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.

Network131.80.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
131.80.0.0
Broadcast address
131.87.255.255
First usable
131.80.0.1
Last usable
131.87.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
B (default /16)
As numbers
Hex 83500000 · Integer 2203058176 to 2203582463
Reverse DNS zones
80.131.in-addr.arpa
81.131.in-addr.arpa
82.131.in-addr.arpa
83.131.in-addr.arpa
84.131.in-addr.arpa
85.131.in-addr.arpa
86.131.in-addr.arpa
87.131.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000011.01010000.00000000.00000000131.80.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10000011.01010000.00000000.00000000131.80.0.0
Broadcast10000011.01010111.11111111.11111111131.87.255.255
Split into smaller subnets/22
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

131.80.0.0/13 makes 512 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1131.80.0.0/22131.80.0.1 to 131.80.3.254131.80.3.2551,022
2131.80.4.0/22131.80.4.1 to 131.80.7.254131.80.7.2551,022
3131.80.8.0/22131.80.8.1 to 131.80.11.254131.80.11.2551,022
4131.80.12.0/22131.80.12.1 to 131.80.15.254131.80.15.2551,022
5131.80.16.0/22131.80.16.1 to 131.80.19.254131.80.19.2551,022
6131.80.20.0/22131.80.20.1 to 131.80.23.254131.80.23.2551,022
7131.80.24.0/22131.80.24.1 to 131.80.27.254131.80.27.2551,022
8131.80.28.0/22131.80.28.1 to 131.80.31.254131.80.31.2551,022
9131.80.32.0/22131.80.32.1 to 131.80.35.254131.80.35.2551,022
10131.80.36.0/22131.80.36.1 to 131.80.39.254131.80.39.2551,022
11131.80.40.0/22131.80.40.1 to 131.80.43.254131.80.43.2551,022
12131.80.44.0/22131.80.44.1 to 131.80.47.254131.80.47.2551,022
13131.80.48.0/22131.80.48.1 to 131.80.51.254131.80.51.2551,022
14131.80.52.0/22131.80.52.1 to 131.80.55.254131.80.55.2551,022
15131.80.56.0/22131.80.56.1 to 131.80.59.254131.80.59.2551,022
16131.80.60.0/22131.80.60.1 to 131.80.63.254131.80.63.2551,022
17131.80.64.0/22131.80.64.1 to 131.80.67.254131.80.67.2551,022
18131.80.68.0/22131.80.68.1 to 131.80.71.254131.80.71.2551,022
19131.80.72.0/22131.80.72.1 to 131.80.75.254131.80.75.2551,022
20131.80.76.0/22131.80.76.1 to 131.80.79.254131.80.79.2551,022
21131.80.80.0/22131.80.80.1 to 131.80.83.254131.80.83.2551,022
22131.80.84.0/22131.80.84.1 to 131.80.87.254131.80.87.2551,022
23131.80.88.0/22131.80.88.1 to 131.80.91.254131.80.91.2551,022
24131.80.92.0/22131.80.92.1 to 131.80.95.254131.80.95.2551,022
25131.80.96.0/22131.80.96.1 to 131.80.99.254131.80.99.2551,022
26131.80.100.0/22131.80.100.1 to 131.80.103.254131.80.103.2551,022
27131.80.104.0/22131.80.104.1 to 131.80.107.254131.80.107.2551,022
28131.80.108.0/22131.80.108.1 to 131.80.111.254131.80.111.2551,022
29131.80.112.0/22131.80.112.1 to 131.80.115.254131.80.115.2551,022
30131.80.116.0/22131.80.116.1 to 131.80.119.254131.80.119.2551,022
31131.80.120.0/22131.80.120.1 to 131.80.123.254131.80.123.2551,022
32131.80.124.0/22131.80.124.1 to 131.80.127.254131.80.127.2551,022
33131.80.128.0/22131.80.128.1 to 131.80.131.254131.80.131.2551,022
34131.80.132.0/22131.80.132.1 to 131.80.135.254131.80.135.2551,022
35131.80.136.0/22131.80.136.1 to 131.80.139.254131.80.139.2551,022
36131.80.140.0/22131.80.140.1 to 131.80.143.254131.80.143.2551,022
37131.80.144.0/22131.80.144.1 to 131.80.147.254131.80.147.2551,022
38131.80.148.0/22131.80.148.1 to 131.80.151.254131.80.151.2551,022
39131.80.152.0/22131.80.152.1 to 131.80.155.254131.80.155.2551,022
40131.80.156.0/22131.80.156.1 to 131.80.159.254131.80.159.2551,022
41131.80.160.0/22131.80.160.1 to 131.80.163.254131.80.163.2551,022
42131.80.164.0/22131.80.164.1 to 131.80.167.254131.80.167.2551,022
43131.80.168.0/22131.80.168.1 to 131.80.171.254131.80.171.2551,022
44131.80.172.0/22131.80.172.1 to 131.80.175.254131.80.175.2551,022
45131.80.176.0/22131.80.176.1 to 131.80.179.254131.80.179.2551,022
46131.80.180.0/22131.80.180.1 to 131.80.183.254131.80.183.2551,022
47131.80.184.0/22131.80.184.1 to 131.80.187.254131.80.187.2551,022
48131.80.188.0/22131.80.188.1 to 131.80.191.254131.80.191.2551,022
49131.80.192.0/22131.80.192.1 to 131.80.195.254131.80.195.2551,022
50131.80.196.0/22131.80.196.1 to 131.80.199.254131.80.199.2551,022
51131.80.200.0/22131.80.200.1 to 131.80.203.254131.80.203.2551,022
52131.80.204.0/22131.80.204.1 to 131.80.207.254131.80.207.2551,022
53131.80.208.0/22131.80.208.1 to 131.80.211.254131.80.211.2551,022
54131.80.212.0/22131.80.212.1 to 131.80.215.254131.80.215.2551,022
55131.80.216.0/22131.80.216.1 to 131.80.219.254131.80.219.2551,022
56131.80.220.0/22131.80.220.1 to 131.80.223.254131.80.223.2551,022
57131.80.224.0/22131.80.224.1 to 131.80.227.254131.80.227.2551,022
58131.80.228.0/22131.80.228.1 to 131.80.231.254131.80.231.2551,022
59131.80.232.0/22131.80.232.1 to 131.80.235.254131.80.235.2551,022
60131.80.236.0/22131.80.236.1 to 131.80.239.254131.80.239.2551,022
61131.80.240.0/22131.80.240.1 to 131.80.243.254131.80.243.2551,022
62131.80.244.0/22131.80.244.1 to 131.80.247.254131.80.247.2551,022
63131.80.248.0/22131.80.248.1 to 131.80.251.254131.80.251.2551,022
64131.80.252.0/22131.80.252.1 to 131.80.255.254131.80.255.2551,022
65131.81.0.0/22131.81.0.1 to 131.81.3.254131.81.3.2551,022
66131.81.4.0/22131.81.4.1 to 131.81.7.254131.81.7.2551,022
67131.81.8.0/22131.81.8.1 to 131.81.11.254131.81.11.2551,022
68131.81.12.0/22131.81.12.1 to 131.81.15.254131.81.15.2551,022
69131.81.16.0/22131.81.16.1 to 131.81.19.254131.81.19.2551,022
70131.81.20.0/22131.81.20.1 to 131.81.23.254131.81.23.2551,022
71131.81.24.0/22131.81.24.1 to 131.81.27.254131.81.27.2551,022
72131.81.28.0/22131.81.28.1 to 131.81.31.254131.81.31.2551,022
73131.81.32.0/22131.81.32.1 to 131.81.35.254131.81.35.2551,022
74131.81.36.0/22131.81.36.1 to 131.81.39.254131.81.39.2551,022
75131.81.40.0/22131.81.40.1 to 131.81.43.254131.81.43.2551,022
76131.81.44.0/22131.81.44.1 to 131.81.47.254131.81.47.2551,022
77131.81.48.0/22131.81.48.1 to 131.81.51.254131.81.51.2551,022
78131.81.52.0/22131.81.52.1 to 131.81.55.254131.81.55.2551,022
79131.81.56.0/22131.81.56.1 to 131.81.59.254131.81.59.2551,022
80131.81.60.0/22131.81.60.1 to 131.81.63.254131.81.63.2551,022
81131.81.64.0/22131.81.64.1 to 131.81.67.254131.81.67.2551,022
82131.81.68.0/22131.81.68.1 to 131.81.71.254131.81.71.2551,022
83131.81.72.0/22131.81.72.1 to 131.81.75.254131.81.75.2551,022
84131.81.76.0/22131.81.76.1 to 131.81.79.254131.81.79.2551,022
85131.81.80.0/22131.81.80.1 to 131.81.83.254131.81.83.2551,022
86131.81.84.0/22131.81.84.1 to 131.81.87.254131.81.87.2551,022
87131.81.88.0/22131.81.88.1 to 131.81.91.254131.81.91.2551,022
88131.81.92.0/22131.81.92.1 to 131.81.95.254131.81.95.2551,022
89131.81.96.0/22131.81.96.1 to 131.81.99.254131.81.99.2551,022
90131.81.100.0/22131.81.100.1 to 131.81.103.254131.81.103.2551,022
91131.81.104.0/22131.81.104.1 to 131.81.107.254131.81.107.2551,022
92131.81.108.0/22131.81.108.1 to 131.81.111.254131.81.111.2551,022
93131.81.112.0/22131.81.112.1 to 131.81.115.254131.81.115.2551,022
94131.81.116.0/22131.81.116.1 to 131.81.119.254131.81.119.2551,022
95131.81.120.0/22131.81.120.1 to 131.81.123.254131.81.123.2551,022
96131.81.124.0/22131.81.124.1 to 131.81.127.254131.81.127.2551,022
97131.81.128.0/22131.81.128.1 to 131.81.131.254131.81.131.2551,022
98131.81.132.0/22131.81.132.1 to 131.81.135.254131.81.135.2551,022
99131.81.136.0/22131.81.136.1 to 131.81.139.254131.81.139.2551,022
100131.81.140.0/22131.81.140.1 to 131.81.143.254131.81.143.2551,022
101131.81.144.0/22131.81.144.1 to 131.81.147.254131.81.147.2551,022
102131.81.148.0/22131.81.148.1 to 131.81.151.254131.81.151.2551,022
103131.81.152.0/22131.81.152.1 to 131.81.155.254131.81.155.2551,022
104131.81.156.0/22131.81.156.1 to 131.81.159.254131.81.159.2551,022
105131.81.160.0/22131.81.160.1 to 131.81.163.254131.81.163.2551,022
106131.81.164.0/22131.81.164.1 to 131.81.167.254131.81.167.2551,022
107131.81.168.0/22131.81.168.1 to 131.81.171.254131.81.171.2551,022
108131.81.172.0/22131.81.172.1 to 131.81.175.254131.81.175.2551,022
109131.81.176.0/22131.81.176.1 to 131.81.179.254131.81.179.2551,022
110131.81.180.0/22131.81.180.1 to 131.81.183.254131.81.183.2551,022
111131.81.184.0/22131.81.184.1 to 131.81.187.254131.81.187.2551,022
112131.81.188.0/22131.81.188.1 to 131.81.191.254131.81.191.2551,022
113131.81.192.0/22131.81.192.1 to 131.81.195.254131.81.195.2551,022
114131.81.196.0/22131.81.196.1 to 131.81.199.254131.81.199.2551,022
115131.81.200.0/22131.81.200.1 to 131.81.203.254131.81.203.2551,022
116131.81.204.0/22131.81.204.1 to 131.81.207.254131.81.207.2551,022
117131.81.208.0/22131.81.208.1 to 131.81.211.254131.81.211.2551,022
118131.81.212.0/22131.81.212.1 to 131.81.215.254131.81.215.2551,022
119131.81.216.0/22131.81.216.1 to 131.81.219.254131.81.219.2551,022
120131.81.220.0/22131.81.220.1 to 131.81.223.254131.81.223.2551,022
121131.81.224.0/22131.81.224.1 to 131.81.227.254131.81.227.2551,022
122131.81.228.0/22131.81.228.1 to 131.81.231.254131.81.231.2551,022
123131.81.232.0/22131.81.232.1 to 131.81.235.254131.81.235.2551,022
124131.81.236.0/22131.81.236.1 to 131.81.239.254131.81.239.2551,022
125131.81.240.0/22131.81.240.1 to 131.81.243.254131.81.243.2551,022
126131.81.244.0/22131.81.244.1 to 131.81.247.254131.81.247.2551,022
127131.81.248.0/22131.81.248.1 to 131.81.251.254131.81.251.2551,022
128131.81.252.0/22131.81.252.1 to 131.81.255.254131.81.255.2551,022
129131.82.0.0/22131.82.0.1 to 131.82.3.254131.82.3.2551,022
130131.82.4.0/22131.82.4.1 to 131.82.7.254131.82.7.2551,022
131131.82.8.0/22131.82.8.1 to 131.82.11.254131.82.11.2551,022
132131.82.12.0/22131.82.12.1 to 131.82.15.254131.82.15.2551,022
133131.82.16.0/22131.82.16.1 to 131.82.19.254131.82.19.2551,022
134131.82.20.0/22131.82.20.1 to 131.82.23.254131.82.23.2551,022
135131.82.24.0/22131.82.24.1 to 131.82.27.254131.82.27.2551,022
136131.82.28.0/22131.82.28.1 to 131.82.31.254131.82.31.2551,022
137131.82.32.0/22131.82.32.1 to 131.82.35.254131.82.35.2551,022
138131.82.36.0/22131.82.36.1 to 131.82.39.254131.82.39.2551,022
139131.82.40.0/22131.82.40.1 to 131.82.43.254131.82.43.2551,022
140131.82.44.0/22131.82.44.1 to 131.82.47.254131.82.47.2551,022
141131.82.48.0/22131.82.48.1 to 131.82.51.254131.82.51.2551,022
142131.82.52.0/22131.82.52.1 to 131.82.55.254131.82.55.2551,022
143131.82.56.0/22131.82.56.1 to 131.82.59.254131.82.59.2551,022
144131.82.60.0/22131.82.60.1 to 131.82.63.254131.82.63.2551,022
145131.82.64.0/22131.82.64.1 to 131.82.67.254131.82.67.2551,022
146131.82.68.0/22131.82.68.1 to 131.82.71.254131.82.71.2551,022
147131.82.72.0/22131.82.72.1 to 131.82.75.254131.82.75.2551,022
148131.82.76.0/22131.82.76.1 to 131.82.79.254131.82.79.2551,022
149131.82.80.0/22131.82.80.1 to 131.82.83.254131.82.83.2551,022
150131.82.84.0/22131.82.84.1 to 131.82.87.254131.82.87.2551,022
151131.82.88.0/22131.82.88.1 to 131.82.91.254131.82.91.2551,022
152131.82.92.0/22131.82.92.1 to 131.82.95.254131.82.95.2551,022
153131.82.96.0/22131.82.96.1 to 131.82.99.254131.82.99.2551,022
154131.82.100.0/22131.82.100.1 to 131.82.103.254131.82.103.2551,022
155131.82.104.0/22131.82.104.1 to 131.82.107.254131.82.107.2551,022
156131.82.108.0/22131.82.108.1 to 131.82.111.254131.82.111.2551,022
157131.82.112.0/22131.82.112.1 to 131.82.115.254131.82.115.2551,022
158131.82.116.0/22131.82.116.1 to 131.82.119.254131.82.119.2551,022
159131.82.120.0/22131.82.120.1 to 131.82.123.254131.82.123.2551,022
160131.82.124.0/22131.82.124.1 to 131.82.127.254131.82.127.2551,022
161131.82.128.0/22131.82.128.1 to 131.82.131.254131.82.131.2551,022
162131.82.132.0/22131.82.132.1 to 131.82.135.254131.82.135.2551,022
163131.82.136.0/22131.82.136.1 to 131.82.139.254131.82.139.2551,022
164131.82.140.0/22131.82.140.1 to 131.82.143.254131.82.143.2551,022
165131.82.144.0/22131.82.144.1 to 131.82.147.254131.82.147.2551,022
166131.82.148.0/22131.82.148.1 to 131.82.151.254131.82.151.2551,022
167131.82.152.0/22131.82.152.1 to 131.82.155.254131.82.155.2551,022
168131.82.156.0/22131.82.156.1 to 131.82.159.254131.82.159.2551,022
169131.82.160.0/22131.82.160.1 to 131.82.163.254131.82.163.2551,022
170131.82.164.0/22131.82.164.1 to 131.82.167.254131.82.167.2551,022
171131.82.168.0/22131.82.168.1 to 131.82.171.254131.82.171.2551,022
172131.82.172.0/22131.82.172.1 to 131.82.175.254131.82.175.2551,022
173131.82.176.0/22131.82.176.1 to 131.82.179.254131.82.179.2551,022
174131.82.180.0/22131.82.180.1 to 131.82.183.254131.82.183.2551,022
175131.82.184.0/22131.82.184.1 to 131.82.187.254131.82.187.2551,022
176131.82.188.0/22131.82.188.1 to 131.82.191.254131.82.191.2551,022
177131.82.192.0/22131.82.192.1 to 131.82.195.254131.82.195.2551,022
178131.82.196.0/22131.82.196.1 to 131.82.199.254131.82.199.2551,022
179131.82.200.0/22131.82.200.1 to 131.82.203.254131.82.203.2551,022
180131.82.204.0/22131.82.204.1 to 131.82.207.254131.82.207.2551,022
181131.82.208.0/22131.82.208.1 to 131.82.211.254131.82.211.2551,022
182131.82.212.0/22131.82.212.1 to 131.82.215.254131.82.215.2551,022
183131.82.216.0/22131.82.216.1 to 131.82.219.254131.82.219.2551,022
184131.82.220.0/22131.82.220.1 to 131.82.223.254131.82.223.2551,022
185131.82.224.0/22131.82.224.1 to 131.82.227.254131.82.227.2551,022
186131.82.228.0/22131.82.228.1 to 131.82.231.254131.82.231.2551,022
187131.82.232.0/22131.82.232.1 to 131.82.235.254131.82.235.2551,022
188131.82.236.0/22131.82.236.1 to 131.82.239.254131.82.239.2551,022
189131.82.240.0/22131.82.240.1 to 131.82.243.254131.82.243.2551,022
190131.82.244.0/22131.82.244.1 to 131.82.247.254131.82.247.2551,022
191131.82.248.0/22131.82.248.1 to 131.82.251.254131.82.251.2551,022
192131.82.252.0/22131.82.252.1 to 131.82.255.254131.82.255.2551,022
193131.83.0.0/22131.83.0.1 to 131.83.3.254131.83.3.2551,022
194131.83.4.0/22131.83.4.1 to 131.83.7.254131.83.7.2551,022
195131.83.8.0/22131.83.8.1 to 131.83.11.254131.83.11.2551,022
196131.83.12.0/22131.83.12.1 to 131.83.15.254131.83.15.2551,022
197131.83.16.0/22131.83.16.1 to 131.83.19.254131.83.19.2551,022
198131.83.20.0/22131.83.20.1 to 131.83.23.254131.83.23.2551,022
199131.83.24.0/22131.83.24.1 to 131.83.27.254131.83.27.2551,022
200131.83.28.0/22131.83.28.1 to 131.83.31.254131.83.31.2551,022
201131.83.32.0/22131.83.32.1 to 131.83.35.254131.83.35.2551,022
202131.83.36.0/22131.83.36.1 to 131.83.39.254131.83.39.2551,022
203131.83.40.0/22131.83.40.1 to 131.83.43.254131.83.43.2551,022
204131.83.44.0/22131.83.44.1 to 131.83.47.254131.83.47.2551,022
205131.83.48.0/22131.83.48.1 to 131.83.51.254131.83.51.2551,022
206131.83.52.0/22131.83.52.1 to 131.83.55.254131.83.55.2551,022
207131.83.56.0/22131.83.56.1 to 131.83.59.254131.83.59.2551,022
208131.83.60.0/22131.83.60.1 to 131.83.63.254131.83.63.2551,022
209131.83.64.0/22131.83.64.1 to 131.83.67.254131.83.67.2551,022
210131.83.68.0/22131.83.68.1 to 131.83.71.254131.83.71.2551,022
211131.83.72.0/22131.83.72.1 to 131.83.75.254131.83.75.2551,022
212131.83.76.0/22131.83.76.1 to 131.83.79.254131.83.79.2551,022
213131.83.80.0/22131.83.80.1 to 131.83.83.254131.83.83.2551,022
214131.83.84.0/22131.83.84.1 to 131.83.87.254131.83.87.2551,022
215131.83.88.0/22131.83.88.1 to 131.83.91.254131.83.91.2551,022
216131.83.92.0/22131.83.92.1 to 131.83.95.254131.83.95.2551,022
217131.83.96.0/22131.83.96.1 to 131.83.99.254131.83.99.2551,022
218131.83.100.0/22131.83.100.1 to 131.83.103.254131.83.103.2551,022
219131.83.104.0/22131.83.104.1 to 131.83.107.254131.83.107.2551,022
220131.83.108.0/22131.83.108.1 to 131.83.111.254131.83.111.2551,022
221131.83.112.0/22131.83.112.1 to 131.83.115.254131.83.115.2551,022
222131.83.116.0/22131.83.116.1 to 131.83.119.254131.83.119.2551,022
223131.83.120.0/22131.83.120.1 to 131.83.123.254131.83.123.2551,022
224131.83.124.0/22131.83.124.1 to 131.83.127.254131.83.127.2551,022
225131.83.128.0/22131.83.128.1 to 131.83.131.254131.83.131.2551,022
226131.83.132.0/22131.83.132.1 to 131.83.135.254131.83.135.2551,022
227131.83.136.0/22131.83.136.1 to 131.83.139.254131.83.139.2551,022
228131.83.140.0/22131.83.140.1 to 131.83.143.254131.83.143.2551,022
229131.83.144.0/22131.83.144.1 to 131.83.147.254131.83.147.2551,022
230131.83.148.0/22131.83.148.1 to 131.83.151.254131.83.151.2551,022
231131.83.152.0/22131.83.152.1 to 131.83.155.254131.83.155.2551,022
232131.83.156.0/22131.83.156.1 to 131.83.159.254131.83.159.2551,022
233131.83.160.0/22131.83.160.1 to 131.83.163.254131.83.163.2551,022
234131.83.164.0/22131.83.164.1 to 131.83.167.254131.83.167.2551,022
235131.83.168.0/22131.83.168.1 to 131.83.171.254131.83.171.2551,022
236131.83.172.0/22131.83.172.1 to 131.83.175.254131.83.175.2551,022
237131.83.176.0/22131.83.176.1 to 131.83.179.254131.83.179.2551,022
238131.83.180.0/22131.83.180.1 to 131.83.183.254131.83.183.2551,022
239131.83.184.0/22131.83.184.1 to 131.83.187.254131.83.187.2551,022
240131.83.188.0/22131.83.188.1 to 131.83.191.254131.83.191.2551,022
241131.83.192.0/22131.83.192.1 to 131.83.195.254131.83.195.2551,022
242131.83.196.0/22131.83.196.1 to 131.83.199.254131.83.199.2551,022
243131.83.200.0/22131.83.200.1 to 131.83.203.254131.83.203.2551,022
244131.83.204.0/22131.83.204.1 to 131.83.207.254131.83.207.2551,022
245131.83.208.0/22131.83.208.1 to 131.83.211.254131.83.211.2551,022
246131.83.212.0/22131.83.212.1 to 131.83.215.254131.83.215.2551,022
247131.83.216.0/22131.83.216.1 to 131.83.219.254131.83.219.2551,022
248131.83.220.0/22131.83.220.1 to 131.83.223.254131.83.223.2551,022
249131.83.224.0/22131.83.224.1 to 131.83.227.254131.83.227.2551,022
250131.83.228.0/22131.83.228.1 to 131.83.231.254131.83.231.2551,022
251131.83.232.0/22131.83.232.1 to 131.83.235.254131.83.235.2551,022
252131.83.236.0/22131.83.236.1 to 131.83.239.254131.83.239.2551,022
253131.83.240.0/22131.83.240.1 to 131.83.243.254131.83.243.2551,022
254131.83.244.0/22131.83.244.1 to 131.83.247.254131.83.247.2551,022
255131.83.248.0/22131.83.248.1 to 131.83.251.254131.83.251.2551,022
256131.83.252.0/22131.83.252.1 to 131.83.255.254131.83.255.2551,022

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.