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.

Network194.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
194.0.0.0
Broadcast address
194.255.255.255
First usable
194.0.0.1
Last usable
194.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
C (default /24)
As numbers
Hex C2000000 · Integer 3254779904 to 3271557119
Reverse DNS zone
194.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000010..00000000.00000000.00000000194.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11000010..00000000.00000000.00000000194.0.0.0
Broadcast11000010..11111111.11111111.11111111194.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

194.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1194.0.0.0/19194.0.0.1 to 194.0.31.254194.0.31.2558,190
2194.0.32.0/19194.0.32.1 to 194.0.63.254194.0.63.2558,190
3194.0.64.0/19194.0.64.1 to 194.0.95.254194.0.95.2558,190
4194.0.96.0/19194.0.96.1 to 194.0.127.254194.0.127.2558,190
5194.0.128.0/19194.0.128.1 to 194.0.159.254194.0.159.2558,190
6194.0.160.0/19194.0.160.1 to 194.0.191.254194.0.191.2558,190
7194.0.192.0/19194.0.192.1 to 194.0.223.254194.0.223.2558,190
8194.0.224.0/19194.0.224.1 to 194.0.255.254194.0.255.2558,190
9194.1.0.0/19194.1.0.1 to 194.1.31.254194.1.31.2558,190
10194.1.32.0/19194.1.32.1 to 194.1.63.254194.1.63.2558,190
11194.1.64.0/19194.1.64.1 to 194.1.95.254194.1.95.2558,190
12194.1.96.0/19194.1.96.1 to 194.1.127.254194.1.127.2558,190
13194.1.128.0/19194.1.128.1 to 194.1.159.254194.1.159.2558,190
14194.1.160.0/19194.1.160.1 to 194.1.191.254194.1.191.2558,190
15194.1.192.0/19194.1.192.1 to 194.1.223.254194.1.223.2558,190
16194.1.224.0/19194.1.224.1 to 194.1.255.254194.1.255.2558,190
17194.2.0.0/19194.2.0.1 to 194.2.31.254194.2.31.2558,190
18194.2.32.0/19194.2.32.1 to 194.2.63.254194.2.63.2558,190
19194.2.64.0/19194.2.64.1 to 194.2.95.254194.2.95.2558,190
20194.2.96.0/19194.2.96.1 to 194.2.127.254194.2.127.2558,190
21194.2.128.0/19194.2.128.1 to 194.2.159.254194.2.159.2558,190
22194.2.160.0/19194.2.160.1 to 194.2.191.254194.2.191.2558,190
23194.2.192.0/19194.2.192.1 to 194.2.223.254194.2.223.2558,190
24194.2.224.0/19194.2.224.1 to 194.2.255.254194.2.255.2558,190
25194.3.0.0/19194.3.0.1 to 194.3.31.254194.3.31.2558,190
26194.3.32.0/19194.3.32.1 to 194.3.63.254194.3.63.2558,190
27194.3.64.0/19194.3.64.1 to 194.3.95.254194.3.95.2558,190
28194.3.96.0/19194.3.96.1 to 194.3.127.254194.3.127.2558,190
29194.3.128.0/19194.3.128.1 to 194.3.159.254194.3.159.2558,190
30194.3.160.0/19194.3.160.1 to 194.3.191.254194.3.191.2558,190
31194.3.192.0/19194.3.192.1 to 194.3.223.254194.3.223.2558,190
32194.3.224.0/19194.3.224.1 to 194.3.255.254194.3.255.2558,190
33194.4.0.0/19194.4.0.1 to 194.4.31.254194.4.31.2558,190
34194.4.32.0/19194.4.32.1 to 194.4.63.254194.4.63.2558,190
35194.4.64.0/19194.4.64.1 to 194.4.95.254194.4.95.2558,190
36194.4.96.0/19194.4.96.1 to 194.4.127.254194.4.127.2558,190
37194.4.128.0/19194.4.128.1 to 194.4.159.254194.4.159.2558,190
38194.4.160.0/19194.4.160.1 to 194.4.191.254194.4.191.2558,190
39194.4.192.0/19194.4.192.1 to 194.4.223.254194.4.223.2558,190
40194.4.224.0/19194.4.224.1 to 194.4.255.254194.4.255.2558,190
41194.5.0.0/19194.5.0.1 to 194.5.31.254194.5.31.2558,190
42194.5.32.0/19194.5.32.1 to 194.5.63.254194.5.63.2558,190
43194.5.64.0/19194.5.64.1 to 194.5.95.254194.5.95.2558,190
44194.5.96.0/19194.5.96.1 to 194.5.127.254194.5.127.2558,190
45194.5.128.0/19194.5.128.1 to 194.5.159.254194.5.159.2558,190
46194.5.160.0/19194.5.160.1 to 194.5.191.254194.5.191.2558,190
47194.5.192.0/19194.5.192.1 to 194.5.223.254194.5.223.2558,190
48194.5.224.0/19194.5.224.1 to 194.5.255.254194.5.255.2558,190
49194.6.0.0/19194.6.0.1 to 194.6.31.254194.6.31.2558,190
50194.6.32.0/19194.6.32.1 to 194.6.63.254194.6.63.2558,190
51194.6.64.0/19194.6.64.1 to 194.6.95.254194.6.95.2558,190
52194.6.96.0/19194.6.96.1 to 194.6.127.254194.6.127.2558,190
53194.6.128.0/19194.6.128.1 to 194.6.159.254194.6.159.2558,190
54194.6.160.0/19194.6.160.1 to 194.6.191.254194.6.191.2558,190
55194.6.192.0/19194.6.192.1 to 194.6.223.254194.6.223.2558,190
56194.6.224.0/19194.6.224.1 to 194.6.255.254194.6.255.2558,190
57194.7.0.0/19194.7.0.1 to 194.7.31.254194.7.31.2558,190
58194.7.32.0/19194.7.32.1 to 194.7.63.254194.7.63.2558,190
59194.7.64.0/19194.7.64.1 to 194.7.95.254194.7.95.2558,190
60194.7.96.0/19194.7.96.1 to 194.7.127.254194.7.127.2558,190
61194.7.128.0/19194.7.128.1 to 194.7.159.254194.7.159.2558,190
62194.7.160.0/19194.7.160.1 to 194.7.191.254194.7.191.2558,190
63194.7.192.0/19194.7.192.1 to 194.7.223.254194.7.223.2558,190
64194.7.224.0/19194.7.224.1 to 194.7.255.254194.7.255.2558,190
65194.8.0.0/19194.8.0.1 to 194.8.31.254194.8.31.2558,190
66194.8.32.0/19194.8.32.1 to 194.8.63.254194.8.63.2558,190
67194.8.64.0/19194.8.64.1 to 194.8.95.254194.8.95.2558,190
68194.8.96.0/19194.8.96.1 to 194.8.127.254194.8.127.2558,190
69194.8.128.0/19194.8.128.1 to 194.8.159.254194.8.159.2558,190
70194.8.160.0/19194.8.160.1 to 194.8.191.254194.8.191.2558,190
71194.8.192.0/19194.8.192.1 to 194.8.223.254194.8.223.2558,190
72194.8.224.0/19194.8.224.1 to 194.8.255.254194.8.255.2558,190
73194.9.0.0/19194.9.0.1 to 194.9.31.254194.9.31.2558,190
74194.9.32.0/19194.9.32.1 to 194.9.63.254194.9.63.2558,190
75194.9.64.0/19194.9.64.1 to 194.9.95.254194.9.95.2558,190
76194.9.96.0/19194.9.96.1 to 194.9.127.254194.9.127.2558,190
77194.9.128.0/19194.9.128.1 to 194.9.159.254194.9.159.2558,190
78194.9.160.0/19194.9.160.1 to 194.9.191.254194.9.191.2558,190
79194.9.192.0/19194.9.192.1 to 194.9.223.254194.9.223.2558,190
80194.9.224.0/19194.9.224.1 to 194.9.255.254194.9.255.2558,190
81194.10.0.0/19194.10.0.1 to 194.10.31.254194.10.31.2558,190
82194.10.32.0/19194.10.32.1 to 194.10.63.254194.10.63.2558,190
83194.10.64.0/19194.10.64.1 to 194.10.95.254194.10.95.2558,190
84194.10.96.0/19194.10.96.1 to 194.10.127.254194.10.127.2558,190
85194.10.128.0/19194.10.128.1 to 194.10.159.254194.10.159.2558,190
86194.10.160.0/19194.10.160.1 to 194.10.191.254194.10.191.2558,190
87194.10.192.0/19194.10.192.1 to 194.10.223.254194.10.223.2558,190
88194.10.224.0/19194.10.224.1 to 194.10.255.254194.10.255.2558,190
89194.11.0.0/19194.11.0.1 to 194.11.31.254194.11.31.2558,190
90194.11.32.0/19194.11.32.1 to 194.11.63.254194.11.63.2558,190
91194.11.64.0/19194.11.64.1 to 194.11.95.254194.11.95.2558,190
92194.11.96.0/19194.11.96.1 to 194.11.127.254194.11.127.2558,190
93194.11.128.0/19194.11.128.1 to 194.11.159.254194.11.159.2558,190
94194.11.160.0/19194.11.160.1 to 194.11.191.254194.11.191.2558,190
95194.11.192.0/19194.11.192.1 to 194.11.223.254194.11.223.2558,190
96194.11.224.0/19194.11.224.1 to 194.11.255.254194.11.255.2558,190
97194.12.0.0/19194.12.0.1 to 194.12.31.254194.12.31.2558,190
98194.12.32.0/19194.12.32.1 to 194.12.63.254194.12.63.2558,190
99194.12.64.0/19194.12.64.1 to 194.12.95.254194.12.95.2558,190
100194.12.96.0/19194.12.96.1 to 194.12.127.254194.12.127.2558,190
101194.12.128.0/19194.12.128.1 to 194.12.159.254194.12.159.2558,190
102194.12.160.0/19194.12.160.1 to 194.12.191.254194.12.191.2558,190
103194.12.192.0/19194.12.192.1 to 194.12.223.254194.12.223.2558,190
104194.12.224.0/19194.12.224.1 to 194.12.255.254194.12.255.2558,190
105194.13.0.0/19194.13.0.1 to 194.13.31.254194.13.31.2558,190
106194.13.32.0/19194.13.32.1 to 194.13.63.254194.13.63.2558,190
107194.13.64.0/19194.13.64.1 to 194.13.95.254194.13.95.2558,190
108194.13.96.0/19194.13.96.1 to 194.13.127.254194.13.127.2558,190
109194.13.128.0/19194.13.128.1 to 194.13.159.254194.13.159.2558,190
110194.13.160.0/19194.13.160.1 to 194.13.191.254194.13.191.2558,190
111194.13.192.0/19194.13.192.1 to 194.13.223.254194.13.223.2558,190
112194.13.224.0/19194.13.224.1 to 194.13.255.254194.13.255.2558,190
113194.14.0.0/19194.14.0.1 to 194.14.31.254194.14.31.2558,190
114194.14.32.0/19194.14.32.1 to 194.14.63.254194.14.63.2558,190
115194.14.64.0/19194.14.64.1 to 194.14.95.254194.14.95.2558,190
116194.14.96.0/19194.14.96.1 to 194.14.127.254194.14.127.2558,190
117194.14.128.0/19194.14.128.1 to 194.14.159.254194.14.159.2558,190
118194.14.160.0/19194.14.160.1 to 194.14.191.254194.14.191.2558,190
119194.14.192.0/19194.14.192.1 to 194.14.223.254194.14.223.2558,190
120194.14.224.0/19194.14.224.1 to 194.14.255.254194.14.255.2558,190
121194.15.0.0/19194.15.0.1 to 194.15.31.254194.15.31.2558,190
122194.15.32.0/19194.15.32.1 to 194.15.63.254194.15.63.2558,190
123194.15.64.0/19194.15.64.1 to 194.15.95.254194.15.95.2558,190
124194.15.96.0/19194.15.96.1 to 194.15.127.254194.15.127.2558,190
125194.15.128.0/19194.15.128.1 to 194.15.159.254194.15.159.2558,190
126194.15.160.0/19194.15.160.1 to 194.15.191.254194.15.191.2558,190
127194.15.192.0/19194.15.192.1 to 194.15.223.254194.15.223.2558,190
128194.15.224.0/19194.15.224.1 to 194.15.255.254194.15.255.2558,190
129194.16.0.0/19194.16.0.1 to 194.16.31.254194.16.31.2558,190
130194.16.32.0/19194.16.32.1 to 194.16.63.254194.16.63.2558,190
131194.16.64.0/19194.16.64.1 to 194.16.95.254194.16.95.2558,190
132194.16.96.0/19194.16.96.1 to 194.16.127.254194.16.127.2558,190
133194.16.128.0/19194.16.128.1 to 194.16.159.254194.16.159.2558,190
134194.16.160.0/19194.16.160.1 to 194.16.191.254194.16.191.2558,190
135194.16.192.0/19194.16.192.1 to 194.16.223.254194.16.223.2558,190
136194.16.224.0/19194.16.224.1 to 194.16.255.254194.16.255.2558,190
137194.17.0.0/19194.17.0.1 to 194.17.31.254194.17.31.2558,190
138194.17.32.0/19194.17.32.1 to 194.17.63.254194.17.63.2558,190
139194.17.64.0/19194.17.64.1 to 194.17.95.254194.17.95.2558,190
140194.17.96.0/19194.17.96.1 to 194.17.127.254194.17.127.2558,190
141194.17.128.0/19194.17.128.1 to 194.17.159.254194.17.159.2558,190
142194.17.160.0/19194.17.160.1 to 194.17.191.254194.17.191.2558,190
143194.17.192.0/19194.17.192.1 to 194.17.223.254194.17.223.2558,190
144194.17.224.0/19194.17.224.1 to 194.17.255.254194.17.255.2558,190
145194.18.0.0/19194.18.0.1 to 194.18.31.254194.18.31.2558,190
146194.18.32.0/19194.18.32.1 to 194.18.63.254194.18.63.2558,190
147194.18.64.0/19194.18.64.1 to 194.18.95.254194.18.95.2558,190
148194.18.96.0/19194.18.96.1 to 194.18.127.254194.18.127.2558,190
149194.18.128.0/19194.18.128.1 to 194.18.159.254194.18.159.2558,190
150194.18.160.0/19194.18.160.1 to 194.18.191.254194.18.191.2558,190
151194.18.192.0/19194.18.192.1 to 194.18.223.254194.18.223.2558,190
152194.18.224.0/19194.18.224.1 to 194.18.255.254194.18.255.2558,190
153194.19.0.0/19194.19.0.1 to 194.19.31.254194.19.31.2558,190
154194.19.32.0/19194.19.32.1 to 194.19.63.254194.19.63.2558,190
155194.19.64.0/19194.19.64.1 to 194.19.95.254194.19.95.2558,190
156194.19.96.0/19194.19.96.1 to 194.19.127.254194.19.127.2558,190
157194.19.128.0/19194.19.128.1 to 194.19.159.254194.19.159.2558,190
158194.19.160.0/19194.19.160.1 to 194.19.191.254194.19.191.2558,190
159194.19.192.0/19194.19.192.1 to 194.19.223.254194.19.223.2558,190
160194.19.224.0/19194.19.224.1 to 194.19.255.254194.19.255.2558,190
161194.20.0.0/19194.20.0.1 to 194.20.31.254194.20.31.2558,190
162194.20.32.0/19194.20.32.1 to 194.20.63.254194.20.63.2558,190
163194.20.64.0/19194.20.64.1 to 194.20.95.254194.20.95.2558,190
164194.20.96.0/19194.20.96.1 to 194.20.127.254194.20.127.2558,190
165194.20.128.0/19194.20.128.1 to 194.20.159.254194.20.159.2558,190
166194.20.160.0/19194.20.160.1 to 194.20.191.254194.20.191.2558,190
167194.20.192.0/19194.20.192.1 to 194.20.223.254194.20.223.2558,190
168194.20.224.0/19194.20.224.1 to 194.20.255.254194.20.255.2558,190
169194.21.0.0/19194.21.0.1 to 194.21.31.254194.21.31.2558,190
170194.21.32.0/19194.21.32.1 to 194.21.63.254194.21.63.2558,190
171194.21.64.0/19194.21.64.1 to 194.21.95.254194.21.95.2558,190
172194.21.96.0/19194.21.96.1 to 194.21.127.254194.21.127.2558,190
173194.21.128.0/19194.21.128.1 to 194.21.159.254194.21.159.2558,190
174194.21.160.0/19194.21.160.1 to 194.21.191.254194.21.191.2558,190
175194.21.192.0/19194.21.192.1 to 194.21.223.254194.21.223.2558,190
176194.21.224.0/19194.21.224.1 to 194.21.255.254194.21.255.2558,190
177194.22.0.0/19194.22.0.1 to 194.22.31.254194.22.31.2558,190
178194.22.32.0/19194.22.32.1 to 194.22.63.254194.22.63.2558,190
179194.22.64.0/19194.22.64.1 to 194.22.95.254194.22.95.2558,190
180194.22.96.0/19194.22.96.1 to 194.22.127.254194.22.127.2558,190
181194.22.128.0/19194.22.128.1 to 194.22.159.254194.22.159.2558,190
182194.22.160.0/19194.22.160.1 to 194.22.191.254194.22.191.2558,190
183194.22.192.0/19194.22.192.1 to 194.22.223.254194.22.223.2558,190
184194.22.224.0/19194.22.224.1 to 194.22.255.254194.22.255.2558,190
185194.23.0.0/19194.23.0.1 to 194.23.31.254194.23.31.2558,190
186194.23.32.0/19194.23.32.1 to 194.23.63.254194.23.63.2558,190
187194.23.64.0/19194.23.64.1 to 194.23.95.254194.23.95.2558,190
188194.23.96.0/19194.23.96.1 to 194.23.127.254194.23.127.2558,190
189194.23.128.0/19194.23.128.1 to 194.23.159.254194.23.159.2558,190
190194.23.160.0/19194.23.160.1 to 194.23.191.254194.23.191.2558,190
191194.23.192.0/19194.23.192.1 to 194.23.223.254194.23.223.2558,190
192194.23.224.0/19194.23.224.1 to 194.23.255.254194.23.255.2558,190
193194.24.0.0/19194.24.0.1 to 194.24.31.254194.24.31.2558,190
194194.24.32.0/19194.24.32.1 to 194.24.63.254194.24.63.2558,190
195194.24.64.0/19194.24.64.1 to 194.24.95.254194.24.95.2558,190
196194.24.96.0/19194.24.96.1 to 194.24.127.254194.24.127.2558,190
197194.24.128.0/19194.24.128.1 to 194.24.159.254194.24.159.2558,190
198194.24.160.0/19194.24.160.1 to 194.24.191.254194.24.191.2558,190
199194.24.192.0/19194.24.192.1 to 194.24.223.254194.24.223.2558,190
200194.24.224.0/19194.24.224.1 to 194.24.255.254194.24.255.2558,190
201194.25.0.0/19194.25.0.1 to 194.25.31.254194.25.31.2558,190
202194.25.32.0/19194.25.32.1 to 194.25.63.254194.25.63.2558,190
203194.25.64.0/19194.25.64.1 to 194.25.95.254194.25.95.2558,190
204194.25.96.0/19194.25.96.1 to 194.25.127.254194.25.127.2558,190
205194.25.128.0/19194.25.128.1 to 194.25.159.254194.25.159.2558,190
206194.25.160.0/19194.25.160.1 to 194.25.191.254194.25.191.2558,190
207194.25.192.0/19194.25.192.1 to 194.25.223.254194.25.223.2558,190
208194.25.224.0/19194.25.224.1 to 194.25.255.254194.25.255.2558,190
209194.26.0.0/19194.26.0.1 to 194.26.31.254194.26.31.2558,190
210194.26.32.0/19194.26.32.1 to 194.26.63.254194.26.63.2558,190
211194.26.64.0/19194.26.64.1 to 194.26.95.254194.26.95.2558,190
212194.26.96.0/19194.26.96.1 to 194.26.127.254194.26.127.2558,190
213194.26.128.0/19194.26.128.1 to 194.26.159.254194.26.159.2558,190
214194.26.160.0/19194.26.160.1 to 194.26.191.254194.26.191.2558,190
215194.26.192.0/19194.26.192.1 to 194.26.223.254194.26.223.2558,190
216194.26.224.0/19194.26.224.1 to 194.26.255.254194.26.255.2558,190
217194.27.0.0/19194.27.0.1 to 194.27.31.254194.27.31.2558,190
218194.27.32.0/19194.27.32.1 to 194.27.63.254194.27.63.2558,190
219194.27.64.0/19194.27.64.1 to 194.27.95.254194.27.95.2558,190
220194.27.96.0/19194.27.96.1 to 194.27.127.254194.27.127.2558,190
221194.27.128.0/19194.27.128.1 to 194.27.159.254194.27.159.2558,190
222194.27.160.0/19194.27.160.1 to 194.27.191.254194.27.191.2558,190
223194.27.192.0/19194.27.192.1 to 194.27.223.254194.27.223.2558,190
224194.27.224.0/19194.27.224.1 to 194.27.255.254194.27.255.2558,190
225194.28.0.0/19194.28.0.1 to 194.28.31.254194.28.31.2558,190
226194.28.32.0/19194.28.32.1 to 194.28.63.254194.28.63.2558,190
227194.28.64.0/19194.28.64.1 to 194.28.95.254194.28.95.2558,190
228194.28.96.0/19194.28.96.1 to 194.28.127.254194.28.127.2558,190
229194.28.128.0/19194.28.128.1 to 194.28.159.254194.28.159.2558,190
230194.28.160.0/19194.28.160.1 to 194.28.191.254194.28.191.2558,190
231194.28.192.0/19194.28.192.1 to 194.28.223.254194.28.223.2558,190
232194.28.224.0/19194.28.224.1 to 194.28.255.254194.28.255.2558,190
233194.29.0.0/19194.29.0.1 to 194.29.31.254194.29.31.2558,190
234194.29.32.0/19194.29.32.1 to 194.29.63.254194.29.63.2558,190
235194.29.64.0/19194.29.64.1 to 194.29.95.254194.29.95.2558,190
236194.29.96.0/19194.29.96.1 to 194.29.127.254194.29.127.2558,190
237194.29.128.0/19194.29.128.1 to 194.29.159.254194.29.159.2558,190
238194.29.160.0/19194.29.160.1 to 194.29.191.254194.29.191.2558,190
239194.29.192.0/19194.29.192.1 to 194.29.223.254194.29.223.2558,190
240194.29.224.0/19194.29.224.1 to 194.29.255.254194.29.255.2558,190
241194.30.0.0/19194.30.0.1 to 194.30.31.254194.30.31.2558,190
242194.30.32.0/19194.30.32.1 to 194.30.63.254194.30.63.2558,190
243194.30.64.0/19194.30.64.1 to 194.30.95.254194.30.95.2558,190
244194.30.96.0/19194.30.96.1 to 194.30.127.254194.30.127.2558,190
245194.30.128.0/19194.30.128.1 to 194.30.159.254194.30.159.2558,190
246194.30.160.0/19194.30.160.1 to 194.30.191.254194.30.191.2558,190
247194.30.192.0/19194.30.192.1 to 194.30.223.254194.30.223.2558,190
248194.30.224.0/19194.30.224.1 to 194.30.255.254194.30.255.2558,190
249194.31.0.0/19194.31.0.1 to 194.31.31.254194.31.31.2558,190
250194.31.32.0/19194.31.32.1 to 194.31.63.254194.31.63.2558,190
251194.31.64.0/19194.31.64.1 to 194.31.95.254194.31.95.2558,190
252194.31.96.0/19194.31.96.1 to 194.31.127.254194.31.127.2558,190
253194.31.128.0/19194.31.128.1 to 194.31.159.254194.31.159.2558,190
254194.31.160.0/19194.31.160.1 to 194.31.191.254194.31.191.2558,190
255194.31.192.0/19194.31.192.1 to 194.31.223.254194.31.223.2558,190
256194.31.224.0/19194.31.224.1 to 194.31.255.254194.31.255.2558,190

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.