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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.

Network240.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
240.0.0.0
Broadcast address
240.63.255.255
First usable
240.0.0.1
Last usable
240.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F0000000 · Integer 4026531840 to 4030726143
Reverse DNS zones
0.240.in-addr.arpa
1.240.in-addr.arpa
2.240.in-addr.arpa
3.240.in-addr.arpa
4.240.in-addr.arpa
5.240.in-addr.arpa
6.240.in-addr.arpa
7.240.in-addr.arpa
8.240.in-addr.arpa
9.240.in-addr.arpa
10.240.in-addr.arpa
11.240.in-addr.arpa
12.240.in-addr.arpa
13.240.in-addr.arpa
14.240.in-addr.arpa
15.240.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110000.00000000.00000000.00000000240.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110000.00000000.00000000.00000000240.0.0.0
Broadcast11110000.00111111.11111111.11111111240.63.255.255
Split into smaller subnets/18
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

240.0.0.0/10 makes 256 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.0.0.0/18240.0.0.1 to 240.0.63.254240.0.63.25516,382
2240.0.64.0/18240.0.64.1 to 240.0.127.254240.0.127.25516,382
3240.0.128.0/18240.0.128.1 to 240.0.191.254240.0.191.25516,382
4240.0.192.0/18240.0.192.1 to 240.0.255.254240.0.255.25516,382
5240.1.0.0/18240.1.0.1 to 240.1.63.254240.1.63.25516,382
6240.1.64.0/18240.1.64.1 to 240.1.127.254240.1.127.25516,382
7240.1.128.0/18240.1.128.1 to 240.1.191.254240.1.191.25516,382
8240.1.192.0/18240.1.192.1 to 240.1.255.254240.1.255.25516,382
9240.2.0.0/18240.2.0.1 to 240.2.63.254240.2.63.25516,382
10240.2.64.0/18240.2.64.1 to 240.2.127.254240.2.127.25516,382
11240.2.128.0/18240.2.128.1 to 240.2.191.254240.2.191.25516,382
12240.2.192.0/18240.2.192.1 to 240.2.255.254240.2.255.25516,382
13240.3.0.0/18240.3.0.1 to 240.3.63.254240.3.63.25516,382
14240.3.64.0/18240.3.64.1 to 240.3.127.254240.3.127.25516,382
15240.3.128.0/18240.3.128.1 to 240.3.191.254240.3.191.25516,382
16240.3.192.0/18240.3.192.1 to 240.3.255.254240.3.255.25516,382
17240.4.0.0/18240.4.0.1 to 240.4.63.254240.4.63.25516,382
18240.4.64.0/18240.4.64.1 to 240.4.127.254240.4.127.25516,382
19240.4.128.0/18240.4.128.1 to 240.4.191.254240.4.191.25516,382
20240.4.192.0/18240.4.192.1 to 240.4.255.254240.4.255.25516,382
21240.5.0.0/18240.5.0.1 to 240.5.63.254240.5.63.25516,382
22240.5.64.0/18240.5.64.1 to 240.5.127.254240.5.127.25516,382
23240.5.128.0/18240.5.128.1 to 240.5.191.254240.5.191.25516,382
24240.5.192.0/18240.5.192.1 to 240.5.255.254240.5.255.25516,382
25240.6.0.0/18240.6.0.1 to 240.6.63.254240.6.63.25516,382
26240.6.64.0/18240.6.64.1 to 240.6.127.254240.6.127.25516,382
27240.6.128.0/18240.6.128.1 to 240.6.191.254240.6.191.25516,382
28240.6.192.0/18240.6.192.1 to 240.6.255.254240.6.255.25516,382
29240.7.0.0/18240.7.0.1 to 240.7.63.254240.7.63.25516,382
30240.7.64.0/18240.7.64.1 to 240.7.127.254240.7.127.25516,382
31240.7.128.0/18240.7.128.1 to 240.7.191.254240.7.191.25516,382
32240.7.192.0/18240.7.192.1 to 240.7.255.254240.7.255.25516,382
33240.8.0.0/18240.8.0.1 to 240.8.63.254240.8.63.25516,382
34240.8.64.0/18240.8.64.1 to 240.8.127.254240.8.127.25516,382
35240.8.128.0/18240.8.128.1 to 240.8.191.254240.8.191.25516,382
36240.8.192.0/18240.8.192.1 to 240.8.255.254240.8.255.25516,382
37240.9.0.0/18240.9.0.1 to 240.9.63.254240.9.63.25516,382
38240.9.64.0/18240.9.64.1 to 240.9.127.254240.9.127.25516,382
39240.9.128.0/18240.9.128.1 to 240.9.191.254240.9.191.25516,382
40240.9.192.0/18240.9.192.1 to 240.9.255.254240.9.255.25516,382
41240.10.0.0/18240.10.0.1 to 240.10.63.254240.10.63.25516,382
42240.10.64.0/18240.10.64.1 to 240.10.127.254240.10.127.25516,382
43240.10.128.0/18240.10.128.1 to 240.10.191.254240.10.191.25516,382
44240.10.192.0/18240.10.192.1 to 240.10.255.254240.10.255.25516,382
45240.11.0.0/18240.11.0.1 to 240.11.63.254240.11.63.25516,382
46240.11.64.0/18240.11.64.1 to 240.11.127.254240.11.127.25516,382
47240.11.128.0/18240.11.128.1 to 240.11.191.254240.11.191.25516,382
48240.11.192.0/18240.11.192.1 to 240.11.255.254240.11.255.25516,382
49240.12.0.0/18240.12.0.1 to 240.12.63.254240.12.63.25516,382
50240.12.64.0/18240.12.64.1 to 240.12.127.254240.12.127.25516,382
51240.12.128.0/18240.12.128.1 to 240.12.191.254240.12.191.25516,382
52240.12.192.0/18240.12.192.1 to 240.12.255.254240.12.255.25516,382
53240.13.0.0/18240.13.0.1 to 240.13.63.254240.13.63.25516,382
54240.13.64.0/18240.13.64.1 to 240.13.127.254240.13.127.25516,382
55240.13.128.0/18240.13.128.1 to 240.13.191.254240.13.191.25516,382
56240.13.192.0/18240.13.192.1 to 240.13.255.254240.13.255.25516,382
57240.14.0.0/18240.14.0.1 to 240.14.63.254240.14.63.25516,382
58240.14.64.0/18240.14.64.1 to 240.14.127.254240.14.127.25516,382
59240.14.128.0/18240.14.128.1 to 240.14.191.254240.14.191.25516,382
60240.14.192.0/18240.14.192.1 to 240.14.255.254240.14.255.25516,382
61240.15.0.0/18240.15.0.1 to 240.15.63.254240.15.63.25516,382
62240.15.64.0/18240.15.64.1 to 240.15.127.254240.15.127.25516,382
63240.15.128.0/18240.15.128.1 to 240.15.191.254240.15.191.25516,382
64240.15.192.0/18240.15.192.1 to 240.15.255.254240.15.255.25516,382
65240.16.0.0/18240.16.0.1 to 240.16.63.254240.16.63.25516,382
66240.16.64.0/18240.16.64.1 to 240.16.127.254240.16.127.25516,382
67240.16.128.0/18240.16.128.1 to 240.16.191.254240.16.191.25516,382
68240.16.192.0/18240.16.192.1 to 240.16.255.254240.16.255.25516,382
69240.17.0.0/18240.17.0.1 to 240.17.63.254240.17.63.25516,382
70240.17.64.0/18240.17.64.1 to 240.17.127.254240.17.127.25516,382
71240.17.128.0/18240.17.128.1 to 240.17.191.254240.17.191.25516,382
72240.17.192.0/18240.17.192.1 to 240.17.255.254240.17.255.25516,382
73240.18.0.0/18240.18.0.1 to 240.18.63.254240.18.63.25516,382
74240.18.64.0/18240.18.64.1 to 240.18.127.254240.18.127.25516,382
75240.18.128.0/18240.18.128.1 to 240.18.191.254240.18.191.25516,382
76240.18.192.0/18240.18.192.1 to 240.18.255.254240.18.255.25516,382
77240.19.0.0/18240.19.0.1 to 240.19.63.254240.19.63.25516,382
78240.19.64.0/18240.19.64.1 to 240.19.127.254240.19.127.25516,382
79240.19.128.0/18240.19.128.1 to 240.19.191.254240.19.191.25516,382
80240.19.192.0/18240.19.192.1 to 240.19.255.254240.19.255.25516,382
81240.20.0.0/18240.20.0.1 to 240.20.63.254240.20.63.25516,382
82240.20.64.0/18240.20.64.1 to 240.20.127.254240.20.127.25516,382
83240.20.128.0/18240.20.128.1 to 240.20.191.254240.20.191.25516,382
84240.20.192.0/18240.20.192.1 to 240.20.255.254240.20.255.25516,382
85240.21.0.0/18240.21.0.1 to 240.21.63.254240.21.63.25516,382
86240.21.64.0/18240.21.64.1 to 240.21.127.254240.21.127.25516,382
87240.21.128.0/18240.21.128.1 to 240.21.191.254240.21.191.25516,382
88240.21.192.0/18240.21.192.1 to 240.21.255.254240.21.255.25516,382
89240.22.0.0/18240.22.0.1 to 240.22.63.254240.22.63.25516,382
90240.22.64.0/18240.22.64.1 to 240.22.127.254240.22.127.25516,382
91240.22.128.0/18240.22.128.1 to 240.22.191.254240.22.191.25516,382
92240.22.192.0/18240.22.192.1 to 240.22.255.254240.22.255.25516,382
93240.23.0.0/18240.23.0.1 to 240.23.63.254240.23.63.25516,382
94240.23.64.0/18240.23.64.1 to 240.23.127.254240.23.127.25516,382
95240.23.128.0/18240.23.128.1 to 240.23.191.254240.23.191.25516,382
96240.23.192.0/18240.23.192.1 to 240.23.255.254240.23.255.25516,382
97240.24.0.0/18240.24.0.1 to 240.24.63.254240.24.63.25516,382
98240.24.64.0/18240.24.64.1 to 240.24.127.254240.24.127.25516,382
99240.24.128.0/18240.24.128.1 to 240.24.191.254240.24.191.25516,382
100240.24.192.0/18240.24.192.1 to 240.24.255.254240.24.255.25516,382
101240.25.0.0/18240.25.0.1 to 240.25.63.254240.25.63.25516,382
102240.25.64.0/18240.25.64.1 to 240.25.127.254240.25.127.25516,382
103240.25.128.0/18240.25.128.1 to 240.25.191.254240.25.191.25516,382
104240.25.192.0/18240.25.192.1 to 240.25.255.254240.25.255.25516,382
105240.26.0.0/18240.26.0.1 to 240.26.63.254240.26.63.25516,382
106240.26.64.0/18240.26.64.1 to 240.26.127.254240.26.127.25516,382
107240.26.128.0/18240.26.128.1 to 240.26.191.254240.26.191.25516,382
108240.26.192.0/18240.26.192.1 to 240.26.255.254240.26.255.25516,382
109240.27.0.0/18240.27.0.1 to 240.27.63.254240.27.63.25516,382
110240.27.64.0/18240.27.64.1 to 240.27.127.254240.27.127.25516,382
111240.27.128.0/18240.27.128.1 to 240.27.191.254240.27.191.25516,382
112240.27.192.0/18240.27.192.1 to 240.27.255.254240.27.255.25516,382
113240.28.0.0/18240.28.0.1 to 240.28.63.254240.28.63.25516,382
114240.28.64.0/18240.28.64.1 to 240.28.127.254240.28.127.25516,382
115240.28.128.0/18240.28.128.1 to 240.28.191.254240.28.191.25516,382
116240.28.192.0/18240.28.192.1 to 240.28.255.254240.28.255.25516,382
117240.29.0.0/18240.29.0.1 to 240.29.63.254240.29.63.25516,382
118240.29.64.0/18240.29.64.1 to 240.29.127.254240.29.127.25516,382
119240.29.128.0/18240.29.128.1 to 240.29.191.254240.29.191.25516,382
120240.29.192.0/18240.29.192.1 to 240.29.255.254240.29.255.25516,382
121240.30.0.0/18240.30.0.1 to 240.30.63.254240.30.63.25516,382
122240.30.64.0/18240.30.64.1 to 240.30.127.254240.30.127.25516,382
123240.30.128.0/18240.30.128.1 to 240.30.191.254240.30.191.25516,382
124240.30.192.0/18240.30.192.1 to 240.30.255.254240.30.255.25516,382
125240.31.0.0/18240.31.0.1 to 240.31.63.254240.31.63.25516,382
126240.31.64.0/18240.31.64.1 to 240.31.127.254240.31.127.25516,382
127240.31.128.0/18240.31.128.1 to 240.31.191.254240.31.191.25516,382
128240.31.192.0/18240.31.192.1 to 240.31.255.254240.31.255.25516,382
129240.32.0.0/18240.32.0.1 to 240.32.63.254240.32.63.25516,382
130240.32.64.0/18240.32.64.1 to 240.32.127.254240.32.127.25516,382
131240.32.128.0/18240.32.128.1 to 240.32.191.254240.32.191.25516,382
132240.32.192.0/18240.32.192.1 to 240.32.255.254240.32.255.25516,382
133240.33.0.0/18240.33.0.1 to 240.33.63.254240.33.63.25516,382
134240.33.64.0/18240.33.64.1 to 240.33.127.254240.33.127.25516,382
135240.33.128.0/18240.33.128.1 to 240.33.191.254240.33.191.25516,382
136240.33.192.0/18240.33.192.1 to 240.33.255.254240.33.255.25516,382
137240.34.0.0/18240.34.0.1 to 240.34.63.254240.34.63.25516,382
138240.34.64.0/18240.34.64.1 to 240.34.127.254240.34.127.25516,382
139240.34.128.0/18240.34.128.1 to 240.34.191.254240.34.191.25516,382
140240.34.192.0/18240.34.192.1 to 240.34.255.254240.34.255.25516,382
141240.35.0.0/18240.35.0.1 to 240.35.63.254240.35.63.25516,382
142240.35.64.0/18240.35.64.1 to 240.35.127.254240.35.127.25516,382
143240.35.128.0/18240.35.128.1 to 240.35.191.254240.35.191.25516,382
144240.35.192.0/18240.35.192.1 to 240.35.255.254240.35.255.25516,382
145240.36.0.0/18240.36.0.1 to 240.36.63.254240.36.63.25516,382
146240.36.64.0/18240.36.64.1 to 240.36.127.254240.36.127.25516,382
147240.36.128.0/18240.36.128.1 to 240.36.191.254240.36.191.25516,382
148240.36.192.0/18240.36.192.1 to 240.36.255.254240.36.255.25516,382
149240.37.0.0/18240.37.0.1 to 240.37.63.254240.37.63.25516,382
150240.37.64.0/18240.37.64.1 to 240.37.127.254240.37.127.25516,382
151240.37.128.0/18240.37.128.1 to 240.37.191.254240.37.191.25516,382
152240.37.192.0/18240.37.192.1 to 240.37.255.254240.37.255.25516,382
153240.38.0.0/18240.38.0.1 to 240.38.63.254240.38.63.25516,382
154240.38.64.0/18240.38.64.1 to 240.38.127.254240.38.127.25516,382
155240.38.128.0/18240.38.128.1 to 240.38.191.254240.38.191.25516,382
156240.38.192.0/18240.38.192.1 to 240.38.255.254240.38.255.25516,382
157240.39.0.0/18240.39.0.1 to 240.39.63.254240.39.63.25516,382
158240.39.64.0/18240.39.64.1 to 240.39.127.254240.39.127.25516,382
159240.39.128.0/18240.39.128.1 to 240.39.191.254240.39.191.25516,382
160240.39.192.0/18240.39.192.1 to 240.39.255.254240.39.255.25516,382
161240.40.0.0/18240.40.0.1 to 240.40.63.254240.40.63.25516,382
162240.40.64.0/18240.40.64.1 to 240.40.127.254240.40.127.25516,382
163240.40.128.0/18240.40.128.1 to 240.40.191.254240.40.191.25516,382
164240.40.192.0/18240.40.192.1 to 240.40.255.254240.40.255.25516,382
165240.41.0.0/18240.41.0.1 to 240.41.63.254240.41.63.25516,382
166240.41.64.0/18240.41.64.1 to 240.41.127.254240.41.127.25516,382
167240.41.128.0/18240.41.128.1 to 240.41.191.254240.41.191.25516,382
168240.41.192.0/18240.41.192.1 to 240.41.255.254240.41.255.25516,382
169240.42.0.0/18240.42.0.1 to 240.42.63.254240.42.63.25516,382
170240.42.64.0/18240.42.64.1 to 240.42.127.254240.42.127.25516,382
171240.42.128.0/18240.42.128.1 to 240.42.191.254240.42.191.25516,382
172240.42.192.0/18240.42.192.1 to 240.42.255.254240.42.255.25516,382
173240.43.0.0/18240.43.0.1 to 240.43.63.254240.43.63.25516,382
174240.43.64.0/18240.43.64.1 to 240.43.127.254240.43.127.25516,382
175240.43.128.0/18240.43.128.1 to 240.43.191.254240.43.191.25516,382
176240.43.192.0/18240.43.192.1 to 240.43.255.254240.43.255.25516,382
177240.44.0.0/18240.44.0.1 to 240.44.63.254240.44.63.25516,382
178240.44.64.0/18240.44.64.1 to 240.44.127.254240.44.127.25516,382
179240.44.128.0/18240.44.128.1 to 240.44.191.254240.44.191.25516,382
180240.44.192.0/18240.44.192.1 to 240.44.255.254240.44.255.25516,382
181240.45.0.0/18240.45.0.1 to 240.45.63.254240.45.63.25516,382
182240.45.64.0/18240.45.64.1 to 240.45.127.254240.45.127.25516,382
183240.45.128.0/18240.45.128.1 to 240.45.191.254240.45.191.25516,382
184240.45.192.0/18240.45.192.1 to 240.45.255.254240.45.255.25516,382
185240.46.0.0/18240.46.0.1 to 240.46.63.254240.46.63.25516,382
186240.46.64.0/18240.46.64.1 to 240.46.127.254240.46.127.25516,382
187240.46.128.0/18240.46.128.1 to 240.46.191.254240.46.191.25516,382
188240.46.192.0/18240.46.192.1 to 240.46.255.254240.46.255.25516,382
189240.47.0.0/18240.47.0.1 to 240.47.63.254240.47.63.25516,382
190240.47.64.0/18240.47.64.1 to 240.47.127.254240.47.127.25516,382
191240.47.128.0/18240.47.128.1 to 240.47.191.254240.47.191.25516,382
192240.47.192.0/18240.47.192.1 to 240.47.255.254240.47.255.25516,382
193240.48.0.0/18240.48.0.1 to 240.48.63.254240.48.63.25516,382
194240.48.64.0/18240.48.64.1 to 240.48.127.254240.48.127.25516,382
195240.48.128.0/18240.48.128.1 to 240.48.191.254240.48.191.25516,382
196240.48.192.0/18240.48.192.1 to 240.48.255.254240.48.255.25516,382
197240.49.0.0/18240.49.0.1 to 240.49.63.254240.49.63.25516,382
198240.49.64.0/18240.49.64.1 to 240.49.127.254240.49.127.25516,382
199240.49.128.0/18240.49.128.1 to 240.49.191.254240.49.191.25516,382
200240.49.192.0/18240.49.192.1 to 240.49.255.254240.49.255.25516,382
201240.50.0.0/18240.50.0.1 to 240.50.63.254240.50.63.25516,382
202240.50.64.0/18240.50.64.1 to 240.50.127.254240.50.127.25516,382
203240.50.128.0/18240.50.128.1 to 240.50.191.254240.50.191.25516,382
204240.50.192.0/18240.50.192.1 to 240.50.255.254240.50.255.25516,382
205240.51.0.0/18240.51.0.1 to 240.51.63.254240.51.63.25516,382
206240.51.64.0/18240.51.64.1 to 240.51.127.254240.51.127.25516,382
207240.51.128.0/18240.51.128.1 to 240.51.191.254240.51.191.25516,382
208240.51.192.0/18240.51.192.1 to 240.51.255.254240.51.255.25516,382
209240.52.0.0/18240.52.0.1 to 240.52.63.254240.52.63.25516,382
210240.52.64.0/18240.52.64.1 to 240.52.127.254240.52.127.25516,382
211240.52.128.0/18240.52.128.1 to 240.52.191.254240.52.191.25516,382
212240.52.192.0/18240.52.192.1 to 240.52.255.254240.52.255.25516,382
213240.53.0.0/18240.53.0.1 to 240.53.63.254240.53.63.25516,382
214240.53.64.0/18240.53.64.1 to 240.53.127.254240.53.127.25516,382
215240.53.128.0/18240.53.128.1 to 240.53.191.254240.53.191.25516,382
216240.53.192.0/18240.53.192.1 to 240.53.255.254240.53.255.25516,382
217240.54.0.0/18240.54.0.1 to 240.54.63.254240.54.63.25516,382
218240.54.64.0/18240.54.64.1 to 240.54.127.254240.54.127.25516,382
219240.54.128.0/18240.54.128.1 to 240.54.191.254240.54.191.25516,382
220240.54.192.0/18240.54.192.1 to 240.54.255.254240.54.255.25516,382
221240.55.0.0/18240.55.0.1 to 240.55.63.254240.55.63.25516,382
222240.55.64.0/18240.55.64.1 to 240.55.127.254240.55.127.25516,382
223240.55.128.0/18240.55.128.1 to 240.55.191.254240.55.191.25516,382
224240.55.192.0/18240.55.192.1 to 240.55.255.254240.55.255.25516,382
225240.56.0.0/18240.56.0.1 to 240.56.63.254240.56.63.25516,382
226240.56.64.0/18240.56.64.1 to 240.56.127.254240.56.127.25516,382
227240.56.128.0/18240.56.128.1 to 240.56.191.254240.56.191.25516,382
228240.56.192.0/18240.56.192.1 to 240.56.255.254240.56.255.25516,382
229240.57.0.0/18240.57.0.1 to 240.57.63.254240.57.63.25516,382
230240.57.64.0/18240.57.64.1 to 240.57.127.254240.57.127.25516,382
231240.57.128.0/18240.57.128.1 to 240.57.191.254240.57.191.25516,382
232240.57.192.0/18240.57.192.1 to 240.57.255.254240.57.255.25516,382
233240.58.0.0/18240.58.0.1 to 240.58.63.254240.58.63.25516,382
234240.58.64.0/18240.58.64.1 to 240.58.127.254240.58.127.25516,382
235240.58.128.0/18240.58.128.1 to 240.58.191.254240.58.191.25516,382
236240.58.192.0/18240.58.192.1 to 240.58.255.254240.58.255.25516,382
237240.59.0.0/18240.59.0.1 to 240.59.63.254240.59.63.25516,382
238240.59.64.0/18240.59.64.1 to 240.59.127.254240.59.127.25516,382
239240.59.128.0/18240.59.128.1 to 240.59.191.254240.59.191.25516,382
240240.59.192.0/18240.59.192.1 to 240.59.255.254240.59.255.25516,382
241240.60.0.0/18240.60.0.1 to 240.60.63.254240.60.63.25516,382
242240.60.64.0/18240.60.64.1 to 240.60.127.254240.60.127.25516,382
243240.60.128.0/18240.60.128.1 to 240.60.191.254240.60.191.25516,382
244240.60.192.0/18240.60.192.1 to 240.60.255.254240.60.255.25516,382
245240.61.0.0/18240.61.0.1 to 240.61.63.254240.61.63.25516,382
246240.61.64.0/18240.61.64.1 to 240.61.127.254240.61.127.25516,382
247240.61.128.0/18240.61.128.1 to 240.61.191.254240.61.191.25516,382
248240.61.192.0/18240.61.192.1 to 240.61.255.254240.61.255.25516,382
249240.62.0.0/18240.62.0.1 to 240.62.63.254240.62.63.25516,382
250240.62.64.0/18240.62.64.1 to 240.62.127.254240.62.127.25516,382
251240.62.128.0/18240.62.128.1 to 240.62.191.254240.62.191.25516,382
252240.62.192.0/18240.62.192.1 to 240.62.255.254240.62.255.25516,382
253240.63.0.0/18240.63.0.1 to 240.63.63.254240.63.63.25516,382
254240.63.64.0/18240.63.64.1 to 240.63.127.254240.63.127.25516,382
255240.63.128.0/18240.63.128.1 to 240.63.191.254240.63.191.25516,382
256240.63.192.0/18240.63.192.1 to 240.63.255.254240.63.255.25516,382

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.