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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.

Network197.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
197.0.0.0
Broadcast address
197.255.255.255
First usable
197.0.0.1
Last usable
197.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
C (default /24)
As numbers
Hex C5000000 · Integer 3305111552 to 3321888767
Reverse DNS zone
197.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000101..00000000.00000000.00000000197.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11000101..00000000.00000000.00000000197.0.0.0
Broadcast11000101..11111111.11111111.11111111197.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

197.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1197.0.0.0/20197.0.0.1 to 197.0.15.254197.0.15.2554,094
2197.0.16.0/20197.0.16.1 to 197.0.31.254197.0.31.2554,094
3197.0.32.0/20197.0.32.1 to 197.0.47.254197.0.47.2554,094
4197.0.48.0/20197.0.48.1 to 197.0.63.254197.0.63.2554,094
5197.0.64.0/20197.0.64.1 to 197.0.79.254197.0.79.2554,094
6197.0.80.0/20197.0.80.1 to 197.0.95.254197.0.95.2554,094
7197.0.96.0/20197.0.96.1 to 197.0.111.254197.0.111.2554,094
8197.0.112.0/20197.0.112.1 to 197.0.127.254197.0.127.2554,094
9197.0.128.0/20197.0.128.1 to 197.0.143.254197.0.143.2554,094
10197.0.144.0/20197.0.144.1 to 197.0.159.254197.0.159.2554,094
11197.0.160.0/20197.0.160.1 to 197.0.175.254197.0.175.2554,094
12197.0.176.0/20197.0.176.1 to 197.0.191.254197.0.191.2554,094
13197.0.192.0/20197.0.192.1 to 197.0.207.254197.0.207.2554,094
14197.0.208.0/20197.0.208.1 to 197.0.223.254197.0.223.2554,094
15197.0.224.0/20197.0.224.1 to 197.0.239.254197.0.239.2554,094
16197.0.240.0/20197.0.240.1 to 197.0.255.254197.0.255.2554,094
17197.1.0.0/20197.1.0.1 to 197.1.15.254197.1.15.2554,094
18197.1.16.0/20197.1.16.1 to 197.1.31.254197.1.31.2554,094
19197.1.32.0/20197.1.32.1 to 197.1.47.254197.1.47.2554,094
20197.1.48.0/20197.1.48.1 to 197.1.63.254197.1.63.2554,094
21197.1.64.0/20197.1.64.1 to 197.1.79.254197.1.79.2554,094
22197.1.80.0/20197.1.80.1 to 197.1.95.254197.1.95.2554,094
23197.1.96.0/20197.1.96.1 to 197.1.111.254197.1.111.2554,094
24197.1.112.0/20197.1.112.1 to 197.1.127.254197.1.127.2554,094
25197.1.128.0/20197.1.128.1 to 197.1.143.254197.1.143.2554,094
26197.1.144.0/20197.1.144.1 to 197.1.159.254197.1.159.2554,094
27197.1.160.0/20197.1.160.1 to 197.1.175.254197.1.175.2554,094
28197.1.176.0/20197.1.176.1 to 197.1.191.254197.1.191.2554,094
29197.1.192.0/20197.1.192.1 to 197.1.207.254197.1.207.2554,094
30197.1.208.0/20197.1.208.1 to 197.1.223.254197.1.223.2554,094
31197.1.224.0/20197.1.224.1 to 197.1.239.254197.1.239.2554,094
32197.1.240.0/20197.1.240.1 to 197.1.255.254197.1.255.2554,094
33197.2.0.0/20197.2.0.1 to 197.2.15.254197.2.15.2554,094
34197.2.16.0/20197.2.16.1 to 197.2.31.254197.2.31.2554,094
35197.2.32.0/20197.2.32.1 to 197.2.47.254197.2.47.2554,094
36197.2.48.0/20197.2.48.1 to 197.2.63.254197.2.63.2554,094
37197.2.64.0/20197.2.64.1 to 197.2.79.254197.2.79.2554,094
38197.2.80.0/20197.2.80.1 to 197.2.95.254197.2.95.2554,094
39197.2.96.0/20197.2.96.1 to 197.2.111.254197.2.111.2554,094
40197.2.112.0/20197.2.112.1 to 197.2.127.254197.2.127.2554,094
41197.2.128.0/20197.2.128.1 to 197.2.143.254197.2.143.2554,094
42197.2.144.0/20197.2.144.1 to 197.2.159.254197.2.159.2554,094
43197.2.160.0/20197.2.160.1 to 197.2.175.254197.2.175.2554,094
44197.2.176.0/20197.2.176.1 to 197.2.191.254197.2.191.2554,094
45197.2.192.0/20197.2.192.1 to 197.2.207.254197.2.207.2554,094
46197.2.208.0/20197.2.208.1 to 197.2.223.254197.2.223.2554,094
47197.2.224.0/20197.2.224.1 to 197.2.239.254197.2.239.2554,094
48197.2.240.0/20197.2.240.1 to 197.2.255.254197.2.255.2554,094
49197.3.0.0/20197.3.0.1 to 197.3.15.254197.3.15.2554,094
50197.3.16.0/20197.3.16.1 to 197.3.31.254197.3.31.2554,094
51197.3.32.0/20197.3.32.1 to 197.3.47.254197.3.47.2554,094
52197.3.48.0/20197.3.48.1 to 197.3.63.254197.3.63.2554,094
53197.3.64.0/20197.3.64.1 to 197.3.79.254197.3.79.2554,094
54197.3.80.0/20197.3.80.1 to 197.3.95.254197.3.95.2554,094
55197.3.96.0/20197.3.96.1 to 197.3.111.254197.3.111.2554,094
56197.3.112.0/20197.3.112.1 to 197.3.127.254197.3.127.2554,094
57197.3.128.0/20197.3.128.1 to 197.3.143.254197.3.143.2554,094
58197.3.144.0/20197.3.144.1 to 197.3.159.254197.3.159.2554,094
59197.3.160.0/20197.3.160.1 to 197.3.175.254197.3.175.2554,094
60197.3.176.0/20197.3.176.1 to 197.3.191.254197.3.191.2554,094
61197.3.192.0/20197.3.192.1 to 197.3.207.254197.3.207.2554,094
62197.3.208.0/20197.3.208.1 to 197.3.223.254197.3.223.2554,094
63197.3.224.0/20197.3.224.1 to 197.3.239.254197.3.239.2554,094
64197.3.240.0/20197.3.240.1 to 197.3.255.254197.3.255.2554,094
65197.4.0.0/20197.4.0.1 to 197.4.15.254197.4.15.2554,094
66197.4.16.0/20197.4.16.1 to 197.4.31.254197.4.31.2554,094
67197.4.32.0/20197.4.32.1 to 197.4.47.254197.4.47.2554,094
68197.4.48.0/20197.4.48.1 to 197.4.63.254197.4.63.2554,094
69197.4.64.0/20197.4.64.1 to 197.4.79.254197.4.79.2554,094
70197.4.80.0/20197.4.80.1 to 197.4.95.254197.4.95.2554,094
71197.4.96.0/20197.4.96.1 to 197.4.111.254197.4.111.2554,094
72197.4.112.0/20197.4.112.1 to 197.4.127.254197.4.127.2554,094
73197.4.128.0/20197.4.128.1 to 197.4.143.254197.4.143.2554,094
74197.4.144.0/20197.4.144.1 to 197.4.159.254197.4.159.2554,094
75197.4.160.0/20197.4.160.1 to 197.4.175.254197.4.175.2554,094
76197.4.176.0/20197.4.176.1 to 197.4.191.254197.4.191.2554,094
77197.4.192.0/20197.4.192.1 to 197.4.207.254197.4.207.2554,094
78197.4.208.0/20197.4.208.1 to 197.4.223.254197.4.223.2554,094
79197.4.224.0/20197.4.224.1 to 197.4.239.254197.4.239.2554,094
80197.4.240.0/20197.4.240.1 to 197.4.255.254197.4.255.2554,094
81197.5.0.0/20197.5.0.1 to 197.5.15.254197.5.15.2554,094
82197.5.16.0/20197.5.16.1 to 197.5.31.254197.5.31.2554,094
83197.5.32.0/20197.5.32.1 to 197.5.47.254197.5.47.2554,094
84197.5.48.0/20197.5.48.1 to 197.5.63.254197.5.63.2554,094
85197.5.64.0/20197.5.64.1 to 197.5.79.254197.5.79.2554,094
86197.5.80.0/20197.5.80.1 to 197.5.95.254197.5.95.2554,094
87197.5.96.0/20197.5.96.1 to 197.5.111.254197.5.111.2554,094
88197.5.112.0/20197.5.112.1 to 197.5.127.254197.5.127.2554,094
89197.5.128.0/20197.5.128.1 to 197.5.143.254197.5.143.2554,094
90197.5.144.0/20197.5.144.1 to 197.5.159.254197.5.159.2554,094
91197.5.160.0/20197.5.160.1 to 197.5.175.254197.5.175.2554,094
92197.5.176.0/20197.5.176.1 to 197.5.191.254197.5.191.2554,094
93197.5.192.0/20197.5.192.1 to 197.5.207.254197.5.207.2554,094
94197.5.208.0/20197.5.208.1 to 197.5.223.254197.5.223.2554,094
95197.5.224.0/20197.5.224.1 to 197.5.239.254197.5.239.2554,094
96197.5.240.0/20197.5.240.1 to 197.5.255.254197.5.255.2554,094
97197.6.0.0/20197.6.0.1 to 197.6.15.254197.6.15.2554,094
98197.6.16.0/20197.6.16.1 to 197.6.31.254197.6.31.2554,094
99197.6.32.0/20197.6.32.1 to 197.6.47.254197.6.47.2554,094
100197.6.48.0/20197.6.48.1 to 197.6.63.254197.6.63.2554,094
101197.6.64.0/20197.6.64.1 to 197.6.79.254197.6.79.2554,094
102197.6.80.0/20197.6.80.1 to 197.6.95.254197.6.95.2554,094
103197.6.96.0/20197.6.96.1 to 197.6.111.254197.6.111.2554,094
104197.6.112.0/20197.6.112.1 to 197.6.127.254197.6.127.2554,094
105197.6.128.0/20197.6.128.1 to 197.6.143.254197.6.143.2554,094
106197.6.144.0/20197.6.144.1 to 197.6.159.254197.6.159.2554,094
107197.6.160.0/20197.6.160.1 to 197.6.175.254197.6.175.2554,094
108197.6.176.0/20197.6.176.1 to 197.6.191.254197.6.191.2554,094
109197.6.192.0/20197.6.192.1 to 197.6.207.254197.6.207.2554,094
110197.6.208.0/20197.6.208.1 to 197.6.223.254197.6.223.2554,094
111197.6.224.0/20197.6.224.1 to 197.6.239.254197.6.239.2554,094
112197.6.240.0/20197.6.240.1 to 197.6.255.254197.6.255.2554,094
113197.7.0.0/20197.7.0.1 to 197.7.15.254197.7.15.2554,094
114197.7.16.0/20197.7.16.1 to 197.7.31.254197.7.31.2554,094
115197.7.32.0/20197.7.32.1 to 197.7.47.254197.7.47.2554,094
116197.7.48.0/20197.7.48.1 to 197.7.63.254197.7.63.2554,094
117197.7.64.0/20197.7.64.1 to 197.7.79.254197.7.79.2554,094
118197.7.80.0/20197.7.80.1 to 197.7.95.254197.7.95.2554,094
119197.7.96.0/20197.7.96.1 to 197.7.111.254197.7.111.2554,094
120197.7.112.0/20197.7.112.1 to 197.7.127.254197.7.127.2554,094
121197.7.128.0/20197.7.128.1 to 197.7.143.254197.7.143.2554,094
122197.7.144.0/20197.7.144.1 to 197.7.159.254197.7.159.2554,094
123197.7.160.0/20197.7.160.1 to 197.7.175.254197.7.175.2554,094
124197.7.176.0/20197.7.176.1 to 197.7.191.254197.7.191.2554,094
125197.7.192.0/20197.7.192.1 to 197.7.207.254197.7.207.2554,094
126197.7.208.0/20197.7.208.1 to 197.7.223.254197.7.223.2554,094
127197.7.224.0/20197.7.224.1 to 197.7.239.254197.7.239.2554,094
128197.7.240.0/20197.7.240.1 to 197.7.255.254197.7.255.2554,094
129197.8.0.0/20197.8.0.1 to 197.8.15.254197.8.15.2554,094
130197.8.16.0/20197.8.16.1 to 197.8.31.254197.8.31.2554,094
131197.8.32.0/20197.8.32.1 to 197.8.47.254197.8.47.2554,094
132197.8.48.0/20197.8.48.1 to 197.8.63.254197.8.63.2554,094
133197.8.64.0/20197.8.64.1 to 197.8.79.254197.8.79.2554,094
134197.8.80.0/20197.8.80.1 to 197.8.95.254197.8.95.2554,094
135197.8.96.0/20197.8.96.1 to 197.8.111.254197.8.111.2554,094
136197.8.112.0/20197.8.112.1 to 197.8.127.254197.8.127.2554,094
137197.8.128.0/20197.8.128.1 to 197.8.143.254197.8.143.2554,094
138197.8.144.0/20197.8.144.1 to 197.8.159.254197.8.159.2554,094
139197.8.160.0/20197.8.160.1 to 197.8.175.254197.8.175.2554,094
140197.8.176.0/20197.8.176.1 to 197.8.191.254197.8.191.2554,094
141197.8.192.0/20197.8.192.1 to 197.8.207.254197.8.207.2554,094
142197.8.208.0/20197.8.208.1 to 197.8.223.254197.8.223.2554,094
143197.8.224.0/20197.8.224.1 to 197.8.239.254197.8.239.2554,094
144197.8.240.0/20197.8.240.1 to 197.8.255.254197.8.255.2554,094
145197.9.0.0/20197.9.0.1 to 197.9.15.254197.9.15.2554,094
146197.9.16.0/20197.9.16.1 to 197.9.31.254197.9.31.2554,094
147197.9.32.0/20197.9.32.1 to 197.9.47.254197.9.47.2554,094
148197.9.48.0/20197.9.48.1 to 197.9.63.254197.9.63.2554,094
149197.9.64.0/20197.9.64.1 to 197.9.79.254197.9.79.2554,094
150197.9.80.0/20197.9.80.1 to 197.9.95.254197.9.95.2554,094
151197.9.96.0/20197.9.96.1 to 197.9.111.254197.9.111.2554,094
152197.9.112.0/20197.9.112.1 to 197.9.127.254197.9.127.2554,094
153197.9.128.0/20197.9.128.1 to 197.9.143.254197.9.143.2554,094
154197.9.144.0/20197.9.144.1 to 197.9.159.254197.9.159.2554,094
155197.9.160.0/20197.9.160.1 to 197.9.175.254197.9.175.2554,094
156197.9.176.0/20197.9.176.1 to 197.9.191.254197.9.191.2554,094
157197.9.192.0/20197.9.192.1 to 197.9.207.254197.9.207.2554,094
158197.9.208.0/20197.9.208.1 to 197.9.223.254197.9.223.2554,094
159197.9.224.0/20197.9.224.1 to 197.9.239.254197.9.239.2554,094
160197.9.240.0/20197.9.240.1 to 197.9.255.254197.9.255.2554,094
161197.10.0.0/20197.10.0.1 to 197.10.15.254197.10.15.2554,094
162197.10.16.0/20197.10.16.1 to 197.10.31.254197.10.31.2554,094
163197.10.32.0/20197.10.32.1 to 197.10.47.254197.10.47.2554,094
164197.10.48.0/20197.10.48.1 to 197.10.63.254197.10.63.2554,094
165197.10.64.0/20197.10.64.1 to 197.10.79.254197.10.79.2554,094
166197.10.80.0/20197.10.80.1 to 197.10.95.254197.10.95.2554,094
167197.10.96.0/20197.10.96.1 to 197.10.111.254197.10.111.2554,094
168197.10.112.0/20197.10.112.1 to 197.10.127.254197.10.127.2554,094
169197.10.128.0/20197.10.128.1 to 197.10.143.254197.10.143.2554,094
170197.10.144.0/20197.10.144.1 to 197.10.159.254197.10.159.2554,094
171197.10.160.0/20197.10.160.1 to 197.10.175.254197.10.175.2554,094
172197.10.176.0/20197.10.176.1 to 197.10.191.254197.10.191.2554,094
173197.10.192.0/20197.10.192.1 to 197.10.207.254197.10.207.2554,094
174197.10.208.0/20197.10.208.1 to 197.10.223.254197.10.223.2554,094
175197.10.224.0/20197.10.224.1 to 197.10.239.254197.10.239.2554,094
176197.10.240.0/20197.10.240.1 to 197.10.255.254197.10.255.2554,094
177197.11.0.0/20197.11.0.1 to 197.11.15.254197.11.15.2554,094
178197.11.16.0/20197.11.16.1 to 197.11.31.254197.11.31.2554,094
179197.11.32.0/20197.11.32.1 to 197.11.47.254197.11.47.2554,094
180197.11.48.0/20197.11.48.1 to 197.11.63.254197.11.63.2554,094
181197.11.64.0/20197.11.64.1 to 197.11.79.254197.11.79.2554,094
182197.11.80.0/20197.11.80.1 to 197.11.95.254197.11.95.2554,094
183197.11.96.0/20197.11.96.1 to 197.11.111.254197.11.111.2554,094
184197.11.112.0/20197.11.112.1 to 197.11.127.254197.11.127.2554,094
185197.11.128.0/20197.11.128.1 to 197.11.143.254197.11.143.2554,094
186197.11.144.0/20197.11.144.1 to 197.11.159.254197.11.159.2554,094
187197.11.160.0/20197.11.160.1 to 197.11.175.254197.11.175.2554,094
188197.11.176.0/20197.11.176.1 to 197.11.191.254197.11.191.2554,094
189197.11.192.0/20197.11.192.1 to 197.11.207.254197.11.207.2554,094
190197.11.208.0/20197.11.208.1 to 197.11.223.254197.11.223.2554,094
191197.11.224.0/20197.11.224.1 to 197.11.239.254197.11.239.2554,094
192197.11.240.0/20197.11.240.1 to 197.11.255.254197.11.255.2554,094
193197.12.0.0/20197.12.0.1 to 197.12.15.254197.12.15.2554,094
194197.12.16.0/20197.12.16.1 to 197.12.31.254197.12.31.2554,094
195197.12.32.0/20197.12.32.1 to 197.12.47.254197.12.47.2554,094
196197.12.48.0/20197.12.48.1 to 197.12.63.254197.12.63.2554,094
197197.12.64.0/20197.12.64.1 to 197.12.79.254197.12.79.2554,094
198197.12.80.0/20197.12.80.1 to 197.12.95.254197.12.95.2554,094
199197.12.96.0/20197.12.96.1 to 197.12.111.254197.12.111.2554,094
200197.12.112.0/20197.12.112.1 to 197.12.127.254197.12.127.2554,094
201197.12.128.0/20197.12.128.1 to 197.12.143.254197.12.143.2554,094
202197.12.144.0/20197.12.144.1 to 197.12.159.254197.12.159.2554,094
203197.12.160.0/20197.12.160.1 to 197.12.175.254197.12.175.2554,094
204197.12.176.0/20197.12.176.1 to 197.12.191.254197.12.191.2554,094
205197.12.192.0/20197.12.192.1 to 197.12.207.254197.12.207.2554,094
206197.12.208.0/20197.12.208.1 to 197.12.223.254197.12.223.2554,094
207197.12.224.0/20197.12.224.1 to 197.12.239.254197.12.239.2554,094
208197.12.240.0/20197.12.240.1 to 197.12.255.254197.12.255.2554,094
209197.13.0.0/20197.13.0.1 to 197.13.15.254197.13.15.2554,094
210197.13.16.0/20197.13.16.1 to 197.13.31.254197.13.31.2554,094
211197.13.32.0/20197.13.32.1 to 197.13.47.254197.13.47.2554,094
212197.13.48.0/20197.13.48.1 to 197.13.63.254197.13.63.2554,094
213197.13.64.0/20197.13.64.1 to 197.13.79.254197.13.79.2554,094
214197.13.80.0/20197.13.80.1 to 197.13.95.254197.13.95.2554,094
215197.13.96.0/20197.13.96.1 to 197.13.111.254197.13.111.2554,094
216197.13.112.0/20197.13.112.1 to 197.13.127.254197.13.127.2554,094
217197.13.128.0/20197.13.128.1 to 197.13.143.254197.13.143.2554,094
218197.13.144.0/20197.13.144.1 to 197.13.159.254197.13.159.2554,094
219197.13.160.0/20197.13.160.1 to 197.13.175.254197.13.175.2554,094
220197.13.176.0/20197.13.176.1 to 197.13.191.254197.13.191.2554,094
221197.13.192.0/20197.13.192.1 to 197.13.207.254197.13.207.2554,094
222197.13.208.0/20197.13.208.1 to 197.13.223.254197.13.223.2554,094
223197.13.224.0/20197.13.224.1 to 197.13.239.254197.13.239.2554,094
224197.13.240.0/20197.13.240.1 to 197.13.255.254197.13.255.2554,094
225197.14.0.0/20197.14.0.1 to 197.14.15.254197.14.15.2554,094
226197.14.16.0/20197.14.16.1 to 197.14.31.254197.14.31.2554,094
227197.14.32.0/20197.14.32.1 to 197.14.47.254197.14.47.2554,094
228197.14.48.0/20197.14.48.1 to 197.14.63.254197.14.63.2554,094
229197.14.64.0/20197.14.64.1 to 197.14.79.254197.14.79.2554,094
230197.14.80.0/20197.14.80.1 to 197.14.95.254197.14.95.2554,094
231197.14.96.0/20197.14.96.1 to 197.14.111.254197.14.111.2554,094
232197.14.112.0/20197.14.112.1 to 197.14.127.254197.14.127.2554,094
233197.14.128.0/20197.14.128.1 to 197.14.143.254197.14.143.2554,094
234197.14.144.0/20197.14.144.1 to 197.14.159.254197.14.159.2554,094
235197.14.160.0/20197.14.160.1 to 197.14.175.254197.14.175.2554,094
236197.14.176.0/20197.14.176.1 to 197.14.191.254197.14.191.2554,094
237197.14.192.0/20197.14.192.1 to 197.14.207.254197.14.207.2554,094
238197.14.208.0/20197.14.208.1 to 197.14.223.254197.14.223.2554,094
239197.14.224.0/20197.14.224.1 to 197.14.239.254197.14.239.2554,094
240197.14.240.0/20197.14.240.1 to 197.14.255.254197.14.255.2554,094
241197.15.0.0/20197.15.0.1 to 197.15.15.254197.15.15.2554,094
242197.15.16.0/20197.15.16.1 to 197.15.31.254197.15.31.2554,094
243197.15.32.0/20197.15.32.1 to 197.15.47.254197.15.47.2554,094
244197.15.48.0/20197.15.48.1 to 197.15.63.254197.15.63.2554,094
245197.15.64.0/20197.15.64.1 to 197.15.79.254197.15.79.2554,094
246197.15.80.0/20197.15.80.1 to 197.15.95.254197.15.95.2554,094
247197.15.96.0/20197.15.96.1 to 197.15.111.254197.15.111.2554,094
248197.15.112.0/20197.15.112.1 to 197.15.127.254197.15.127.2554,094
249197.15.128.0/20197.15.128.1 to 197.15.143.254197.15.143.2554,094
250197.15.144.0/20197.15.144.1 to 197.15.159.254197.15.159.2554,094
251197.15.160.0/20197.15.160.1 to 197.15.175.254197.15.175.2554,094
252197.15.176.0/20197.15.176.1 to 197.15.191.254197.15.191.2554,094
253197.15.192.0/20197.15.192.1 to 197.15.207.254197.15.207.2554,094
254197.15.208.0/20197.15.208.1 to 197.15.223.254197.15.223.2554,094
255197.15.224.0/20197.15.224.1 to 197.15.239.254197.15.239.2554,094
256197.15.240.0/20197.15.240.1 to 197.15.255.254197.15.255.2554,094

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.