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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.

Network202.3.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
202.3.0.0
Broadcast address
202.3.15.255
First usable
202.3.0.1
Last usable
202.3.15.254
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 CA030000 · Integer 3389194240 to 3389198335
Reverse DNS zones
0.3.202.in-addr.arpa
1.3.202.in-addr.arpa
2.3.202.in-addr.arpa
3.3.202.in-addr.arpa
4.3.202.in-addr.arpa
5.3.202.in-addr.arpa
6.3.202.in-addr.arpa
7.3.202.in-addr.arpa
8.3.202.in-addr.arpa
9.3.202.in-addr.arpa
10.3.202.in-addr.arpa
11.3.202.in-addr.arpa
12.3.202.in-addr.arpa
13.3.202.in-addr.arpa
14.3.202.in-addr.arpa
15.3.202.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
Address11001010.00000011.00000000.00000000202.3.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11001010.00000011.00000000.00000000202.3.0.0
Broadcast11001010.00000011.00001111.11111111202.3.15.255
Split into smaller subnets/28
/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)

202.3.0.0/20 makes 256 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1202.3.0.0/28202.3.0.1 to 202.3.0.14202.3.0.1514
2202.3.0.16/28202.3.0.17 to 202.3.0.30202.3.0.3114
3202.3.0.32/28202.3.0.33 to 202.3.0.46202.3.0.4714
4202.3.0.48/28202.3.0.49 to 202.3.0.62202.3.0.6314
5202.3.0.64/28202.3.0.65 to 202.3.0.78202.3.0.7914
6202.3.0.80/28202.3.0.81 to 202.3.0.94202.3.0.9514
7202.3.0.96/28202.3.0.97 to 202.3.0.110202.3.0.11114
8202.3.0.112/28202.3.0.113 to 202.3.0.126202.3.0.12714
9202.3.0.128/28202.3.0.129 to 202.3.0.142202.3.0.14314
10202.3.0.144/28202.3.0.145 to 202.3.0.158202.3.0.15914
11202.3.0.160/28202.3.0.161 to 202.3.0.174202.3.0.17514
12202.3.0.176/28202.3.0.177 to 202.3.0.190202.3.0.19114
13202.3.0.192/28202.3.0.193 to 202.3.0.206202.3.0.20714
14202.3.0.208/28202.3.0.209 to 202.3.0.222202.3.0.22314
15202.3.0.224/28202.3.0.225 to 202.3.0.238202.3.0.23914
16202.3.0.240/28202.3.0.241 to 202.3.0.254202.3.0.25514
17202.3.1.0/28202.3.1.1 to 202.3.1.14202.3.1.1514
18202.3.1.16/28202.3.1.17 to 202.3.1.30202.3.1.3114
19202.3.1.32/28202.3.1.33 to 202.3.1.46202.3.1.4714
20202.3.1.48/28202.3.1.49 to 202.3.1.62202.3.1.6314
21202.3.1.64/28202.3.1.65 to 202.3.1.78202.3.1.7914
22202.3.1.80/28202.3.1.81 to 202.3.1.94202.3.1.9514
23202.3.1.96/28202.3.1.97 to 202.3.1.110202.3.1.11114
24202.3.1.112/28202.3.1.113 to 202.3.1.126202.3.1.12714
25202.3.1.128/28202.3.1.129 to 202.3.1.142202.3.1.14314
26202.3.1.144/28202.3.1.145 to 202.3.1.158202.3.1.15914
27202.3.1.160/28202.3.1.161 to 202.3.1.174202.3.1.17514
28202.3.1.176/28202.3.1.177 to 202.3.1.190202.3.1.19114
29202.3.1.192/28202.3.1.193 to 202.3.1.206202.3.1.20714
30202.3.1.208/28202.3.1.209 to 202.3.1.222202.3.1.22314
31202.3.1.224/28202.3.1.225 to 202.3.1.238202.3.1.23914
32202.3.1.240/28202.3.1.241 to 202.3.1.254202.3.1.25514
33202.3.2.0/28202.3.2.1 to 202.3.2.14202.3.2.1514
34202.3.2.16/28202.3.2.17 to 202.3.2.30202.3.2.3114
35202.3.2.32/28202.3.2.33 to 202.3.2.46202.3.2.4714
36202.3.2.48/28202.3.2.49 to 202.3.2.62202.3.2.6314
37202.3.2.64/28202.3.2.65 to 202.3.2.78202.3.2.7914
38202.3.2.80/28202.3.2.81 to 202.3.2.94202.3.2.9514
39202.3.2.96/28202.3.2.97 to 202.3.2.110202.3.2.11114
40202.3.2.112/28202.3.2.113 to 202.3.2.126202.3.2.12714
41202.3.2.128/28202.3.2.129 to 202.3.2.142202.3.2.14314
42202.3.2.144/28202.3.2.145 to 202.3.2.158202.3.2.15914
43202.3.2.160/28202.3.2.161 to 202.3.2.174202.3.2.17514
44202.3.2.176/28202.3.2.177 to 202.3.2.190202.3.2.19114
45202.3.2.192/28202.3.2.193 to 202.3.2.206202.3.2.20714
46202.3.2.208/28202.3.2.209 to 202.3.2.222202.3.2.22314
47202.3.2.224/28202.3.2.225 to 202.3.2.238202.3.2.23914
48202.3.2.240/28202.3.2.241 to 202.3.2.254202.3.2.25514
49202.3.3.0/28202.3.3.1 to 202.3.3.14202.3.3.1514
50202.3.3.16/28202.3.3.17 to 202.3.3.30202.3.3.3114
51202.3.3.32/28202.3.3.33 to 202.3.3.46202.3.3.4714
52202.3.3.48/28202.3.3.49 to 202.3.3.62202.3.3.6314
53202.3.3.64/28202.3.3.65 to 202.3.3.78202.3.3.7914
54202.3.3.80/28202.3.3.81 to 202.3.3.94202.3.3.9514
55202.3.3.96/28202.3.3.97 to 202.3.3.110202.3.3.11114
56202.3.3.112/28202.3.3.113 to 202.3.3.126202.3.3.12714
57202.3.3.128/28202.3.3.129 to 202.3.3.142202.3.3.14314
58202.3.3.144/28202.3.3.145 to 202.3.3.158202.3.3.15914
59202.3.3.160/28202.3.3.161 to 202.3.3.174202.3.3.17514
60202.3.3.176/28202.3.3.177 to 202.3.3.190202.3.3.19114
61202.3.3.192/28202.3.3.193 to 202.3.3.206202.3.3.20714
62202.3.3.208/28202.3.3.209 to 202.3.3.222202.3.3.22314
63202.3.3.224/28202.3.3.225 to 202.3.3.238202.3.3.23914
64202.3.3.240/28202.3.3.241 to 202.3.3.254202.3.3.25514
65202.3.4.0/28202.3.4.1 to 202.3.4.14202.3.4.1514
66202.3.4.16/28202.3.4.17 to 202.3.4.30202.3.4.3114
67202.3.4.32/28202.3.4.33 to 202.3.4.46202.3.4.4714
68202.3.4.48/28202.3.4.49 to 202.3.4.62202.3.4.6314
69202.3.4.64/28202.3.4.65 to 202.3.4.78202.3.4.7914
70202.3.4.80/28202.3.4.81 to 202.3.4.94202.3.4.9514
71202.3.4.96/28202.3.4.97 to 202.3.4.110202.3.4.11114
72202.3.4.112/28202.3.4.113 to 202.3.4.126202.3.4.12714
73202.3.4.128/28202.3.4.129 to 202.3.4.142202.3.4.14314
74202.3.4.144/28202.3.4.145 to 202.3.4.158202.3.4.15914
75202.3.4.160/28202.3.4.161 to 202.3.4.174202.3.4.17514
76202.3.4.176/28202.3.4.177 to 202.3.4.190202.3.4.19114
77202.3.4.192/28202.3.4.193 to 202.3.4.206202.3.4.20714
78202.3.4.208/28202.3.4.209 to 202.3.4.222202.3.4.22314
79202.3.4.224/28202.3.4.225 to 202.3.4.238202.3.4.23914
80202.3.4.240/28202.3.4.241 to 202.3.4.254202.3.4.25514
81202.3.5.0/28202.3.5.1 to 202.3.5.14202.3.5.1514
82202.3.5.16/28202.3.5.17 to 202.3.5.30202.3.5.3114
83202.3.5.32/28202.3.5.33 to 202.3.5.46202.3.5.4714
84202.3.5.48/28202.3.5.49 to 202.3.5.62202.3.5.6314
85202.3.5.64/28202.3.5.65 to 202.3.5.78202.3.5.7914
86202.3.5.80/28202.3.5.81 to 202.3.5.94202.3.5.9514
87202.3.5.96/28202.3.5.97 to 202.3.5.110202.3.5.11114
88202.3.5.112/28202.3.5.113 to 202.3.5.126202.3.5.12714
89202.3.5.128/28202.3.5.129 to 202.3.5.142202.3.5.14314
90202.3.5.144/28202.3.5.145 to 202.3.5.158202.3.5.15914
91202.3.5.160/28202.3.5.161 to 202.3.5.174202.3.5.17514
92202.3.5.176/28202.3.5.177 to 202.3.5.190202.3.5.19114
93202.3.5.192/28202.3.5.193 to 202.3.5.206202.3.5.20714
94202.3.5.208/28202.3.5.209 to 202.3.5.222202.3.5.22314
95202.3.5.224/28202.3.5.225 to 202.3.5.238202.3.5.23914
96202.3.5.240/28202.3.5.241 to 202.3.5.254202.3.5.25514
97202.3.6.0/28202.3.6.1 to 202.3.6.14202.3.6.1514
98202.3.6.16/28202.3.6.17 to 202.3.6.30202.3.6.3114
99202.3.6.32/28202.3.6.33 to 202.3.6.46202.3.6.4714
100202.3.6.48/28202.3.6.49 to 202.3.6.62202.3.6.6314
101202.3.6.64/28202.3.6.65 to 202.3.6.78202.3.6.7914
102202.3.6.80/28202.3.6.81 to 202.3.6.94202.3.6.9514
103202.3.6.96/28202.3.6.97 to 202.3.6.110202.3.6.11114
104202.3.6.112/28202.3.6.113 to 202.3.6.126202.3.6.12714
105202.3.6.128/28202.3.6.129 to 202.3.6.142202.3.6.14314
106202.3.6.144/28202.3.6.145 to 202.3.6.158202.3.6.15914
107202.3.6.160/28202.3.6.161 to 202.3.6.174202.3.6.17514
108202.3.6.176/28202.3.6.177 to 202.3.6.190202.3.6.19114
109202.3.6.192/28202.3.6.193 to 202.3.6.206202.3.6.20714
110202.3.6.208/28202.3.6.209 to 202.3.6.222202.3.6.22314
111202.3.6.224/28202.3.6.225 to 202.3.6.238202.3.6.23914
112202.3.6.240/28202.3.6.241 to 202.3.6.254202.3.6.25514
113202.3.7.0/28202.3.7.1 to 202.3.7.14202.3.7.1514
114202.3.7.16/28202.3.7.17 to 202.3.7.30202.3.7.3114
115202.3.7.32/28202.3.7.33 to 202.3.7.46202.3.7.4714
116202.3.7.48/28202.3.7.49 to 202.3.7.62202.3.7.6314
117202.3.7.64/28202.3.7.65 to 202.3.7.78202.3.7.7914
118202.3.7.80/28202.3.7.81 to 202.3.7.94202.3.7.9514
119202.3.7.96/28202.3.7.97 to 202.3.7.110202.3.7.11114
120202.3.7.112/28202.3.7.113 to 202.3.7.126202.3.7.12714
121202.3.7.128/28202.3.7.129 to 202.3.7.142202.3.7.14314
122202.3.7.144/28202.3.7.145 to 202.3.7.158202.3.7.15914
123202.3.7.160/28202.3.7.161 to 202.3.7.174202.3.7.17514
124202.3.7.176/28202.3.7.177 to 202.3.7.190202.3.7.19114
125202.3.7.192/28202.3.7.193 to 202.3.7.206202.3.7.20714
126202.3.7.208/28202.3.7.209 to 202.3.7.222202.3.7.22314
127202.3.7.224/28202.3.7.225 to 202.3.7.238202.3.7.23914
128202.3.7.240/28202.3.7.241 to 202.3.7.254202.3.7.25514
129202.3.8.0/28202.3.8.1 to 202.3.8.14202.3.8.1514
130202.3.8.16/28202.3.8.17 to 202.3.8.30202.3.8.3114
131202.3.8.32/28202.3.8.33 to 202.3.8.46202.3.8.4714
132202.3.8.48/28202.3.8.49 to 202.3.8.62202.3.8.6314
133202.3.8.64/28202.3.8.65 to 202.3.8.78202.3.8.7914
134202.3.8.80/28202.3.8.81 to 202.3.8.94202.3.8.9514
135202.3.8.96/28202.3.8.97 to 202.3.8.110202.3.8.11114
136202.3.8.112/28202.3.8.113 to 202.3.8.126202.3.8.12714
137202.3.8.128/28202.3.8.129 to 202.3.8.142202.3.8.14314
138202.3.8.144/28202.3.8.145 to 202.3.8.158202.3.8.15914
139202.3.8.160/28202.3.8.161 to 202.3.8.174202.3.8.17514
140202.3.8.176/28202.3.8.177 to 202.3.8.190202.3.8.19114
141202.3.8.192/28202.3.8.193 to 202.3.8.206202.3.8.20714
142202.3.8.208/28202.3.8.209 to 202.3.8.222202.3.8.22314
143202.3.8.224/28202.3.8.225 to 202.3.8.238202.3.8.23914
144202.3.8.240/28202.3.8.241 to 202.3.8.254202.3.8.25514
145202.3.9.0/28202.3.9.1 to 202.3.9.14202.3.9.1514
146202.3.9.16/28202.3.9.17 to 202.3.9.30202.3.9.3114
147202.3.9.32/28202.3.9.33 to 202.3.9.46202.3.9.4714
148202.3.9.48/28202.3.9.49 to 202.3.9.62202.3.9.6314
149202.3.9.64/28202.3.9.65 to 202.3.9.78202.3.9.7914
150202.3.9.80/28202.3.9.81 to 202.3.9.94202.3.9.9514
151202.3.9.96/28202.3.9.97 to 202.3.9.110202.3.9.11114
152202.3.9.112/28202.3.9.113 to 202.3.9.126202.3.9.12714
153202.3.9.128/28202.3.9.129 to 202.3.9.142202.3.9.14314
154202.3.9.144/28202.3.9.145 to 202.3.9.158202.3.9.15914
155202.3.9.160/28202.3.9.161 to 202.3.9.174202.3.9.17514
156202.3.9.176/28202.3.9.177 to 202.3.9.190202.3.9.19114
157202.3.9.192/28202.3.9.193 to 202.3.9.206202.3.9.20714
158202.3.9.208/28202.3.9.209 to 202.3.9.222202.3.9.22314
159202.3.9.224/28202.3.9.225 to 202.3.9.238202.3.9.23914
160202.3.9.240/28202.3.9.241 to 202.3.9.254202.3.9.25514
161202.3.10.0/28202.3.10.1 to 202.3.10.14202.3.10.1514
162202.3.10.16/28202.3.10.17 to 202.3.10.30202.3.10.3114
163202.3.10.32/28202.3.10.33 to 202.3.10.46202.3.10.4714
164202.3.10.48/28202.3.10.49 to 202.3.10.62202.3.10.6314
165202.3.10.64/28202.3.10.65 to 202.3.10.78202.3.10.7914
166202.3.10.80/28202.3.10.81 to 202.3.10.94202.3.10.9514
167202.3.10.96/28202.3.10.97 to 202.3.10.110202.3.10.11114
168202.3.10.112/28202.3.10.113 to 202.3.10.126202.3.10.12714
169202.3.10.128/28202.3.10.129 to 202.3.10.142202.3.10.14314
170202.3.10.144/28202.3.10.145 to 202.3.10.158202.3.10.15914
171202.3.10.160/28202.3.10.161 to 202.3.10.174202.3.10.17514
172202.3.10.176/28202.3.10.177 to 202.3.10.190202.3.10.19114
173202.3.10.192/28202.3.10.193 to 202.3.10.206202.3.10.20714
174202.3.10.208/28202.3.10.209 to 202.3.10.222202.3.10.22314
175202.3.10.224/28202.3.10.225 to 202.3.10.238202.3.10.23914
176202.3.10.240/28202.3.10.241 to 202.3.10.254202.3.10.25514
177202.3.11.0/28202.3.11.1 to 202.3.11.14202.3.11.1514
178202.3.11.16/28202.3.11.17 to 202.3.11.30202.3.11.3114
179202.3.11.32/28202.3.11.33 to 202.3.11.46202.3.11.4714
180202.3.11.48/28202.3.11.49 to 202.3.11.62202.3.11.6314
181202.3.11.64/28202.3.11.65 to 202.3.11.78202.3.11.7914
182202.3.11.80/28202.3.11.81 to 202.3.11.94202.3.11.9514
183202.3.11.96/28202.3.11.97 to 202.3.11.110202.3.11.11114
184202.3.11.112/28202.3.11.113 to 202.3.11.126202.3.11.12714
185202.3.11.128/28202.3.11.129 to 202.3.11.142202.3.11.14314
186202.3.11.144/28202.3.11.145 to 202.3.11.158202.3.11.15914
187202.3.11.160/28202.3.11.161 to 202.3.11.174202.3.11.17514
188202.3.11.176/28202.3.11.177 to 202.3.11.190202.3.11.19114
189202.3.11.192/28202.3.11.193 to 202.3.11.206202.3.11.20714
190202.3.11.208/28202.3.11.209 to 202.3.11.222202.3.11.22314
191202.3.11.224/28202.3.11.225 to 202.3.11.238202.3.11.23914
192202.3.11.240/28202.3.11.241 to 202.3.11.254202.3.11.25514
193202.3.12.0/28202.3.12.1 to 202.3.12.14202.3.12.1514
194202.3.12.16/28202.3.12.17 to 202.3.12.30202.3.12.3114
195202.3.12.32/28202.3.12.33 to 202.3.12.46202.3.12.4714
196202.3.12.48/28202.3.12.49 to 202.3.12.62202.3.12.6314
197202.3.12.64/28202.3.12.65 to 202.3.12.78202.3.12.7914
198202.3.12.80/28202.3.12.81 to 202.3.12.94202.3.12.9514
199202.3.12.96/28202.3.12.97 to 202.3.12.110202.3.12.11114
200202.3.12.112/28202.3.12.113 to 202.3.12.126202.3.12.12714
201202.3.12.128/28202.3.12.129 to 202.3.12.142202.3.12.14314
202202.3.12.144/28202.3.12.145 to 202.3.12.158202.3.12.15914
203202.3.12.160/28202.3.12.161 to 202.3.12.174202.3.12.17514
204202.3.12.176/28202.3.12.177 to 202.3.12.190202.3.12.19114
205202.3.12.192/28202.3.12.193 to 202.3.12.206202.3.12.20714
206202.3.12.208/28202.3.12.209 to 202.3.12.222202.3.12.22314
207202.3.12.224/28202.3.12.225 to 202.3.12.238202.3.12.23914
208202.3.12.240/28202.3.12.241 to 202.3.12.254202.3.12.25514
209202.3.13.0/28202.3.13.1 to 202.3.13.14202.3.13.1514
210202.3.13.16/28202.3.13.17 to 202.3.13.30202.3.13.3114
211202.3.13.32/28202.3.13.33 to 202.3.13.46202.3.13.4714
212202.3.13.48/28202.3.13.49 to 202.3.13.62202.3.13.6314
213202.3.13.64/28202.3.13.65 to 202.3.13.78202.3.13.7914
214202.3.13.80/28202.3.13.81 to 202.3.13.94202.3.13.9514
215202.3.13.96/28202.3.13.97 to 202.3.13.110202.3.13.11114
216202.3.13.112/28202.3.13.113 to 202.3.13.126202.3.13.12714
217202.3.13.128/28202.3.13.129 to 202.3.13.142202.3.13.14314
218202.3.13.144/28202.3.13.145 to 202.3.13.158202.3.13.15914
219202.3.13.160/28202.3.13.161 to 202.3.13.174202.3.13.17514
220202.3.13.176/28202.3.13.177 to 202.3.13.190202.3.13.19114
221202.3.13.192/28202.3.13.193 to 202.3.13.206202.3.13.20714
222202.3.13.208/28202.3.13.209 to 202.3.13.222202.3.13.22314
223202.3.13.224/28202.3.13.225 to 202.3.13.238202.3.13.23914
224202.3.13.240/28202.3.13.241 to 202.3.13.254202.3.13.25514
225202.3.14.0/28202.3.14.1 to 202.3.14.14202.3.14.1514
226202.3.14.16/28202.3.14.17 to 202.3.14.30202.3.14.3114
227202.3.14.32/28202.3.14.33 to 202.3.14.46202.3.14.4714
228202.3.14.48/28202.3.14.49 to 202.3.14.62202.3.14.6314
229202.3.14.64/28202.3.14.65 to 202.3.14.78202.3.14.7914
230202.3.14.80/28202.3.14.81 to 202.3.14.94202.3.14.9514
231202.3.14.96/28202.3.14.97 to 202.3.14.110202.3.14.11114
232202.3.14.112/28202.3.14.113 to 202.3.14.126202.3.14.12714
233202.3.14.128/28202.3.14.129 to 202.3.14.142202.3.14.14314
234202.3.14.144/28202.3.14.145 to 202.3.14.158202.3.14.15914
235202.3.14.160/28202.3.14.161 to 202.3.14.174202.3.14.17514
236202.3.14.176/28202.3.14.177 to 202.3.14.190202.3.14.19114
237202.3.14.192/28202.3.14.193 to 202.3.14.206202.3.14.20714
238202.3.14.208/28202.3.14.209 to 202.3.14.222202.3.14.22314
239202.3.14.224/28202.3.14.225 to 202.3.14.238202.3.14.23914
240202.3.14.240/28202.3.14.241 to 202.3.14.254202.3.14.25514
241202.3.15.0/28202.3.15.1 to 202.3.15.14202.3.15.1514
242202.3.15.16/28202.3.15.17 to 202.3.15.30202.3.15.3114
243202.3.15.32/28202.3.15.33 to 202.3.15.46202.3.15.4714
244202.3.15.48/28202.3.15.49 to 202.3.15.62202.3.15.6314
245202.3.15.64/28202.3.15.65 to 202.3.15.78202.3.15.7914
246202.3.15.80/28202.3.15.81 to 202.3.15.94202.3.15.9514
247202.3.15.96/28202.3.15.97 to 202.3.15.110202.3.15.11114
248202.3.15.112/28202.3.15.113 to 202.3.15.126202.3.15.12714
249202.3.15.128/28202.3.15.129 to 202.3.15.142202.3.15.14314
250202.3.15.144/28202.3.15.145 to 202.3.15.158202.3.15.15914
251202.3.15.160/28202.3.15.161 to 202.3.15.174202.3.15.17514
252202.3.15.176/28202.3.15.177 to 202.3.15.190202.3.15.19114
253202.3.15.192/28202.3.15.193 to 202.3.15.206202.3.15.20714
254202.3.15.208/28202.3.15.209 to 202.3.15.222202.3.15.22314
255202.3.15.224/28202.3.15.225 to 202.3.15.238202.3.15.23914
256202.3.15.240/28202.3.15.241 to 202.3.15.254202.3.15.25514

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.