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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.

Network240.7.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
240.7.0.0
Broadcast address
240.7.127.255
First usable
240.7.0.1
Last usable
240.7.127.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F0070000 · Integer 4026990592 to 4027023359
Reverse DNS zones
0.7.240.in-addr.arpa
1.7.240.in-addr.arpa
2.7.240.in-addr.arpa
3.7.240.in-addr.arpa
4.7.240.in-addr.arpa
5.7.240.in-addr.arpa
6.7.240.in-addr.arpa
7.7.240.in-addr.arpa
8.7.240.in-addr.arpa
9.7.240.in-addr.arpa
10.7.240.in-addr.arpa
11.7.240.in-addr.arpa
12.7.240.in-addr.arpa
13.7.240.in-addr.arpa
14.7.240.in-addr.arpa
15.7.240.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
Address11110000.00000111.00000000.00000000240.7.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11110000.00000111.00000000.00000000240.7.0.0
Broadcast11110000.00000111.01111111.11111111240.7.127.255
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)

240.7.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.7.0.0/29240.7.0.1 to 240.7.0.6240.7.0.76
2240.7.0.8/29240.7.0.9 to 240.7.0.14240.7.0.156
3240.7.0.16/29240.7.0.17 to 240.7.0.22240.7.0.236
4240.7.0.24/29240.7.0.25 to 240.7.0.30240.7.0.316
5240.7.0.32/29240.7.0.33 to 240.7.0.38240.7.0.396
6240.7.0.40/29240.7.0.41 to 240.7.0.46240.7.0.476
7240.7.0.48/29240.7.0.49 to 240.7.0.54240.7.0.556
8240.7.0.56/29240.7.0.57 to 240.7.0.62240.7.0.636
9240.7.0.64/29240.7.0.65 to 240.7.0.70240.7.0.716
10240.7.0.72/29240.7.0.73 to 240.7.0.78240.7.0.796
11240.7.0.80/29240.7.0.81 to 240.7.0.86240.7.0.876
12240.7.0.88/29240.7.0.89 to 240.7.0.94240.7.0.956
13240.7.0.96/29240.7.0.97 to 240.7.0.102240.7.0.1036
14240.7.0.104/29240.7.0.105 to 240.7.0.110240.7.0.1116
15240.7.0.112/29240.7.0.113 to 240.7.0.118240.7.0.1196
16240.7.0.120/29240.7.0.121 to 240.7.0.126240.7.0.1276
17240.7.0.128/29240.7.0.129 to 240.7.0.134240.7.0.1356
18240.7.0.136/29240.7.0.137 to 240.7.0.142240.7.0.1436
19240.7.0.144/29240.7.0.145 to 240.7.0.150240.7.0.1516
20240.7.0.152/29240.7.0.153 to 240.7.0.158240.7.0.1596
21240.7.0.160/29240.7.0.161 to 240.7.0.166240.7.0.1676
22240.7.0.168/29240.7.0.169 to 240.7.0.174240.7.0.1756
23240.7.0.176/29240.7.0.177 to 240.7.0.182240.7.0.1836
24240.7.0.184/29240.7.0.185 to 240.7.0.190240.7.0.1916
25240.7.0.192/29240.7.0.193 to 240.7.0.198240.7.0.1996
26240.7.0.200/29240.7.0.201 to 240.7.0.206240.7.0.2076
27240.7.0.208/29240.7.0.209 to 240.7.0.214240.7.0.2156
28240.7.0.216/29240.7.0.217 to 240.7.0.222240.7.0.2236
29240.7.0.224/29240.7.0.225 to 240.7.0.230240.7.0.2316
30240.7.0.232/29240.7.0.233 to 240.7.0.238240.7.0.2396
31240.7.0.240/29240.7.0.241 to 240.7.0.246240.7.0.2476
32240.7.0.248/29240.7.0.249 to 240.7.0.254240.7.0.2556
33240.7.1.0/29240.7.1.1 to 240.7.1.6240.7.1.76
34240.7.1.8/29240.7.1.9 to 240.7.1.14240.7.1.156
35240.7.1.16/29240.7.1.17 to 240.7.1.22240.7.1.236
36240.7.1.24/29240.7.1.25 to 240.7.1.30240.7.1.316
37240.7.1.32/29240.7.1.33 to 240.7.1.38240.7.1.396
38240.7.1.40/29240.7.1.41 to 240.7.1.46240.7.1.476
39240.7.1.48/29240.7.1.49 to 240.7.1.54240.7.1.556
40240.7.1.56/29240.7.1.57 to 240.7.1.62240.7.1.636
41240.7.1.64/29240.7.1.65 to 240.7.1.70240.7.1.716
42240.7.1.72/29240.7.1.73 to 240.7.1.78240.7.1.796
43240.7.1.80/29240.7.1.81 to 240.7.1.86240.7.1.876
44240.7.1.88/29240.7.1.89 to 240.7.1.94240.7.1.956
45240.7.1.96/29240.7.1.97 to 240.7.1.102240.7.1.1036
46240.7.1.104/29240.7.1.105 to 240.7.1.110240.7.1.1116
47240.7.1.112/29240.7.1.113 to 240.7.1.118240.7.1.1196
48240.7.1.120/29240.7.1.121 to 240.7.1.126240.7.1.1276
49240.7.1.128/29240.7.1.129 to 240.7.1.134240.7.1.1356
50240.7.1.136/29240.7.1.137 to 240.7.1.142240.7.1.1436
51240.7.1.144/29240.7.1.145 to 240.7.1.150240.7.1.1516
52240.7.1.152/29240.7.1.153 to 240.7.1.158240.7.1.1596
53240.7.1.160/29240.7.1.161 to 240.7.1.166240.7.1.1676
54240.7.1.168/29240.7.1.169 to 240.7.1.174240.7.1.1756
55240.7.1.176/29240.7.1.177 to 240.7.1.182240.7.1.1836
56240.7.1.184/29240.7.1.185 to 240.7.1.190240.7.1.1916
57240.7.1.192/29240.7.1.193 to 240.7.1.198240.7.1.1996
58240.7.1.200/29240.7.1.201 to 240.7.1.206240.7.1.2076
59240.7.1.208/29240.7.1.209 to 240.7.1.214240.7.1.2156
60240.7.1.216/29240.7.1.217 to 240.7.1.222240.7.1.2236
61240.7.1.224/29240.7.1.225 to 240.7.1.230240.7.1.2316
62240.7.1.232/29240.7.1.233 to 240.7.1.238240.7.1.2396
63240.7.1.240/29240.7.1.241 to 240.7.1.246240.7.1.2476
64240.7.1.248/29240.7.1.249 to 240.7.1.254240.7.1.2556
65240.7.2.0/29240.7.2.1 to 240.7.2.6240.7.2.76
66240.7.2.8/29240.7.2.9 to 240.7.2.14240.7.2.156
67240.7.2.16/29240.7.2.17 to 240.7.2.22240.7.2.236
68240.7.2.24/29240.7.2.25 to 240.7.2.30240.7.2.316
69240.7.2.32/29240.7.2.33 to 240.7.2.38240.7.2.396
70240.7.2.40/29240.7.2.41 to 240.7.2.46240.7.2.476
71240.7.2.48/29240.7.2.49 to 240.7.2.54240.7.2.556
72240.7.2.56/29240.7.2.57 to 240.7.2.62240.7.2.636
73240.7.2.64/29240.7.2.65 to 240.7.2.70240.7.2.716
74240.7.2.72/29240.7.2.73 to 240.7.2.78240.7.2.796
75240.7.2.80/29240.7.2.81 to 240.7.2.86240.7.2.876
76240.7.2.88/29240.7.2.89 to 240.7.2.94240.7.2.956
77240.7.2.96/29240.7.2.97 to 240.7.2.102240.7.2.1036
78240.7.2.104/29240.7.2.105 to 240.7.2.110240.7.2.1116
79240.7.2.112/29240.7.2.113 to 240.7.2.118240.7.2.1196
80240.7.2.120/29240.7.2.121 to 240.7.2.126240.7.2.1276
81240.7.2.128/29240.7.2.129 to 240.7.2.134240.7.2.1356
82240.7.2.136/29240.7.2.137 to 240.7.2.142240.7.2.1436
83240.7.2.144/29240.7.2.145 to 240.7.2.150240.7.2.1516
84240.7.2.152/29240.7.2.153 to 240.7.2.158240.7.2.1596
85240.7.2.160/29240.7.2.161 to 240.7.2.166240.7.2.1676
86240.7.2.168/29240.7.2.169 to 240.7.2.174240.7.2.1756
87240.7.2.176/29240.7.2.177 to 240.7.2.182240.7.2.1836
88240.7.2.184/29240.7.2.185 to 240.7.2.190240.7.2.1916
89240.7.2.192/29240.7.2.193 to 240.7.2.198240.7.2.1996
90240.7.2.200/29240.7.2.201 to 240.7.2.206240.7.2.2076
91240.7.2.208/29240.7.2.209 to 240.7.2.214240.7.2.2156
92240.7.2.216/29240.7.2.217 to 240.7.2.222240.7.2.2236
93240.7.2.224/29240.7.2.225 to 240.7.2.230240.7.2.2316
94240.7.2.232/29240.7.2.233 to 240.7.2.238240.7.2.2396
95240.7.2.240/29240.7.2.241 to 240.7.2.246240.7.2.2476
96240.7.2.248/29240.7.2.249 to 240.7.2.254240.7.2.2556
97240.7.3.0/29240.7.3.1 to 240.7.3.6240.7.3.76
98240.7.3.8/29240.7.3.9 to 240.7.3.14240.7.3.156
99240.7.3.16/29240.7.3.17 to 240.7.3.22240.7.3.236
100240.7.3.24/29240.7.3.25 to 240.7.3.30240.7.3.316
101240.7.3.32/29240.7.3.33 to 240.7.3.38240.7.3.396
102240.7.3.40/29240.7.3.41 to 240.7.3.46240.7.3.476
103240.7.3.48/29240.7.3.49 to 240.7.3.54240.7.3.556
104240.7.3.56/29240.7.3.57 to 240.7.3.62240.7.3.636
105240.7.3.64/29240.7.3.65 to 240.7.3.70240.7.3.716
106240.7.3.72/29240.7.3.73 to 240.7.3.78240.7.3.796
107240.7.3.80/29240.7.3.81 to 240.7.3.86240.7.3.876
108240.7.3.88/29240.7.3.89 to 240.7.3.94240.7.3.956
109240.7.3.96/29240.7.3.97 to 240.7.3.102240.7.3.1036
110240.7.3.104/29240.7.3.105 to 240.7.3.110240.7.3.1116
111240.7.3.112/29240.7.3.113 to 240.7.3.118240.7.3.1196
112240.7.3.120/29240.7.3.121 to 240.7.3.126240.7.3.1276
113240.7.3.128/29240.7.3.129 to 240.7.3.134240.7.3.1356
114240.7.3.136/29240.7.3.137 to 240.7.3.142240.7.3.1436
115240.7.3.144/29240.7.3.145 to 240.7.3.150240.7.3.1516
116240.7.3.152/29240.7.3.153 to 240.7.3.158240.7.3.1596
117240.7.3.160/29240.7.3.161 to 240.7.3.166240.7.3.1676
118240.7.3.168/29240.7.3.169 to 240.7.3.174240.7.3.1756
119240.7.3.176/29240.7.3.177 to 240.7.3.182240.7.3.1836
120240.7.3.184/29240.7.3.185 to 240.7.3.190240.7.3.1916
121240.7.3.192/29240.7.3.193 to 240.7.3.198240.7.3.1996
122240.7.3.200/29240.7.3.201 to 240.7.3.206240.7.3.2076
123240.7.3.208/29240.7.3.209 to 240.7.3.214240.7.3.2156
124240.7.3.216/29240.7.3.217 to 240.7.3.222240.7.3.2236
125240.7.3.224/29240.7.3.225 to 240.7.3.230240.7.3.2316
126240.7.3.232/29240.7.3.233 to 240.7.3.238240.7.3.2396
127240.7.3.240/29240.7.3.241 to 240.7.3.246240.7.3.2476
128240.7.3.248/29240.7.3.249 to 240.7.3.254240.7.3.2556
129240.7.4.0/29240.7.4.1 to 240.7.4.6240.7.4.76
130240.7.4.8/29240.7.4.9 to 240.7.4.14240.7.4.156
131240.7.4.16/29240.7.4.17 to 240.7.4.22240.7.4.236
132240.7.4.24/29240.7.4.25 to 240.7.4.30240.7.4.316
133240.7.4.32/29240.7.4.33 to 240.7.4.38240.7.4.396
134240.7.4.40/29240.7.4.41 to 240.7.4.46240.7.4.476
135240.7.4.48/29240.7.4.49 to 240.7.4.54240.7.4.556
136240.7.4.56/29240.7.4.57 to 240.7.4.62240.7.4.636
137240.7.4.64/29240.7.4.65 to 240.7.4.70240.7.4.716
138240.7.4.72/29240.7.4.73 to 240.7.4.78240.7.4.796
139240.7.4.80/29240.7.4.81 to 240.7.4.86240.7.4.876
140240.7.4.88/29240.7.4.89 to 240.7.4.94240.7.4.956
141240.7.4.96/29240.7.4.97 to 240.7.4.102240.7.4.1036
142240.7.4.104/29240.7.4.105 to 240.7.4.110240.7.4.1116
143240.7.4.112/29240.7.4.113 to 240.7.4.118240.7.4.1196
144240.7.4.120/29240.7.4.121 to 240.7.4.126240.7.4.1276
145240.7.4.128/29240.7.4.129 to 240.7.4.134240.7.4.1356
146240.7.4.136/29240.7.4.137 to 240.7.4.142240.7.4.1436
147240.7.4.144/29240.7.4.145 to 240.7.4.150240.7.4.1516
148240.7.4.152/29240.7.4.153 to 240.7.4.158240.7.4.1596
149240.7.4.160/29240.7.4.161 to 240.7.4.166240.7.4.1676
150240.7.4.168/29240.7.4.169 to 240.7.4.174240.7.4.1756
151240.7.4.176/29240.7.4.177 to 240.7.4.182240.7.4.1836
152240.7.4.184/29240.7.4.185 to 240.7.4.190240.7.4.1916
153240.7.4.192/29240.7.4.193 to 240.7.4.198240.7.4.1996
154240.7.4.200/29240.7.4.201 to 240.7.4.206240.7.4.2076
155240.7.4.208/29240.7.4.209 to 240.7.4.214240.7.4.2156
156240.7.4.216/29240.7.4.217 to 240.7.4.222240.7.4.2236
157240.7.4.224/29240.7.4.225 to 240.7.4.230240.7.4.2316
158240.7.4.232/29240.7.4.233 to 240.7.4.238240.7.4.2396
159240.7.4.240/29240.7.4.241 to 240.7.4.246240.7.4.2476
160240.7.4.248/29240.7.4.249 to 240.7.4.254240.7.4.2556
161240.7.5.0/29240.7.5.1 to 240.7.5.6240.7.5.76
162240.7.5.8/29240.7.5.9 to 240.7.5.14240.7.5.156
163240.7.5.16/29240.7.5.17 to 240.7.5.22240.7.5.236
164240.7.5.24/29240.7.5.25 to 240.7.5.30240.7.5.316
165240.7.5.32/29240.7.5.33 to 240.7.5.38240.7.5.396
166240.7.5.40/29240.7.5.41 to 240.7.5.46240.7.5.476
167240.7.5.48/29240.7.5.49 to 240.7.5.54240.7.5.556
168240.7.5.56/29240.7.5.57 to 240.7.5.62240.7.5.636
169240.7.5.64/29240.7.5.65 to 240.7.5.70240.7.5.716
170240.7.5.72/29240.7.5.73 to 240.7.5.78240.7.5.796
171240.7.5.80/29240.7.5.81 to 240.7.5.86240.7.5.876
172240.7.5.88/29240.7.5.89 to 240.7.5.94240.7.5.956
173240.7.5.96/29240.7.5.97 to 240.7.5.102240.7.5.1036
174240.7.5.104/29240.7.5.105 to 240.7.5.110240.7.5.1116
175240.7.5.112/29240.7.5.113 to 240.7.5.118240.7.5.1196
176240.7.5.120/29240.7.5.121 to 240.7.5.126240.7.5.1276
177240.7.5.128/29240.7.5.129 to 240.7.5.134240.7.5.1356
178240.7.5.136/29240.7.5.137 to 240.7.5.142240.7.5.1436
179240.7.5.144/29240.7.5.145 to 240.7.5.150240.7.5.1516
180240.7.5.152/29240.7.5.153 to 240.7.5.158240.7.5.1596
181240.7.5.160/29240.7.5.161 to 240.7.5.166240.7.5.1676
182240.7.5.168/29240.7.5.169 to 240.7.5.174240.7.5.1756
183240.7.5.176/29240.7.5.177 to 240.7.5.182240.7.5.1836
184240.7.5.184/29240.7.5.185 to 240.7.5.190240.7.5.1916
185240.7.5.192/29240.7.5.193 to 240.7.5.198240.7.5.1996
186240.7.5.200/29240.7.5.201 to 240.7.5.206240.7.5.2076
187240.7.5.208/29240.7.5.209 to 240.7.5.214240.7.5.2156
188240.7.5.216/29240.7.5.217 to 240.7.5.222240.7.5.2236
189240.7.5.224/29240.7.5.225 to 240.7.5.230240.7.5.2316
190240.7.5.232/29240.7.5.233 to 240.7.5.238240.7.5.2396
191240.7.5.240/29240.7.5.241 to 240.7.5.246240.7.5.2476
192240.7.5.248/29240.7.5.249 to 240.7.5.254240.7.5.2556
193240.7.6.0/29240.7.6.1 to 240.7.6.6240.7.6.76
194240.7.6.8/29240.7.6.9 to 240.7.6.14240.7.6.156
195240.7.6.16/29240.7.6.17 to 240.7.6.22240.7.6.236
196240.7.6.24/29240.7.6.25 to 240.7.6.30240.7.6.316
197240.7.6.32/29240.7.6.33 to 240.7.6.38240.7.6.396
198240.7.6.40/29240.7.6.41 to 240.7.6.46240.7.6.476
199240.7.6.48/29240.7.6.49 to 240.7.6.54240.7.6.556
200240.7.6.56/29240.7.6.57 to 240.7.6.62240.7.6.636
201240.7.6.64/29240.7.6.65 to 240.7.6.70240.7.6.716
202240.7.6.72/29240.7.6.73 to 240.7.6.78240.7.6.796
203240.7.6.80/29240.7.6.81 to 240.7.6.86240.7.6.876
204240.7.6.88/29240.7.6.89 to 240.7.6.94240.7.6.956
205240.7.6.96/29240.7.6.97 to 240.7.6.102240.7.6.1036
206240.7.6.104/29240.7.6.105 to 240.7.6.110240.7.6.1116
207240.7.6.112/29240.7.6.113 to 240.7.6.118240.7.6.1196
208240.7.6.120/29240.7.6.121 to 240.7.6.126240.7.6.1276
209240.7.6.128/29240.7.6.129 to 240.7.6.134240.7.6.1356
210240.7.6.136/29240.7.6.137 to 240.7.6.142240.7.6.1436
211240.7.6.144/29240.7.6.145 to 240.7.6.150240.7.6.1516
212240.7.6.152/29240.7.6.153 to 240.7.6.158240.7.6.1596
213240.7.6.160/29240.7.6.161 to 240.7.6.166240.7.6.1676
214240.7.6.168/29240.7.6.169 to 240.7.6.174240.7.6.1756
215240.7.6.176/29240.7.6.177 to 240.7.6.182240.7.6.1836
216240.7.6.184/29240.7.6.185 to 240.7.6.190240.7.6.1916
217240.7.6.192/29240.7.6.193 to 240.7.6.198240.7.6.1996
218240.7.6.200/29240.7.6.201 to 240.7.6.206240.7.6.2076
219240.7.6.208/29240.7.6.209 to 240.7.6.214240.7.6.2156
220240.7.6.216/29240.7.6.217 to 240.7.6.222240.7.6.2236
221240.7.6.224/29240.7.6.225 to 240.7.6.230240.7.6.2316
222240.7.6.232/29240.7.6.233 to 240.7.6.238240.7.6.2396
223240.7.6.240/29240.7.6.241 to 240.7.6.246240.7.6.2476
224240.7.6.248/29240.7.6.249 to 240.7.6.254240.7.6.2556
225240.7.7.0/29240.7.7.1 to 240.7.7.6240.7.7.76
226240.7.7.8/29240.7.7.9 to 240.7.7.14240.7.7.156
227240.7.7.16/29240.7.7.17 to 240.7.7.22240.7.7.236
228240.7.7.24/29240.7.7.25 to 240.7.7.30240.7.7.316
229240.7.7.32/29240.7.7.33 to 240.7.7.38240.7.7.396
230240.7.7.40/29240.7.7.41 to 240.7.7.46240.7.7.476
231240.7.7.48/29240.7.7.49 to 240.7.7.54240.7.7.556
232240.7.7.56/29240.7.7.57 to 240.7.7.62240.7.7.636
233240.7.7.64/29240.7.7.65 to 240.7.7.70240.7.7.716
234240.7.7.72/29240.7.7.73 to 240.7.7.78240.7.7.796
235240.7.7.80/29240.7.7.81 to 240.7.7.86240.7.7.876
236240.7.7.88/29240.7.7.89 to 240.7.7.94240.7.7.956
237240.7.7.96/29240.7.7.97 to 240.7.7.102240.7.7.1036
238240.7.7.104/29240.7.7.105 to 240.7.7.110240.7.7.1116
239240.7.7.112/29240.7.7.113 to 240.7.7.118240.7.7.1196
240240.7.7.120/29240.7.7.121 to 240.7.7.126240.7.7.1276
241240.7.7.128/29240.7.7.129 to 240.7.7.134240.7.7.1356
242240.7.7.136/29240.7.7.137 to 240.7.7.142240.7.7.1436
243240.7.7.144/29240.7.7.145 to 240.7.7.150240.7.7.1516
244240.7.7.152/29240.7.7.153 to 240.7.7.158240.7.7.1596
245240.7.7.160/29240.7.7.161 to 240.7.7.166240.7.7.1676
246240.7.7.168/29240.7.7.169 to 240.7.7.174240.7.7.1756
247240.7.7.176/29240.7.7.177 to 240.7.7.182240.7.7.1836
248240.7.7.184/29240.7.7.185 to 240.7.7.190240.7.7.1916
249240.7.7.192/29240.7.7.193 to 240.7.7.198240.7.7.1996
250240.7.7.200/29240.7.7.201 to 240.7.7.206240.7.7.2076
251240.7.7.208/29240.7.7.209 to 240.7.7.214240.7.7.2156
252240.7.7.216/29240.7.7.217 to 240.7.7.222240.7.7.2236
253240.7.7.224/29240.7.7.225 to 240.7.7.230240.7.7.2316
254240.7.7.232/29240.7.7.233 to 240.7.7.238240.7.7.2396
255240.7.7.240/29240.7.7.241 to 240.7.7.246240.7.7.2476
256240.7.7.248/29240.7.7.249 to 240.7.7.254240.7.7.2556

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.