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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.

Network218.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
218.0.0.0
Broadcast address
218.127.255.255
First usable
218.0.0.1
Last usable
218.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
C (default /24)
As numbers
Hex DA000000 · Integer 3657433088 to 3665821695
Reverse DNS zones
0.218.in-addr.arpa
1.218.in-addr.arpa
2.218.in-addr.arpa
3.218.in-addr.arpa
4.218.in-addr.arpa
5.218.in-addr.arpa
6.218.in-addr.arpa
7.218.in-addr.arpa
8.218.in-addr.arpa
9.218.in-addr.arpa
10.218.in-addr.arpa
11.218.in-addr.arpa
12.218.in-addr.arpa
13.218.in-addr.arpa
14.218.in-addr.arpa
15.218.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011010.00000000.00000000.00000000218.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11011010.00000000.00000000.00000000218.0.0.0
Broadcast11011010.01111111.11111111.11111111218.127.255.255
Split into smaller subnets/18
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

218.0.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1218.0.0.0/18218.0.0.1 to 218.0.63.254218.0.63.25516,382
2218.0.64.0/18218.0.64.1 to 218.0.127.254218.0.127.25516,382
3218.0.128.0/18218.0.128.1 to 218.0.191.254218.0.191.25516,382
4218.0.192.0/18218.0.192.1 to 218.0.255.254218.0.255.25516,382
5218.1.0.0/18218.1.0.1 to 218.1.63.254218.1.63.25516,382
6218.1.64.0/18218.1.64.1 to 218.1.127.254218.1.127.25516,382
7218.1.128.0/18218.1.128.1 to 218.1.191.254218.1.191.25516,382
8218.1.192.0/18218.1.192.1 to 218.1.255.254218.1.255.25516,382
9218.2.0.0/18218.2.0.1 to 218.2.63.254218.2.63.25516,382
10218.2.64.0/18218.2.64.1 to 218.2.127.254218.2.127.25516,382
11218.2.128.0/18218.2.128.1 to 218.2.191.254218.2.191.25516,382
12218.2.192.0/18218.2.192.1 to 218.2.255.254218.2.255.25516,382
13218.3.0.0/18218.3.0.1 to 218.3.63.254218.3.63.25516,382
14218.3.64.0/18218.3.64.1 to 218.3.127.254218.3.127.25516,382
15218.3.128.0/18218.3.128.1 to 218.3.191.254218.3.191.25516,382
16218.3.192.0/18218.3.192.1 to 218.3.255.254218.3.255.25516,382
17218.4.0.0/18218.4.0.1 to 218.4.63.254218.4.63.25516,382
18218.4.64.0/18218.4.64.1 to 218.4.127.254218.4.127.25516,382
19218.4.128.0/18218.4.128.1 to 218.4.191.254218.4.191.25516,382
20218.4.192.0/18218.4.192.1 to 218.4.255.254218.4.255.25516,382
21218.5.0.0/18218.5.0.1 to 218.5.63.254218.5.63.25516,382
22218.5.64.0/18218.5.64.1 to 218.5.127.254218.5.127.25516,382
23218.5.128.0/18218.5.128.1 to 218.5.191.254218.5.191.25516,382
24218.5.192.0/18218.5.192.1 to 218.5.255.254218.5.255.25516,382
25218.6.0.0/18218.6.0.1 to 218.6.63.254218.6.63.25516,382
26218.6.64.0/18218.6.64.1 to 218.6.127.254218.6.127.25516,382
27218.6.128.0/18218.6.128.1 to 218.6.191.254218.6.191.25516,382
28218.6.192.0/18218.6.192.1 to 218.6.255.254218.6.255.25516,382
29218.7.0.0/18218.7.0.1 to 218.7.63.254218.7.63.25516,382
30218.7.64.0/18218.7.64.1 to 218.7.127.254218.7.127.25516,382
31218.7.128.0/18218.7.128.1 to 218.7.191.254218.7.191.25516,382
32218.7.192.0/18218.7.192.1 to 218.7.255.254218.7.255.25516,382
33218.8.0.0/18218.8.0.1 to 218.8.63.254218.8.63.25516,382
34218.8.64.0/18218.8.64.1 to 218.8.127.254218.8.127.25516,382
35218.8.128.0/18218.8.128.1 to 218.8.191.254218.8.191.25516,382
36218.8.192.0/18218.8.192.1 to 218.8.255.254218.8.255.25516,382
37218.9.0.0/18218.9.0.1 to 218.9.63.254218.9.63.25516,382
38218.9.64.0/18218.9.64.1 to 218.9.127.254218.9.127.25516,382
39218.9.128.0/18218.9.128.1 to 218.9.191.254218.9.191.25516,382
40218.9.192.0/18218.9.192.1 to 218.9.255.254218.9.255.25516,382
41218.10.0.0/18218.10.0.1 to 218.10.63.254218.10.63.25516,382
42218.10.64.0/18218.10.64.1 to 218.10.127.254218.10.127.25516,382
43218.10.128.0/18218.10.128.1 to 218.10.191.254218.10.191.25516,382
44218.10.192.0/18218.10.192.1 to 218.10.255.254218.10.255.25516,382
45218.11.0.0/18218.11.0.1 to 218.11.63.254218.11.63.25516,382
46218.11.64.0/18218.11.64.1 to 218.11.127.254218.11.127.25516,382
47218.11.128.0/18218.11.128.1 to 218.11.191.254218.11.191.25516,382
48218.11.192.0/18218.11.192.1 to 218.11.255.254218.11.255.25516,382
49218.12.0.0/18218.12.0.1 to 218.12.63.254218.12.63.25516,382
50218.12.64.0/18218.12.64.1 to 218.12.127.254218.12.127.25516,382
51218.12.128.0/18218.12.128.1 to 218.12.191.254218.12.191.25516,382
52218.12.192.0/18218.12.192.1 to 218.12.255.254218.12.255.25516,382
53218.13.0.0/18218.13.0.1 to 218.13.63.254218.13.63.25516,382
54218.13.64.0/18218.13.64.1 to 218.13.127.254218.13.127.25516,382
55218.13.128.0/18218.13.128.1 to 218.13.191.254218.13.191.25516,382
56218.13.192.0/18218.13.192.1 to 218.13.255.254218.13.255.25516,382
57218.14.0.0/18218.14.0.1 to 218.14.63.254218.14.63.25516,382
58218.14.64.0/18218.14.64.1 to 218.14.127.254218.14.127.25516,382
59218.14.128.0/18218.14.128.1 to 218.14.191.254218.14.191.25516,382
60218.14.192.0/18218.14.192.1 to 218.14.255.254218.14.255.25516,382
61218.15.0.0/18218.15.0.1 to 218.15.63.254218.15.63.25516,382
62218.15.64.0/18218.15.64.1 to 218.15.127.254218.15.127.25516,382
63218.15.128.0/18218.15.128.1 to 218.15.191.254218.15.191.25516,382
64218.15.192.0/18218.15.192.1 to 218.15.255.254218.15.255.25516,382
65218.16.0.0/18218.16.0.1 to 218.16.63.254218.16.63.25516,382
66218.16.64.0/18218.16.64.1 to 218.16.127.254218.16.127.25516,382
67218.16.128.0/18218.16.128.1 to 218.16.191.254218.16.191.25516,382
68218.16.192.0/18218.16.192.1 to 218.16.255.254218.16.255.25516,382
69218.17.0.0/18218.17.0.1 to 218.17.63.254218.17.63.25516,382
70218.17.64.0/18218.17.64.1 to 218.17.127.254218.17.127.25516,382
71218.17.128.0/18218.17.128.1 to 218.17.191.254218.17.191.25516,382
72218.17.192.0/18218.17.192.1 to 218.17.255.254218.17.255.25516,382
73218.18.0.0/18218.18.0.1 to 218.18.63.254218.18.63.25516,382
74218.18.64.0/18218.18.64.1 to 218.18.127.254218.18.127.25516,382
75218.18.128.0/18218.18.128.1 to 218.18.191.254218.18.191.25516,382
76218.18.192.0/18218.18.192.1 to 218.18.255.254218.18.255.25516,382
77218.19.0.0/18218.19.0.1 to 218.19.63.254218.19.63.25516,382
78218.19.64.0/18218.19.64.1 to 218.19.127.254218.19.127.25516,382
79218.19.128.0/18218.19.128.1 to 218.19.191.254218.19.191.25516,382
80218.19.192.0/18218.19.192.1 to 218.19.255.254218.19.255.25516,382
81218.20.0.0/18218.20.0.1 to 218.20.63.254218.20.63.25516,382
82218.20.64.0/18218.20.64.1 to 218.20.127.254218.20.127.25516,382
83218.20.128.0/18218.20.128.1 to 218.20.191.254218.20.191.25516,382
84218.20.192.0/18218.20.192.1 to 218.20.255.254218.20.255.25516,382
85218.21.0.0/18218.21.0.1 to 218.21.63.254218.21.63.25516,382
86218.21.64.0/18218.21.64.1 to 218.21.127.254218.21.127.25516,382
87218.21.128.0/18218.21.128.1 to 218.21.191.254218.21.191.25516,382
88218.21.192.0/18218.21.192.1 to 218.21.255.254218.21.255.25516,382
89218.22.0.0/18218.22.0.1 to 218.22.63.254218.22.63.25516,382
90218.22.64.0/18218.22.64.1 to 218.22.127.254218.22.127.25516,382
91218.22.128.0/18218.22.128.1 to 218.22.191.254218.22.191.25516,382
92218.22.192.0/18218.22.192.1 to 218.22.255.254218.22.255.25516,382
93218.23.0.0/18218.23.0.1 to 218.23.63.254218.23.63.25516,382
94218.23.64.0/18218.23.64.1 to 218.23.127.254218.23.127.25516,382
95218.23.128.0/18218.23.128.1 to 218.23.191.254218.23.191.25516,382
96218.23.192.0/18218.23.192.1 to 218.23.255.254218.23.255.25516,382
97218.24.0.0/18218.24.0.1 to 218.24.63.254218.24.63.25516,382
98218.24.64.0/18218.24.64.1 to 218.24.127.254218.24.127.25516,382
99218.24.128.0/18218.24.128.1 to 218.24.191.254218.24.191.25516,382
100218.24.192.0/18218.24.192.1 to 218.24.255.254218.24.255.25516,382
101218.25.0.0/18218.25.0.1 to 218.25.63.254218.25.63.25516,382
102218.25.64.0/18218.25.64.1 to 218.25.127.254218.25.127.25516,382
103218.25.128.0/18218.25.128.1 to 218.25.191.254218.25.191.25516,382
104218.25.192.0/18218.25.192.1 to 218.25.255.254218.25.255.25516,382
105218.26.0.0/18218.26.0.1 to 218.26.63.254218.26.63.25516,382
106218.26.64.0/18218.26.64.1 to 218.26.127.254218.26.127.25516,382
107218.26.128.0/18218.26.128.1 to 218.26.191.254218.26.191.25516,382
108218.26.192.0/18218.26.192.1 to 218.26.255.254218.26.255.25516,382
109218.27.0.0/18218.27.0.1 to 218.27.63.254218.27.63.25516,382
110218.27.64.0/18218.27.64.1 to 218.27.127.254218.27.127.25516,382
111218.27.128.0/18218.27.128.1 to 218.27.191.254218.27.191.25516,382
112218.27.192.0/18218.27.192.1 to 218.27.255.254218.27.255.25516,382
113218.28.0.0/18218.28.0.1 to 218.28.63.254218.28.63.25516,382
114218.28.64.0/18218.28.64.1 to 218.28.127.254218.28.127.25516,382
115218.28.128.0/18218.28.128.1 to 218.28.191.254218.28.191.25516,382
116218.28.192.0/18218.28.192.1 to 218.28.255.254218.28.255.25516,382
117218.29.0.0/18218.29.0.1 to 218.29.63.254218.29.63.25516,382
118218.29.64.0/18218.29.64.1 to 218.29.127.254218.29.127.25516,382
119218.29.128.0/18218.29.128.1 to 218.29.191.254218.29.191.25516,382
120218.29.192.0/18218.29.192.1 to 218.29.255.254218.29.255.25516,382
121218.30.0.0/18218.30.0.1 to 218.30.63.254218.30.63.25516,382
122218.30.64.0/18218.30.64.1 to 218.30.127.254218.30.127.25516,382
123218.30.128.0/18218.30.128.1 to 218.30.191.254218.30.191.25516,382
124218.30.192.0/18218.30.192.1 to 218.30.255.254218.30.255.25516,382
125218.31.0.0/18218.31.0.1 to 218.31.63.254218.31.63.25516,382
126218.31.64.0/18218.31.64.1 to 218.31.127.254218.31.127.25516,382
127218.31.128.0/18218.31.128.1 to 218.31.191.254218.31.191.25516,382
128218.31.192.0/18218.31.192.1 to 218.31.255.254218.31.255.25516,382
129218.32.0.0/18218.32.0.1 to 218.32.63.254218.32.63.25516,382
130218.32.64.0/18218.32.64.1 to 218.32.127.254218.32.127.25516,382
131218.32.128.0/18218.32.128.1 to 218.32.191.254218.32.191.25516,382
132218.32.192.0/18218.32.192.1 to 218.32.255.254218.32.255.25516,382
133218.33.0.0/18218.33.0.1 to 218.33.63.254218.33.63.25516,382
134218.33.64.0/18218.33.64.1 to 218.33.127.254218.33.127.25516,382
135218.33.128.0/18218.33.128.1 to 218.33.191.254218.33.191.25516,382
136218.33.192.0/18218.33.192.1 to 218.33.255.254218.33.255.25516,382
137218.34.0.0/18218.34.0.1 to 218.34.63.254218.34.63.25516,382
138218.34.64.0/18218.34.64.1 to 218.34.127.254218.34.127.25516,382
139218.34.128.0/18218.34.128.1 to 218.34.191.254218.34.191.25516,382
140218.34.192.0/18218.34.192.1 to 218.34.255.254218.34.255.25516,382
141218.35.0.0/18218.35.0.1 to 218.35.63.254218.35.63.25516,382
142218.35.64.0/18218.35.64.1 to 218.35.127.254218.35.127.25516,382
143218.35.128.0/18218.35.128.1 to 218.35.191.254218.35.191.25516,382
144218.35.192.0/18218.35.192.1 to 218.35.255.254218.35.255.25516,382
145218.36.0.0/18218.36.0.1 to 218.36.63.254218.36.63.25516,382
146218.36.64.0/18218.36.64.1 to 218.36.127.254218.36.127.25516,382
147218.36.128.0/18218.36.128.1 to 218.36.191.254218.36.191.25516,382
148218.36.192.0/18218.36.192.1 to 218.36.255.254218.36.255.25516,382
149218.37.0.0/18218.37.0.1 to 218.37.63.254218.37.63.25516,382
150218.37.64.0/18218.37.64.1 to 218.37.127.254218.37.127.25516,382
151218.37.128.0/18218.37.128.1 to 218.37.191.254218.37.191.25516,382
152218.37.192.0/18218.37.192.1 to 218.37.255.254218.37.255.25516,382
153218.38.0.0/18218.38.0.1 to 218.38.63.254218.38.63.25516,382
154218.38.64.0/18218.38.64.1 to 218.38.127.254218.38.127.25516,382
155218.38.128.0/18218.38.128.1 to 218.38.191.254218.38.191.25516,382
156218.38.192.0/18218.38.192.1 to 218.38.255.254218.38.255.25516,382
157218.39.0.0/18218.39.0.1 to 218.39.63.254218.39.63.25516,382
158218.39.64.0/18218.39.64.1 to 218.39.127.254218.39.127.25516,382
159218.39.128.0/18218.39.128.1 to 218.39.191.254218.39.191.25516,382
160218.39.192.0/18218.39.192.1 to 218.39.255.254218.39.255.25516,382
161218.40.0.0/18218.40.0.1 to 218.40.63.254218.40.63.25516,382
162218.40.64.0/18218.40.64.1 to 218.40.127.254218.40.127.25516,382
163218.40.128.0/18218.40.128.1 to 218.40.191.254218.40.191.25516,382
164218.40.192.0/18218.40.192.1 to 218.40.255.254218.40.255.25516,382
165218.41.0.0/18218.41.0.1 to 218.41.63.254218.41.63.25516,382
166218.41.64.0/18218.41.64.1 to 218.41.127.254218.41.127.25516,382
167218.41.128.0/18218.41.128.1 to 218.41.191.254218.41.191.25516,382
168218.41.192.0/18218.41.192.1 to 218.41.255.254218.41.255.25516,382
169218.42.0.0/18218.42.0.1 to 218.42.63.254218.42.63.25516,382
170218.42.64.0/18218.42.64.1 to 218.42.127.254218.42.127.25516,382
171218.42.128.0/18218.42.128.1 to 218.42.191.254218.42.191.25516,382
172218.42.192.0/18218.42.192.1 to 218.42.255.254218.42.255.25516,382
173218.43.0.0/18218.43.0.1 to 218.43.63.254218.43.63.25516,382
174218.43.64.0/18218.43.64.1 to 218.43.127.254218.43.127.25516,382
175218.43.128.0/18218.43.128.1 to 218.43.191.254218.43.191.25516,382
176218.43.192.0/18218.43.192.1 to 218.43.255.254218.43.255.25516,382
177218.44.0.0/18218.44.0.1 to 218.44.63.254218.44.63.25516,382
178218.44.64.0/18218.44.64.1 to 218.44.127.254218.44.127.25516,382
179218.44.128.0/18218.44.128.1 to 218.44.191.254218.44.191.25516,382
180218.44.192.0/18218.44.192.1 to 218.44.255.254218.44.255.25516,382
181218.45.0.0/18218.45.0.1 to 218.45.63.254218.45.63.25516,382
182218.45.64.0/18218.45.64.1 to 218.45.127.254218.45.127.25516,382
183218.45.128.0/18218.45.128.1 to 218.45.191.254218.45.191.25516,382
184218.45.192.0/18218.45.192.1 to 218.45.255.254218.45.255.25516,382
185218.46.0.0/18218.46.0.1 to 218.46.63.254218.46.63.25516,382
186218.46.64.0/18218.46.64.1 to 218.46.127.254218.46.127.25516,382
187218.46.128.0/18218.46.128.1 to 218.46.191.254218.46.191.25516,382
188218.46.192.0/18218.46.192.1 to 218.46.255.254218.46.255.25516,382
189218.47.0.0/18218.47.0.1 to 218.47.63.254218.47.63.25516,382
190218.47.64.0/18218.47.64.1 to 218.47.127.254218.47.127.25516,382
191218.47.128.0/18218.47.128.1 to 218.47.191.254218.47.191.25516,382
192218.47.192.0/18218.47.192.1 to 218.47.255.254218.47.255.25516,382
193218.48.0.0/18218.48.0.1 to 218.48.63.254218.48.63.25516,382
194218.48.64.0/18218.48.64.1 to 218.48.127.254218.48.127.25516,382
195218.48.128.0/18218.48.128.1 to 218.48.191.254218.48.191.25516,382
196218.48.192.0/18218.48.192.1 to 218.48.255.254218.48.255.25516,382
197218.49.0.0/18218.49.0.1 to 218.49.63.254218.49.63.25516,382
198218.49.64.0/18218.49.64.1 to 218.49.127.254218.49.127.25516,382
199218.49.128.0/18218.49.128.1 to 218.49.191.254218.49.191.25516,382
200218.49.192.0/18218.49.192.1 to 218.49.255.254218.49.255.25516,382
201218.50.0.0/18218.50.0.1 to 218.50.63.254218.50.63.25516,382
202218.50.64.0/18218.50.64.1 to 218.50.127.254218.50.127.25516,382
203218.50.128.0/18218.50.128.1 to 218.50.191.254218.50.191.25516,382
204218.50.192.0/18218.50.192.1 to 218.50.255.254218.50.255.25516,382
205218.51.0.0/18218.51.0.1 to 218.51.63.254218.51.63.25516,382
206218.51.64.0/18218.51.64.1 to 218.51.127.254218.51.127.25516,382
207218.51.128.0/18218.51.128.1 to 218.51.191.254218.51.191.25516,382
208218.51.192.0/18218.51.192.1 to 218.51.255.254218.51.255.25516,382
209218.52.0.0/18218.52.0.1 to 218.52.63.254218.52.63.25516,382
210218.52.64.0/18218.52.64.1 to 218.52.127.254218.52.127.25516,382
211218.52.128.0/18218.52.128.1 to 218.52.191.254218.52.191.25516,382
212218.52.192.0/18218.52.192.1 to 218.52.255.254218.52.255.25516,382
213218.53.0.0/18218.53.0.1 to 218.53.63.254218.53.63.25516,382
214218.53.64.0/18218.53.64.1 to 218.53.127.254218.53.127.25516,382
215218.53.128.0/18218.53.128.1 to 218.53.191.254218.53.191.25516,382
216218.53.192.0/18218.53.192.1 to 218.53.255.254218.53.255.25516,382
217218.54.0.0/18218.54.0.1 to 218.54.63.254218.54.63.25516,382
218218.54.64.0/18218.54.64.1 to 218.54.127.254218.54.127.25516,382
219218.54.128.0/18218.54.128.1 to 218.54.191.254218.54.191.25516,382
220218.54.192.0/18218.54.192.1 to 218.54.255.254218.54.255.25516,382
221218.55.0.0/18218.55.0.1 to 218.55.63.254218.55.63.25516,382
222218.55.64.0/18218.55.64.1 to 218.55.127.254218.55.127.25516,382
223218.55.128.0/18218.55.128.1 to 218.55.191.254218.55.191.25516,382
224218.55.192.0/18218.55.192.1 to 218.55.255.254218.55.255.25516,382
225218.56.0.0/18218.56.0.1 to 218.56.63.254218.56.63.25516,382
226218.56.64.0/18218.56.64.1 to 218.56.127.254218.56.127.25516,382
227218.56.128.0/18218.56.128.1 to 218.56.191.254218.56.191.25516,382
228218.56.192.0/18218.56.192.1 to 218.56.255.254218.56.255.25516,382
229218.57.0.0/18218.57.0.1 to 218.57.63.254218.57.63.25516,382
230218.57.64.0/18218.57.64.1 to 218.57.127.254218.57.127.25516,382
231218.57.128.0/18218.57.128.1 to 218.57.191.254218.57.191.25516,382
232218.57.192.0/18218.57.192.1 to 218.57.255.254218.57.255.25516,382
233218.58.0.0/18218.58.0.1 to 218.58.63.254218.58.63.25516,382
234218.58.64.0/18218.58.64.1 to 218.58.127.254218.58.127.25516,382
235218.58.128.0/18218.58.128.1 to 218.58.191.254218.58.191.25516,382
236218.58.192.0/18218.58.192.1 to 218.58.255.254218.58.255.25516,382
237218.59.0.0/18218.59.0.1 to 218.59.63.254218.59.63.25516,382
238218.59.64.0/18218.59.64.1 to 218.59.127.254218.59.127.25516,382
239218.59.128.0/18218.59.128.1 to 218.59.191.254218.59.191.25516,382
240218.59.192.0/18218.59.192.1 to 218.59.255.254218.59.255.25516,382
241218.60.0.0/18218.60.0.1 to 218.60.63.254218.60.63.25516,382
242218.60.64.0/18218.60.64.1 to 218.60.127.254218.60.127.25516,382
243218.60.128.0/18218.60.128.1 to 218.60.191.254218.60.191.25516,382
244218.60.192.0/18218.60.192.1 to 218.60.255.254218.60.255.25516,382
245218.61.0.0/18218.61.0.1 to 218.61.63.254218.61.63.25516,382
246218.61.64.0/18218.61.64.1 to 218.61.127.254218.61.127.25516,382
247218.61.128.0/18218.61.128.1 to 218.61.191.254218.61.191.25516,382
248218.61.192.0/18218.61.192.1 to 218.61.255.254218.61.255.25516,382
249218.62.0.0/18218.62.0.1 to 218.62.63.254218.62.63.25516,382
250218.62.64.0/18218.62.64.1 to 218.62.127.254218.62.127.25516,382
251218.62.128.0/18218.62.128.1 to 218.62.191.254218.62.191.25516,382
252218.62.192.0/18218.62.192.1 to 218.62.255.254218.62.255.25516,382
253218.63.0.0/18218.63.0.1 to 218.63.63.254218.63.63.25516,382
254218.63.64.0/18218.63.64.1 to 218.63.127.254218.63.127.25516,382
255218.63.128.0/18218.63.128.1 to 218.63.191.254218.63.191.25516,382
256218.63.192.0/18218.63.192.1 to 218.63.255.254218.63.255.25516,382

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.