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.

Network130.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
130.136.0.0
Broadcast address
130.143.255.255
First usable
130.136.0.1
Last usable
130.143.255.254
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 82880000 · Integer 2189950976 to 2190475263
Reverse DNS zones
136.130.in-addr.arpa
137.130.in-addr.arpa
138.130.in-addr.arpa
139.130.in-addr.arpa
140.130.in-addr.arpa
141.130.in-addr.arpa
142.130.in-addr.arpa
143.130.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
Address10000010.10001000.00000000.00000000130.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10000010.10001000.00000000.00000000130.136.0.0
Broadcast10000010.10001111.11111111.11111111130.143.255.255
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)

130.136.0.0/13 makes 256 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1130.136.0.0/21130.136.0.1 to 130.136.7.254130.136.7.2552,046
2130.136.8.0/21130.136.8.1 to 130.136.15.254130.136.15.2552,046
3130.136.16.0/21130.136.16.1 to 130.136.23.254130.136.23.2552,046
4130.136.24.0/21130.136.24.1 to 130.136.31.254130.136.31.2552,046
5130.136.32.0/21130.136.32.1 to 130.136.39.254130.136.39.2552,046
6130.136.40.0/21130.136.40.1 to 130.136.47.254130.136.47.2552,046
7130.136.48.0/21130.136.48.1 to 130.136.55.254130.136.55.2552,046
8130.136.56.0/21130.136.56.1 to 130.136.63.254130.136.63.2552,046
9130.136.64.0/21130.136.64.1 to 130.136.71.254130.136.71.2552,046
10130.136.72.0/21130.136.72.1 to 130.136.79.254130.136.79.2552,046
11130.136.80.0/21130.136.80.1 to 130.136.87.254130.136.87.2552,046
12130.136.88.0/21130.136.88.1 to 130.136.95.254130.136.95.2552,046
13130.136.96.0/21130.136.96.1 to 130.136.103.254130.136.103.2552,046
14130.136.104.0/21130.136.104.1 to 130.136.111.254130.136.111.2552,046
15130.136.112.0/21130.136.112.1 to 130.136.119.254130.136.119.2552,046
16130.136.120.0/21130.136.120.1 to 130.136.127.254130.136.127.2552,046
17130.136.128.0/21130.136.128.1 to 130.136.135.254130.136.135.2552,046
18130.136.136.0/21130.136.136.1 to 130.136.143.254130.136.143.2552,046
19130.136.144.0/21130.136.144.1 to 130.136.151.254130.136.151.2552,046
20130.136.152.0/21130.136.152.1 to 130.136.159.254130.136.159.2552,046
21130.136.160.0/21130.136.160.1 to 130.136.167.254130.136.167.2552,046
22130.136.168.0/21130.136.168.1 to 130.136.175.254130.136.175.2552,046
23130.136.176.0/21130.136.176.1 to 130.136.183.254130.136.183.2552,046
24130.136.184.0/21130.136.184.1 to 130.136.191.254130.136.191.2552,046
25130.136.192.0/21130.136.192.1 to 130.136.199.254130.136.199.2552,046
26130.136.200.0/21130.136.200.1 to 130.136.207.254130.136.207.2552,046
27130.136.208.0/21130.136.208.1 to 130.136.215.254130.136.215.2552,046
28130.136.216.0/21130.136.216.1 to 130.136.223.254130.136.223.2552,046
29130.136.224.0/21130.136.224.1 to 130.136.231.254130.136.231.2552,046
30130.136.232.0/21130.136.232.1 to 130.136.239.254130.136.239.2552,046
31130.136.240.0/21130.136.240.1 to 130.136.247.254130.136.247.2552,046
32130.136.248.0/21130.136.248.1 to 130.136.255.254130.136.255.2552,046
33130.137.0.0/21130.137.0.1 to 130.137.7.254130.137.7.2552,046
34130.137.8.0/21130.137.8.1 to 130.137.15.254130.137.15.2552,046
35130.137.16.0/21130.137.16.1 to 130.137.23.254130.137.23.2552,046
36130.137.24.0/21130.137.24.1 to 130.137.31.254130.137.31.2552,046
37130.137.32.0/21130.137.32.1 to 130.137.39.254130.137.39.2552,046
38130.137.40.0/21130.137.40.1 to 130.137.47.254130.137.47.2552,046
39130.137.48.0/21130.137.48.1 to 130.137.55.254130.137.55.2552,046
40130.137.56.0/21130.137.56.1 to 130.137.63.254130.137.63.2552,046
41130.137.64.0/21130.137.64.1 to 130.137.71.254130.137.71.2552,046
42130.137.72.0/21130.137.72.1 to 130.137.79.254130.137.79.2552,046
43130.137.80.0/21130.137.80.1 to 130.137.87.254130.137.87.2552,046
44130.137.88.0/21130.137.88.1 to 130.137.95.254130.137.95.2552,046
45130.137.96.0/21130.137.96.1 to 130.137.103.254130.137.103.2552,046
46130.137.104.0/21130.137.104.1 to 130.137.111.254130.137.111.2552,046
47130.137.112.0/21130.137.112.1 to 130.137.119.254130.137.119.2552,046
48130.137.120.0/21130.137.120.1 to 130.137.127.254130.137.127.2552,046
49130.137.128.0/21130.137.128.1 to 130.137.135.254130.137.135.2552,046
50130.137.136.0/21130.137.136.1 to 130.137.143.254130.137.143.2552,046
51130.137.144.0/21130.137.144.1 to 130.137.151.254130.137.151.2552,046
52130.137.152.0/21130.137.152.1 to 130.137.159.254130.137.159.2552,046
53130.137.160.0/21130.137.160.1 to 130.137.167.254130.137.167.2552,046
54130.137.168.0/21130.137.168.1 to 130.137.175.254130.137.175.2552,046
55130.137.176.0/21130.137.176.1 to 130.137.183.254130.137.183.2552,046
56130.137.184.0/21130.137.184.1 to 130.137.191.254130.137.191.2552,046
57130.137.192.0/21130.137.192.1 to 130.137.199.254130.137.199.2552,046
58130.137.200.0/21130.137.200.1 to 130.137.207.254130.137.207.2552,046
59130.137.208.0/21130.137.208.1 to 130.137.215.254130.137.215.2552,046
60130.137.216.0/21130.137.216.1 to 130.137.223.254130.137.223.2552,046
61130.137.224.0/21130.137.224.1 to 130.137.231.254130.137.231.2552,046
62130.137.232.0/21130.137.232.1 to 130.137.239.254130.137.239.2552,046
63130.137.240.0/21130.137.240.1 to 130.137.247.254130.137.247.2552,046
64130.137.248.0/21130.137.248.1 to 130.137.255.254130.137.255.2552,046
65130.138.0.0/21130.138.0.1 to 130.138.7.254130.138.7.2552,046
66130.138.8.0/21130.138.8.1 to 130.138.15.254130.138.15.2552,046
67130.138.16.0/21130.138.16.1 to 130.138.23.254130.138.23.2552,046
68130.138.24.0/21130.138.24.1 to 130.138.31.254130.138.31.2552,046
69130.138.32.0/21130.138.32.1 to 130.138.39.254130.138.39.2552,046
70130.138.40.0/21130.138.40.1 to 130.138.47.254130.138.47.2552,046
71130.138.48.0/21130.138.48.1 to 130.138.55.254130.138.55.2552,046
72130.138.56.0/21130.138.56.1 to 130.138.63.254130.138.63.2552,046
73130.138.64.0/21130.138.64.1 to 130.138.71.254130.138.71.2552,046
74130.138.72.0/21130.138.72.1 to 130.138.79.254130.138.79.2552,046
75130.138.80.0/21130.138.80.1 to 130.138.87.254130.138.87.2552,046
76130.138.88.0/21130.138.88.1 to 130.138.95.254130.138.95.2552,046
77130.138.96.0/21130.138.96.1 to 130.138.103.254130.138.103.2552,046
78130.138.104.0/21130.138.104.1 to 130.138.111.254130.138.111.2552,046
79130.138.112.0/21130.138.112.1 to 130.138.119.254130.138.119.2552,046
80130.138.120.0/21130.138.120.1 to 130.138.127.254130.138.127.2552,046
81130.138.128.0/21130.138.128.1 to 130.138.135.254130.138.135.2552,046
82130.138.136.0/21130.138.136.1 to 130.138.143.254130.138.143.2552,046
83130.138.144.0/21130.138.144.1 to 130.138.151.254130.138.151.2552,046
84130.138.152.0/21130.138.152.1 to 130.138.159.254130.138.159.2552,046
85130.138.160.0/21130.138.160.1 to 130.138.167.254130.138.167.2552,046
86130.138.168.0/21130.138.168.1 to 130.138.175.254130.138.175.2552,046
87130.138.176.0/21130.138.176.1 to 130.138.183.254130.138.183.2552,046
88130.138.184.0/21130.138.184.1 to 130.138.191.254130.138.191.2552,046
89130.138.192.0/21130.138.192.1 to 130.138.199.254130.138.199.2552,046
90130.138.200.0/21130.138.200.1 to 130.138.207.254130.138.207.2552,046
91130.138.208.0/21130.138.208.1 to 130.138.215.254130.138.215.2552,046
92130.138.216.0/21130.138.216.1 to 130.138.223.254130.138.223.2552,046
93130.138.224.0/21130.138.224.1 to 130.138.231.254130.138.231.2552,046
94130.138.232.0/21130.138.232.1 to 130.138.239.254130.138.239.2552,046
95130.138.240.0/21130.138.240.1 to 130.138.247.254130.138.247.2552,046
96130.138.248.0/21130.138.248.1 to 130.138.255.254130.138.255.2552,046
97130.139.0.0/21130.139.0.1 to 130.139.7.254130.139.7.2552,046
98130.139.8.0/21130.139.8.1 to 130.139.15.254130.139.15.2552,046
99130.139.16.0/21130.139.16.1 to 130.139.23.254130.139.23.2552,046
100130.139.24.0/21130.139.24.1 to 130.139.31.254130.139.31.2552,046
101130.139.32.0/21130.139.32.1 to 130.139.39.254130.139.39.2552,046
102130.139.40.0/21130.139.40.1 to 130.139.47.254130.139.47.2552,046
103130.139.48.0/21130.139.48.1 to 130.139.55.254130.139.55.2552,046
104130.139.56.0/21130.139.56.1 to 130.139.63.254130.139.63.2552,046
105130.139.64.0/21130.139.64.1 to 130.139.71.254130.139.71.2552,046
106130.139.72.0/21130.139.72.1 to 130.139.79.254130.139.79.2552,046
107130.139.80.0/21130.139.80.1 to 130.139.87.254130.139.87.2552,046
108130.139.88.0/21130.139.88.1 to 130.139.95.254130.139.95.2552,046
109130.139.96.0/21130.139.96.1 to 130.139.103.254130.139.103.2552,046
110130.139.104.0/21130.139.104.1 to 130.139.111.254130.139.111.2552,046
111130.139.112.0/21130.139.112.1 to 130.139.119.254130.139.119.2552,046
112130.139.120.0/21130.139.120.1 to 130.139.127.254130.139.127.2552,046
113130.139.128.0/21130.139.128.1 to 130.139.135.254130.139.135.2552,046
114130.139.136.0/21130.139.136.1 to 130.139.143.254130.139.143.2552,046
115130.139.144.0/21130.139.144.1 to 130.139.151.254130.139.151.2552,046
116130.139.152.0/21130.139.152.1 to 130.139.159.254130.139.159.2552,046
117130.139.160.0/21130.139.160.1 to 130.139.167.254130.139.167.2552,046
118130.139.168.0/21130.139.168.1 to 130.139.175.254130.139.175.2552,046
119130.139.176.0/21130.139.176.1 to 130.139.183.254130.139.183.2552,046
120130.139.184.0/21130.139.184.1 to 130.139.191.254130.139.191.2552,046
121130.139.192.0/21130.139.192.1 to 130.139.199.254130.139.199.2552,046
122130.139.200.0/21130.139.200.1 to 130.139.207.254130.139.207.2552,046
123130.139.208.0/21130.139.208.1 to 130.139.215.254130.139.215.2552,046
124130.139.216.0/21130.139.216.1 to 130.139.223.254130.139.223.2552,046
125130.139.224.0/21130.139.224.1 to 130.139.231.254130.139.231.2552,046
126130.139.232.0/21130.139.232.1 to 130.139.239.254130.139.239.2552,046
127130.139.240.0/21130.139.240.1 to 130.139.247.254130.139.247.2552,046
128130.139.248.0/21130.139.248.1 to 130.139.255.254130.139.255.2552,046
129130.140.0.0/21130.140.0.1 to 130.140.7.254130.140.7.2552,046
130130.140.8.0/21130.140.8.1 to 130.140.15.254130.140.15.2552,046
131130.140.16.0/21130.140.16.1 to 130.140.23.254130.140.23.2552,046
132130.140.24.0/21130.140.24.1 to 130.140.31.254130.140.31.2552,046
133130.140.32.0/21130.140.32.1 to 130.140.39.254130.140.39.2552,046
134130.140.40.0/21130.140.40.1 to 130.140.47.254130.140.47.2552,046
135130.140.48.0/21130.140.48.1 to 130.140.55.254130.140.55.2552,046
136130.140.56.0/21130.140.56.1 to 130.140.63.254130.140.63.2552,046
137130.140.64.0/21130.140.64.1 to 130.140.71.254130.140.71.2552,046
138130.140.72.0/21130.140.72.1 to 130.140.79.254130.140.79.2552,046
139130.140.80.0/21130.140.80.1 to 130.140.87.254130.140.87.2552,046
140130.140.88.0/21130.140.88.1 to 130.140.95.254130.140.95.2552,046
141130.140.96.0/21130.140.96.1 to 130.140.103.254130.140.103.2552,046
142130.140.104.0/21130.140.104.1 to 130.140.111.254130.140.111.2552,046
143130.140.112.0/21130.140.112.1 to 130.140.119.254130.140.119.2552,046
144130.140.120.0/21130.140.120.1 to 130.140.127.254130.140.127.2552,046
145130.140.128.0/21130.140.128.1 to 130.140.135.254130.140.135.2552,046
146130.140.136.0/21130.140.136.1 to 130.140.143.254130.140.143.2552,046
147130.140.144.0/21130.140.144.1 to 130.140.151.254130.140.151.2552,046
148130.140.152.0/21130.140.152.1 to 130.140.159.254130.140.159.2552,046
149130.140.160.0/21130.140.160.1 to 130.140.167.254130.140.167.2552,046
150130.140.168.0/21130.140.168.1 to 130.140.175.254130.140.175.2552,046
151130.140.176.0/21130.140.176.1 to 130.140.183.254130.140.183.2552,046
152130.140.184.0/21130.140.184.1 to 130.140.191.254130.140.191.2552,046
153130.140.192.0/21130.140.192.1 to 130.140.199.254130.140.199.2552,046
154130.140.200.0/21130.140.200.1 to 130.140.207.254130.140.207.2552,046
155130.140.208.0/21130.140.208.1 to 130.140.215.254130.140.215.2552,046
156130.140.216.0/21130.140.216.1 to 130.140.223.254130.140.223.2552,046
157130.140.224.0/21130.140.224.1 to 130.140.231.254130.140.231.2552,046
158130.140.232.0/21130.140.232.1 to 130.140.239.254130.140.239.2552,046
159130.140.240.0/21130.140.240.1 to 130.140.247.254130.140.247.2552,046
160130.140.248.0/21130.140.248.1 to 130.140.255.254130.140.255.2552,046
161130.141.0.0/21130.141.0.1 to 130.141.7.254130.141.7.2552,046
162130.141.8.0/21130.141.8.1 to 130.141.15.254130.141.15.2552,046
163130.141.16.0/21130.141.16.1 to 130.141.23.254130.141.23.2552,046
164130.141.24.0/21130.141.24.1 to 130.141.31.254130.141.31.2552,046
165130.141.32.0/21130.141.32.1 to 130.141.39.254130.141.39.2552,046
166130.141.40.0/21130.141.40.1 to 130.141.47.254130.141.47.2552,046
167130.141.48.0/21130.141.48.1 to 130.141.55.254130.141.55.2552,046
168130.141.56.0/21130.141.56.1 to 130.141.63.254130.141.63.2552,046
169130.141.64.0/21130.141.64.1 to 130.141.71.254130.141.71.2552,046
170130.141.72.0/21130.141.72.1 to 130.141.79.254130.141.79.2552,046
171130.141.80.0/21130.141.80.1 to 130.141.87.254130.141.87.2552,046
172130.141.88.0/21130.141.88.1 to 130.141.95.254130.141.95.2552,046
173130.141.96.0/21130.141.96.1 to 130.141.103.254130.141.103.2552,046
174130.141.104.0/21130.141.104.1 to 130.141.111.254130.141.111.2552,046
175130.141.112.0/21130.141.112.1 to 130.141.119.254130.141.119.2552,046
176130.141.120.0/21130.141.120.1 to 130.141.127.254130.141.127.2552,046
177130.141.128.0/21130.141.128.1 to 130.141.135.254130.141.135.2552,046
178130.141.136.0/21130.141.136.1 to 130.141.143.254130.141.143.2552,046
179130.141.144.0/21130.141.144.1 to 130.141.151.254130.141.151.2552,046
180130.141.152.0/21130.141.152.1 to 130.141.159.254130.141.159.2552,046
181130.141.160.0/21130.141.160.1 to 130.141.167.254130.141.167.2552,046
182130.141.168.0/21130.141.168.1 to 130.141.175.254130.141.175.2552,046
183130.141.176.0/21130.141.176.1 to 130.141.183.254130.141.183.2552,046
184130.141.184.0/21130.141.184.1 to 130.141.191.254130.141.191.2552,046
185130.141.192.0/21130.141.192.1 to 130.141.199.254130.141.199.2552,046
186130.141.200.0/21130.141.200.1 to 130.141.207.254130.141.207.2552,046
187130.141.208.0/21130.141.208.1 to 130.141.215.254130.141.215.2552,046
188130.141.216.0/21130.141.216.1 to 130.141.223.254130.141.223.2552,046
189130.141.224.0/21130.141.224.1 to 130.141.231.254130.141.231.2552,046
190130.141.232.0/21130.141.232.1 to 130.141.239.254130.141.239.2552,046
191130.141.240.0/21130.141.240.1 to 130.141.247.254130.141.247.2552,046
192130.141.248.0/21130.141.248.1 to 130.141.255.254130.141.255.2552,046
193130.142.0.0/21130.142.0.1 to 130.142.7.254130.142.7.2552,046
194130.142.8.0/21130.142.8.1 to 130.142.15.254130.142.15.2552,046
195130.142.16.0/21130.142.16.1 to 130.142.23.254130.142.23.2552,046
196130.142.24.0/21130.142.24.1 to 130.142.31.254130.142.31.2552,046
197130.142.32.0/21130.142.32.1 to 130.142.39.254130.142.39.2552,046
198130.142.40.0/21130.142.40.1 to 130.142.47.254130.142.47.2552,046
199130.142.48.0/21130.142.48.1 to 130.142.55.254130.142.55.2552,046
200130.142.56.0/21130.142.56.1 to 130.142.63.254130.142.63.2552,046
201130.142.64.0/21130.142.64.1 to 130.142.71.254130.142.71.2552,046
202130.142.72.0/21130.142.72.1 to 130.142.79.254130.142.79.2552,046
203130.142.80.0/21130.142.80.1 to 130.142.87.254130.142.87.2552,046
204130.142.88.0/21130.142.88.1 to 130.142.95.254130.142.95.2552,046
205130.142.96.0/21130.142.96.1 to 130.142.103.254130.142.103.2552,046
206130.142.104.0/21130.142.104.1 to 130.142.111.254130.142.111.2552,046
207130.142.112.0/21130.142.112.1 to 130.142.119.254130.142.119.2552,046
208130.142.120.0/21130.142.120.1 to 130.142.127.254130.142.127.2552,046
209130.142.128.0/21130.142.128.1 to 130.142.135.254130.142.135.2552,046
210130.142.136.0/21130.142.136.1 to 130.142.143.254130.142.143.2552,046
211130.142.144.0/21130.142.144.1 to 130.142.151.254130.142.151.2552,046
212130.142.152.0/21130.142.152.1 to 130.142.159.254130.142.159.2552,046
213130.142.160.0/21130.142.160.1 to 130.142.167.254130.142.167.2552,046
214130.142.168.0/21130.142.168.1 to 130.142.175.254130.142.175.2552,046
215130.142.176.0/21130.142.176.1 to 130.142.183.254130.142.183.2552,046
216130.142.184.0/21130.142.184.1 to 130.142.191.254130.142.191.2552,046
217130.142.192.0/21130.142.192.1 to 130.142.199.254130.142.199.2552,046
218130.142.200.0/21130.142.200.1 to 130.142.207.254130.142.207.2552,046
219130.142.208.0/21130.142.208.1 to 130.142.215.254130.142.215.2552,046
220130.142.216.0/21130.142.216.1 to 130.142.223.254130.142.223.2552,046
221130.142.224.0/21130.142.224.1 to 130.142.231.254130.142.231.2552,046
222130.142.232.0/21130.142.232.1 to 130.142.239.254130.142.239.2552,046
223130.142.240.0/21130.142.240.1 to 130.142.247.254130.142.247.2552,046
224130.142.248.0/21130.142.248.1 to 130.142.255.254130.142.255.2552,046
225130.143.0.0/21130.143.0.1 to 130.143.7.254130.143.7.2552,046
226130.143.8.0/21130.143.8.1 to 130.143.15.254130.143.15.2552,046
227130.143.16.0/21130.143.16.1 to 130.143.23.254130.143.23.2552,046
228130.143.24.0/21130.143.24.1 to 130.143.31.254130.143.31.2552,046
229130.143.32.0/21130.143.32.1 to 130.143.39.254130.143.39.2552,046
230130.143.40.0/21130.143.40.1 to 130.143.47.254130.143.47.2552,046
231130.143.48.0/21130.143.48.1 to 130.143.55.254130.143.55.2552,046
232130.143.56.0/21130.143.56.1 to 130.143.63.254130.143.63.2552,046
233130.143.64.0/21130.143.64.1 to 130.143.71.254130.143.71.2552,046
234130.143.72.0/21130.143.72.1 to 130.143.79.254130.143.79.2552,046
235130.143.80.0/21130.143.80.1 to 130.143.87.254130.143.87.2552,046
236130.143.88.0/21130.143.88.1 to 130.143.95.254130.143.95.2552,046
237130.143.96.0/21130.143.96.1 to 130.143.103.254130.143.103.2552,046
238130.143.104.0/21130.143.104.1 to 130.143.111.254130.143.111.2552,046
239130.143.112.0/21130.143.112.1 to 130.143.119.254130.143.119.2552,046
240130.143.120.0/21130.143.120.1 to 130.143.127.254130.143.127.2552,046
241130.143.128.0/21130.143.128.1 to 130.143.135.254130.143.135.2552,046
242130.143.136.0/21130.143.136.1 to 130.143.143.254130.143.143.2552,046
243130.143.144.0/21130.143.144.1 to 130.143.151.254130.143.151.2552,046
244130.143.152.0/21130.143.152.1 to 130.143.159.254130.143.159.2552,046
245130.143.160.0/21130.143.160.1 to 130.143.167.254130.143.167.2552,046
246130.143.168.0/21130.143.168.1 to 130.143.175.254130.143.175.2552,046
247130.143.176.0/21130.143.176.1 to 130.143.183.254130.143.183.2552,046
248130.143.184.0/21130.143.184.1 to 130.143.191.254130.143.191.2552,046
249130.143.192.0/21130.143.192.1 to 130.143.199.254130.143.199.2552,046
250130.143.200.0/21130.143.200.1 to 130.143.207.254130.143.207.2552,046
251130.143.208.0/21130.143.208.1 to 130.143.215.254130.143.215.2552,046
252130.143.216.0/21130.143.216.1 to 130.143.223.254130.143.223.2552,046
253130.143.224.0/21130.143.224.1 to 130.143.231.254130.143.231.2552,046
254130.143.232.0/21130.143.232.1 to 130.143.239.254130.143.239.2552,046
255130.143.240.0/21130.143.240.1 to 130.143.247.254130.143.247.2552,046
256130.143.248.0/21130.143.248.1 to 130.143.255.254130.143.255.2552,046

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.