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.

Network160.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
160.0.0.0
Broadcast address
175.255.255.255
First usable
160.0.0.1
Last usable
175.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
B (default /16)
As numbers
Hex A0000000 · Integer 2684354560 to 2952790015
Reverse DNS zones
160.in-addr.arpa
161.in-addr.arpa
162.in-addr.arpa
163.in-addr.arpa
164.in-addr.arpa
165.in-addr.arpa
166.in-addr.arpa
167.in-addr.arpa
168.in-addr.arpa
169.in-addr.arpa
170.in-addr.arpa
171.in-addr.arpa
172.in-addr.arpa
173.in-addr.arpa
174.in-addr.arpa
175.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100000.00000000.00000000.00000000160.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network10100000.00000000.00000000.00000000160.0.0.0
Broadcast10101111.11111111.11111111.11111111175.255.255.255
Split into smaller subnets/14
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

160.0.0.0/4 makes 1,024 subnets of /14; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1160.0.0.0/14160.0.0.1 to 160.3.255.254160.3.255.255262,142
2160.4.0.0/14160.4.0.1 to 160.7.255.254160.7.255.255262,142
3160.8.0.0/14160.8.0.1 to 160.11.255.254160.11.255.255262,142
4160.12.0.0/14160.12.0.1 to 160.15.255.254160.15.255.255262,142
5160.16.0.0/14160.16.0.1 to 160.19.255.254160.19.255.255262,142
6160.20.0.0/14160.20.0.1 to 160.23.255.254160.23.255.255262,142
7160.24.0.0/14160.24.0.1 to 160.27.255.254160.27.255.255262,142
8160.28.0.0/14160.28.0.1 to 160.31.255.254160.31.255.255262,142
9160.32.0.0/14160.32.0.1 to 160.35.255.254160.35.255.255262,142
10160.36.0.0/14160.36.0.1 to 160.39.255.254160.39.255.255262,142
11160.40.0.0/14160.40.0.1 to 160.43.255.254160.43.255.255262,142
12160.44.0.0/14160.44.0.1 to 160.47.255.254160.47.255.255262,142
13160.48.0.0/14160.48.0.1 to 160.51.255.254160.51.255.255262,142
14160.52.0.0/14160.52.0.1 to 160.55.255.254160.55.255.255262,142
15160.56.0.0/14160.56.0.1 to 160.59.255.254160.59.255.255262,142
16160.60.0.0/14160.60.0.1 to 160.63.255.254160.63.255.255262,142
17160.64.0.0/14160.64.0.1 to 160.67.255.254160.67.255.255262,142
18160.68.0.0/14160.68.0.1 to 160.71.255.254160.71.255.255262,142
19160.72.0.0/14160.72.0.1 to 160.75.255.254160.75.255.255262,142
20160.76.0.0/14160.76.0.1 to 160.79.255.254160.79.255.255262,142
21160.80.0.0/14160.80.0.1 to 160.83.255.254160.83.255.255262,142
22160.84.0.0/14160.84.0.1 to 160.87.255.254160.87.255.255262,142
23160.88.0.0/14160.88.0.1 to 160.91.255.254160.91.255.255262,142
24160.92.0.0/14160.92.0.1 to 160.95.255.254160.95.255.255262,142
25160.96.0.0/14160.96.0.1 to 160.99.255.254160.99.255.255262,142
26160.100.0.0/14160.100.0.1 to 160.103.255.254160.103.255.255262,142
27160.104.0.0/14160.104.0.1 to 160.107.255.254160.107.255.255262,142
28160.108.0.0/14160.108.0.1 to 160.111.255.254160.111.255.255262,142
29160.112.0.0/14160.112.0.1 to 160.115.255.254160.115.255.255262,142
30160.116.0.0/14160.116.0.1 to 160.119.255.254160.119.255.255262,142
31160.120.0.0/14160.120.0.1 to 160.123.255.254160.123.255.255262,142
32160.124.0.0/14160.124.0.1 to 160.127.255.254160.127.255.255262,142
33160.128.0.0/14160.128.0.1 to 160.131.255.254160.131.255.255262,142
34160.132.0.0/14160.132.0.1 to 160.135.255.254160.135.255.255262,142
35160.136.0.0/14160.136.0.1 to 160.139.255.254160.139.255.255262,142
36160.140.0.0/14160.140.0.1 to 160.143.255.254160.143.255.255262,142
37160.144.0.0/14160.144.0.1 to 160.147.255.254160.147.255.255262,142
38160.148.0.0/14160.148.0.1 to 160.151.255.254160.151.255.255262,142
39160.152.0.0/14160.152.0.1 to 160.155.255.254160.155.255.255262,142
40160.156.0.0/14160.156.0.1 to 160.159.255.254160.159.255.255262,142
41160.160.0.0/14160.160.0.1 to 160.163.255.254160.163.255.255262,142
42160.164.0.0/14160.164.0.1 to 160.167.255.254160.167.255.255262,142
43160.168.0.0/14160.168.0.1 to 160.171.255.254160.171.255.255262,142
44160.172.0.0/14160.172.0.1 to 160.175.255.254160.175.255.255262,142
45160.176.0.0/14160.176.0.1 to 160.179.255.254160.179.255.255262,142
46160.180.0.0/14160.180.0.1 to 160.183.255.254160.183.255.255262,142
47160.184.0.0/14160.184.0.1 to 160.187.255.254160.187.255.255262,142
48160.188.0.0/14160.188.0.1 to 160.191.255.254160.191.255.255262,142
49160.192.0.0/14160.192.0.1 to 160.195.255.254160.195.255.255262,142
50160.196.0.0/14160.196.0.1 to 160.199.255.254160.199.255.255262,142
51160.200.0.0/14160.200.0.1 to 160.203.255.254160.203.255.255262,142
52160.204.0.0/14160.204.0.1 to 160.207.255.254160.207.255.255262,142
53160.208.0.0/14160.208.0.1 to 160.211.255.254160.211.255.255262,142
54160.212.0.0/14160.212.0.1 to 160.215.255.254160.215.255.255262,142
55160.216.0.0/14160.216.0.1 to 160.219.255.254160.219.255.255262,142
56160.220.0.0/14160.220.0.1 to 160.223.255.254160.223.255.255262,142
57160.224.0.0/14160.224.0.1 to 160.227.255.254160.227.255.255262,142
58160.228.0.0/14160.228.0.1 to 160.231.255.254160.231.255.255262,142
59160.232.0.0/14160.232.0.1 to 160.235.255.254160.235.255.255262,142
60160.236.0.0/14160.236.0.1 to 160.239.255.254160.239.255.255262,142
61160.240.0.0/14160.240.0.1 to 160.243.255.254160.243.255.255262,142
62160.244.0.0/14160.244.0.1 to 160.247.255.254160.247.255.255262,142
63160.248.0.0/14160.248.0.1 to 160.251.255.254160.251.255.255262,142
64160.252.0.0/14160.252.0.1 to 160.255.255.254160.255.255.255262,142
65161.0.0.0/14161.0.0.1 to 161.3.255.254161.3.255.255262,142
66161.4.0.0/14161.4.0.1 to 161.7.255.254161.7.255.255262,142
67161.8.0.0/14161.8.0.1 to 161.11.255.254161.11.255.255262,142
68161.12.0.0/14161.12.0.1 to 161.15.255.254161.15.255.255262,142
69161.16.0.0/14161.16.0.1 to 161.19.255.254161.19.255.255262,142
70161.20.0.0/14161.20.0.1 to 161.23.255.254161.23.255.255262,142
71161.24.0.0/14161.24.0.1 to 161.27.255.254161.27.255.255262,142
72161.28.0.0/14161.28.0.1 to 161.31.255.254161.31.255.255262,142
73161.32.0.0/14161.32.0.1 to 161.35.255.254161.35.255.255262,142
74161.36.0.0/14161.36.0.1 to 161.39.255.254161.39.255.255262,142
75161.40.0.0/14161.40.0.1 to 161.43.255.254161.43.255.255262,142
76161.44.0.0/14161.44.0.1 to 161.47.255.254161.47.255.255262,142
77161.48.0.0/14161.48.0.1 to 161.51.255.254161.51.255.255262,142
78161.52.0.0/14161.52.0.1 to 161.55.255.254161.55.255.255262,142
79161.56.0.0/14161.56.0.1 to 161.59.255.254161.59.255.255262,142
80161.60.0.0/14161.60.0.1 to 161.63.255.254161.63.255.255262,142
81161.64.0.0/14161.64.0.1 to 161.67.255.254161.67.255.255262,142
82161.68.0.0/14161.68.0.1 to 161.71.255.254161.71.255.255262,142
83161.72.0.0/14161.72.0.1 to 161.75.255.254161.75.255.255262,142
84161.76.0.0/14161.76.0.1 to 161.79.255.254161.79.255.255262,142
85161.80.0.0/14161.80.0.1 to 161.83.255.254161.83.255.255262,142
86161.84.0.0/14161.84.0.1 to 161.87.255.254161.87.255.255262,142
87161.88.0.0/14161.88.0.1 to 161.91.255.254161.91.255.255262,142
88161.92.0.0/14161.92.0.1 to 161.95.255.254161.95.255.255262,142
89161.96.0.0/14161.96.0.1 to 161.99.255.254161.99.255.255262,142
90161.100.0.0/14161.100.0.1 to 161.103.255.254161.103.255.255262,142
91161.104.0.0/14161.104.0.1 to 161.107.255.254161.107.255.255262,142
92161.108.0.0/14161.108.0.1 to 161.111.255.254161.111.255.255262,142
93161.112.0.0/14161.112.0.1 to 161.115.255.254161.115.255.255262,142
94161.116.0.0/14161.116.0.1 to 161.119.255.254161.119.255.255262,142
95161.120.0.0/14161.120.0.1 to 161.123.255.254161.123.255.255262,142
96161.124.0.0/14161.124.0.1 to 161.127.255.254161.127.255.255262,142
97161.128.0.0/14161.128.0.1 to 161.131.255.254161.131.255.255262,142
98161.132.0.0/14161.132.0.1 to 161.135.255.254161.135.255.255262,142
99161.136.0.0/14161.136.0.1 to 161.139.255.254161.139.255.255262,142
100161.140.0.0/14161.140.0.1 to 161.143.255.254161.143.255.255262,142
101161.144.0.0/14161.144.0.1 to 161.147.255.254161.147.255.255262,142
102161.148.0.0/14161.148.0.1 to 161.151.255.254161.151.255.255262,142
103161.152.0.0/14161.152.0.1 to 161.155.255.254161.155.255.255262,142
104161.156.0.0/14161.156.0.1 to 161.159.255.254161.159.255.255262,142
105161.160.0.0/14161.160.0.1 to 161.163.255.254161.163.255.255262,142
106161.164.0.0/14161.164.0.1 to 161.167.255.254161.167.255.255262,142
107161.168.0.0/14161.168.0.1 to 161.171.255.254161.171.255.255262,142
108161.172.0.0/14161.172.0.1 to 161.175.255.254161.175.255.255262,142
109161.176.0.0/14161.176.0.1 to 161.179.255.254161.179.255.255262,142
110161.180.0.0/14161.180.0.1 to 161.183.255.254161.183.255.255262,142
111161.184.0.0/14161.184.0.1 to 161.187.255.254161.187.255.255262,142
112161.188.0.0/14161.188.0.1 to 161.191.255.254161.191.255.255262,142
113161.192.0.0/14161.192.0.1 to 161.195.255.254161.195.255.255262,142
114161.196.0.0/14161.196.0.1 to 161.199.255.254161.199.255.255262,142
115161.200.0.0/14161.200.0.1 to 161.203.255.254161.203.255.255262,142
116161.204.0.0/14161.204.0.1 to 161.207.255.254161.207.255.255262,142
117161.208.0.0/14161.208.0.1 to 161.211.255.254161.211.255.255262,142
118161.212.0.0/14161.212.0.1 to 161.215.255.254161.215.255.255262,142
119161.216.0.0/14161.216.0.1 to 161.219.255.254161.219.255.255262,142
120161.220.0.0/14161.220.0.1 to 161.223.255.254161.223.255.255262,142
121161.224.0.0/14161.224.0.1 to 161.227.255.254161.227.255.255262,142
122161.228.0.0/14161.228.0.1 to 161.231.255.254161.231.255.255262,142
123161.232.0.0/14161.232.0.1 to 161.235.255.254161.235.255.255262,142
124161.236.0.0/14161.236.0.1 to 161.239.255.254161.239.255.255262,142
125161.240.0.0/14161.240.0.1 to 161.243.255.254161.243.255.255262,142
126161.244.0.0/14161.244.0.1 to 161.247.255.254161.247.255.255262,142
127161.248.0.0/14161.248.0.1 to 161.251.255.254161.251.255.255262,142
128161.252.0.0/14161.252.0.1 to 161.255.255.254161.255.255.255262,142
129162.0.0.0/14162.0.0.1 to 162.3.255.254162.3.255.255262,142
130162.4.0.0/14162.4.0.1 to 162.7.255.254162.7.255.255262,142
131162.8.0.0/14162.8.0.1 to 162.11.255.254162.11.255.255262,142
132162.12.0.0/14162.12.0.1 to 162.15.255.254162.15.255.255262,142
133162.16.0.0/14162.16.0.1 to 162.19.255.254162.19.255.255262,142
134162.20.0.0/14162.20.0.1 to 162.23.255.254162.23.255.255262,142
135162.24.0.0/14162.24.0.1 to 162.27.255.254162.27.255.255262,142
136162.28.0.0/14162.28.0.1 to 162.31.255.254162.31.255.255262,142
137162.32.0.0/14162.32.0.1 to 162.35.255.254162.35.255.255262,142
138162.36.0.0/14162.36.0.1 to 162.39.255.254162.39.255.255262,142
139162.40.0.0/14162.40.0.1 to 162.43.255.254162.43.255.255262,142
140162.44.0.0/14162.44.0.1 to 162.47.255.254162.47.255.255262,142
141162.48.0.0/14162.48.0.1 to 162.51.255.254162.51.255.255262,142
142162.52.0.0/14162.52.0.1 to 162.55.255.254162.55.255.255262,142
143162.56.0.0/14162.56.0.1 to 162.59.255.254162.59.255.255262,142
144162.60.0.0/14162.60.0.1 to 162.63.255.254162.63.255.255262,142
145162.64.0.0/14162.64.0.1 to 162.67.255.254162.67.255.255262,142
146162.68.0.0/14162.68.0.1 to 162.71.255.254162.71.255.255262,142
147162.72.0.0/14162.72.0.1 to 162.75.255.254162.75.255.255262,142
148162.76.0.0/14162.76.0.1 to 162.79.255.254162.79.255.255262,142
149162.80.0.0/14162.80.0.1 to 162.83.255.254162.83.255.255262,142
150162.84.0.0/14162.84.0.1 to 162.87.255.254162.87.255.255262,142
151162.88.0.0/14162.88.0.1 to 162.91.255.254162.91.255.255262,142
152162.92.0.0/14162.92.0.1 to 162.95.255.254162.95.255.255262,142
153162.96.0.0/14162.96.0.1 to 162.99.255.254162.99.255.255262,142
154162.100.0.0/14162.100.0.1 to 162.103.255.254162.103.255.255262,142
155162.104.0.0/14162.104.0.1 to 162.107.255.254162.107.255.255262,142
156162.108.0.0/14162.108.0.1 to 162.111.255.254162.111.255.255262,142
157162.112.0.0/14162.112.0.1 to 162.115.255.254162.115.255.255262,142
158162.116.0.0/14162.116.0.1 to 162.119.255.254162.119.255.255262,142
159162.120.0.0/14162.120.0.1 to 162.123.255.254162.123.255.255262,142
160162.124.0.0/14162.124.0.1 to 162.127.255.254162.127.255.255262,142
161162.128.0.0/14162.128.0.1 to 162.131.255.254162.131.255.255262,142
162162.132.0.0/14162.132.0.1 to 162.135.255.254162.135.255.255262,142
163162.136.0.0/14162.136.0.1 to 162.139.255.254162.139.255.255262,142
164162.140.0.0/14162.140.0.1 to 162.143.255.254162.143.255.255262,142
165162.144.0.0/14162.144.0.1 to 162.147.255.254162.147.255.255262,142
166162.148.0.0/14162.148.0.1 to 162.151.255.254162.151.255.255262,142
167162.152.0.0/14162.152.0.1 to 162.155.255.254162.155.255.255262,142
168162.156.0.0/14162.156.0.1 to 162.159.255.254162.159.255.255262,142
169162.160.0.0/14162.160.0.1 to 162.163.255.254162.163.255.255262,142
170162.164.0.0/14162.164.0.1 to 162.167.255.254162.167.255.255262,142
171162.168.0.0/14162.168.0.1 to 162.171.255.254162.171.255.255262,142
172162.172.0.0/14162.172.0.1 to 162.175.255.254162.175.255.255262,142
173162.176.0.0/14162.176.0.1 to 162.179.255.254162.179.255.255262,142
174162.180.0.0/14162.180.0.1 to 162.183.255.254162.183.255.255262,142
175162.184.0.0/14162.184.0.1 to 162.187.255.254162.187.255.255262,142
176162.188.0.0/14162.188.0.1 to 162.191.255.254162.191.255.255262,142
177162.192.0.0/14162.192.0.1 to 162.195.255.254162.195.255.255262,142
178162.196.0.0/14162.196.0.1 to 162.199.255.254162.199.255.255262,142
179162.200.0.0/14162.200.0.1 to 162.203.255.254162.203.255.255262,142
180162.204.0.0/14162.204.0.1 to 162.207.255.254162.207.255.255262,142
181162.208.0.0/14162.208.0.1 to 162.211.255.254162.211.255.255262,142
182162.212.0.0/14162.212.0.1 to 162.215.255.254162.215.255.255262,142
183162.216.0.0/14162.216.0.1 to 162.219.255.254162.219.255.255262,142
184162.220.0.0/14162.220.0.1 to 162.223.255.254162.223.255.255262,142
185162.224.0.0/14162.224.0.1 to 162.227.255.254162.227.255.255262,142
186162.228.0.0/14162.228.0.1 to 162.231.255.254162.231.255.255262,142
187162.232.0.0/14162.232.0.1 to 162.235.255.254162.235.255.255262,142
188162.236.0.0/14162.236.0.1 to 162.239.255.254162.239.255.255262,142
189162.240.0.0/14162.240.0.1 to 162.243.255.254162.243.255.255262,142
190162.244.0.0/14162.244.0.1 to 162.247.255.254162.247.255.255262,142
191162.248.0.0/14162.248.0.1 to 162.251.255.254162.251.255.255262,142
192162.252.0.0/14162.252.0.1 to 162.255.255.254162.255.255.255262,142
193163.0.0.0/14163.0.0.1 to 163.3.255.254163.3.255.255262,142
194163.4.0.0/14163.4.0.1 to 163.7.255.254163.7.255.255262,142
195163.8.0.0/14163.8.0.1 to 163.11.255.254163.11.255.255262,142
196163.12.0.0/14163.12.0.1 to 163.15.255.254163.15.255.255262,142
197163.16.0.0/14163.16.0.1 to 163.19.255.254163.19.255.255262,142
198163.20.0.0/14163.20.0.1 to 163.23.255.254163.23.255.255262,142
199163.24.0.0/14163.24.0.1 to 163.27.255.254163.27.255.255262,142
200163.28.0.0/14163.28.0.1 to 163.31.255.254163.31.255.255262,142
201163.32.0.0/14163.32.0.1 to 163.35.255.254163.35.255.255262,142
202163.36.0.0/14163.36.0.1 to 163.39.255.254163.39.255.255262,142
203163.40.0.0/14163.40.0.1 to 163.43.255.254163.43.255.255262,142
204163.44.0.0/14163.44.0.1 to 163.47.255.254163.47.255.255262,142
205163.48.0.0/14163.48.0.1 to 163.51.255.254163.51.255.255262,142
206163.52.0.0/14163.52.0.1 to 163.55.255.254163.55.255.255262,142
207163.56.0.0/14163.56.0.1 to 163.59.255.254163.59.255.255262,142
208163.60.0.0/14163.60.0.1 to 163.63.255.254163.63.255.255262,142
209163.64.0.0/14163.64.0.1 to 163.67.255.254163.67.255.255262,142
210163.68.0.0/14163.68.0.1 to 163.71.255.254163.71.255.255262,142
211163.72.0.0/14163.72.0.1 to 163.75.255.254163.75.255.255262,142
212163.76.0.0/14163.76.0.1 to 163.79.255.254163.79.255.255262,142
213163.80.0.0/14163.80.0.1 to 163.83.255.254163.83.255.255262,142
214163.84.0.0/14163.84.0.1 to 163.87.255.254163.87.255.255262,142
215163.88.0.0/14163.88.0.1 to 163.91.255.254163.91.255.255262,142
216163.92.0.0/14163.92.0.1 to 163.95.255.254163.95.255.255262,142
217163.96.0.0/14163.96.0.1 to 163.99.255.254163.99.255.255262,142
218163.100.0.0/14163.100.0.1 to 163.103.255.254163.103.255.255262,142
219163.104.0.0/14163.104.0.1 to 163.107.255.254163.107.255.255262,142
220163.108.0.0/14163.108.0.1 to 163.111.255.254163.111.255.255262,142
221163.112.0.0/14163.112.0.1 to 163.115.255.254163.115.255.255262,142
222163.116.0.0/14163.116.0.1 to 163.119.255.254163.119.255.255262,142
223163.120.0.0/14163.120.0.1 to 163.123.255.254163.123.255.255262,142
224163.124.0.0/14163.124.0.1 to 163.127.255.254163.127.255.255262,142
225163.128.0.0/14163.128.0.1 to 163.131.255.254163.131.255.255262,142
226163.132.0.0/14163.132.0.1 to 163.135.255.254163.135.255.255262,142
227163.136.0.0/14163.136.0.1 to 163.139.255.254163.139.255.255262,142
228163.140.0.0/14163.140.0.1 to 163.143.255.254163.143.255.255262,142
229163.144.0.0/14163.144.0.1 to 163.147.255.254163.147.255.255262,142
230163.148.0.0/14163.148.0.1 to 163.151.255.254163.151.255.255262,142
231163.152.0.0/14163.152.0.1 to 163.155.255.254163.155.255.255262,142
232163.156.0.0/14163.156.0.1 to 163.159.255.254163.159.255.255262,142
233163.160.0.0/14163.160.0.1 to 163.163.255.254163.163.255.255262,142
234163.164.0.0/14163.164.0.1 to 163.167.255.254163.167.255.255262,142
235163.168.0.0/14163.168.0.1 to 163.171.255.254163.171.255.255262,142
236163.172.0.0/14163.172.0.1 to 163.175.255.254163.175.255.255262,142
237163.176.0.0/14163.176.0.1 to 163.179.255.254163.179.255.255262,142
238163.180.0.0/14163.180.0.1 to 163.183.255.254163.183.255.255262,142
239163.184.0.0/14163.184.0.1 to 163.187.255.254163.187.255.255262,142
240163.188.0.0/14163.188.0.1 to 163.191.255.254163.191.255.255262,142
241163.192.0.0/14163.192.0.1 to 163.195.255.254163.195.255.255262,142
242163.196.0.0/14163.196.0.1 to 163.199.255.254163.199.255.255262,142
243163.200.0.0/14163.200.0.1 to 163.203.255.254163.203.255.255262,142
244163.204.0.0/14163.204.0.1 to 163.207.255.254163.207.255.255262,142
245163.208.0.0/14163.208.0.1 to 163.211.255.254163.211.255.255262,142
246163.212.0.0/14163.212.0.1 to 163.215.255.254163.215.255.255262,142
247163.216.0.0/14163.216.0.1 to 163.219.255.254163.219.255.255262,142
248163.220.0.0/14163.220.0.1 to 163.223.255.254163.223.255.255262,142
249163.224.0.0/14163.224.0.1 to 163.227.255.254163.227.255.255262,142
250163.228.0.0/14163.228.0.1 to 163.231.255.254163.231.255.255262,142
251163.232.0.0/14163.232.0.1 to 163.235.255.254163.235.255.255262,142
252163.236.0.0/14163.236.0.1 to 163.239.255.254163.239.255.255262,142
253163.240.0.0/14163.240.0.1 to 163.243.255.254163.243.255.255262,142
254163.244.0.0/14163.244.0.1 to 163.247.255.254163.247.255.255262,142
255163.248.0.0/14163.248.0.1 to 163.251.255.254163.251.255.255262,142
256163.252.0.0/14163.252.0.1 to 163.255.255.254163.255.255.255262,142

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.