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.

Network108.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
108.0.0.0
Broadcast address
108.31.255.255
First usable
108.0.0.1
Last usable
108.31.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 6C000000 · Integer 1811939328 to 1814036479
Reverse DNS zones
0.108.in-addr.arpa
1.108.in-addr.arpa
2.108.in-addr.arpa
3.108.in-addr.arpa
4.108.in-addr.arpa
5.108.in-addr.arpa
6.108.in-addr.arpa
7.108.in-addr.arpa
8.108.in-addr.arpa
9.108.in-addr.arpa
10.108.in-addr.arpa
11.108.in-addr.arpa
12.108.in-addr.arpa
13.108.in-addr.arpa
14.108.in-addr.arpa
15.108.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01101100.00000000.00000000.00000000108.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network01101100.00000000.00000000.00000000108.0.0.0
Broadcast01101100.00011111.11111111.11111111108.31.255.255
Split into smaller subnets/19
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

108.0.0.0/11 makes 256 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1108.0.0.0/19108.0.0.1 to 108.0.31.254108.0.31.2558,190
2108.0.32.0/19108.0.32.1 to 108.0.63.254108.0.63.2558,190
3108.0.64.0/19108.0.64.1 to 108.0.95.254108.0.95.2558,190
4108.0.96.0/19108.0.96.1 to 108.0.127.254108.0.127.2558,190
5108.0.128.0/19108.0.128.1 to 108.0.159.254108.0.159.2558,190
6108.0.160.0/19108.0.160.1 to 108.0.191.254108.0.191.2558,190
7108.0.192.0/19108.0.192.1 to 108.0.223.254108.0.223.2558,190
8108.0.224.0/19108.0.224.1 to 108.0.255.254108.0.255.2558,190
9108.1.0.0/19108.1.0.1 to 108.1.31.254108.1.31.2558,190
10108.1.32.0/19108.1.32.1 to 108.1.63.254108.1.63.2558,190
11108.1.64.0/19108.1.64.1 to 108.1.95.254108.1.95.2558,190
12108.1.96.0/19108.1.96.1 to 108.1.127.254108.1.127.2558,190
13108.1.128.0/19108.1.128.1 to 108.1.159.254108.1.159.2558,190
14108.1.160.0/19108.1.160.1 to 108.1.191.254108.1.191.2558,190
15108.1.192.0/19108.1.192.1 to 108.1.223.254108.1.223.2558,190
16108.1.224.0/19108.1.224.1 to 108.1.255.254108.1.255.2558,190
17108.2.0.0/19108.2.0.1 to 108.2.31.254108.2.31.2558,190
18108.2.32.0/19108.2.32.1 to 108.2.63.254108.2.63.2558,190
19108.2.64.0/19108.2.64.1 to 108.2.95.254108.2.95.2558,190
20108.2.96.0/19108.2.96.1 to 108.2.127.254108.2.127.2558,190
21108.2.128.0/19108.2.128.1 to 108.2.159.254108.2.159.2558,190
22108.2.160.0/19108.2.160.1 to 108.2.191.254108.2.191.2558,190
23108.2.192.0/19108.2.192.1 to 108.2.223.254108.2.223.2558,190
24108.2.224.0/19108.2.224.1 to 108.2.255.254108.2.255.2558,190
25108.3.0.0/19108.3.0.1 to 108.3.31.254108.3.31.2558,190
26108.3.32.0/19108.3.32.1 to 108.3.63.254108.3.63.2558,190
27108.3.64.0/19108.3.64.1 to 108.3.95.254108.3.95.2558,190
28108.3.96.0/19108.3.96.1 to 108.3.127.254108.3.127.2558,190
29108.3.128.0/19108.3.128.1 to 108.3.159.254108.3.159.2558,190
30108.3.160.0/19108.3.160.1 to 108.3.191.254108.3.191.2558,190
31108.3.192.0/19108.3.192.1 to 108.3.223.254108.3.223.2558,190
32108.3.224.0/19108.3.224.1 to 108.3.255.254108.3.255.2558,190
33108.4.0.0/19108.4.0.1 to 108.4.31.254108.4.31.2558,190
34108.4.32.0/19108.4.32.1 to 108.4.63.254108.4.63.2558,190
35108.4.64.0/19108.4.64.1 to 108.4.95.254108.4.95.2558,190
36108.4.96.0/19108.4.96.1 to 108.4.127.254108.4.127.2558,190
37108.4.128.0/19108.4.128.1 to 108.4.159.254108.4.159.2558,190
38108.4.160.0/19108.4.160.1 to 108.4.191.254108.4.191.2558,190
39108.4.192.0/19108.4.192.1 to 108.4.223.254108.4.223.2558,190
40108.4.224.0/19108.4.224.1 to 108.4.255.254108.4.255.2558,190
41108.5.0.0/19108.5.0.1 to 108.5.31.254108.5.31.2558,190
42108.5.32.0/19108.5.32.1 to 108.5.63.254108.5.63.2558,190
43108.5.64.0/19108.5.64.1 to 108.5.95.254108.5.95.2558,190
44108.5.96.0/19108.5.96.1 to 108.5.127.254108.5.127.2558,190
45108.5.128.0/19108.5.128.1 to 108.5.159.254108.5.159.2558,190
46108.5.160.0/19108.5.160.1 to 108.5.191.254108.5.191.2558,190
47108.5.192.0/19108.5.192.1 to 108.5.223.254108.5.223.2558,190
48108.5.224.0/19108.5.224.1 to 108.5.255.254108.5.255.2558,190
49108.6.0.0/19108.6.0.1 to 108.6.31.254108.6.31.2558,190
50108.6.32.0/19108.6.32.1 to 108.6.63.254108.6.63.2558,190
51108.6.64.0/19108.6.64.1 to 108.6.95.254108.6.95.2558,190
52108.6.96.0/19108.6.96.1 to 108.6.127.254108.6.127.2558,190
53108.6.128.0/19108.6.128.1 to 108.6.159.254108.6.159.2558,190
54108.6.160.0/19108.6.160.1 to 108.6.191.254108.6.191.2558,190
55108.6.192.0/19108.6.192.1 to 108.6.223.254108.6.223.2558,190
56108.6.224.0/19108.6.224.1 to 108.6.255.254108.6.255.2558,190
57108.7.0.0/19108.7.0.1 to 108.7.31.254108.7.31.2558,190
58108.7.32.0/19108.7.32.1 to 108.7.63.254108.7.63.2558,190
59108.7.64.0/19108.7.64.1 to 108.7.95.254108.7.95.2558,190
60108.7.96.0/19108.7.96.1 to 108.7.127.254108.7.127.2558,190
61108.7.128.0/19108.7.128.1 to 108.7.159.254108.7.159.2558,190
62108.7.160.0/19108.7.160.1 to 108.7.191.254108.7.191.2558,190
63108.7.192.0/19108.7.192.1 to 108.7.223.254108.7.223.2558,190
64108.7.224.0/19108.7.224.1 to 108.7.255.254108.7.255.2558,190
65108.8.0.0/19108.8.0.1 to 108.8.31.254108.8.31.2558,190
66108.8.32.0/19108.8.32.1 to 108.8.63.254108.8.63.2558,190
67108.8.64.0/19108.8.64.1 to 108.8.95.254108.8.95.2558,190
68108.8.96.0/19108.8.96.1 to 108.8.127.254108.8.127.2558,190
69108.8.128.0/19108.8.128.1 to 108.8.159.254108.8.159.2558,190
70108.8.160.0/19108.8.160.1 to 108.8.191.254108.8.191.2558,190
71108.8.192.0/19108.8.192.1 to 108.8.223.254108.8.223.2558,190
72108.8.224.0/19108.8.224.1 to 108.8.255.254108.8.255.2558,190
73108.9.0.0/19108.9.0.1 to 108.9.31.254108.9.31.2558,190
74108.9.32.0/19108.9.32.1 to 108.9.63.254108.9.63.2558,190
75108.9.64.0/19108.9.64.1 to 108.9.95.254108.9.95.2558,190
76108.9.96.0/19108.9.96.1 to 108.9.127.254108.9.127.2558,190
77108.9.128.0/19108.9.128.1 to 108.9.159.254108.9.159.2558,190
78108.9.160.0/19108.9.160.1 to 108.9.191.254108.9.191.2558,190
79108.9.192.0/19108.9.192.1 to 108.9.223.254108.9.223.2558,190
80108.9.224.0/19108.9.224.1 to 108.9.255.254108.9.255.2558,190
81108.10.0.0/19108.10.0.1 to 108.10.31.254108.10.31.2558,190
82108.10.32.0/19108.10.32.1 to 108.10.63.254108.10.63.2558,190
83108.10.64.0/19108.10.64.1 to 108.10.95.254108.10.95.2558,190
84108.10.96.0/19108.10.96.1 to 108.10.127.254108.10.127.2558,190
85108.10.128.0/19108.10.128.1 to 108.10.159.254108.10.159.2558,190
86108.10.160.0/19108.10.160.1 to 108.10.191.254108.10.191.2558,190
87108.10.192.0/19108.10.192.1 to 108.10.223.254108.10.223.2558,190
88108.10.224.0/19108.10.224.1 to 108.10.255.254108.10.255.2558,190
89108.11.0.0/19108.11.0.1 to 108.11.31.254108.11.31.2558,190
90108.11.32.0/19108.11.32.1 to 108.11.63.254108.11.63.2558,190
91108.11.64.0/19108.11.64.1 to 108.11.95.254108.11.95.2558,190
92108.11.96.0/19108.11.96.1 to 108.11.127.254108.11.127.2558,190
93108.11.128.0/19108.11.128.1 to 108.11.159.254108.11.159.2558,190
94108.11.160.0/19108.11.160.1 to 108.11.191.254108.11.191.2558,190
95108.11.192.0/19108.11.192.1 to 108.11.223.254108.11.223.2558,190
96108.11.224.0/19108.11.224.1 to 108.11.255.254108.11.255.2558,190
97108.12.0.0/19108.12.0.1 to 108.12.31.254108.12.31.2558,190
98108.12.32.0/19108.12.32.1 to 108.12.63.254108.12.63.2558,190
99108.12.64.0/19108.12.64.1 to 108.12.95.254108.12.95.2558,190
100108.12.96.0/19108.12.96.1 to 108.12.127.254108.12.127.2558,190
101108.12.128.0/19108.12.128.1 to 108.12.159.254108.12.159.2558,190
102108.12.160.0/19108.12.160.1 to 108.12.191.254108.12.191.2558,190
103108.12.192.0/19108.12.192.1 to 108.12.223.254108.12.223.2558,190
104108.12.224.0/19108.12.224.1 to 108.12.255.254108.12.255.2558,190
105108.13.0.0/19108.13.0.1 to 108.13.31.254108.13.31.2558,190
106108.13.32.0/19108.13.32.1 to 108.13.63.254108.13.63.2558,190
107108.13.64.0/19108.13.64.1 to 108.13.95.254108.13.95.2558,190
108108.13.96.0/19108.13.96.1 to 108.13.127.254108.13.127.2558,190
109108.13.128.0/19108.13.128.1 to 108.13.159.254108.13.159.2558,190
110108.13.160.0/19108.13.160.1 to 108.13.191.254108.13.191.2558,190
111108.13.192.0/19108.13.192.1 to 108.13.223.254108.13.223.2558,190
112108.13.224.0/19108.13.224.1 to 108.13.255.254108.13.255.2558,190
113108.14.0.0/19108.14.0.1 to 108.14.31.254108.14.31.2558,190
114108.14.32.0/19108.14.32.1 to 108.14.63.254108.14.63.2558,190
115108.14.64.0/19108.14.64.1 to 108.14.95.254108.14.95.2558,190
116108.14.96.0/19108.14.96.1 to 108.14.127.254108.14.127.2558,190
117108.14.128.0/19108.14.128.1 to 108.14.159.254108.14.159.2558,190
118108.14.160.0/19108.14.160.1 to 108.14.191.254108.14.191.2558,190
119108.14.192.0/19108.14.192.1 to 108.14.223.254108.14.223.2558,190
120108.14.224.0/19108.14.224.1 to 108.14.255.254108.14.255.2558,190
121108.15.0.0/19108.15.0.1 to 108.15.31.254108.15.31.2558,190
122108.15.32.0/19108.15.32.1 to 108.15.63.254108.15.63.2558,190
123108.15.64.0/19108.15.64.1 to 108.15.95.254108.15.95.2558,190
124108.15.96.0/19108.15.96.1 to 108.15.127.254108.15.127.2558,190
125108.15.128.0/19108.15.128.1 to 108.15.159.254108.15.159.2558,190
126108.15.160.0/19108.15.160.1 to 108.15.191.254108.15.191.2558,190
127108.15.192.0/19108.15.192.1 to 108.15.223.254108.15.223.2558,190
128108.15.224.0/19108.15.224.1 to 108.15.255.254108.15.255.2558,190
129108.16.0.0/19108.16.0.1 to 108.16.31.254108.16.31.2558,190
130108.16.32.0/19108.16.32.1 to 108.16.63.254108.16.63.2558,190
131108.16.64.0/19108.16.64.1 to 108.16.95.254108.16.95.2558,190
132108.16.96.0/19108.16.96.1 to 108.16.127.254108.16.127.2558,190
133108.16.128.0/19108.16.128.1 to 108.16.159.254108.16.159.2558,190
134108.16.160.0/19108.16.160.1 to 108.16.191.254108.16.191.2558,190
135108.16.192.0/19108.16.192.1 to 108.16.223.254108.16.223.2558,190
136108.16.224.0/19108.16.224.1 to 108.16.255.254108.16.255.2558,190
137108.17.0.0/19108.17.0.1 to 108.17.31.254108.17.31.2558,190
138108.17.32.0/19108.17.32.1 to 108.17.63.254108.17.63.2558,190
139108.17.64.0/19108.17.64.1 to 108.17.95.254108.17.95.2558,190
140108.17.96.0/19108.17.96.1 to 108.17.127.254108.17.127.2558,190
141108.17.128.0/19108.17.128.1 to 108.17.159.254108.17.159.2558,190
142108.17.160.0/19108.17.160.1 to 108.17.191.254108.17.191.2558,190
143108.17.192.0/19108.17.192.1 to 108.17.223.254108.17.223.2558,190
144108.17.224.0/19108.17.224.1 to 108.17.255.254108.17.255.2558,190
145108.18.0.0/19108.18.0.1 to 108.18.31.254108.18.31.2558,190
146108.18.32.0/19108.18.32.1 to 108.18.63.254108.18.63.2558,190
147108.18.64.0/19108.18.64.1 to 108.18.95.254108.18.95.2558,190
148108.18.96.0/19108.18.96.1 to 108.18.127.254108.18.127.2558,190
149108.18.128.0/19108.18.128.1 to 108.18.159.254108.18.159.2558,190
150108.18.160.0/19108.18.160.1 to 108.18.191.254108.18.191.2558,190
151108.18.192.0/19108.18.192.1 to 108.18.223.254108.18.223.2558,190
152108.18.224.0/19108.18.224.1 to 108.18.255.254108.18.255.2558,190
153108.19.0.0/19108.19.0.1 to 108.19.31.254108.19.31.2558,190
154108.19.32.0/19108.19.32.1 to 108.19.63.254108.19.63.2558,190
155108.19.64.0/19108.19.64.1 to 108.19.95.254108.19.95.2558,190
156108.19.96.0/19108.19.96.1 to 108.19.127.254108.19.127.2558,190
157108.19.128.0/19108.19.128.1 to 108.19.159.254108.19.159.2558,190
158108.19.160.0/19108.19.160.1 to 108.19.191.254108.19.191.2558,190
159108.19.192.0/19108.19.192.1 to 108.19.223.254108.19.223.2558,190
160108.19.224.0/19108.19.224.1 to 108.19.255.254108.19.255.2558,190
161108.20.0.0/19108.20.0.1 to 108.20.31.254108.20.31.2558,190
162108.20.32.0/19108.20.32.1 to 108.20.63.254108.20.63.2558,190
163108.20.64.0/19108.20.64.1 to 108.20.95.254108.20.95.2558,190
164108.20.96.0/19108.20.96.1 to 108.20.127.254108.20.127.2558,190
165108.20.128.0/19108.20.128.1 to 108.20.159.254108.20.159.2558,190
166108.20.160.0/19108.20.160.1 to 108.20.191.254108.20.191.2558,190
167108.20.192.0/19108.20.192.1 to 108.20.223.254108.20.223.2558,190
168108.20.224.0/19108.20.224.1 to 108.20.255.254108.20.255.2558,190
169108.21.0.0/19108.21.0.1 to 108.21.31.254108.21.31.2558,190
170108.21.32.0/19108.21.32.1 to 108.21.63.254108.21.63.2558,190
171108.21.64.0/19108.21.64.1 to 108.21.95.254108.21.95.2558,190
172108.21.96.0/19108.21.96.1 to 108.21.127.254108.21.127.2558,190
173108.21.128.0/19108.21.128.1 to 108.21.159.254108.21.159.2558,190
174108.21.160.0/19108.21.160.1 to 108.21.191.254108.21.191.2558,190
175108.21.192.0/19108.21.192.1 to 108.21.223.254108.21.223.2558,190
176108.21.224.0/19108.21.224.1 to 108.21.255.254108.21.255.2558,190
177108.22.0.0/19108.22.0.1 to 108.22.31.254108.22.31.2558,190
178108.22.32.0/19108.22.32.1 to 108.22.63.254108.22.63.2558,190
179108.22.64.0/19108.22.64.1 to 108.22.95.254108.22.95.2558,190
180108.22.96.0/19108.22.96.1 to 108.22.127.254108.22.127.2558,190
181108.22.128.0/19108.22.128.1 to 108.22.159.254108.22.159.2558,190
182108.22.160.0/19108.22.160.1 to 108.22.191.254108.22.191.2558,190
183108.22.192.0/19108.22.192.1 to 108.22.223.254108.22.223.2558,190
184108.22.224.0/19108.22.224.1 to 108.22.255.254108.22.255.2558,190
185108.23.0.0/19108.23.0.1 to 108.23.31.254108.23.31.2558,190
186108.23.32.0/19108.23.32.1 to 108.23.63.254108.23.63.2558,190
187108.23.64.0/19108.23.64.1 to 108.23.95.254108.23.95.2558,190
188108.23.96.0/19108.23.96.1 to 108.23.127.254108.23.127.2558,190
189108.23.128.0/19108.23.128.1 to 108.23.159.254108.23.159.2558,190
190108.23.160.0/19108.23.160.1 to 108.23.191.254108.23.191.2558,190
191108.23.192.0/19108.23.192.1 to 108.23.223.254108.23.223.2558,190
192108.23.224.0/19108.23.224.1 to 108.23.255.254108.23.255.2558,190
193108.24.0.0/19108.24.0.1 to 108.24.31.254108.24.31.2558,190
194108.24.32.0/19108.24.32.1 to 108.24.63.254108.24.63.2558,190
195108.24.64.0/19108.24.64.1 to 108.24.95.254108.24.95.2558,190
196108.24.96.0/19108.24.96.1 to 108.24.127.254108.24.127.2558,190
197108.24.128.0/19108.24.128.1 to 108.24.159.254108.24.159.2558,190
198108.24.160.0/19108.24.160.1 to 108.24.191.254108.24.191.2558,190
199108.24.192.0/19108.24.192.1 to 108.24.223.254108.24.223.2558,190
200108.24.224.0/19108.24.224.1 to 108.24.255.254108.24.255.2558,190
201108.25.0.0/19108.25.0.1 to 108.25.31.254108.25.31.2558,190
202108.25.32.0/19108.25.32.1 to 108.25.63.254108.25.63.2558,190
203108.25.64.0/19108.25.64.1 to 108.25.95.254108.25.95.2558,190
204108.25.96.0/19108.25.96.1 to 108.25.127.254108.25.127.2558,190
205108.25.128.0/19108.25.128.1 to 108.25.159.254108.25.159.2558,190
206108.25.160.0/19108.25.160.1 to 108.25.191.254108.25.191.2558,190
207108.25.192.0/19108.25.192.1 to 108.25.223.254108.25.223.2558,190
208108.25.224.0/19108.25.224.1 to 108.25.255.254108.25.255.2558,190
209108.26.0.0/19108.26.0.1 to 108.26.31.254108.26.31.2558,190
210108.26.32.0/19108.26.32.1 to 108.26.63.254108.26.63.2558,190
211108.26.64.0/19108.26.64.1 to 108.26.95.254108.26.95.2558,190
212108.26.96.0/19108.26.96.1 to 108.26.127.254108.26.127.2558,190
213108.26.128.0/19108.26.128.1 to 108.26.159.254108.26.159.2558,190
214108.26.160.0/19108.26.160.1 to 108.26.191.254108.26.191.2558,190
215108.26.192.0/19108.26.192.1 to 108.26.223.254108.26.223.2558,190
216108.26.224.0/19108.26.224.1 to 108.26.255.254108.26.255.2558,190
217108.27.0.0/19108.27.0.1 to 108.27.31.254108.27.31.2558,190
218108.27.32.0/19108.27.32.1 to 108.27.63.254108.27.63.2558,190
219108.27.64.0/19108.27.64.1 to 108.27.95.254108.27.95.2558,190
220108.27.96.0/19108.27.96.1 to 108.27.127.254108.27.127.2558,190
221108.27.128.0/19108.27.128.1 to 108.27.159.254108.27.159.2558,190
222108.27.160.0/19108.27.160.1 to 108.27.191.254108.27.191.2558,190
223108.27.192.0/19108.27.192.1 to 108.27.223.254108.27.223.2558,190
224108.27.224.0/19108.27.224.1 to 108.27.255.254108.27.255.2558,190
225108.28.0.0/19108.28.0.1 to 108.28.31.254108.28.31.2558,190
226108.28.32.0/19108.28.32.1 to 108.28.63.254108.28.63.2558,190
227108.28.64.0/19108.28.64.1 to 108.28.95.254108.28.95.2558,190
228108.28.96.0/19108.28.96.1 to 108.28.127.254108.28.127.2558,190
229108.28.128.0/19108.28.128.1 to 108.28.159.254108.28.159.2558,190
230108.28.160.0/19108.28.160.1 to 108.28.191.254108.28.191.2558,190
231108.28.192.0/19108.28.192.1 to 108.28.223.254108.28.223.2558,190
232108.28.224.0/19108.28.224.1 to 108.28.255.254108.28.255.2558,190
233108.29.0.0/19108.29.0.1 to 108.29.31.254108.29.31.2558,190
234108.29.32.0/19108.29.32.1 to 108.29.63.254108.29.63.2558,190
235108.29.64.0/19108.29.64.1 to 108.29.95.254108.29.95.2558,190
236108.29.96.0/19108.29.96.1 to 108.29.127.254108.29.127.2558,190
237108.29.128.0/19108.29.128.1 to 108.29.159.254108.29.159.2558,190
238108.29.160.0/19108.29.160.1 to 108.29.191.254108.29.191.2558,190
239108.29.192.0/19108.29.192.1 to 108.29.223.254108.29.223.2558,190
240108.29.224.0/19108.29.224.1 to 108.29.255.254108.29.255.2558,190
241108.30.0.0/19108.30.0.1 to 108.30.31.254108.30.31.2558,190
242108.30.32.0/19108.30.32.1 to 108.30.63.254108.30.63.2558,190
243108.30.64.0/19108.30.64.1 to 108.30.95.254108.30.95.2558,190
244108.30.96.0/19108.30.96.1 to 108.30.127.254108.30.127.2558,190
245108.30.128.0/19108.30.128.1 to 108.30.159.254108.30.159.2558,190
246108.30.160.0/19108.30.160.1 to 108.30.191.254108.30.191.2558,190
247108.30.192.0/19108.30.192.1 to 108.30.223.254108.30.223.2558,190
248108.30.224.0/19108.30.224.1 to 108.30.255.254108.30.255.2558,190
249108.31.0.0/19108.31.0.1 to 108.31.31.254108.31.31.2558,190
250108.31.32.0/19108.31.32.1 to 108.31.63.254108.31.63.2558,190
251108.31.64.0/19108.31.64.1 to 108.31.95.254108.31.95.2558,190
252108.31.96.0/19108.31.96.1 to 108.31.127.254108.31.127.2558,190
253108.31.128.0/19108.31.128.1 to 108.31.159.254108.31.159.2558,190
254108.31.160.0/19108.31.160.1 to 108.31.191.254108.31.191.2558,190
255108.31.192.0/19108.31.192.1 to 108.31.223.254108.31.223.2558,190
256108.31.224.0/19108.31.224.1 to 108.31.255.254108.31.255.2558,190

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.