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.

Network116.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
116.128.0.0
Broadcast address
116.255.255.255
First usable
116.128.0.1
Last usable
116.255.255.254
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
A (default /8)
As numbers
Hex 74800000 · Integer 1954545664 to 1962934271
Reverse DNS zones
128.116.in-addr.arpa
129.116.in-addr.arpa
130.116.in-addr.arpa
131.116.in-addr.arpa
132.116.in-addr.arpa
133.116.in-addr.arpa
134.116.in-addr.arpa
135.116.in-addr.arpa
136.116.in-addr.arpa
137.116.in-addr.arpa
138.116.in-addr.arpa
139.116.in-addr.arpa
140.116.in-addr.arpa
141.116.in-addr.arpa
142.116.in-addr.arpa
143.116.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
Address01110100.10000000.00000000.00000000116.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01110100.10000000.00000000.00000000116.128.0.0
Broadcast01110100.11111111.11111111.11111111116.255.255.255
Split into smaller subnets/17
/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)

116.128.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1116.128.0.0/17116.128.0.1 to 116.128.127.254116.128.127.25532,766
2116.128.128.0/17116.128.128.1 to 116.128.255.254116.128.255.25532,766
3116.129.0.0/17116.129.0.1 to 116.129.127.254116.129.127.25532,766
4116.129.128.0/17116.129.128.1 to 116.129.255.254116.129.255.25532,766
5116.130.0.0/17116.130.0.1 to 116.130.127.254116.130.127.25532,766
6116.130.128.0/17116.130.128.1 to 116.130.255.254116.130.255.25532,766
7116.131.0.0/17116.131.0.1 to 116.131.127.254116.131.127.25532,766
8116.131.128.0/17116.131.128.1 to 116.131.255.254116.131.255.25532,766
9116.132.0.0/17116.132.0.1 to 116.132.127.254116.132.127.25532,766
10116.132.128.0/17116.132.128.1 to 116.132.255.254116.132.255.25532,766
11116.133.0.0/17116.133.0.1 to 116.133.127.254116.133.127.25532,766
12116.133.128.0/17116.133.128.1 to 116.133.255.254116.133.255.25532,766
13116.134.0.0/17116.134.0.1 to 116.134.127.254116.134.127.25532,766
14116.134.128.0/17116.134.128.1 to 116.134.255.254116.134.255.25532,766
15116.135.0.0/17116.135.0.1 to 116.135.127.254116.135.127.25532,766
16116.135.128.0/17116.135.128.1 to 116.135.255.254116.135.255.25532,766
17116.136.0.0/17116.136.0.1 to 116.136.127.254116.136.127.25532,766
18116.136.128.0/17116.136.128.1 to 116.136.255.254116.136.255.25532,766
19116.137.0.0/17116.137.0.1 to 116.137.127.254116.137.127.25532,766
20116.137.128.0/17116.137.128.1 to 116.137.255.254116.137.255.25532,766
21116.138.0.0/17116.138.0.1 to 116.138.127.254116.138.127.25532,766
22116.138.128.0/17116.138.128.1 to 116.138.255.254116.138.255.25532,766
23116.139.0.0/17116.139.0.1 to 116.139.127.254116.139.127.25532,766
24116.139.128.0/17116.139.128.1 to 116.139.255.254116.139.255.25532,766
25116.140.0.0/17116.140.0.1 to 116.140.127.254116.140.127.25532,766
26116.140.128.0/17116.140.128.1 to 116.140.255.254116.140.255.25532,766
27116.141.0.0/17116.141.0.1 to 116.141.127.254116.141.127.25532,766
28116.141.128.0/17116.141.128.1 to 116.141.255.254116.141.255.25532,766
29116.142.0.0/17116.142.0.1 to 116.142.127.254116.142.127.25532,766
30116.142.128.0/17116.142.128.1 to 116.142.255.254116.142.255.25532,766
31116.143.0.0/17116.143.0.1 to 116.143.127.254116.143.127.25532,766
32116.143.128.0/17116.143.128.1 to 116.143.255.254116.143.255.25532,766
33116.144.0.0/17116.144.0.1 to 116.144.127.254116.144.127.25532,766
34116.144.128.0/17116.144.128.1 to 116.144.255.254116.144.255.25532,766
35116.145.0.0/17116.145.0.1 to 116.145.127.254116.145.127.25532,766
36116.145.128.0/17116.145.128.1 to 116.145.255.254116.145.255.25532,766
37116.146.0.0/17116.146.0.1 to 116.146.127.254116.146.127.25532,766
38116.146.128.0/17116.146.128.1 to 116.146.255.254116.146.255.25532,766
39116.147.0.0/17116.147.0.1 to 116.147.127.254116.147.127.25532,766
40116.147.128.0/17116.147.128.1 to 116.147.255.254116.147.255.25532,766
41116.148.0.0/17116.148.0.1 to 116.148.127.254116.148.127.25532,766
42116.148.128.0/17116.148.128.1 to 116.148.255.254116.148.255.25532,766
43116.149.0.0/17116.149.0.1 to 116.149.127.254116.149.127.25532,766
44116.149.128.0/17116.149.128.1 to 116.149.255.254116.149.255.25532,766
45116.150.0.0/17116.150.0.1 to 116.150.127.254116.150.127.25532,766
46116.150.128.0/17116.150.128.1 to 116.150.255.254116.150.255.25532,766
47116.151.0.0/17116.151.0.1 to 116.151.127.254116.151.127.25532,766
48116.151.128.0/17116.151.128.1 to 116.151.255.254116.151.255.25532,766
49116.152.0.0/17116.152.0.1 to 116.152.127.254116.152.127.25532,766
50116.152.128.0/17116.152.128.1 to 116.152.255.254116.152.255.25532,766
51116.153.0.0/17116.153.0.1 to 116.153.127.254116.153.127.25532,766
52116.153.128.0/17116.153.128.1 to 116.153.255.254116.153.255.25532,766
53116.154.0.0/17116.154.0.1 to 116.154.127.254116.154.127.25532,766
54116.154.128.0/17116.154.128.1 to 116.154.255.254116.154.255.25532,766
55116.155.0.0/17116.155.0.1 to 116.155.127.254116.155.127.25532,766
56116.155.128.0/17116.155.128.1 to 116.155.255.254116.155.255.25532,766
57116.156.0.0/17116.156.0.1 to 116.156.127.254116.156.127.25532,766
58116.156.128.0/17116.156.128.1 to 116.156.255.254116.156.255.25532,766
59116.157.0.0/17116.157.0.1 to 116.157.127.254116.157.127.25532,766
60116.157.128.0/17116.157.128.1 to 116.157.255.254116.157.255.25532,766
61116.158.0.0/17116.158.0.1 to 116.158.127.254116.158.127.25532,766
62116.158.128.0/17116.158.128.1 to 116.158.255.254116.158.255.25532,766
63116.159.0.0/17116.159.0.1 to 116.159.127.254116.159.127.25532,766
64116.159.128.0/17116.159.128.1 to 116.159.255.254116.159.255.25532,766
65116.160.0.0/17116.160.0.1 to 116.160.127.254116.160.127.25532,766
66116.160.128.0/17116.160.128.1 to 116.160.255.254116.160.255.25532,766
67116.161.0.0/17116.161.0.1 to 116.161.127.254116.161.127.25532,766
68116.161.128.0/17116.161.128.1 to 116.161.255.254116.161.255.25532,766
69116.162.0.0/17116.162.0.1 to 116.162.127.254116.162.127.25532,766
70116.162.128.0/17116.162.128.1 to 116.162.255.254116.162.255.25532,766
71116.163.0.0/17116.163.0.1 to 116.163.127.254116.163.127.25532,766
72116.163.128.0/17116.163.128.1 to 116.163.255.254116.163.255.25532,766
73116.164.0.0/17116.164.0.1 to 116.164.127.254116.164.127.25532,766
74116.164.128.0/17116.164.128.1 to 116.164.255.254116.164.255.25532,766
75116.165.0.0/17116.165.0.1 to 116.165.127.254116.165.127.25532,766
76116.165.128.0/17116.165.128.1 to 116.165.255.254116.165.255.25532,766
77116.166.0.0/17116.166.0.1 to 116.166.127.254116.166.127.25532,766
78116.166.128.0/17116.166.128.1 to 116.166.255.254116.166.255.25532,766
79116.167.0.0/17116.167.0.1 to 116.167.127.254116.167.127.25532,766
80116.167.128.0/17116.167.128.1 to 116.167.255.254116.167.255.25532,766
81116.168.0.0/17116.168.0.1 to 116.168.127.254116.168.127.25532,766
82116.168.128.0/17116.168.128.1 to 116.168.255.254116.168.255.25532,766
83116.169.0.0/17116.169.0.1 to 116.169.127.254116.169.127.25532,766
84116.169.128.0/17116.169.128.1 to 116.169.255.254116.169.255.25532,766
85116.170.0.0/17116.170.0.1 to 116.170.127.254116.170.127.25532,766
86116.170.128.0/17116.170.128.1 to 116.170.255.254116.170.255.25532,766
87116.171.0.0/17116.171.0.1 to 116.171.127.254116.171.127.25532,766
88116.171.128.0/17116.171.128.1 to 116.171.255.254116.171.255.25532,766
89116.172.0.0/17116.172.0.1 to 116.172.127.254116.172.127.25532,766
90116.172.128.0/17116.172.128.1 to 116.172.255.254116.172.255.25532,766
91116.173.0.0/17116.173.0.1 to 116.173.127.254116.173.127.25532,766
92116.173.128.0/17116.173.128.1 to 116.173.255.254116.173.255.25532,766
93116.174.0.0/17116.174.0.1 to 116.174.127.254116.174.127.25532,766
94116.174.128.0/17116.174.128.1 to 116.174.255.254116.174.255.25532,766
95116.175.0.0/17116.175.0.1 to 116.175.127.254116.175.127.25532,766
96116.175.128.0/17116.175.128.1 to 116.175.255.254116.175.255.25532,766
97116.176.0.0/17116.176.0.1 to 116.176.127.254116.176.127.25532,766
98116.176.128.0/17116.176.128.1 to 116.176.255.254116.176.255.25532,766
99116.177.0.0/17116.177.0.1 to 116.177.127.254116.177.127.25532,766
100116.177.128.0/17116.177.128.1 to 116.177.255.254116.177.255.25532,766
101116.178.0.0/17116.178.0.1 to 116.178.127.254116.178.127.25532,766
102116.178.128.0/17116.178.128.1 to 116.178.255.254116.178.255.25532,766
103116.179.0.0/17116.179.0.1 to 116.179.127.254116.179.127.25532,766
104116.179.128.0/17116.179.128.1 to 116.179.255.254116.179.255.25532,766
105116.180.0.0/17116.180.0.1 to 116.180.127.254116.180.127.25532,766
106116.180.128.0/17116.180.128.1 to 116.180.255.254116.180.255.25532,766
107116.181.0.0/17116.181.0.1 to 116.181.127.254116.181.127.25532,766
108116.181.128.0/17116.181.128.1 to 116.181.255.254116.181.255.25532,766
109116.182.0.0/17116.182.0.1 to 116.182.127.254116.182.127.25532,766
110116.182.128.0/17116.182.128.1 to 116.182.255.254116.182.255.25532,766
111116.183.0.0/17116.183.0.1 to 116.183.127.254116.183.127.25532,766
112116.183.128.0/17116.183.128.1 to 116.183.255.254116.183.255.25532,766
113116.184.0.0/17116.184.0.1 to 116.184.127.254116.184.127.25532,766
114116.184.128.0/17116.184.128.1 to 116.184.255.254116.184.255.25532,766
115116.185.0.0/17116.185.0.1 to 116.185.127.254116.185.127.25532,766
116116.185.128.0/17116.185.128.1 to 116.185.255.254116.185.255.25532,766
117116.186.0.0/17116.186.0.1 to 116.186.127.254116.186.127.25532,766
118116.186.128.0/17116.186.128.1 to 116.186.255.254116.186.255.25532,766
119116.187.0.0/17116.187.0.1 to 116.187.127.254116.187.127.25532,766
120116.187.128.0/17116.187.128.1 to 116.187.255.254116.187.255.25532,766
121116.188.0.0/17116.188.0.1 to 116.188.127.254116.188.127.25532,766
122116.188.128.0/17116.188.128.1 to 116.188.255.254116.188.255.25532,766
123116.189.0.0/17116.189.0.1 to 116.189.127.254116.189.127.25532,766
124116.189.128.0/17116.189.128.1 to 116.189.255.254116.189.255.25532,766
125116.190.0.0/17116.190.0.1 to 116.190.127.254116.190.127.25532,766
126116.190.128.0/17116.190.128.1 to 116.190.255.254116.190.255.25532,766
127116.191.0.0/17116.191.0.1 to 116.191.127.254116.191.127.25532,766
128116.191.128.0/17116.191.128.1 to 116.191.255.254116.191.255.25532,766
129116.192.0.0/17116.192.0.1 to 116.192.127.254116.192.127.25532,766
130116.192.128.0/17116.192.128.1 to 116.192.255.254116.192.255.25532,766
131116.193.0.0/17116.193.0.1 to 116.193.127.254116.193.127.25532,766
132116.193.128.0/17116.193.128.1 to 116.193.255.254116.193.255.25532,766
133116.194.0.0/17116.194.0.1 to 116.194.127.254116.194.127.25532,766
134116.194.128.0/17116.194.128.1 to 116.194.255.254116.194.255.25532,766
135116.195.0.0/17116.195.0.1 to 116.195.127.254116.195.127.25532,766
136116.195.128.0/17116.195.128.1 to 116.195.255.254116.195.255.25532,766
137116.196.0.0/17116.196.0.1 to 116.196.127.254116.196.127.25532,766
138116.196.128.0/17116.196.128.1 to 116.196.255.254116.196.255.25532,766
139116.197.0.0/17116.197.0.1 to 116.197.127.254116.197.127.25532,766
140116.197.128.0/17116.197.128.1 to 116.197.255.254116.197.255.25532,766
141116.198.0.0/17116.198.0.1 to 116.198.127.254116.198.127.25532,766
142116.198.128.0/17116.198.128.1 to 116.198.255.254116.198.255.25532,766
143116.199.0.0/17116.199.0.1 to 116.199.127.254116.199.127.25532,766
144116.199.128.0/17116.199.128.1 to 116.199.255.254116.199.255.25532,766
145116.200.0.0/17116.200.0.1 to 116.200.127.254116.200.127.25532,766
146116.200.128.0/17116.200.128.1 to 116.200.255.254116.200.255.25532,766
147116.201.0.0/17116.201.0.1 to 116.201.127.254116.201.127.25532,766
148116.201.128.0/17116.201.128.1 to 116.201.255.254116.201.255.25532,766
149116.202.0.0/17116.202.0.1 to 116.202.127.254116.202.127.25532,766
150116.202.128.0/17116.202.128.1 to 116.202.255.254116.202.255.25532,766
151116.203.0.0/17116.203.0.1 to 116.203.127.254116.203.127.25532,766
152116.203.128.0/17116.203.128.1 to 116.203.255.254116.203.255.25532,766
153116.204.0.0/17116.204.0.1 to 116.204.127.254116.204.127.25532,766
154116.204.128.0/17116.204.128.1 to 116.204.255.254116.204.255.25532,766
155116.205.0.0/17116.205.0.1 to 116.205.127.254116.205.127.25532,766
156116.205.128.0/17116.205.128.1 to 116.205.255.254116.205.255.25532,766
157116.206.0.0/17116.206.0.1 to 116.206.127.254116.206.127.25532,766
158116.206.128.0/17116.206.128.1 to 116.206.255.254116.206.255.25532,766
159116.207.0.0/17116.207.0.1 to 116.207.127.254116.207.127.25532,766
160116.207.128.0/17116.207.128.1 to 116.207.255.254116.207.255.25532,766
161116.208.0.0/17116.208.0.1 to 116.208.127.254116.208.127.25532,766
162116.208.128.0/17116.208.128.1 to 116.208.255.254116.208.255.25532,766
163116.209.0.0/17116.209.0.1 to 116.209.127.254116.209.127.25532,766
164116.209.128.0/17116.209.128.1 to 116.209.255.254116.209.255.25532,766
165116.210.0.0/17116.210.0.1 to 116.210.127.254116.210.127.25532,766
166116.210.128.0/17116.210.128.1 to 116.210.255.254116.210.255.25532,766
167116.211.0.0/17116.211.0.1 to 116.211.127.254116.211.127.25532,766
168116.211.128.0/17116.211.128.1 to 116.211.255.254116.211.255.25532,766
169116.212.0.0/17116.212.0.1 to 116.212.127.254116.212.127.25532,766
170116.212.128.0/17116.212.128.1 to 116.212.255.254116.212.255.25532,766
171116.213.0.0/17116.213.0.1 to 116.213.127.254116.213.127.25532,766
172116.213.128.0/17116.213.128.1 to 116.213.255.254116.213.255.25532,766
173116.214.0.0/17116.214.0.1 to 116.214.127.254116.214.127.25532,766
174116.214.128.0/17116.214.128.1 to 116.214.255.254116.214.255.25532,766
175116.215.0.0/17116.215.0.1 to 116.215.127.254116.215.127.25532,766
176116.215.128.0/17116.215.128.1 to 116.215.255.254116.215.255.25532,766
177116.216.0.0/17116.216.0.1 to 116.216.127.254116.216.127.25532,766
178116.216.128.0/17116.216.128.1 to 116.216.255.254116.216.255.25532,766
179116.217.0.0/17116.217.0.1 to 116.217.127.254116.217.127.25532,766
180116.217.128.0/17116.217.128.1 to 116.217.255.254116.217.255.25532,766
181116.218.0.0/17116.218.0.1 to 116.218.127.254116.218.127.25532,766
182116.218.128.0/17116.218.128.1 to 116.218.255.254116.218.255.25532,766
183116.219.0.0/17116.219.0.1 to 116.219.127.254116.219.127.25532,766
184116.219.128.0/17116.219.128.1 to 116.219.255.254116.219.255.25532,766
185116.220.0.0/17116.220.0.1 to 116.220.127.254116.220.127.25532,766
186116.220.128.0/17116.220.128.1 to 116.220.255.254116.220.255.25532,766
187116.221.0.0/17116.221.0.1 to 116.221.127.254116.221.127.25532,766
188116.221.128.0/17116.221.128.1 to 116.221.255.254116.221.255.25532,766
189116.222.0.0/17116.222.0.1 to 116.222.127.254116.222.127.25532,766
190116.222.128.0/17116.222.128.1 to 116.222.255.254116.222.255.25532,766
191116.223.0.0/17116.223.0.1 to 116.223.127.254116.223.127.25532,766
192116.223.128.0/17116.223.128.1 to 116.223.255.254116.223.255.25532,766
193116.224.0.0/17116.224.0.1 to 116.224.127.254116.224.127.25532,766
194116.224.128.0/17116.224.128.1 to 116.224.255.254116.224.255.25532,766
195116.225.0.0/17116.225.0.1 to 116.225.127.254116.225.127.25532,766
196116.225.128.0/17116.225.128.1 to 116.225.255.254116.225.255.25532,766
197116.226.0.0/17116.226.0.1 to 116.226.127.254116.226.127.25532,766
198116.226.128.0/17116.226.128.1 to 116.226.255.254116.226.255.25532,766
199116.227.0.0/17116.227.0.1 to 116.227.127.254116.227.127.25532,766
200116.227.128.0/17116.227.128.1 to 116.227.255.254116.227.255.25532,766
201116.228.0.0/17116.228.0.1 to 116.228.127.254116.228.127.25532,766
202116.228.128.0/17116.228.128.1 to 116.228.255.254116.228.255.25532,766
203116.229.0.0/17116.229.0.1 to 116.229.127.254116.229.127.25532,766
204116.229.128.0/17116.229.128.1 to 116.229.255.254116.229.255.25532,766
205116.230.0.0/17116.230.0.1 to 116.230.127.254116.230.127.25532,766
206116.230.128.0/17116.230.128.1 to 116.230.255.254116.230.255.25532,766
207116.231.0.0/17116.231.0.1 to 116.231.127.254116.231.127.25532,766
208116.231.128.0/17116.231.128.1 to 116.231.255.254116.231.255.25532,766
209116.232.0.0/17116.232.0.1 to 116.232.127.254116.232.127.25532,766
210116.232.128.0/17116.232.128.1 to 116.232.255.254116.232.255.25532,766
211116.233.0.0/17116.233.0.1 to 116.233.127.254116.233.127.25532,766
212116.233.128.0/17116.233.128.1 to 116.233.255.254116.233.255.25532,766
213116.234.0.0/17116.234.0.1 to 116.234.127.254116.234.127.25532,766
214116.234.128.0/17116.234.128.1 to 116.234.255.254116.234.255.25532,766
215116.235.0.0/17116.235.0.1 to 116.235.127.254116.235.127.25532,766
216116.235.128.0/17116.235.128.1 to 116.235.255.254116.235.255.25532,766
217116.236.0.0/17116.236.0.1 to 116.236.127.254116.236.127.25532,766
218116.236.128.0/17116.236.128.1 to 116.236.255.254116.236.255.25532,766
219116.237.0.0/17116.237.0.1 to 116.237.127.254116.237.127.25532,766
220116.237.128.0/17116.237.128.1 to 116.237.255.254116.237.255.25532,766
221116.238.0.0/17116.238.0.1 to 116.238.127.254116.238.127.25532,766
222116.238.128.0/17116.238.128.1 to 116.238.255.254116.238.255.25532,766
223116.239.0.0/17116.239.0.1 to 116.239.127.254116.239.127.25532,766
224116.239.128.0/17116.239.128.1 to 116.239.255.254116.239.255.25532,766
225116.240.0.0/17116.240.0.1 to 116.240.127.254116.240.127.25532,766
226116.240.128.0/17116.240.128.1 to 116.240.255.254116.240.255.25532,766
227116.241.0.0/17116.241.0.1 to 116.241.127.254116.241.127.25532,766
228116.241.128.0/17116.241.128.1 to 116.241.255.254116.241.255.25532,766
229116.242.0.0/17116.242.0.1 to 116.242.127.254116.242.127.25532,766
230116.242.128.0/17116.242.128.1 to 116.242.255.254116.242.255.25532,766
231116.243.0.0/17116.243.0.1 to 116.243.127.254116.243.127.25532,766
232116.243.128.0/17116.243.128.1 to 116.243.255.254116.243.255.25532,766
233116.244.0.0/17116.244.0.1 to 116.244.127.254116.244.127.25532,766
234116.244.128.0/17116.244.128.1 to 116.244.255.254116.244.255.25532,766
235116.245.0.0/17116.245.0.1 to 116.245.127.254116.245.127.25532,766
236116.245.128.0/17116.245.128.1 to 116.245.255.254116.245.255.25532,766
237116.246.0.0/17116.246.0.1 to 116.246.127.254116.246.127.25532,766
238116.246.128.0/17116.246.128.1 to 116.246.255.254116.246.255.25532,766
239116.247.0.0/17116.247.0.1 to 116.247.127.254116.247.127.25532,766
240116.247.128.0/17116.247.128.1 to 116.247.255.254116.247.255.25532,766
241116.248.0.0/17116.248.0.1 to 116.248.127.254116.248.127.25532,766
242116.248.128.0/17116.248.128.1 to 116.248.255.254116.248.255.25532,766
243116.249.0.0/17116.249.0.1 to 116.249.127.254116.249.127.25532,766
244116.249.128.0/17116.249.128.1 to 116.249.255.254116.249.255.25532,766
245116.250.0.0/17116.250.0.1 to 116.250.127.254116.250.127.25532,766
246116.250.128.0/17116.250.128.1 to 116.250.255.254116.250.255.25532,766
247116.251.0.0/17116.251.0.1 to 116.251.127.254116.251.127.25532,766
248116.251.128.0/17116.251.128.1 to 116.251.255.254116.251.255.25532,766
249116.252.0.0/17116.252.0.1 to 116.252.127.254116.252.127.25532,766
250116.252.128.0/17116.252.128.1 to 116.252.255.254116.252.255.25532,766
251116.253.0.0/17116.253.0.1 to 116.253.127.254116.253.127.25532,766
252116.253.128.0/17116.253.128.1 to 116.253.255.254116.253.255.25532,766
253116.254.0.0/17116.254.0.1 to 116.254.127.254116.254.127.25532,766
254116.254.128.0/17116.254.128.1 to 116.254.255.254116.254.255.25532,766
255116.255.0.0/17116.255.0.1 to 116.255.127.254116.255.127.25532,766
256116.255.128.0/17116.255.128.1 to 116.255.255.254116.255.255.25532,766

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.