Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

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.

Network158.112.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
158.112.0.0
Broadcast address
158.119.255.255
First usable
158.112.0.1
Last usable
158.119.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
B (default /16)
As numbers
Hex 9E700000 · Integer 2658140160 to 2658664447
Reverse DNS zones
112.158.in-addr.arpa
113.158.in-addr.arpa
114.158.in-addr.arpa
115.158.in-addr.arpa
116.158.in-addr.arpa
117.158.in-addr.arpa
118.158.in-addr.arpa
119.158.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011110.01110000.00000000.00000000158.112.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10011110.01110000.00000000.00000000158.112.0.0
Broadcast10011110.01110111.11111111.11111111158.119.255.255
Split into smaller subnets/21
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

158.112.0.0/13 makes 256 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1158.112.0.0/21158.112.0.1 to 158.112.7.254158.112.7.2552,046
2158.112.8.0/21158.112.8.1 to 158.112.15.254158.112.15.2552,046
3158.112.16.0/21158.112.16.1 to 158.112.23.254158.112.23.2552,046
4158.112.24.0/21158.112.24.1 to 158.112.31.254158.112.31.2552,046
5158.112.32.0/21158.112.32.1 to 158.112.39.254158.112.39.2552,046
6158.112.40.0/21158.112.40.1 to 158.112.47.254158.112.47.2552,046
7158.112.48.0/21158.112.48.1 to 158.112.55.254158.112.55.2552,046
8158.112.56.0/21158.112.56.1 to 158.112.63.254158.112.63.2552,046
9158.112.64.0/21158.112.64.1 to 158.112.71.254158.112.71.2552,046
10158.112.72.0/21158.112.72.1 to 158.112.79.254158.112.79.2552,046
11158.112.80.0/21158.112.80.1 to 158.112.87.254158.112.87.2552,046
12158.112.88.0/21158.112.88.1 to 158.112.95.254158.112.95.2552,046
13158.112.96.0/21158.112.96.1 to 158.112.103.254158.112.103.2552,046
14158.112.104.0/21158.112.104.1 to 158.112.111.254158.112.111.2552,046
15158.112.112.0/21158.112.112.1 to 158.112.119.254158.112.119.2552,046
16158.112.120.0/21158.112.120.1 to 158.112.127.254158.112.127.2552,046
17158.112.128.0/21158.112.128.1 to 158.112.135.254158.112.135.2552,046
18158.112.136.0/21158.112.136.1 to 158.112.143.254158.112.143.2552,046
19158.112.144.0/21158.112.144.1 to 158.112.151.254158.112.151.2552,046
20158.112.152.0/21158.112.152.1 to 158.112.159.254158.112.159.2552,046
21158.112.160.0/21158.112.160.1 to 158.112.167.254158.112.167.2552,046
22158.112.168.0/21158.112.168.1 to 158.112.175.254158.112.175.2552,046
23158.112.176.0/21158.112.176.1 to 158.112.183.254158.112.183.2552,046
24158.112.184.0/21158.112.184.1 to 158.112.191.254158.112.191.2552,046
25158.112.192.0/21158.112.192.1 to 158.112.199.254158.112.199.2552,046
26158.112.200.0/21158.112.200.1 to 158.112.207.254158.112.207.2552,046
27158.112.208.0/21158.112.208.1 to 158.112.215.254158.112.215.2552,046
28158.112.216.0/21158.112.216.1 to 158.112.223.254158.112.223.2552,046
29158.112.224.0/21158.112.224.1 to 158.112.231.254158.112.231.2552,046
30158.112.232.0/21158.112.232.1 to 158.112.239.254158.112.239.2552,046
31158.112.240.0/21158.112.240.1 to 158.112.247.254158.112.247.2552,046
32158.112.248.0/21158.112.248.1 to 158.112.255.254158.112.255.2552,046
33158.113.0.0/21158.113.0.1 to 158.113.7.254158.113.7.2552,046
34158.113.8.0/21158.113.8.1 to 158.113.15.254158.113.15.2552,046
35158.113.16.0/21158.113.16.1 to 158.113.23.254158.113.23.2552,046
36158.113.24.0/21158.113.24.1 to 158.113.31.254158.113.31.2552,046
37158.113.32.0/21158.113.32.1 to 158.113.39.254158.113.39.2552,046
38158.113.40.0/21158.113.40.1 to 158.113.47.254158.113.47.2552,046
39158.113.48.0/21158.113.48.1 to 158.113.55.254158.113.55.2552,046
40158.113.56.0/21158.113.56.1 to 158.113.63.254158.113.63.2552,046
41158.113.64.0/21158.113.64.1 to 158.113.71.254158.113.71.2552,046
42158.113.72.0/21158.113.72.1 to 158.113.79.254158.113.79.2552,046
43158.113.80.0/21158.113.80.1 to 158.113.87.254158.113.87.2552,046
44158.113.88.0/21158.113.88.1 to 158.113.95.254158.113.95.2552,046
45158.113.96.0/21158.113.96.1 to 158.113.103.254158.113.103.2552,046
46158.113.104.0/21158.113.104.1 to 158.113.111.254158.113.111.2552,046
47158.113.112.0/21158.113.112.1 to 158.113.119.254158.113.119.2552,046
48158.113.120.0/21158.113.120.1 to 158.113.127.254158.113.127.2552,046
49158.113.128.0/21158.113.128.1 to 158.113.135.254158.113.135.2552,046
50158.113.136.0/21158.113.136.1 to 158.113.143.254158.113.143.2552,046
51158.113.144.0/21158.113.144.1 to 158.113.151.254158.113.151.2552,046
52158.113.152.0/21158.113.152.1 to 158.113.159.254158.113.159.2552,046
53158.113.160.0/21158.113.160.1 to 158.113.167.254158.113.167.2552,046
54158.113.168.0/21158.113.168.1 to 158.113.175.254158.113.175.2552,046
55158.113.176.0/21158.113.176.1 to 158.113.183.254158.113.183.2552,046
56158.113.184.0/21158.113.184.1 to 158.113.191.254158.113.191.2552,046
57158.113.192.0/21158.113.192.1 to 158.113.199.254158.113.199.2552,046
58158.113.200.0/21158.113.200.1 to 158.113.207.254158.113.207.2552,046
59158.113.208.0/21158.113.208.1 to 158.113.215.254158.113.215.2552,046
60158.113.216.0/21158.113.216.1 to 158.113.223.254158.113.223.2552,046
61158.113.224.0/21158.113.224.1 to 158.113.231.254158.113.231.2552,046
62158.113.232.0/21158.113.232.1 to 158.113.239.254158.113.239.2552,046
63158.113.240.0/21158.113.240.1 to 158.113.247.254158.113.247.2552,046
64158.113.248.0/21158.113.248.1 to 158.113.255.254158.113.255.2552,046
65158.114.0.0/21158.114.0.1 to 158.114.7.254158.114.7.2552,046
66158.114.8.0/21158.114.8.1 to 158.114.15.254158.114.15.2552,046
67158.114.16.0/21158.114.16.1 to 158.114.23.254158.114.23.2552,046
68158.114.24.0/21158.114.24.1 to 158.114.31.254158.114.31.2552,046
69158.114.32.0/21158.114.32.1 to 158.114.39.254158.114.39.2552,046
70158.114.40.0/21158.114.40.1 to 158.114.47.254158.114.47.2552,046
71158.114.48.0/21158.114.48.1 to 158.114.55.254158.114.55.2552,046
72158.114.56.0/21158.114.56.1 to 158.114.63.254158.114.63.2552,046
73158.114.64.0/21158.114.64.1 to 158.114.71.254158.114.71.2552,046
74158.114.72.0/21158.114.72.1 to 158.114.79.254158.114.79.2552,046
75158.114.80.0/21158.114.80.1 to 158.114.87.254158.114.87.2552,046
76158.114.88.0/21158.114.88.1 to 158.114.95.254158.114.95.2552,046
77158.114.96.0/21158.114.96.1 to 158.114.103.254158.114.103.2552,046
78158.114.104.0/21158.114.104.1 to 158.114.111.254158.114.111.2552,046
79158.114.112.0/21158.114.112.1 to 158.114.119.254158.114.119.2552,046
80158.114.120.0/21158.114.120.1 to 158.114.127.254158.114.127.2552,046
81158.114.128.0/21158.114.128.1 to 158.114.135.254158.114.135.2552,046
82158.114.136.0/21158.114.136.1 to 158.114.143.254158.114.143.2552,046
83158.114.144.0/21158.114.144.1 to 158.114.151.254158.114.151.2552,046
84158.114.152.0/21158.114.152.1 to 158.114.159.254158.114.159.2552,046
85158.114.160.0/21158.114.160.1 to 158.114.167.254158.114.167.2552,046
86158.114.168.0/21158.114.168.1 to 158.114.175.254158.114.175.2552,046
87158.114.176.0/21158.114.176.1 to 158.114.183.254158.114.183.2552,046
88158.114.184.0/21158.114.184.1 to 158.114.191.254158.114.191.2552,046
89158.114.192.0/21158.114.192.1 to 158.114.199.254158.114.199.2552,046
90158.114.200.0/21158.114.200.1 to 158.114.207.254158.114.207.2552,046
91158.114.208.0/21158.114.208.1 to 158.114.215.254158.114.215.2552,046
92158.114.216.0/21158.114.216.1 to 158.114.223.254158.114.223.2552,046
93158.114.224.0/21158.114.224.1 to 158.114.231.254158.114.231.2552,046
94158.114.232.0/21158.114.232.1 to 158.114.239.254158.114.239.2552,046
95158.114.240.0/21158.114.240.1 to 158.114.247.254158.114.247.2552,046
96158.114.248.0/21158.114.248.1 to 158.114.255.254158.114.255.2552,046
97158.115.0.0/21158.115.0.1 to 158.115.7.254158.115.7.2552,046
98158.115.8.0/21158.115.8.1 to 158.115.15.254158.115.15.2552,046
99158.115.16.0/21158.115.16.1 to 158.115.23.254158.115.23.2552,046
100158.115.24.0/21158.115.24.1 to 158.115.31.254158.115.31.2552,046
101158.115.32.0/21158.115.32.1 to 158.115.39.254158.115.39.2552,046
102158.115.40.0/21158.115.40.1 to 158.115.47.254158.115.47.2552,046
103158.115.48.0/21158.115.48.1 to 158.115.55.254158.115.55.2552,046
104158.115.56.0/21158.115.56.1 to 158.115.63.254158.115.63.2552,046
105158.115.64.0/21158.115.64.1 to 158.115.71.254158.115.71.2552,046
106158.115.72.0/21158.115.72.1 to 158.115.79.254158.115.79.2552,046
107158.115.80.0/21158.115.80.1 to 158.115.87.254158.115.87.2552,046
108158.115.88.0/21158.115.88.1 to 158.115.95.254158.115.95.2552,046
109158.115.96.0/21158.115.96.1 to 158.115.103.254158.115.103.2552,046
110158.115.104.0/21158.115.104.1 to 158.115.111.254158.115.111.2552,046
111158.115.112.0/21158.115.112.1 to 158.115.119.254158.115.119.2552,046
112158.115.120.0/21158.115.120.1 to 158.115.127.254158.115.127.2552,046
113158.115.128.0/21158.115.128.1 to 158.115.135.254158.115.135.2552,046
114158.115.136.0/21158.115.136.1 to 158.115.143.254158.115.143.2552,046
115158.115.144.0/21158.115.144.1 to 158.115.151.254158.115.151.2552,046
116158.115.152.0/21158.115.152.1 to 158.115.159.254158.115.159.2552,046
117158.115.160.0/21158.115.160.1 to 158.115.167.254158.115.167.2552,046
118158.115.168.0/21158.115.168.1 to 158.115.175.254158.115.175.2552,046
119158.115.176.0/21158.115.176.1 to 158.115.183.254158.115.183.2552,046
120158.115.184.0/21158.115.184.1 to 158.115.191.254158.115.191.2552,046
121158.115.192.0/21158.115.192.1 to 158.115.199.254158.115.199.2552,046
122158.115.200.0/21158.115.200.1 to 158.115.207.254158.115.207.2552,046
123158.115.208.0/21158.115.208.1 to 158.115.215.254158.115.215.2552,046
124158.115.216.0/21158.115.216.1 to 158.115.223.254158.115.223.2552,046
125158.115.224.0/21158.115.224.1 to 158.115.231.254158.115.231.2552,046
126158.115.232.0/21158.115.232.1 to 158.115.239.254158.115.239.2552,046
127158.115.240.0/21158.115.240.1 to 158.115.247.254158.115.247.2552,046
128158.115.248.0/21158.115.248.1 to 158.115.255.254158.115.255.2552,046
129158.116.0.0/21158.116.0.1 to 158.116.7.254158.116.7.2552,046
130158.116.8.0/21158.116.8.1 to 158.116.15.254158.116.15.2552,046
131158.116.16.0/21158.116.16.1 to 158.116.23.254158.116.23.2552,046
132158.116.24.0/21158.116.24.1 to 158.116.31.254158.116.31.2552,046
133158.116.32.0/21158.116.32.1 to 158.116.39.254158.116.39.2552,046
134158.116.40.0/21158.116.40.1 to 158.116.47.254158.116.47.2552,046
135158.116.48.0/21158.116.48.1 to 158.116.55.254158.116.55.2552,046
136158.116.56.0/21158.116.56.1 to 158.116.63.254158.116.63.2552,046
137158.116.64.0/21158.116.64.1 to 158.116.71.254158.116.71.2552,046
138158.116.72.0/21158.116.72.1 to 158.116.79.254158.116.79.2552,046
139158.116.80.0/21158.116.80.1 to 158.116.87.254158.116.87.2552,046
140158.116.88.0/21158.116.88.1 to 158.116.95.254158.116.95.2552,046
141158.116.96.0/21158.116.96.1 to 158.116.103.254158.116.103.2552,046
142158.116.104.0/21158.116.104.1 to 158.116.111.254158.116.111.2552,046
143158.116.112.0/21158.116.112.1 to 158.116.119.254158.116.119.2552,046
144158.116.120.0/21158.116.120.1 to 158.116.127.254158.116.127.2552,046
145158.116.128.0/21158.116.128.1 to 158.116.135.254158.116.135.2552,046
146158.116.136.0/21158.116.136.1 to 158.116.143.254158.116.143.2552,046
147158.116.144.0/21158.116.144.1 to 158.116.151.254158.116.151.2552,046
148158.116.152.0/21158.116.152.1 to 158.116.159.254158.116.159.2552,046
149158.116.160.0/21158.116.160.1 to 158.116.167.254158.116.167.2552,046
150158.116.168.0/21158.116.168.1 to 158.116.175.254158.116.175.2552,046
151158.116.176.0/21158.116.176.1 to 158.116.183.254158.116.183.2552,046
152158.116.184.0/21158.116.184.1 to 158.116.191.254158.116.191.2552,046
153158.116.192.0/21158.116.192.1 to 158.116.199.254158.116.199.2552,046
154158.116.200.0/21158.116.200.1 to 158.116.207.254158.116.207.2552,046
155158.116.208.0/21158.116.208.1 to 158.116.215.254158.116.215.2552,046
156158.116.216.0/21158.116.216.1 to 158.116.223.254158.116.223.2552,046
157158.116.224.0/21158.116.224.1 to 158.116.231.254158.116.231.2552,046
158158.116.232.0/21158.116.232.1 to 158.116.239.254158.116.239.2552,046
159158.116.240.0/21158.116.240.1 to 158.116.247.254158.116.247.2552,046
160158.116.248.0/21158.116.248.1 to 158.116.255.254158.116.255.2552,046
161158.117.0.0/21158.117.0.1 to 158.117.7.254158.117.7.2552,046
162158.117.8.0/21158.117.8.1 to 158.117.15.254158.117.15.2552,046
163158.117.16.0/21158.117.16.1 to 158.117.23.254158.117.23.2552,046
164158.117.24.0/21158.117.24.1 to 158.117.31.254158.117.31.2552,046
165158.117.32.0/21158.117.32.1 to 158.117.39.254158.117.39.2552,046
166158.117.40.0/21158.117.40.1 to 158.117.47.254158.117.47.2552,046
167158.117.48.0/21158.117.48.1 to 158.117.55.254158.117.55.2552,046
168158.117.56.0/21158.117.56.1 to 158.117.63.254158.117.63.2552,046
169158.117.64.0/21158.117.64.1 to 158.117.71.254158.117.71.2552,046
170158.117.72.0/21158.117.72.1 to 158.117.79.254158.117.79.2552,046
171158.117.80.0/21158.117.80.1 to 158.117.87.254158.117.87.2552,046
172158.117.88.0/21158.117.88.1 to 158.117.95.254158.117.95.2552,046
173158.117.96.0/21158.117.96.1 to 158.117.103.254158.117.103.2552,046
174158.117.104.0/21158.117.104.1 to 158.117.111.254158.117.111.2552,046
175158.117.112.0/21158.117.112.1 to 158.117.119.254158.117.119.2552,046
176158.117.120.0/21158.117.120.1 to 158.117.127.254158.117.127.2552,046
177158.117.128.0/21158.117.128.1 to 158.117.135.254158.117.135.2552,046
178158.117.136.0/21158.117.136.1 to 158.117.143.254158.117.143.2552,046
179158.117.144.0/21158.117.144.1 to 158.117.151.254158.117.151.2552,046
180158.117.152.0/21158.117.152.1 to 158.117.159.254158.117.159.2552,046
181158.117.160.0/21158.117.160.1 to 158.117.167.254158.117.167.2552,046
182158.117.168.0/21158.117.168.1 to 158.117.175.254158.117.175.2552,046
183158.117.176.0/21158.117.176.1 to 158.117.183.254158.117.183.2552,046
184158.117.184.0/21158.117.184.1 to 158.117.191.254158.117.191.2552,046
185158.117.192.0/21158.117.192.1 to 158.117.199.254158.117.199.2552,046
186158.117.200.0/21158.117.200.1 to 158.117.207.254158.117.207.2552,046
187158.117.208.0/21158.117.208.1 to 158.117.215.254158.117.215.2552,046
188158.117.216.0/21158.117.216.1 to 158.117.223.254158.117.223.2552,046
189158.117.224.0/21158.117.224.1 to 158.117.231.254158.117.231.2552,046
190158.117.232.0/21158.117.232.1 to 158.117.239.254158.117.239.2552,046
191158.117.240.0/21158.117.240.1 to 158.117.247.254158.117.247.2552,046
192158.117.248.0/21158.117.248.1 to 158.117.255.254158.117.255.2552,046
193158.118.0.0/21158.118.0.1 to 158.118.7.254158.118.7.2552,046
194158.118.8.0/21158.118.8.1 to 158.118.15.254158.118.15.2552,046
195158.118.16.0/21158.118.16.1 to 158.118.23.254158.118.23.2552,046
196158.118.24.0/21158.118.24.1 to 158.118.31.254158.118.31.2552,046
197158.118.32.0/21158.118.32.1 to 158.118.39.254158.118.39.2552,046
198158.118.40.0/21158.118.40.1 to 158.118.47.254158.118.47.2552,046
199158.118.48.0/21158.118.48.1 to 158.118.55.254158.118.55.2552,046
200158.118.56.0/21158.118.56.1 to 158.118.63.254158.118.63.2552,046
201158.118.64.0/21158.118.64.1 to 158.118.71.254158.118.71.2552,046
202158.118.72.0/21158.118.72.1 to 158.118.79.254158.118.79.2552,046
203158.118.80.0/21158.118.80.1 to 158.118.87.254158.118.87.2552,046
204158.118.88.0/21158.118.88.1 to 158.118.95.254158.118.95.2552,046
205158.118.96.0/21158.118.96.1 to 158.118.103.254158.118.103.2552,046
206158.118.104.0/21158.118.104.1 to 158.118.111.254158.118.111.2552,046
207158.118.112.0/21158.118.112.1 to 158.118.119.254158.118.119.2552,046
208158.118.120.0/21158.118.120.1 to 158.118.127.254158.118.127.2552,046
209158.118.128.0/21158.118.128.1 to 158.118.135.254158.118.135.2552,046
210158.118.136.0/21158.118.136.1 to 158.118.143.254158.118.143.2552,046
211158.118.144.0/21158.118.144.1 to 158.118.151.254158.118.151.2552,046
212158.118.152.0/21158.118.152.1 to 158.118.159.254158.118.159.2552,046
213158.118.160.0/21158.118.160.1 to 158.118.167.254158.118.167.2552,046
214158.118.168.0/21158.118.168.1 to 158.118.175.254158.118.175.2552,046
215158.118.176.0/21158.118.176.1 to 158.118.183.254158.118.183.2552,046
216158.118.184.0/21158.118.184.1 to 158.118.191.254158.118.191.2552,046
217158.118.192.0/21158.118.192.1 to 158.118.199.254158.118.199.2552,046
218158.118.200.0/21158.118.200.1 to 158.118.207.254158.118.207.2552,046
219158.118.208.0/21158.118.208.1 to 158.118.215.254158.118.215.2552,046
220158.118.216.0/21158.118.216.1 to 158.118.223.254158.118.223.2552,046
221158.118.224.0/21158.118.224.1 to 158.118.231.254158.118.231.2552,046
222158.118.232.0/21158.118.232.1 to 158.118.239.254158.118.239.2552,046
223158.118.240.0/21158.118.240.1 to 158.118.247.254158.118.247.2552,046
224158.118.248.0/21158.118.248.1 to 158.118.255.254158.118.255.2552,046
225158.119.0.0/21158.119.0.1 to 158.119.7.254158.119.7.2552,046
226158.119.8.0/21158.119.8.1 to 158.119.15.254158.119.15.2552,046
227158.119.16.0/21158.119.16.1 to 158.119.23.254158.119.23.2552,046
228158.119.24.0/21158.119.24.1 to 158.119.31.254158.119.31.2552,046
229158.119.32.0/21158.119.32.1 to 158.119.39.254158.119.39.2552,046
230158.119.40.0/21158.119.40.1 to 158.119.47.254158.119.47.2552,046
231158.119.48.0/21158.119.48.1 to 158.119.55.254158.119.55.2552,046
232158.119.56.0/21158.119.56.1 to 158.119.63.254158.119.63.2552,046
233158.119.64.0/21158.119.64.1 to 158.119.71.254158.119.71.2552,046
234158.119.72.0/21158.119.72.1 to 158.119.79.254158.119.79.2552,046
235158.119.80.0/21158.119.80.1 to 158.119.87.254158.119.87.2552,046
236158.119.88.0/21158.119.88.1 to 158.119.95.254158.119.95.2552,046
237158.119.96.0/21158.119.96.1 to 158.119.103.254158.119.103.2552,046
238158.119.104.0/21158.119.104.1 to 158.119.111.254158.119.111.2552,046
239158.119.112.0/21158.119.112.1 to 158.119.119.254158.119.119.2552,046
240158.119.120.0/21158.119.120.1 to 158.119.127.254158.119.127.2552,046
241158.119.128.0/21158.119.128.1 to 158.119.135.254158.119.135.2552,046
242158.119.136.0/21158.119.136.1 to 158.119.143.254158.119.143.2552,046
243158.119.144.0/21158.119.144.1 to 158.119.151.254158.119.151.2552,046
244158.119.152.0/21158.119.152.1 to 158.119.159.254158.119.159.2552,046
245158.119.160.0/21158.119.160.1 to 158.119.167.254158.119.167.2552,046
246158.119.168.0/21158.119.168.1 to 158.119.175.254158.119.175.2552,046
247158.119.176.0/21158.119.176.1 to 158.119.183.254158.119.183.2552,046
248158.119.184.0/21158.119.184.1 to 158.119.191.254158.119.191.2552,046
249158.119.192.0/21158.119.192.1 to 158.119.199.254158.119.199.2552,046
250158.119.200.0/21158.119.200.1 to 158.119.207.254158.119.207.2552,046
251158.119.208.0/21158.119.208.1 to 158.119.215.254158.119.215.2552,046
252158.119.216.0/21158.119.216.1 to 158.119.223.254158.119.223.2552,046
253158.119.224.0/21158.119.224.1 to 158.119.231.254158.119.231.2552,046
254158.119.232.0/21158.119.232.1 to 158.119.239.254158.119.239.2552,046
255158.119.240.0/21158.119.240.1 to 158.119.247.254158.119.247.2552,046
256158.119.248.0/21158.119.248.1 to 158.119.255.254158.119.255.2552,046

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.