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.

Network136.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
136.0.0.0
Broadcast address
136.127.255.255
First usable
136.0.0.1
Last usable
136.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
B (default /16)
As numbers
Hex 88000000 · Integer 2281701376 to 2290089983
Reverse DNS zones
0.136.in-addr.arpa
1.136.in-addr.arpa
2.136.in-addr.arpa
3.136.in-addr.arpa
4.136.in-addr.arpa
5.136.in-addr.arpa
6.136.in-addr.arpa
7.136.in-addr.arpa
8.136.in-addr.arpa
9.136.in-addr.arpa
10.136.in-addr.arpa
11.136.in-addr.arpa
12.136.in-addr.arpa
13.136.in-addr.arpa
14.136.in-addr.arpa
15.136.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001000.00000000.00000000.00000000136.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10001000.00000000.00000000.00000000136.0.0.0
Broadcast10001000.01111111.11111111.11111111136.127.255.255
Split into smaller subnets/20
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

136.0.0.0/9 makes 2,048 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1136.0.0.0/20136.0.0.1 to 136.0.15.254136.0.15.2554,094
2136.0.16.0/20136.0.16.1 to 136.0.31.254136.0.31.2554,094
3136.0.32.0/20136.0.32.1 to 136.0.47.254136.0.47.2554,094
4136.0.48.0/20136.0.48.1 to 136.0.63.254136.0.63.2554,094
5136.0.64.0/20136.0.64.1 to 136.0.79.254136.0.79.2554,094
6136.0.80.0/20136.0.80.1 to 136.0.95.254136.0.95.2554,094
7136.0.96.0/20136.0.96.1 to 136.0.111.254136.0.111.2554,094
8136.0.112.0/20136.0.112.1 to 136.0.127.254136.0.127.2554,094
9136.0.128.0/20136.0.128.1 to 136.0.143.254136.0.143.2554,094
10136.0.144.0/20136.0.144.1 to 136.0.159.254136.0.159.2554,094
11136.0.160.0/20136.0.160.1 to 136.0.175.254136.0.175.2554,094
12136.0.176.0/20136.0.176.1 to 136.0.191.254136.0.191.2554,094
13136.0.192.0/20136.0.192.1 to 136.0.207.254136.0.207.2554,094
14136.0.208.0/20136.0.208.1 to 136.0.223.254136.0.223.2554,094
15136.0.224.0/20136.0.224.1 to 136.0.239.254136.0.239.2554,094
16136.0.240.0/20136.0.240.1 to 136.0.255.254136.0.255.2554,094
17136.1.0.0/20136.1.0.1 to 136.1.15.254136.1.15.2554,094
18136.1.16.0/20136.1.16.1 to 136.1.31.254136.1.31.2554,094
19136.1.32.0/20136.1.32.1 to 136.1.47.254136.1.47.2554,094
20136.1.48.0/20136.1.48.1 to 136.1.63.254136.1.63.2554,094
21136.1.64.0/20136.1.64.1 to 136.1.79.254136.1.79.2554,094
22136.1.80.0/20136.1.80.1 to 136.1.95.254136.1.95.2554,094
23136.1.96.0/20136.1.96.1 to 136.1.111.254136.1.111.2554,094
24136.1.112.0/20136.1.112.1 to 136.1.127.254136.1.127.2554,094
25136.1.128.0/20136.1.128.1 to 136.1.143.254136.1.143.2554,094
26136.1.144.0/20136.1.144.1 to 136.1.159.254136.1.159.2554,094
27136.1.160.0/20136.1.160.1 to 136.1.175.254136.1.175.2554,094
28136.1.176.0/20136.1.176.1 to 136.1.191.254136.1.191.2554,094
29136.1.192.0/20136.1.192.1 to 136.1.207.254136.1.207.2554,094
30136.1.208.0/20136.1.208.1 to 136.1.223.254136.1.223.2554,094
31136.1.224.0/20136.1.224.1 to 136.1.239.254136.1.239.2554,094
32136.1.240.0/20136.1.240.1 to 136.1.255.254136.1.255.2554,094
33136.2.0.0/20136.2.0.1 to 136.2.15.254136.2.15.2554,094
34136.2.16.0/20136.2.16.1 to 136.2.31.254136.2.31.2554,094
35136.2.32.0/20136.2.32.1 to 136.2.47.254136.2.47.2554,094
36136.2.48.0/20136.2.48.1 to 136.2.63.254136.2.63.2554,094
37136.2.64.0/20136.2.64.1 to 136.2.79.254136.2.79.2554,094
38136.2.80.0/20136.2.80.1 to 136.2.95.254136.2.95.2554,094
39136.2.96.0/20136.2.96.1 to 136.2.111.254136.2.111.2554,094
40136.2.112.0/20136.2.112.1 to 136.2.127.254136.2.127.2554,094
41136.2.128.0/20136.2.128.1 to 136.2.143.254136.2.143.2554,094
42136.2.144.0/20136.2.144.1 to 136.2.159.254136.2.159.2554,094
43136.2.160.0/20136.2.160.1 to 136.2.175.254136.2.175.2554,094
44136.2.176.0/20136.2.176.1 to 136.2.191.254136.2.191.2554,094
45136.2.192.0/20136.2.192.1 to 136.2.207.254136.2.207.2554,094
46136.2.208.0/20136.2.208.1 to 136.2.223.254136.2.223.2554,094
47136.2.224.0/20136.2.224.1 to 136.2.239.254136.2.239.2554,094
48136.2.240.0/20136.2.240.1 to 136.2.255.254136.2.255.2554,094
49136.3.0.0/20136.3.0.1 to 136.3.15.254136.3.15.2554,094
50136.3.16.0/20136.3.16.1 to 136.3.31.254136.3.31.2554,094
51136.3.32.0/20136.3.32.1 to 136.3.47.254136.3.47.2554,094
52136.3.48.0/20136.3.48.1 to 136.3.63.254136.3.63.2554,094
53136.3.64.0/20136.3.64.1 to 136.3.79.254136.3.79.2554,094
54136.3.80.0/20136.3.80.1 to 136.3.95.254136.3.95.2554,094
55136.3.96.0/20136.3.96.1 to 136.3.111.254136.3.111.2554,094
56136.3.112.0/20136.3.112.1 to 136.3.127.254136.3.127.2554,094
57136.3.128.0/20136.3.128.1 to 136.3.143.254136.3.143.2554,094
58136.3.144.0/20136.3.144.1 to 136.3.159.254136.3.159.2554,094
59136.3.160.0/20136.3.160.1 to 136.3.175.254136.3.175.2554,094
60136.3.176.0/20136.3.176.1 to 136.3.191.254136.3.191.2554,094
61136.3.192.0/20136.3.192.1 to 136.3.207.254136.3.207.2554,094
62136.3.208.0/20136.3.208.1 to 136.3.223.254136.3.223.2554,094
63136.3.224.0/20136.3.224.1 to 136.3.239.254136.3.239.2554,094
64136.3.240.0/20136.3.240.1 to 136.3.255.254136.3.255.2554,094
65136.4.0.0/20136.4.0.1 to 136.4.15.254136.4.15.2554,094
66136.4.16.0/20136.4.16.1 to 136.4.31.254136.4.31.2554,094
67136.4.32.0/20136.4.32.1 to 136.4.47.254136.4.47.2554,094
68136.4.48.0/20136.4.48.1 to 136.4.63.254136.4.63.2554,094
69136.4.64.0/20136.4.64.1 to 136.4.79.254136.4.79.2554,094
70136.4.80.0/20136.4.80.1 to 136.4.95.254136.4.95.2554,094
71136.4.96.0/20136.4.96.1 to 136.4.111.254136.4.111.2554,094
72136.4.112.0/20136.4.112.1 to 136.4.127.254136.4.127.2554,094
73136.4.128.0/20136.4.128.1 to 136.4.143.254136.4.143.2554,094
74136.4.144.0/20136.4.144.1 to 136.4.159.254136.4.159.2554,094
75136.4.160.0/20136.4.160.1 to 136.4.175.254136.4.175.2554,094
76136.4.176.0/20136.4.176.1 to 136.4.191.254136.4.191.2554,094
77136.4.192.0/20136.4.192.1 to 136.4.207.254136.4.207.2554,094
78136.4.208.0/20136.4.208.1 to 136.4.223.254136.4.223.2554,094
79136.4.224.0/20136.4.224.1 to 136.4.239.254136.4.239.2554,094
80136.4.240.0/20136.4.240.1 to 136.4.255.254136.4.255.2554,094
81136.5.0.0/20136.5.0.1 to 136.5.15.254136.5.15.2554,094
82136.5.16.0/20136.5.16.1 to 136.5.31.254136.5.31.2554,094
83136.5.32.0/20136.5.32.1 to 136.5.47.254136.5.47.2554,094
84136.5.48.0/20136.5.48.1 to 136.5.63.254136.5.63.2554,094
85136.5.64.0/20136.5.64.1 to 136.5.79.254136.5.79.2554,094
86136.5.80.0/20136.5.80.1 to 136.5.95.254136.5.95.2554,094
87136.5.96.0/20136.5.96.1 to 136.5.111.254136.5.111.2554,094
88136.5.112.0/20136.5.112.1 to 136.5.127.254136.5.127.2554,094
89136.5.128.0/20136.5.128.1 to 136.5.143.254136.5.143.2554,094
90136.5.144.0/20136.5.144.1 to 136.5.159.254136.5.159.2554,094
91136.5.160.0/20136.5.160.1 to 136.5.175.254136.5.175.2554,094
92136.5.176.0/20136.5.176.1 to 136.5.191.254136.5.191.2554,094
93136.5.192.0/20136.5.192.1 to 136.5.207.254136.5.207.2554,094
94136.5.208.0/20136.5.208.1 to 136.5.223.254136.5.223.2554,094
95136.5.224.0/20136.5.224.1 to 136.5.239.254136.5.239.2554,094
96136.5.240.0/20136.5.240.1 to 136.5.255.254136.5.255.2554,094
97136.6.0.0/20136.6.0.1 to 136.6.15.254136.6.15.2554,094
98136.6.16.0/20136.6.16.1 to 136.6.31.254136.6.31.2554,094
99136.6.32.0/20136.6.32.1 to 136.6.47.254136.6.47.2554,094
100136.6.48.0/20136.6.48.1 to 136.6.63.254136.6.63.2554,094
101136.6.64.0/20136.6.64.1 to 136.6.79.254136.6.79.2554,094
102136.6.80.0/20136.6.80.1 to 136.6.95.254136.6.95.2554,094
103136.6.96.0/20136.6.96.1 to 136.6.111.254136.6.111.2554,094
104136.6.112.0/20136.6.112.1 to 136.6.127.254136.6.127.2554,094
105136.6.128.0/20136.6.128.1 to 136.6.143.254136.6.143.2554,094
106136.6.144.0/20136.6.144.1 to 136.6.159.254136.6.159.2554,094
107136.6.160.0/20136.6.160.1 to 136.6.175.254136.6.175.2554,094
108136.6.176.0/20136.6.176.1 to 136.6.191.254136.6.191.2554,094
109136.6.192.0/20136.6.192.1 to 136.6.207.254136.6.207.2554,094
110136.6.208.0/20136.6.208.1 to 136.6.223.254136.6.223.2554,094
111136.6.224.0/20136.6.224.1 to 136.6.239.254136.6.239.2554,094
112136.6.240.0/20136.6.240.1 to 136.6.255.254136.6.255.2554,094
113136.7.0.0/20136.7.0.1 to 136.7.15.254136.7.15.2554,094
114136.7.16.0/20136.7.16.1 to 136.7.31.254136.7.31.2554,094
115136.7.32.0/20136.7.32.1 to 136.7.47.254136.7.47.2554,094
116136.7.48.0/20136.7.48.1 to 136.7.63.254136.7.63.2554,094
117136.7.64.0/20136.7.64.1 to 136.7.79.254136.7.79.2554,094
118136.7.80.0/20136.7.80.1 to 136.7.95.254136.7.95.2554,094
119136.7.96.0/20136.7.96.1 to 136.7.111.254136.7.111.2554,094
120136.7.112.0/20136.7.112.1 to 136.7.127.254136.7.127.2554,094
121136.7.128.0/20136.7.128.1 to 136.7.143.254136.7.143.2554,094
122136.7.144.0/20136.7.144.1 to 136.7.159.254136.7.159.2554,094
123136.7.160.0/20136.7.160.1 to 136.7.175.254136.7.175.2554,094
124136.7.176.0/20136.7.176.1 to 136.7.191.254136.7.191.2554,094
125136.7.192.0/20136.7.192.1 to 136.7.207.254136.7.207.2554,094
126136.7.208.0/20136.7.208.1 to 136.7.223.254136.7.223.2554,094
127136.7.224.0/20136.7.224.1 to 136.7.239.254136.7.239.2554,094
128136.7.240.0/20136.7.240.1 to 136.7.255.254136.7.255.2554,094
129136.8.0.0/20136.8.0.1 to 136.8.15.254136.8.15.2554,094
130136.8.16.0/20136.8.16.1 to 136.8.31.254136.8.31.2554,094
131136.8.32.0/20136.8.32.1 to 136.8.47.254136.8.47.2554,094
132136.8.48.0/20136.8.48.1 to 136.8.63.254136.8.63.2554,094
133136.8.64.0/20136.8.64.1 to 136.8.79.254136.8.79.2554,094
134136.8.80.0/20136.8.80.1 to 136.8.95.254136.8.95.2554,094
135136.8.96.0/20136.8.96.1 to 136.8.111.254136.8.111.2554,094
136136.8.112.0/20136.8.112.1 to 136.8.127.254136.8.127.2554,094
137136.8.128.0/20136.8.128.1 to 136.8.143.254136.8.143.2554,094
138136.8.144.0/20136.8.144.1 to 136.8.159.254136.8.159.2554,094
139136.8.160.0/20136.8.160.1 to 136.8.175.254136.8.175.2554,094
140136.8.176.0/20136.8.176.1 to 136.8.191.254136.8.191.2554,094
141136.8.192.0/20136.8.192.1 to 136.8.207.254136.8.207.2554,094
142136.8.208.0/20136.8.208.1 to 136.8.223.254136.8.223.2554,094
143136.8.224.0/20136.8.224.1 to 136.8.239.254136.8.239.2554,094
144136.8.240.0/20136.8.240.1 to 136.8.255.254136.8.255.2554,094
145136.9.0.0/20136.9.0.1 to 136.9.15.254136.9.15.2554,094
146136.9.16.0/20136.9.16.1 to 136.9.31.254136.9.31.2554,094
147136.9.32.0/20136.9.32.1 to 136.9.47.254136.9.47.2554,094
148136.9.48.0/20136.9.48.1 to 136.9.63.254136.9.63.2554,094
149136.9.64.0/20136.9.64.1 to 136.9.79.254136.9.79.2554,094
150136.9.80.0/20136.9.80.1 to 136.9.95.254136.9.95.2554,094
151136.9.96.0/20136.9.96.1 to 136.9.111.254136.9.111.2554,094
152136.9.112.0/20136.9.112.1 to 136.9.127.254136.9.127.2554,094
153136.9.128.0/20136.9.128.1 to 136.9.143.254136.9.143.2554,094
154136.9.144.0/20136.9.144.1 to 136.9.159.254136.9.159.2554,094
155136.9.160.0/20136.9.160.1 to 136.9.175.254136.9.175.2554,094
156136.9.176.0/20136.9.176.1 to 136.9.191.254136.9.191.2554,094
157136.9.192.0/20136.9.192.1 to 136.9.207.254136.9.207.2554,094
158136.9.208.0/20136.9.208.1 to 136.9.223.254136.9.223.2554,094
159136.9.224.0/20136.9.224.1 to 136.9.239.254136.9.239.2554,094
160136.9.240.0/20136.9.240.1 to 136.9.255.254136.9.255.2554,094
161136.10.0.0/20136.10.0.1 to 136.10.15.254136.10.15.2554,094
162136.10.16.0/20136.10.16.1 to 136.10.31.254136.10.31.2554,094
163136.10.32.0/20136.10.32.1 to 136.10.47.254136.10.47.2554,094
164136.10.48.0/20136.10.48.1 to 136.10.63.254136.10.63.2554,094
165136.10.64.0/20136.10.64.1 to 136.10.79.254136.10.79.2554,094
166136.10.80.0/20136.10.80.1 to 136.10.95.254136.10.95.2554,094
167136.10.96.0/20136.10.96.1 to 136.10.111.254136.10.111.2554,094
168136.10.112.0/20136.10.112.1 to 136.10.127.254136.10.127.2554,094
169136.10.128.0/20136.10.128.1 to 136.10.143.254136.10.143.2554,094
170136.10.144.0/20136.10.144.1 to 136.10.159.254136.10.159.2554,094
171136.10.160.0/20136.10.160.1 to 136.10.175.254136.10.175.2554,094
172136.10.176.0/20136.10.176.1 to 136.10.191.254136.10.191.2554,094
173136.10.192.0/20136.10.192.1 to 136.10.207.254136.10.207.2554,094
174136.10.208.0/20136.10.208.1 to 136.10.223.254136.10.223.2554,094
175136.10.224.0/20136.10.224.1 to 136.10.239.254136.10.239.2554,094
176136.10.240.0/20136.10.240.1 to 136.10.255.254136.10.255.2554,094
177136.11.0.0/20136.11.0.1 to 136.11.15.254136.11.15.2554,094
178136.11.16.0/20136.11.16.1 to 136.11.31.254136.11.31.2554,094
179136.11.32.0/20136.11.32.1 to 136.11.47.254136.11.47.2554,094
180136.11.48.0/20136.11.48.1 to 136.11.63.254136.11.63.2554,094
181136.11.64.0/20136.11.64.1 to 136.11.79.254136.11.79.2554,094
182136.11.80.0/20136.11.80.1 to 136.11.95.254136.11.95.2554,094
183136.11.96.0/20136.11.96.1 to 136.11.111.254136.11.111.2554,094
184136.11.112.0/20136.11.112.1 to 136.11.127.254136.11.127.2554,094
185136.11.128.0/20136.11.128.1 to 136.11.143.254136.11.143.2554,094
186136.11.144.0/20136.11.144.1 to 136.11.159.254136.11.159.2554,094
187136.11.160.0/20136.11.160.1 to 136.11.175.254136.11.175.2554,094
188136.11.176.0/20136.11.176.1 to 136.11.191.254136.11.191.2554,094
189136.11.192.0/20136.11.192.1 to 136.11.207.254136.11.207.2554,094
190136.11.208.0/20136.11.208.1 to 136.11.223.254136.11.223.2554,094
191136.11.224.0/20136.11.224.1 to 136.11.239.254136.11.239.2554,094
192136.11.240.0/20136.11.240.1 to 136.11.255.254136.11.255.2554,094
193136.12.0.0/20136.12.0.1 to 136.12.15.254136.12.15.2554,094
194136.12.16.0/20136.12.16.1 to 136.12.31.254136.12.31.2554,094
195136.12.32.0/20136.12.32.1 to 136.12.47.254136.12.47.2554,094
196136.12.48.0/20136.12.48.1 to 136.12.63.254136.12.63.2554,094
197136.12.64.0/20136.12.64.1 to 136.12.79.254136.12.79.2554,094
198136.12.80.0/20136.12.80.1 to 136.12.95.254136.12.95.2554,094
199136.12.96.0/20136.12.96.1 to 136.12.111.254136.12.111.2554,094
200136.12.112.0/20136.12.112.1 to 136.12.127.254136.12.127.2554,094
201136.12.128.0/20136.12.128.1 to 136.12.143.254136.12.143.2554,094
202136.12.144.0/20136.12.144.1 to 136.12.159.254136.12.159.2554,094
203136.12.160.0/20136.12.160.1 to 136.12.175.254136.12.175.2554,094
204136.12.176.0/20136.12.176.1 to 136.12.191.254136.12.191.2554,094
205136.12.192.0/20136.12.192.1 to 136.12.207.254136.12.207.2554,094
206136.12.208.0/20136.12.208.1 to 136.12.223.254136.12.223.2554,094
207136.12.224.0/20136.12.224.1 to 136.12.239.254136.12.239.2554,094
208136.12.240.0/20136.12.240.1 to 136.12.255.254136.12.255.2554,094
209136.13.0.0/20136.13.0.1 to 136.13.15.254136.13.15.2554,094
210136.13.16.0/20136.13.16.1 to 136.13.31.254136.13.31.2554,094
211136.13.32.0/20136.13.32.1 to 136.13.47.254136.13.47.2554,094
212136.13.48.0/20136.13.48.1 to 136.13.63.254136.13.63.2554,094
213136.13.64.0/20136.13.64.1 to 136.13.79.254136.13.79.2554,094
214136.13.80.0/20136.13.80.1 to 136.13.95.254136.13.95.2554,094
215136.13.96.0/20136.13.96.1 to 136.13.111.254136.13.111.2554,094
216136.13.112.0/20136.13.112.1 to 136.13.127.254136.13.127.2554,094
217136.13.128.0/20136.13.128.1 to 136.13.143.254136.13.143.2554,094
218136.13.144.0/20136.13.144.1 to 136.13.159.254136.13.159.2554,094
219136.13.160.0/20136.13.160.1 to 136.13.175.254136.13.175.2554,094
220136.13.176.0/20136.13.176.1 to 136.13.191.254136.13.191.2554,094
221136.13.192.0/20136.13.192.1 to 136.13.207.254136.13.207.2554,094
222136.13.208.0/20136.13.208.1 to 136.13.223.254136.13.223.2554,094
223136.13.224.0/20136.13.224.1 to 136.13.239.254136.13.239.2554,094
224136.13.240.0/20136.13.240.1 to 136.13.255.254136.13.255.2554,094
225136.14.0.0/20136.14.0.1 to 136.14.15.254136.14.15.2554,094
226136.14.16.0/20136.14.16.1 to 136.14.31.254136.14.31.2554,094
227136.14.32.0/20136.14.32.1 to 136.14.47.254136.14.47.2554,094
228136.14.48.0/20136.14.48.1 to 136.14.63.254136.14.63.2554,094
229136.14.64.0/20136.14.64.1 to 136.14.79.254136.14.79.2554,094
230136.14.80.0/20136.14.80.1 to 136.14.95.254136.14.95.2554,094
231136.14.96.0/20136.14.96.1 to 136.14.111.254136.14.111.2554,094
232136.14.112.0/20136.14.112.1 to 136.14.127.254136.14.127.2554,094
233136.14.128.0/20136.14.128.1 to 136.14.143.254136.14.143.2554,094
234136.14.144.0/20136.14.144.1 to 136.14.159.254136.14.159.2554,094
235136.14.160.0/20136.14.160.1 to 136.14.175.254136.14.175.2554,094
236136.14.176.0/20136.14.176.1 to 136.14.191.254136.14.191.2554,094
237136.14.192.0/20136.14.192.1 to 136.14.207.254136.14.207.2554,094
238136.14.208.0/20136.14.208.1 to 136.14.223.254136.14.223.2554,094
239136.14.224.0/20136.14.224.1 to 136.14.239.254136.14.239.2554,094
240136.14.240.0/20136.14.240.1 to 136.14.255.254136.14.255.2554,094
241136.15.0.0/20136.15.0.1 to 136.15.15.254136.15.15.2554,094
242136.15.16.0/20136.15.16.1 to 136.15.31.254136.15.31.2554,094
243136.15.32.0/20136.15.32.1 to 136.15.47.254136.15.47.2554,094
244136.15.48.0/20136.15.48.1 to 136.15.63.254136.15.63.2554,094
245136.15.64.0/20136.15.64.1 to 136.15.79.254136.15.79.2554,094
246136.15.80.0/20136.15.80.1 to 136.15.95.254136.15.95.2554,094
247136.15.96.0/20136.15.96.1 to 136.15.111.254136.15.111.2554,094
248136.15.112.0/20136.15.112.1 to 136.15.127.254136.15.127.2554,094
249136.15.128.0/20136.15.128.1 to 136.15.143.254136.15.143.2554,094
250136.15.144.0/20136.15.144.1 to 136.15.159.254136.15.159.2554,094
251136.15.160.0/20136.15.160.1 to 136.15.175.254136.15.175.2554,094
252136.15.176.0/20136.15.176.1 to 136.15.191.254136.15.191.2554,094
253136.15.192.0/20136.15.192.1 to 136.15.207.254136.15.207.2554,094
254136.15.208.0/20136.15.208.1 to 136.15.223.254136.15.223.2554,094
255136.15.224.0/20136.15.224.1 to 136.15.239.254136.15.239.2554,094
256136.15.240.0/20136.15.240.1 to 136.15.255.254136.15.255.2554,094

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.