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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.

Network170.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
170.0.0.0
Broadcast address
170.15.255.255
First usable
170.0.0.1
Last usable
170.15.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
B (default /16)
As numbers
Hex AA000000 · Integer 2852126720 to 2853175295
Reverse DNS zones
0.170.in-addr.arpa
1.170.in-addr.arpa
2.170.in-addr.arpa
3.170.in-addr.arpa
4.170.in-addr.arpa
5.170.in-addr.arpa
6.170.in-addr.arpa
7.170.in-addr.arpa
8.170.in-addr.arpa
9.170.in-addr.arpa
10.170.in-addr.arpa
11.170.in-addr.arpa
12.170.in-addr.arpa
13.170.in-addr.arpa
14.170.in-addr.arpa
15.170.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101010.00000000.00000000.00000000170.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10101010.00000000.00000000.00000000170.0.0.0
Broadcast10101010.00001111.11111111.11111111170.15.255.255
Split into smaller subnets/22
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

170.0.0.0/12 makes 1,024 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1170.0.0.0/22170.0.0.1 to 170.0.3.254170.0.3.2551,022
2170.0.4.0/22170.0.4.1 to 170.0.7.254170.0.7.2551,022
3170.0.8.0/22170.0.8.1 to 170.0.11.254170.0.11.2551,022
4170.0.12.0/22170.0.12.1 to 170.0.15.254170.0.15.2551,022
5170.0.16.0/22170.0.16.1 to 170.0.19.254170.0.19.2551,022
6170.0.20.0/22170.0.20.1 to 170.0.23.254170.0.23.2551,022
7170.0.24.0/22170.0.24.1 to 170.0.27.254170.0.27.2551,022
8170.0.28.0/22170.0.28.1 to 170.0.31.254170.0.31.2551,022
9170.0.32.0/22170.0.32.1 to 170.0.35.254170.0.35.2551,022
10170.0.36.0/22170.0.36.1 to 170.0.39.254170.0.39.2551,022
11170.0.40.0/22170.0.40.1 to 170.0.43.254170.0.43.2551,022
12170.0.44.0/22170.0.44.1 to 170.0.47.254170.0.47.2551,022
13170.0.48.0/22170.0.48.1 to 170.0.51.254170.0.51.2551,022
14170.0.52.0/22170.0.52.1 to 170.0.55.254170.0.55.2551,022
15170.0.56.0/22170.0.56.1 to 170.0.59.254170.0.59.2551,022
16170.0.60.0/22170.0.60.1 to 170.0.63.254170.0.63.2551,022
17170.0.64.0/22170.0.64.1 to 170.0.67.254170.0.67.2551,022
18170.0.68.0/22170.0.68.1 to 170.0.71.254170.0.71.2551,022
19170.0.72.0/22170.0.72.1 to 170.0.75.254170.0.75.2551,022
20170.0.76.0/22170.0.76.1 to 170.0.79.254170.0.79.2551,022
21170.0.80.0/22170.0.80.1 to 170.0.83.254170.0.83.2551,022
22170.0.84.0/22170.0.84.1 to 170.0.87.254170.0.87.2551,022
23170.0.88.0/22170.0.88.1 to 170.0.91.254170.0.91.2551,022
24170.0.92.0/22170.0.92.1 to 170.0.95.254170.0.95.2551,022
25170.0.96.0/22170.0.96.1 to 170.0.99.254170.0.99.2551,022
26170.0.100.0/22170.0.100.1 to 170.0.103.254170.0.103.2551,022
27170.0.104.0/22170.0.104.1 to 170.0.107.254170.0.107.2551,022
28170.0.108.0/22170.0.108.1 to 170.0.111.254170.0.111.2551,022
29170.0.112.0/22170.0.112.1 to 170.0.115.254170.0.115.2551,022
30170.0.116.0/22170.0.116.1 to 170.0.119.254170.0.119.2551,022
31170.0.120.0/22170.0.120.1 to 170.0.123.254170.0.123.2551,022
32170.0.124.0/22170.0.124.1 to 170.0.127.254170.0.127.2551,022
33170.0.128.0/22170.0.128.1 to 170.0.131.254170.0.131.2551,022
34170.0.132.0/22170.0.132.1 to 170.0.135.254170.0.135.2551,022
35170.0.136.0/22170.0.136.1 to 170.0.139.254170.0.139.2551,022
36170.0.140.0/22170.0.140.1 to 170.0.143.254170.0.143.2551,022
37170.0.144.0/22170.0.144.1 to 170.0.147.254170.0.147.2551,022
38170.0.148.0/22170.0.148.1 to 170.0.151.254170.0.151.2551,022
39170.0.152.0/22170.0.152.1 to 170.0.155.254170.0.155.2551,022
40170.0.156.0/22170.0.156.1 to 170.0.159.254170.0.159.2551,022
41170.0.160.0/22170.0.160.1 to 170.0.163.254170.0.163.2551,022
42170.0.164.0/22170.0.164.1 to 170.0.167.254170.0.167.2551,022
43170.0.168.0/22170.0.168.1 to 170.0.171.254170.0.171.2551,022
44170.0.172.0/22170.0.172.1 to 170.0.175.254170.0.175.2551,022
45170.0.176.0/22170.0.176.1 to 170.0.179.254170.0.179.2551,022
46170.0.180.0/22170.0.180.1 to 170.0.183.254170.0.183.2551,022
47170.0.184.0/22170.0.184.1 to 170.0.187.254170.0.187.2551,022
48170.0.188.0/22170.0.188.1 to 170.0.191.254170.0.191.2551,022
49170.0.192.0/22170.0.192.1 to 170.0.195.254170.0.195.2551,022
50170.0.196.0/22170.0.196.1 to 170.0.199.254170.0.199.2551,022
51170.0.200.0/22170.0.200.1 to 170.0.203.254170.0.203.2551,022
52170.0.204.0/22170.0.204.1 to 170.0.207.254170.0.207.2551,022
53170.0.208.0/22170.0.208.1 to 170.0.211.254170.0.211.2551,022
54170.0.212.0/22170.0.212.1 to 170.0.215.254170.0.215.2551,022
55170.0.216.0/22170.0.216.1 to 170.0.219.254170.0.219.2551,022
56170.0.220.0/22170.0.220.1 to 170.0.223.254170.0.223.2551,022
57170.0.224.0/22170.0.224.1 to 170.0.227.254170.0.227.2551,022
58170.0.228.0/22170.0.228.1 to 170.0.231.254170.0.231.2551,022
59170.0.232.0/22170.0.232.1 to 170.0.235.254170.0.235.2551,022
60170.0.236.0/22170.0.236.1 to 170.0.239.254170.0.239.2551,022
61170.0.240.0/22170.0.240.1 to 170.0.243.254170.0.243.2551,022
62170.0.244.0/22170.0.244.1 to 170.0.247.254170.0.247.2551,022
63170.0.248.0/22170.0.248.1 to 170.0.251.254170.0.251.2551,022
64170.0.252.0/22170.0.252.1 to 170.0.255.254170.0.255.2551,022
65170.1.0.0/22170.1.0.1 to 170.1.3.254170.1.3.2551,022
66170.1.4.0/22170.1.4.1 to 170.1.7.254170.1.7.2551,022
67170.1.8.0/22170.1.8.1 to 170.1.11.254170.1.11.2551,022
68170.1.12.0/22170.1.12.1 to 170.1.15.254170.1.15.2551,022
69170.1.16.0/22170.1.16.1 to 170.1.19.254170.1.19.2551,022
70170.1.20.0/22170.1.20.1 to 170.1.23.254170.1.23.2551,022
71170.1.24.0/22170.1.24.1 to 170.1.27.254170.1.27.2551,022
72170.1.28.0/22170.1.28.1 to 170.1.31.254170.1.31.2551,022
73170.1.32.0/22170.1.32.1 to 170.1.35.254170.1.35.2551,022
74170.1.36.0/22170.1.36.1 to 170.1.39.254170.1.39.2551,022
75170.1.40.0/22170.1.40.1 to 170.1.43.254170.1.43.2551,022
76170.1.44.0/22170.1.44.1 to 170.1.47.254170.1.47.2551,022
77170.1.48.0/22170.1.48.1 to 170.1.51.254170.1.51.2551,022
78170.1.52.0/22170.1.52.1 to 170.1.55.254170.1.55.2551,022
79170.1.56.0/22170.1.56.1 to 170.1.59.254170.1.59.2551,022
80170.1.60.0/22170.1.60.1 to 170.1.63.254170.1.63.2551,022
81170.1.64.0/22170.1.64.1 to 170.1.67.254170.1.67.2551,022
82170.1.68.0/22170.1.68.1 to 170.1.71.254170.1.71.2551,022
83170.1.72.0/22170.1.72.1 to 170.1.75.254170.1.75.2551,022
84170.1.76.0/22170.1.76.1 to 170.1.79.254170.1.79.2551,022
85170.1.80.0/22170.1.80.1 to 170.1.83.254170.1.83.2551,022
86170.1.84.0/22170.1.84.1 to 170.1.87.254170.1.87.2551,022
87170.1.88.0/22170.1.88.1 to 170.1.91.254170.1.91.2551,022
88170.1.92.0/22170.1.92.1 to 170.1.95.254170.1.95.2551,022
89170.1.96.0/22170.1.96.1 to 170.1.99.254170.1.99.2551,022
90170.1.100.0/22170.1.100.1 to 170.1.103.254170.1.103.2551,022
91170.1.104.0/22170.1.104.1 to 170.1.107.254170.1.107.2551,022
92170.1.108.0/22170.1.108.1 to 170.1.111.254170.1.111.2551,022
93170.1.112.0/22170.1.112.1 to 170.1.115.254170.1.115.2551,022
94170.1.116.0/22170.1.116.1 to 170.1.119.254170.1.119.2551,022
95170.1.120.0/22170.1.120.1 to 170.1.123.254170.1.123.2551,022
96170.1.124.0/22170.1.124.1 to 170.1.127.254170.1.127.2551,022
97170.1.128.0/22170.1.128.1 to 170.1.131.254170.1.131.2551,022
98170.1.132.0/22170.1.132.1 to 170.1.135.254170.1.135.2551,022
99170.1.136.0/22170.1.136.1 to 170.1.139.254170.1.139.2551,022
100170.1.140.0/22170.1.140.1 to 170.1.143.254170.1.143.2551,022
101170.1.144.0/22170.1.144.1 to 170.1.147.254170.1.147.2551,022
102170.1.148.0/22170.1.148.1 to 170.1.151.254170.1.151.2551,022
103170.1.152.0/22170.1.152.1 to 170.1.155.254170.1.155.2551,022
104170.1.156.0/22170.1.156.1 to 170.1.159.254170.1.159.2551,022
105170.1.160.0/22170.1.160.1 to 170.1.163.254170.1.163.2551,022
106170.1.164.0/22170.1.164.1 to 170.1.167.254170.1.167.2551,022
107170.1.168.0/22170.1.168.1 to 170.1.171.254170.1.171.2551,022
108170.1.172.0/22170.1.172.1 to 170.1.175.254170.1.175.2551,022
109170.1.176.0/22170.1.176.1 to 170.1.179.254170.1.179.2551,022
110170.1.180.0/22170.1.180.1 to 170.1.183.254170.1.183.2551,022
111170.1.184.0/22170.1.184.1 to 170.1.187.254170.1.187.2551,022
112170.1.188.0/22170.1.188.1 to 170.1.191.254170.1.191.2551,022
113170.1.192.0/22170.1.192.1 to 170.1.195.254170.1.195.2551,022
114170.1.196.0/22170.1.196.1 to 170.1.199.254170.1.199.2551,022
115170.1.200.0/22170.1.200.1 to 170.1.203.254170.1.203.2551,022
116170.1.204.0/22170.1.204.1 to 170.1.207.254170.1.207.2551,022
117170.1.208.0/22170.1.208.1 to 170.1.211.254170.1.211.2551,022
118170.1.212.0/22170.1.212.1 to 170.1.215.254170.1.215.2551,022
119170.1.216.0/22170.1.216.1 to 170.1.219.254170.1.219.2551,022
120170.1.220.0/22170.1.220.1 to 170.1.223.254170.1.223.2551,022
121170.1.224.0/22170.1.224.1 to 170.1.227.254170.1.227.2551,022
122170.1.228.0/22170.1.228.1 to 170.1.231.254170.1.231.2551,022
123170.1.232.0/22170.1.232.1 to 170.1.235.254170.1.235.2551,022
124170.1.236.0/22170.1.236.1 to 170.1.239.254170.1.239.2551,022
125170.1.240.0/22170.1.240.1 to 170.1.243.254170.1.243.2551,022
126170.1.244.0/22170.1.244.1 to 170.1.247.254170.1.247.2551,022
127170.1.248.0/22170.1.248.1 to 170.1.251.254170.1.251.2551,022
128170.1.252.0/22170.1.252.1 to 170.1.255.254170.1.255.2551,022
129170.2.0.0/22170.2.0.1 to 170.2.3.254170.2.3.2551,022
130170.2.4.0/22170.2.4.1 to 170.2.7.254170.2.7.2551,022
131170.2.8.0/22170.2.8.1 to 170.2.11.254170.2.11.2551,022
132170.2.12.0/22170.2.12.1 to 170.2.15.254170.2.15.2551,022
133170.2.16.0/22170.2.16.1 to 170.2.19.254170.2.19.2551,022
134170.2.20.0/22170.2.20.1 to 170.2.23.254170.2.23.2551,022
135170.2.24.0/22170.2.24.1 to 170.2.27.254170.2.27.2551,022
136170.2.28.0/22170.2.28.1 to 170.2.31.254170.2.31.2551,022
137170.2.32.0/22170.2.32.1 to 170.2.35.254170.2.35.2551,022
138170.2.36.0/22170.2.36.1 to 170.2.39.254170.2.39.2551,022
139170.2.40.0/22170.2.40.1 to 170.2.43.254170.2.43.2551,022
140170.2.44.0/22170.2.44.1 to 170.2.47.254170.2.47.2551,022
141170.2.48.0/22170.2.48.1 to 170.2.51.254170.2.51.2551,022
142170.2.52.0/22170.2.52.1 to 170.2.55.254170.2.55.2551,022
143170.2.56.0/22170.2.56.1 to 170.2.59.254170.2.59.2551,022
144170.2.60.0/22170.2.60.1 to 170.2.63.254170.2.63.2551,022
145170.2.64.0/22170.2.64.1 to 170.2.67.254170.2.67.2551,022
146170.2.68.0/22170.2.68.1 to 170.2.71.254170.2.71.2551,022
147170.2.72.0/22170.2.72.1 to 170.2.75.254170.2.75.2551,022
148170.2.76.0/22170.2.76.1 to 170.2.79.254170.2.79.2551,022
149170.2.80.0/22170.2.80.1 to 170.2.83.254170.2.83.2551,022
150170.2.84.0/22170.2.84.1 to 170.2.87.254170.2.87.2551,022
151170.2.88.0/22170.2.88.1 to 170.2.91.254170.2.91.2551,022
152170.2.92.0/22170.2.92.1 to 170.2.95.254170.2.95.2551,022
153170.2.96.0/22170.2.96.1 to 170.2.99.254170.2.99.2551,022
154170.2.100.0/22170.2.100.1 to 170.2.103.254170.2.103.2551,022
155170.2.104.0/22170.2.104.1 to 170.2.107.254170.2.107.2551,022
156170.2.108.0/22170.2.108.1 to 170.2.111.254170.2.111.2551,022
157170.2.112.0/22170.2.112.1 to 170.2.115.254170.2.115.2551,022
158170.2.116.0/22170.2.116.1 to 170.2.119.254170.2.119.2551,022
159170.2.120.0/22170.2.120.1 to 170.2.123.254170.2.123.2551,022
160170.2.124.0/22170.2.124.1 to 170.2.127.254170.2.127.2551,022
161170.2.128.0/22170.2.128.1 to 170.2.131.254170.2.131.2551,022
162170.2.132.0/22170.2.132.1 to 170.2.135.254170.2.135.2551,022
163170.2.136.0/22170.2.136.1 to 170.2.139.254170.2.139.2551,022
164170.2.140.0/22170.2.140.1 to 170.2.143.254170.2.143.2551,022
165170.2.144.0/22170.2.144.1 to 170.2.147.254170.2.147.2551,022
166170.2.148.0/22170.2.148.1 to 170.2.151.254170.2.151.2551,022
167170.2.152.0/22170.2.152.1 to 170.2.155.254170.2.155.2551,022
168170.2.156.0/22170.2.156.1 to 170.2.159.254170.2.159.2551,022
169170.2.160.0/22170.2.160.1 to 170.2.163.254170.2.163.2551,022
170170.2.164.0/22170.2.164.1 to 170.2.167.254170.2.167.2551,022
171170.2.168.0/22170.2.168.1 to 170.2.171.254170.2.171.2551,022
172170.2.172.0/22170.2.172.1 to 170.2.175.254170.2.175.2551,022
173170.2.176.0/22170.2.176.1 to 170.2.179.254170.2.179.2551,022
174170.2.180.0/22170.2.180.1 to 170.2.183.254170.2.183.2551,022
175170.2.184.0/22170.2.184.1 to 170.2.187.254170.2.187.2551,022
176170.2.188.0/22170.2.188.1 to 170.2.191.254170.2.191.2551,022
177170.2.192.0/22170.2.192.1 to 170.2.195.254170.2.195.2551,022
178170.2.196.0/22170.2.196.1 to 170.2.199.254170.2.199.2551,022
179170.2.200.0/22170.2.200.1 to 170.2.203.254170.2.203.2551,022
180170.2.204.0/22170.2.204.1 to 170.2.207.254170.2.207.2551,022
181170.2.208.0/22170.2.208.1 to 170.2.211.254170.2.211.2551,022
182170.2.212.0/22170.2.212.1 to 170.2.215.254170.2.215.2551,022
183170.2.216.0/22170.2.216.1 to 170.2.219.254170.2.219.2551,022
184170.2.220.0/22170.2.220.1 to 170.2.223.254170.2.223.2551,022
185170.2.224.0/22170.2.224.1 to 170.2.227.254170.2.227.2551,022
186170.2.228.0/22170.2.228.1 to 170.2.231.254170.2.231.2551,022
187170.2.232.0/22170.2.232.1 to 170.2.235.254170.2.235.2551,022
188170.2.236.0/22170.2.236.1 to 170.2.239.254170.2.239.2551,022
189170.2.240.0/22170.2.240.1 to 170.2.243.254170.2.243.2551,022
190170.2.244.0/22170.2.244.1 to 170.2.247.254170.2.247.2551,022
191170.2.248.0/22170.2.248.1 to 170.2.251.254170.2.251.2551,022
192170.2.252.0/22170.2.252.1 to 170.2.255.254170.2.255.2551,022
193170.3.0.0/22170.3.0.1 to 170.3.3.254170.3.3.2551,022
194170.3.4.0/22170.3.4.1 to 170.3.7.254170.3.7.2551,022
195170.3.8.0/22170.3.8.1 to 170.3.11.254170.3.11.2551,022
196170.3.12.0/22170.3.12.1 to 170.3.15.254170.3.15.2551,022
197170.3.16.0/22170.3.16.1 to 170.3.19.254170.3.19.2551,022
198170.3.20.0/22170.3.20.1 to 170.3.23.254170.3.23.2551,022
199170.3.24.0/22170.3.24.1 to 170.3.27.254170.3.27.2551,022
200170.3.28.0/22170.3.28.1 to 170.3.31.254170.3.31.2551,022
201170.3.32.0/22170.3.32.1 to 170.3.35.254170.3.35.2551,022
202170.3.36.0/22170.3.36.1 to 170.3.39.254170.3.39.2551,022
203170.3.40.0/22170.3.40.1 to 170.3.43.254170.3.43.2551,022
204170.3.44.0/22170.3.44.1 to 170.3.47.254170.3.47.2551,022
205170.3.48.0/22170.3.48.1 to 170.3.51.254170.3.51.2551,022
206170.3.52.0/22170.3.52.1 to 170.3.55.254170.3.55.2551,022
207170.3.56.0/22170.3.56.1 to 170.3.59.254170.3.59.2551,022
208170.3.60.0/22170.3.60.1 to 170.3.63.254170.3.63.2551,022
209170.3.64.0/22170.3.64.1 to 170.3.67.254170.3.67.2551,022
210170.3.68.0/22170.3.68.1 to 170.3.71.254170.3.71.2551,022
211170.3.72.0/22170.3.72.1 to 170.3.75.254170.3.75.2551,022
212170.3.76.0/22170.3.76.1 to 170.3.79.254170.3.79.2551,022
213170.3.80.0/22170.3.80.1 to 170.3.83.254170.3.83.2551,022
214170.3.84.0/22170.3.84.1 to 170.3.87.254170.3.87.2551,022
215170.3.88.0/22170.3.88.1 to 170.3.91.254170.3.91.2551,022
216170.3.92.0/22170.3.92.1 to 170.3.95.254170.3.95.2551,022
217170.3.96.0/22170.3.96.1 to 170.3.99.254170.3.99.2551,022
218170.3.100.0/22170.3.100.1 to 170.3.103.254170.3.103.2551,022
219170.3.104.0/22170.3.104.1 to 170.3.107.254170.3.107.2551,022
220170.3.108.0/22170.3.108.1 to 170.3.111.254170.3.111.2551,022
221170.3.112.0/22170.3.112.1 to 170.3.115.254170.3.115.2551,022
222170.3.116.0/22170.3.116.1 to 170.3.119.254170.3.119.2551,022
223170.3.120.0/22170.3.120.1 to 170.3.123.254170.3.123.2551,022
224170.3.124.0/22170.3.124.1 to 170.3.127.254170.3.127.2551,022
225170.3.128.0/22170.3.128.1 to 170.3.131.254170.3.131.2551,022
226170.3.132.0/22170.3.132.1 to 170.3.135.254170.3.135.2551,022
227170.3.136.0/22170.3.136.1 to 170.3.139.254170.3.139.2551,022
228170.3.140.0/22170.3.140.1 to 170.3.143.254170.3.143.2551,022
229170.3.144.0/22170.3.144.1 to 170.3.147.254170.3.147.2551,022
230170.3.148.0/22170.3.148.1 to 170.3.151.254170.3.151.2551,022
231170.3.152.0/22170.3.152.1 to 170.3.155.254170.3.155.2551,022
232170.3.156.0/22170.3.156.1 to 170.3.159.254170.3.159.2551,022
233170.3.160.0/22170.3.160.1 to 170.3.163.254170.3.163.2551,022
234170.3.164.0/22170.3.164.1 to 170.3.167.254170.3.167.2551,022
235170.3.168.0/22170.3.168.1 to 170.3.171.254170.3.171.2551,022
236170.3.172.0/22170.3.172.1 to 170.3.175.254170.3.175.2551,022
237170.3.176.0/22170.3.176.1 to 170.3.179.254170.3.179.2551,022
238170.3.180.0/22170.3.180.1 to 170.3.183.254170.3.183.2551,022
239170.3.184.0/22170.3.184.1 to 170.3.187.254170.3.187.2551,022
240170.3.188.0/22170.3.188.1 to 170.3.191.254170.3.191.2551,022
241170.3.192.0/22170.3.192.1 to 170.3.195.254170.3.195.2551,022
242170.3.196.0/22170.3.196.1 to 170.3.199.254170.3.199.2551,022
243170.3.200.0/22170.3.200.1 to 170.3.203.254170.3.203.2551,022
244170.3.204.0/22170.3.204.1 to 170.3.207.254170.3.207.2551,022
245170.3.208.0/22170.3.208.1 to 170.3.211.254170.3.211.2551,022
246170.3.212.0/22170.3.212.1 to 170.3.215.254170.3.215.2551,022
247170.3.216.0/22170.3.216.1 to 170.3.219.254170.3.219.2551,022
248170.3.220.0/22170.3.220.1 to 170.3.223.254170.3.223.2551,022
249170.3.224.0/22170.3.224.1 to 170.3.227.254170.3.227.2551,022
250170.3.228.0/22170.3.228.1 to 170.3.231.254170.3.231.2551,022
251170.3.232.0/22170.3.232.1 to 170.3.235.254170.3.235.2551,022
252170.3.236.0/22170.3.236.1 to 170.3.239.254170.3.239.2551,022
253170.3.240.0/22170.3.240.1 to 170.3.243.254170.3.243.2551,022
254170.3.244.0/22170.3.244.1 to 170.3.247.254170.3.247.2551,022
255170.3.248.0/22170.3.248.1 to 170.3.251.254170.3.251.2551,022
256170.3.252.0/22170.3.252.1 to 170.3.255.254170.3.255.2551,022

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.