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.

Network180.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
180.0.0.0
Broadcast address
180.127.255.255
First usable
180.0.0.1
Last usable
180.127.255.254
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 B4000000 · Integer 3019898880 to 3028287487
Reverse DNS zones
0.180.in-addr.arpa
1.180.in-addr.arpa
2.180.in-addr.arpa
3.180.in-addr.arpa
4.180.in-addr.arpa
5.180.in-addr.arpa
6.180.in-addr.arpa
7.180.in-addr.arpa
8.180.in-addr.arpa
9.180.in-addr.arpa
10.180.in-addr.arpa
11.180.in-addr.arpa
12.180.in-addr.arpa
13.180.in-addr.arpa
14.180.in-addr.arpa
15.180.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
Address10110100.00000000.00000000.00000000180.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10110100.00000000.00000000.00000000180.0.0.0
Broadcast10110100.01111111.11111111.11111111180.127.255.255
Split into smaller subnets/19
/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)

180.0.0.0/9 makes 1,024 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1180.0.0.0/19180.0.0.1 to 180.0.31.254180.0.31.2558,190
2180.0.32.0/19180.0.32.1 to 180.0.63.254180.0.63.2558,190
3180.0.64.0/19180.0.64.1 to 180.0.95.254180.0.95.2558,190
4180.0.96.0/19180.0.96.1 to 180.0.127.254180.0.127.2558,190
5180.0.128.0/19180.0.128.1 to 180.0.159.254180.0.159.2558,190
6180.0.160.0/19180.0.160.1 to 180.0.191.254180.0.191.2558,190
7180.0.192.0/19180.0.192.1 to 180.0.223.254180.0.223.2558,190
8180.0.224.0/19180.0.224.1 to 180.0.255.254180.0.255.2558,190
9180.1.0.0/19180.1.0.1 to 180.1.31.254180.1.31.2558,190
10180.1.32.0/19180.1.32.1 to 180.1.63.254180.1.63.2558,190
11180.1.64.0/19180.1.64.1 to 180.1.95.254180.1.95.2558,190
12180.1.96.0/19180.1.96.1 to 180.1.127.254180.1.127.2558,190
13180.1.128.0/19180.1.128.1 to 180.1.159.254180.1.159.2558,190
14180.1.160.0/19180.1.160.1 to 180.1.191.254180.1.191.2558,190
15180.1.192.0/19180.1.192.1 to 180.1.223.254180.1.223.2558,190
16180.1.224.0/19180.1.224.1 to 180.1.255.254180.1.255.2558,190
17180.2.0.0/19180.2.0.1 to 180.2.31.254180.2.31.2558,190
18180.2.32.0/19180.2.32.1 to 180.2.63.254180.2.63.2558,190
19180.2.64.0/19180.2.64.1 to 180.2.95.254180.2.95.2558,190
20180.2.96.0/19180.2.96.1 to 180.2.127.254180.2.127.2558,190
21180.2.128.0/19180.2.128.1 to 180.2.159.254180.2.159.2558,190
22180.2.160.0/19180.2.160.1 to 180.2.191.254180.2.191.2558,190
23180.2.192.0/19180.2.192.1 to 180.2.223.254180.2.223.2558,190
24180.2.224.0/19180.2.224.1 to 180.2.255.254180.2.255.2558,190
25180.3.0.0/19180.3.0.1 to 180.3.31.254180.3.31.2558,190
26180.3.32.0/19180.3.32.1 to 180.3.63.254180.3.63.2558,190
27180.3.64.0/19180.3.64.1 to 180.3.95.254180.3.95.2558,190
28180.3.96.0/19180.3.96.1 to 180.3.127.254180.3.127.2558,190
29180.3.128.0/19180.3.128.1 to 180.3.159.254180.3.159.2558,190
30180.3.160.0/19180.3.160.1 to 180.3.191.254180.3.191.2558,190
31180.3.192.0/19180.3.192.1 to 180.3.223.254180.3.223.2558,190
32180.3.224.0/19180.3.224.1 to 180.3.255.254180.3.255.2558,190
33180.4.0.0/19180.4.0.1 to 180.4.31.254180.4.31.2558,190
34180.4.32.0/19180.4.32.1 to 180.4.63.254180.4.63.2558,190
35180.4.64.0/19180.4.64.1 to 180.4.95.254180.4.95.2558,190
36180.4.96.0/19180.4.96.1 to 180.4.127.254180.4.127.2558,190
37180.4.128.0/19180.4.128.1 to 180.4.159.254180.4.159.2558,190
38180.4.160.0/19180.4.160.1 to 180.4.191.254180.4.191.2558,190
39180.4.192.0/19180.4.192.1 to 180.4.223.254180.4.223.2558,190
40180.4.224.0/19180.4.224.1 to 180.4.255.254180.4.255.2558,190
41180.5.0.0/19180.5.0.1 to 180.5.31.254180.5.31.2558,190
42180.5.32.0/19180.5.32.1 to 180.5.63.254180.5.63.2558,190
43180.5.64.0/19180.5.64.1 to 180.5.95.254180.5.95.2558,190
44180.5.96.0/19180.5.96.1 to 180.5.127.254180.5.127.2558,190
45180.5.128.0/19180.5.128.1 to 180.5.159.254180.5.159.2558,190
46180.5.160.0/19180.5.160.1 to 180.5.191.254180.5.191.2558,190
47180.5.192.0/19180.5.192.1 to 180.5.223.254180.5.223.2558,190
48180.5.224.0/19180.5.224.1 to 180.5.255.254180.5.255.2558,190
49180.6.0.0/19180.6.0.1 to 180.6.31.254180.6.31.2558,190
50180.6.32.0/19180.6.32.1 to 180.6.63.254180.6.63.2558,190
51180.6.64.0/19180.6.64.1 to 180.6.95.254180.6.95.2558,190
52180.6.96.0/19180.6.96.1 to 180.6.127.254180.6.127.2558,190
53180.6.128.0/19180.6.128.1 to 180.6.159.254180.6.159.2558,190
54180.6.160.0/19180.6.160.1 to 180.6.191.254180.6.191.2558,190
55180.6.192.0/19180.6.192.1 to 180.6.223.254180.6.223.2558,190
56180.6.224.0/19180.6.224.1 to 180.6.255.254180.6.255.2558,190
57180.7.0.0/19180.7.0.1 to 180.7.31.254180.7.31.2558,190
58180.7.32.0/19180.7.32.1 to 180.7.63.254180.7.63.2558,190
59180.7.64.0/19180.7.64.1 to 180.7.95.254180.7.95.2558,190
60180.7.96.0/19180.7.96.1 to 180.7.127.254180.7.127.2558,190
61180.7.128.0/19180.7.128.1 to 180.7.159.254180.7.159.2558,190
62180.7.160.0/19180.7.160.1 to 180.7.191.254180.7.191.2558,190
63180.7.192.0/19180.7.192.1 to 180.7.223.254180.7.223.2558,190
64180.7.224.0/19180.7.224.1 to 180.7.255.254180.7.255.2558,190
65180.8.0.0/19180.8.0.1 to 180.8.31.254180.8.31.2558,190
66180.8.32.0/19180.8.32.1 to 180.8.63.254180.8.63.2558,190
67180.8.64.0/19180.8.64.1 to 180.8.95.254180.8.95.2558,190
68180.8.96.0/19180.8.96.1 to 180.8.127.254180.8.127.2558,190
69180.8.128.0/19180.8.128.1 to 180.8.159.254180.8.159.2558,190
70180.8.160.0/19180.8.160.1 to 180.8.191.254180.8.191.2558,190
71180.8.192.0/19180.8.192.1 to 180.8.223.254180.8.223.2558,190
72180.8.224.0/19180.8.224.1 to 180.8.255.254180.8.255.2558,190
73180.9.0.0/19180.9.0.1 to 180.9.31.254180.9.31.2558,190
74180.9.32.0/19180.9.32.1 to 180.9.63.254180.9.63.2558,190
75180.9.64.0/19180.9.64.1 to 180.9.95.254180.9.95.2558,190
76180.9.96.0/19180.9.96.1 to 180.9.127.254180.9.127.2558,190
77180.9.128.0/19180.9.128.1 to 180.9.159.254180.9.159.2558,190
78180.9.160.0/19180.9.160.1 to 180.9.191.254180.9.191.2558,190
79180.9.192.0/19180.9.192.1 to 180.9.223.254180.9.223.2558,190
80180.9.224.0/19180.9.224.1 to 180.9.255.254180.9.255.2558,190
81180.10.0.0/19180.10.0.1 to 180.10.31.254180.10.31.2558,190
82180.10.32.0/19180.10.32.1 to 180.10.63.254180.10.63.2558,190
83180.10.64.0/19180.10.64.1 to 180.10.95.254180.10.95.2558,190
84180.10.96.0/19180.10.96.1 to 180.10.127.254180.10.127.2558,190
85180.10.128.0/19180.10.128.1 to 180.10.159.254180.10.159.2558,190
86180.10.160.0/19180.10.160.1 to 180.10.191.254180.10.191.2558,190
87180.10.192.0/19180.10.192.1 to 180.10.223.254180.10.223.2558,190
88180.10.224.0/19180.10.224.1 to 180.10.255.254180.10.255.2558,190
89180.11.0.0/19180.11.0.1 to 180.11.31.254180.11.31.2558,190
90180.11.32.0/19180.11.32.1 to 180.11.63.254180.11.63.2558,190
91180.11.64.0/19180.11.64.1 to 180.11.95.254180.11.95.2558,190
92180.11.96.0/19180.11.96.1 to 180.11.127.254180.11.127.2558,190
93180.11.128.0/19180.11.128.1 to 180.11.159.254180.11.159.2558,190
94180.11.160.0/19180.11.160.1 to 180.11.191.254180.11.191.2558,190
95180.11.192.0/19180.11.192.1 to 180.11.223.254180.11.223.2558,190
96180.11.224.0/19180.11.224.1 to 180.11.255.254180.11.255.2558,190
97180.12.0.0/19180.12.0.1 to 180.12.31.254180.12.31.2558,190
98180.12.32.0/19180.12.32.1 to 180.12.63.254180.12.63.2558,190
99180.12.64.0/19180.12.64.1 to 180.12.95.254180.12.95.2558,190
100180.12.96.0/19180.12.96.1 to 180.12.127.254180.12.127.2558,190
101180.12.128.0/19180.12.128.1 to 180.12.159.254180.12.159.2558,190
102180.12.160.0/19180.12.160.1 to 180.12.191.254180.12.191.2558,190
103180.12.192.0/19180.12.192.1 to 180.12.223.254180.12.223.2558,190
104180.12.224.0/19180.12.224.1 to 180.12.255.254180.12.255.2558,190
105180.13.0.0/19180.13.0.1 to 180.13.31.254180.13.31.2558,190
106180.13.32.0/19180.13.32.1 to 180.13.63.254180.13.63.2558,190
107180.13.64.0/19180.13.64.1 to 180.13.95.254180.13.95.2558,190
108180.13.96.0/19180.13.96.1 to 180.13.127.254180.13.127.2558,190
109180.13.128.0/19180.13.128.1 to 180.13.159.254180.13.159.2558,190
110180.13.160.0/19180.13.160.1 to 180.13.191.254180.13.191.2558,190
111180.13.192.0/19180.13.192.1 to 180.13.223.254180.13.223.2558,190
112180.13.224.0/19180.13.224.1 to 180.13.255.254180.13.255.2558,190
113180.14.0.0/19180.14.0.1 to 180.14.31.254180.14.31.2558,190
114180.14.32.0/19180.14.32.1 to 180.14.63.254180.14.63.2558,190
115180.14.64.0/19180.14.64.1 to 180.14.95.254180.14.95.2558,190
116180.14.96.0/19180.14.96.1 to 180.14.127.254180.14.127.2558,190
117180.14.128.0/19180.14.128.1 to 180.14.159.254180.14.159.2558,190
118180.14.160.0/19180.14.160.1 to 180.14.191.254180.14.191.2558,190
119180.14.192.0/19180.14.192.1 to 180.14.223.254180.14.223.2558,190
120180.14.224.0/19180.14.224.1 to 180.14.255.254180.14.255.2558,190
121180.15.0.0/19180.15.0.1 to 180.15.31.254180.15.31.2558,190
122180.15.32.0/19180.15.32.1 to 180.15.63.254180.15.63.2558,190
123180.15.64.0/19180.15.64.1 to 180.15.95.254180.15.95.2558,190
124180.15.96.0/19180.15.96.1 to 180.15.127.254180.15.127.2558,190
125180.15.128.0/19180.15.128.1 to 180.15.159.254180.15.159.2558,190
126180.15.160.0/19180.15.160.1 to 180.15.191.254180.15.191.2558,190
127180.15.192.0/19180.15.192.1 to 180.15.223.254180.15.223.2558,190
128180.15.224.0/19180.15.224.1 to 180.15.255.254180.15.255.2558,190
129180.16.0.0/19180.16.0.1 to 180.16.31.254180.16.31.2558,190
130180.16.32.0/19180.16.32.1 to 180.16.63.254180.16.63.2558,190
131180.16.64.0/19180.16.64.1 to 180.16.95.254180.16.95.2558,190
132180.16.96.0/19180.16.96.1 to 180.16.127.254180.16.127.2558,190
133180.16.128.0/19180.16.128.1 to 180.16.159.254180.16.159.2558,190
134180.16.160.0/19180.16.160.1 to 180.16.191.254180.16.191.2558,190
135180.16.192.0/19180.16.192.1 to 180.16.223.254180.16.223.2558,190
136180.16.224.0/19180.16.224.1 to 180.16.255.254180.16.255.2558,190
137180.17.0.0/19180.17.0.1 to 180.17.31.254180.17.31.2558,190
138180.17.32.0/19180.17.32.1 to 180.17.63.254180.17.63.2558,190
139180.17.64.0/19180.17.64.1 to 180.17.95.254180.17.95.2558,190
140180.17.96.0/19180.17.96.1 to 180.17.127.254180.17.127.2558,190
141180.17.128.0/19180.17.128.1 to 180.17.159.254180.17.159.2558,190
142180.17.160.0/19180.17.160.1 to 180.17.191.254180.17.191.2558,190
143180.17.192.0/19180.17.192.1 to 180.17.223.254180.17.223.2558,190
144180.17.224.0/19180.17.224.1 to 180.17.255.254180.17.255.2558,190
145180.18.0.0/19180.18.0.1 to 180.18.31.254180.18.31.2558,190
146180.18.32.0/19180.18.32.1 to 180.18.63.254180.18.63.2558,190
147180.18.64.0/19180.18.64.1 to 180.18.95.254180.18.95.2558,190
148180.18.96.0/19180.18.96.1 to 180.18.127.254180.18.127.2558,190
149180.18.128.0/19180.18.128.1 to 180.18.159.254180.18.159.2558,190
150180.18.160.0/19180.18.160.1 to 180.18.191.254180.18.191.2558,190
151180.18.192.0/19180.18.192.1 to 180.18.223.254180.18.223.2558,190
152180.18.224.0/19180.18.224.1 to 180.18.255.254180.18.255.2558,190
153180.19.0.0/19180.19.0.1 to 180.19.31.254180.19.31.2558,190
154180.19.32.0/19180.19.32.1 to 180.19.63.254180.19.63.2558,190
155180.19.64.0/19180.19.64.1 to 180.19.95.254180.19.95.2558,190
156180.19.96.0/19180.19.96.1 to 180.19.127.254180.19.127.2558,190
157180.19.128.0/19180.19.128.1 to 180.19.159.254180.19.159.2558,190
158180.19.160.0/19180.19.160.1 to 180.19.191.254180.19.191.2558,190
159180.19.192.0/19180.19.192.1 to 180.19.223.254180.19.223.2558,190
160180.19.224.0/19180.19.224.1 to 180.19.255.254180.19.255.2558,190
161180.20.0.0/19180.20.0.1 to 180.20.31.254180.20.31.2558,190
162180.20.32.0/19180.20.32.1 to 180.20.63.254180.20.63.2558,190
163180.20.64.0/19180.20.64.1 to 180.20.95.254180.20.95.2558,190
164180.20.96.0/19180.20.96.1 to 180.20.127.254180.20.127.2558,190
165180.20.128.0/19180.20.128.1 to 180.20.159.254180.20.159.2558,190
166180.20.160.0/19180.20.160.1 to 180.20.191.254180.20.191.2558,190
167180.20.192.0/19180.20.192.1 to 180.20.223.254180.20.223.2558,190
168180.20.224.0/19180.20.224.1 to 180.20.255.254180.20.255.2558,190
169180.21.0.0/19180.21.0.1 to 180.21.31.254180.21.31.2558,190
170180.21.32.0/19180.21.32.1 to 180.21.63.254180.21.63.2558,190
171180.21.64.0/19180.21.64.1 to 180.21.95.254180.21.95.2558,190
172180.21.96.0/19180.21.96.1 to 180.21.127.254180.21.127.2558,190
173180.21.128.0/19180.21.128.1 to 180.21.159.254180.21.159.2558,190
174180.21.160.0/19180.21.160.1 to 180.21.191.254180.21.191.2558,190
175180.21.192.0/19180.21.192.1 to 180.21.223.254180.21.223.2558,190
176180.21.224.0/19180.21.224.1 to 180.21.255.254180.21.255.2558,190
177180.22.0.0/19180.22.0.1 to 180.22.31.254180.22.31.2558,190
178180.22.32.0/19180.22.32.1 to 180.22.63.254180.22.63.2558,190
179180.22.64.0/19180.22.64.1 to 180.22.95.254180.22.95.2558,190
180180.22.96.0/19180.22.96.1 to 180.22.127.254180.22.127.2558,190
181180.22.128.0/19180.22.128.1 to 180.22.159.254180.22.159.2558,190
182180.22.160.0/19180.22.160.1 to 180.22.191.254180.22.191.2558,190
183180.22.192.0/19180.22.192.1 to 180.22.223.254180.22.223.2558,190
184180.22.224.0/19180.22.224.1 to 180.22.255.254180.22.255.2558,190
185180.23.0.0/19180.23.0.1 to 180.23.31.254180.23.31.2558,190
186180.23.32.0/19180.23.32.1 to 180.23.63.254180.23.63.2558,190
187180.23.64.0/19180.23.64.1 to 180.23.95.254180.23.95.2558,190
188180.23.96.0/19180.23.96.1 to 180.23.127.254180.23.127.2558,190
189180.23.128.0/19180.23.128.1 to 180.23.159.254180.23.159.2558,190
190180.23.160.0/19180.23.160.1 to 180.23.191.254180.23.191.2558,190
191180.23.192.0/19180.23.192.1 to 180.23.223.254180.23.223.2558,190
192180.23.224.0/19180.23.224.1 to 180.23.255.254180.23.255.2558,190
193180.24.0.0/19180.24.0.1 to 180.24.31.254180.24.31.2558,190
194180.24.32.0/19180.24.32.1 to 180.24.63.254180.24.63.2558,190
195180.24.64.0/19180.24.64.1 to 180.24.95.254180.24.95.2558,190
196180.24.96.0/19180.24.96.1 to 180.24.127.254180.24.127.2558,190
197180.24.128.0/19180.24.128.1 to 180.24.159.254180.24.159.2558,190
198180.24.160.0/19180.24.160.1 to 180.24.191.254180.24.191.2558,190
199180.24.192.0/19180.24.192.1 to 180.24.223.254180.24.223.2558,190
200180.24.224.0/19180.24.224.1 to 180.24.255.254180.24.255.2558,190
201180.25.0.0/19180.25.0.1 to 180.25.31.254180.25.31.2558,190
202180.25.32.0/19180.25.32.1 to 180.25.63.254180.25.63.2558,190
203180.25.64.0/19180.25.64.1 to 180.25.95.254180.25.95.2558,190
204180.25.96.0/19180.25.96.1 to 180.25.127.254180.25.127.2558,190
205180.25.128.0/19180.25.128.1 to 180.25.159.254180.25.159.2558,190
206180.25.160.0/19180.25.160.1 to 180.25.191.254180.25.191.2558,190
207180.25.192.0/19180.25.192.1 to 180.25.223.254180.25.223.2558,190
208180.25.224.0/19180.25.224.1 to 180.25.255.254180.25.255.2558,190
209180.26.0.0/19180.26.0.1 to 180.26.31.254180.26.31.2558,190
210180.26.32.0/19180.26.32.1 to 180.26.63.254180.26.63.2558,190
211180.26.64.0/19180.26.64.1 to 180.26.95.254180.26.95.2558,190
212180.26.96.0/19180.26.96.1 to 180.26.127.254180.26.127.2558,190
213180.26.128.0/19180.26.128.1 to 180.26.159.254180.26.159.2558,190
214180.26.160.0/19180.26.160.1 to 180.26.191.254180.26.191.2558,190
215180.26.192.0/19180.26.192.1 to 180.26.223.254180.26.223.2558,190
216180.26.224.0/19180.26.224.1 to 180.26.255.254180.26.255.2558,190
217180.27.0.0/19180.27.0.1 to 180.27.31.254180.27.31.2558,190
218180.27.32.0/19180.27.32.1 to 180.27.63.254180.27.63.2558,190
219180.27.64.0/19180.27.64.1 to 180.27.95.254180.27.95.2558,190
220180.27.96.0/19180.27.96.1 to 180.27.127.254180.27.127.2558,190
221180.27.128.0/19180.27.128.1 to 180.27.159.254180.27.159.2558,190
222180.27.160.0/19180.27.160.1 to 180.27.191.254180.27.191.2558,190
223180.27.192.0/19180.27.192.1 to 180.27.223.254180.27.223.2558,190
224180.27.224.0/19180.27.224.1 to 180.27.255.254180.27.255.2558,190
225180.28.0.0/19180.28.0.1 to 180.28.31.254180.28.31.2558,190
226180.28.32.0/19180.28.32.1 to 180.28.63.254180.28.63.2558,190
227180.28.64.0/19180.28.64.1 to 180.28.95.254180.28.95.2558,190
228180.28.96.0/19180.28.96.1 to 180.28.127.254180.28.127.2558,190
229180.28.128.0/19180.28.128.1 to 180.28.159.254180.28.159.2558,190
230180.28.160.0/19180.28.160.1 to 180.28.191.254180.28.191.2558,190
231180.28.192.0/19180.28.192.1 to 180.28.223.254180.28.223.2558,190
232180.28.224.0/19180.28.224.1 to 180.28.255.254180.28.255.2558,190
233180.29.0.0/19180.29.0.1 to 180.29.31.254180.29.31.2558,190
234180.29.32.0/19180.29.32.1 to 180.29.63.254180.29.63.2558,190
235180.29.64.0/19180.29.64.1 to 180.29.95.254180.29.95.2558,190
236180.29.96.0/19180.29.96.1 to 180.29.127.254180.29.127.2558,190
237180.29.128.0/19180.29.128.1 to 180.29.159.254180.29.159.2558,190
238180.29.160.0/19180.29.160.1 to 180.29.191.254180.29.191.2558,190
239180.29.192.0/19180.29.192.1 to 180.29.223.254180.29.223.2558,190
240180.29.224.0/19180.29.224.1 to 180.29.255.254180.29.255.2558,190
241180.30.0.0/19180.30.0.1 to 180.30.31.254180.30.31.2558,190
242180.30.32.0/19180.30.32.1 to 180.30.63.254180.30.63.2558,190
243180.30.64.0/19180.30.64.1 to 180.30.95.254180.30.95.2558,190
244180.30.96.0/19180.30.96.1 to 180.30.127.254180.30.127.2558,190
245180.30.128.0/19180.30.128.1 to 180.30.159.254180.30.159.2558,190
246180.30.160.0/19180.30.160.1 to 180.30.191.254180.30.191.2558,190
247180.30.192.0/19180.30.192.1 to 180.30.223.254180.30.223.2558,190
248180.30.224.0/19180.30.224.1 to 180.30.255.254180.30.255.2558,190
249180.31.0.0/19180.31.0.1 to 180.31.31.254180.31.31.2558,190
250180.31.32.0/19180.31.32.1 to 180.31.63.254180.31.63.2558,190
251180.31.64.0/19180.31.64.1 to 180.31.95.254180.31.95.2558,190
252180.31.96.0/19180.31.96.1 to 180.31.127.254180.31.127.2558,190
253180.31.128.0/19180.31.128.1 to 180.31.159.254180.31.159.2558,190
254180.31.160.0/19180.31.160.1 to 180.31.191.254180.31.191.2558,190
255180.31.192.0/19180.31.192.1 to 180.31.223.254180.31.223.2558,190
256180.31.224.0/19180.31.224.1 to 180.31.255.254180.31.255.2558,190

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.