1516
52204.2.1.152/29204.2.1.153 to 204.2.1.158204.2.1.1596
53204.2.1.160/29204.2.1.161 to 204.2.1.166204.2.1.1676
54204.2.1.168/29204.2.1.169 to 204.2.1.174204.2.1.1756
55204.2.1.176/29204.2.1.177 to 204.2.1.182204.2.1.1836
56204.2.1.184/29204.2.1.185 to 204.2.1.190204.2.1.1916
57204.2.1.192/29204.2.1.193 to 204.2.1.198204.2.1.1996
58204.2.1.200/29204.2.1.201 to 204.2.1.206204.2.1.2076
59204.2.1.208/29204.2.1.209 to 204.2.1.214204.2.1.2156
60204.2.1.216/29204.2.1.217 to 204.2.1.222204.2.1.2236
61204.2.1.224/29204.2.1.225 to 204.2.1.230204.2.1.2316
62204.2.1.232/29204.2.1.233 to 204.2.1.238204.2.1.2396
63204.2.1.240/29204.2.1.241 to 204.2.1.246204.2.1.2476
64204.2.1.248/29204.2.1.249 to 204.2.1.254204.2.1.2556
65204.2.2.0/29204.2.2.1 to 204.2.2.6204.2.2.76
66204.2.2.8/29204.2.2.9 to 204.2.2.14204.2.2.156
67204.2.2.16/29204.2.2.17 to 204.2.2.22204.2.2.236
68204.2.2.24/29204.2.2.25 to 204.2.2.30204.2.2.316
69204.2.2.32/29204.2.2.33 to 204.2.2.38204.2.2.396
70204.2.2.40/29204.2.2.41 to 204.2.2.46204.2.2.476
71204.2.2.48/29204.2.2.49 to 204.2.2.54204.2.2.556
72204.2.2.56/29204.2.2.57 to 204.2.2.62204.2.2.636
73204.2.2.64/29204.2.2.65 to 204.2.2.70204.2.2.716
74204.2.2.72/29204.2.2.73 to 204.2.2.78204.2.2.796
75204.2.2.80/29204.2.2.81 to 204.2.2.86204.2.2.876
76204.2.2.88/29204.2.2.89 to 204.2.2.94204.2.2.956
77204.2.2.96/29204.2.2.97 to 204.2.2.102204.2.2.1036
78204.2.2.104/29204.2.2.105 to 204.2.2.110204.2.2.1116
79204.2.2.112/29204.2.2.113 to 204.2.2.118204.2.2.1196
80204.2.2.120/29204.2.2.121 to 204.2.2.126204.2.2.1276
81204.2.2.128/29204.2.2.129 to 204.2.2.134204.2.2.1356
82204.2.2.136/29204.2.2.137 to 204.2.2.142204.2.2.1436
83204.2.2.144/29204.2.2.145 to 204.2.2.150204.2.2.1516
84204.2.2.152/29204.2.2.153 to 204.2.2.158204.2.2.1596
85204.2.2.160/29204.2.2.161 to 204.2.2.166204.2.2.1676
86204.2.2.168/29204.2.2.169 to 204.2.2.174204.2.2.1756
87204.2.2.176/29204.2.2.177 to 204.2.2.182204.2.2.1836
88204.2.2.184/29204.2.2.185 to 204.2.2.190204.2.2.1916
89204.2.2.192/29204.2.2.193 to 204.2.2.198204.2.2.1996
90204.2.2.200/29204.2.2.201 to 204.2.2.206204.2.2.2076
91204.2.2.208/29204.2.2.209 to 204.2.2.214204.2.2.2156
92204.2.2.216/29204.2.2.217 to 204.2.2.222204.2.2.2236
93204.2.2.224/29204.2.2.225 to 204.2.2.230204.2.2.2316
94204.2.2.232/29204.2.2.233 to 204.2.2.238204.2.2.2396
95204.2.2.240/29204.2.2.241 to 204.2.2.246204.2.2.2476
96204.2.2.248/29204.2.2.249 to 204.2.2.254204.2.2.2556
97204.2.3.0/29204.2.3.1 to 204.2.3.6204.2.3.76
98204.2.3.8/29204.2.3.9 to 204.2.3.14204.2.3.156
99204.2.3.16/29204.2.3.17 to 204.2.3.22204.2.3.236
100204.2.3.24/29204.2.3.25 to 204.2.3.30204.2.3.316
101204.2.3.32/29204.2.3.33 to 204.2.3.38204.2.3.396
102204.2.3.40/29204.2.3.41 to 204.2.3.46204.2.3.476
103204.2.3.48/29204.2.3.49 to 204.2.3.54204.2.3.556
104204.2.3.56/29204.2.3.57 to 204.2.3.62204.2.3.636
105204.2.3.64/29204.2.3.65 to 204.2.3.70204.2.3.716
106204.2.3.72/29204.2.3.73 to 204.2.3.78204.2.3.796
107204.2.3.80/29204.2.3.81 to 204.2.3.86204.2.3.876
108204.2.3.88/29204.2.3.89 to 204.2.3.94204.2.3.956
109204.2.3.96/29204.2.3.97 to 204.2.3.102204.2.3.1036
110204.2.3.104/29204.2.3.105 to 204.2.3.110204.2.3.1116
111204.2.3.112/29204.2.3.113 to 204.2.3.118204.2.3.1196
112204.2.3.120/29204.2.3.121 to 204.2.3.126204.2.3.1276
113204.2.3.128/29204.2.3.129 to 204.2.3.134204.2.3.1356
114204.2.3.136/29204.2.3.137 to 204.2.3.142204.2.3.1436
115204.2.3.144/29204.2.3.145 to 204.2.3.150204.2.3.1516
116204.2.3.152/29204.2.3.153 to 204.2.3.158204.2.3.1596
117204.2.3.160/29204.2.3.161 to 204.2.3.166204.2.3.1676
118204.2.3.168/29204.2.3.169 to 204.2.3.174204.2.3.1756
119204.2.3.176/29204.2.3.177 to 204.2.3.182204.2.3.1836
120204.2.3.184/29204.2.3.185 to 204.2.3.190204.2.3.1916
121204.2.3.192/29204.2.3.193 to 204.2.3.198204.2.3.1996
122204.2.3.200/29204.2.3.201 to 204.2.3.206204.2.3.2076
123204.2.3.208/29204.2.3.209 to 204.2.3.214204.2.3.2156
124204.2.3.216/29204.2.3.217 to 204.2.3.222204.2.3.2236
125204.2.3.224/29204.2.3.225 to 204.2.3.230204.2.3.2316
126204.2.3.232/29204.2.3.233 to 204.2.3.238204.2.3.2396
127204.2.3.240/29204.2.3.241 to 204.2.3.246204.2.3.2476
128204.2.3.248/29204.2.3.249 to 204.2.3.254204.2.3.2556
129204.2.4.0/29204.2.4.1 to 204.2.4.6204.2.4.76
130204.2.4.8/29204.2.4.9 to 204.2.4.14204.2.4.156
131204.2.4.16/29204.2.4.17 to 204.2.4.22204.2.4.236
132204.2.4.24/29204.2.4.25 to 204.2.4.30204.2.4.316
133204.2.4.32/29204.2.4.33 to 204.2.4.38204.2.4.396
134204.2.4.40/29204.2.4.41 to 204.2.4.46204.2.4.476
135204.2.4.48/29204.2.4.49 to 204.2.4.54204.2.4.556
136204.2.4.56/29204.2.4.57 to 204.2.4.62204.2.4.636
137204.2.4.64/29204.2.4.65 to 204.2.4.70204.2.4.716
138204.2.4.72/29204.2.4.73 to 204.2.4.78204.2.4.796
139204.2.4.80/29204.2.4.81 to 204.2.4.86204.2.4.876
140204.2.4.88/29204.2.4.89 to 204.2.4.94204.2.4.956
141204.2.4.96/29204.2.4.97 to 204.2.4.102204.2.4.1036
142204.2.4.104/29204.2.4.105 to 204.2.4.110204.2.4.1116
143204.2.4.112/29204.2.4.113 to 204.2.4.118204.2.4.1196
144204.2.4.120/29204.2.4.121 to 204.2.4.126204.2.4.1276
145204.2.4.128/29204.2.4.129 to 204.2.4.134204.2.4.1356
146204.2.4.136/29204.2.4.137 to 204.2.4.142204.2.4.1436
147204.2.4.144/29204.2.4.145 to 204.2.4.150204.2.4.1516
148204.2.4.152/29204.2.4.153 to 204.2.4.158204.2.4.1596
149204.2.4.160/29204.2.4.161 to 204.2.4.166204.2.4.1676
150204.2.4.168/29204.2.4.169 to 204.2.4.174204.2.4.1756
151204.2.4.176/29204.2.4.177 to 204.2.4.182204.2.4.1836
152204.2.4.184/29204.2.4.185 to 204.2.4.190204.2.4.1916
153204.2.4.192/29204.2.4.193 to 204.2.4.198204.2.4.1996
154204.2.4.200/29204.2.4.201 to 204.2.4.206204.2.4.2076
155204.2.4.208/29204.2.4.209 to 204.2.4.214204.2.4.2156
156204.2.4.216/29204.2.4.217 to 204.2.4.222204.2.4.2236
157204.2.4.224/29204.2.4.225 to 204.2.4.230204.2.4.2316
158204.2.4.232/29204.2.4.233 to 204.2.4.238204.2.4.2396
159204.2.4.240/29204.2.4.241 to 204.2.4.246204.2.4.2476
160204.2.4.248/29204.2.4.249 to 204.2.4.254204.2.4.2556
161204.2.5.0/29204.2.5.1 to 204.2.5.6204.2.5.76
162204.2.5.8/29204.2.5.9 to 204.2.5.14204.2.5.156
163204.2.5.16/29204.2.5.17 to 204.2.5.22204.2.5.236
164204.2.5.24/29204.2.5.25 to 204.2.5.30204.2.5.316
165204.2.5.32/29204.2.5.33 to 204.2.5.38204.2.5.396
166204.2.5.40/29204.2.5.41 to 204.2.5.46204.2.5.476
167204.2.5.48/29204.2.5.49 to 204.2.5.54204.2.5.556
168204.2.5.56/29204.2.5.57 to 204.2.5.62204.2.5.636
169204.2.5.64/29204.2.5.65 to 204.2.5.70204.2.5.716
170204.2.5.72/29204.2.5.73 to 204.2.5.78204.2.5.796
171204.2.5.80/29204.2.5.81 to 204.2.5.86204.2.5.876
172204.2.5.88/29204.2.5.89 to 204.2.5.94204.2.5.956
173204.2.5.96/29204.2.5.97 to 204.2.5.102204.2.5.1036
174204.2.5.104/29204.2.5.105 to 204.2.5.110204.2.5.1116
175204.2.5.112/29204.2.5.113 to 204.2.5.118204.2.5.1196
176204.2.5.120/29204.2.5.121 to 204.2.5.126204.2.5.1276
177204.2.5.128/29204.2.5.129 to 204.2.5.134204.2.5.1356
178204.2.5.136/29204.2.5.137 to 204.2.5.142204.2.5.1436
179204.2.5.144/29204.2.5.145 to 204.2.5.150204.2.5.1516
180204.2.5.152/29204.2.5.153 to 204.2.5.158204.2.5.1596
181204.2.5.160/29204.2.5.161 to 204.2.5.166204.2.5.1676
182204.2.5.168/29204.2.5.169 to 204.2.5.174204.2.5.1756
183204.2.5.176/29204.2.5.177 to 204.2.5.182204.2.5.1836
184204.2.5.184/29204.2.5.185 to 204.2.5.190204.2.5.1916
185204.2.5.192/29204.2.5.193 to 204.2.5.198204.2.5.1996
186204.2.5.200/29204.2.5.201 to 204.2.5.206204.2.5.2076
187204.2.5.208/29204.2.5.209 to 204.2.5.214204.2.5.2156
188204.2.5.216/29204.2.5.217 to 204.2.5.222204.2.5.2236
189204.2.5.224/29204.2.5.225 to 204.2.5.230204.2.5.2316
190204.2.5.232/29204.2.5.233 to 204.2.5.238204.2.5.2396
191204.2.5.240/29204.2.5.241 to 204.2.5.246204.2.5.2476
192204.2.5.248/29204.2.5.249 to 204.2.5.254204.2.5.2556
193204.2.6.0/29204.2.6.1 to 204.2.6.6204.2.6.76
194204.2.6.8/29204.2.6.9 to 204.2.6.14204.2.6.156
195204.2.6.16/29204.2.6.17 to 204.2.6.22204.2.6.236
196204.2.6.24/29204.2.6.25 to 204.2.6.30204.2.6.316
197204.2.6.32/29204.2.6.33 to 204.2.6.38204.2.6.396
198204.2.6.40/29204.2.6.41 to 204.2.6.46204.2.6.476
199204.2.6.48/29204.2.6.49 to 204.2.6.54204.2.6.556
200204.2.6.56/29204.2.6.57 to 204.2.6.62204.2.6.636
201204.2.6.64/29204.2.6.65 to 204.2.6.70204.2.6.716
202204.2.6.72/29204.2.6.73 to 204.2.6.78204.2.6.796
203204.2.6.80/29204.2.6.81 to 204.2.6.86204.2.6.876
204204.2.6.88/29204.2.6.89 to 204.2.6.94204.2.6.956
205204.2.6.96/29204.2.6.97 to 204.2.6.102204.2.6.1036
206204.2.6.104/29204.2.6.105 to 204.2.6.110204.2.6.1116
207204.2.6.112/29204.2.6.113 to 204.2.6.118204.2.6.1196
208204.2.6.120/29204.2.6.121 to 204.2.6.126204.2.6.1276
209204.2.6.128/29204.2.6.129 to 204.2.6.134204.2.6.1356
210204.2.6.136/29204.2.6.137 to 204.2.6.142204.2.6.1436
211204.2.6.144/29204.2.6.145 to 204.2.6.150204.2.6.1516
212204.2.6.152/29204.2.6.153 to 204.2.6.158204.2.6.1596
213204.2.6.160/29204.2.6.161 to 204.2.6.166204.2.6.1676
214204.2.6.168/29204.2.6.169 to 204.2.6.174204.2.6.1756
215204.2.6.176/29204.2.6.177 to 204.2.6.182204.2.6.1836
216204.2.6.184/29204.2.6.185 to 204.2.6.190204.2.6.1916
217204.2.6.192/29204.2.6.193 to 204.2.6.198204.2.6.1996
218204.2.6.200/29204.2.6.201 to 204.2.6.206204.2.6.2076
219204.2.6.208/29204.2.6.209 to 204.2.6.214204.2.6.2156
220204.2.6.216/29204.2.6.217 to 204.2.6.222204.2.6.2236
221204.2.6.224/29204.2.6.225 to 204.2.6.230204.2.6.2316
222204.2.6.232/29204.2.6.233 to 204.2.6.238204.2.6.2396
223204.2.6.240/29204.2.6.241 to 204.2.6.246204.2.6.2476
224204.2.6.248/29204.2.6.249 to 204.2.6.254204.2.6.2556
225204.2.7.0/29204.2.7.1 to 204.2.7.6204.2.7.76
226204.2.7.8/29204.2.7.9 to 204.2.7.14204.2.7.156
227204.2.7.16/29204.2.7.17 to 204.2.7.22204.2.7.236
228204.2.7.24/29204.2.7.25 to 204.2.7.30204.2.7.316
229204.2.7.32/29204.2.7.33 to 204.2.7.38204.2.7.396
230204.2.7.40/29204.2.7.41 to 204.2.7.46204.2.7.476
231204.2.7.48/29204.2.7.49 to 204.2.7.54204.2.7.556
232204.2.7.56/29204.2.7.57 to 204.2.7.62204.2.7.636
233204.2.7.64/29204.2.7.65 to 204.2.7.70204.2.7.716
234204.2.7.72/29204.2.7.73 to 204.2.7.78204.2.7.796
235204.2.7.80/29204.2.7.81 to 204.2.7.86204.2.7.876
236204.2.7.88/29204.2.7.89 to 204.2.7.94204.2.7.956
237204.2.7.96/29204.2.7.97 to 204.2.7.102204.2.7.1036
238204.2.7.104/29204.2.7.105 to 204.2.7.110204.2.7.1116
239204.2.7.112/29204.2.7.113 to 204.2.7.118204.2.7.1196
240204.2.7.120/29204.2.7.121 to 204.2.7.126204.2.7.1276
241204.2.7.128/29204.2.7.129 to 204.2.7.134204.2.7.1356
242204.2.7.136/29204.2.7.137 to 204.2.7.142204.2.7.1436
243204.2.7.144/29204.2.7.145 to 204.2.7.150204.2.7.1516
244204.2.7.152/29204.2.7.153 to 204.2.7.158204.2.7.1596
245204.2.7.160/29204.2.7.161 to 204.2.7.166204.2.7.1676
246204.2.7.168/29204.2.7.169 to 204.2.7.174204.2.7.1756
247204.2.7.176/29204.2.7.177 to 204.2.7.182204.2.7.1836
248204.2.7.184/29204.2.7.185 to 204.2.7.190204.2.7.1916
249204.2.7.192/29204.2.7.193 to 204.2.7.198204.2.7.1996
250204.2.7.200/29204.2.7.201 to 204.2.7.206204.2.7.2076
251204.2.7.208/29204.2.7.209 to 204.2.7.214204.2.7.2156
252204.2.7.216/29204.2.7.217 to 204.2.7.222204.2.7.2236
253204.2.7.224/29204.2.7.225 to 204.2.7.230204.2.7.2316
254204.2.7.232/29204.2.7.233 to 204.2.7.238204.2.7.2396
255204.2.7.240/29204.2.7.241 to 204.2.7.246204.2.7.2476
256204.2.7.248/29204.2.7.249 to 204.2.7.254204.2.7.2556

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.