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.

Network201.80.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
201.80.0.0
Broadcast address
201.83.255.255
First usable
201.80.0.1
Last usable
201.83.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
C (default /24)
As numbers
Hex C9500000 · Integer 3377463296 to 3377725439
Reverse DNS zones
80.201.in-addr.arpa
81.201.in-addr.arpa
82.201.in-addr.arpa
83.201.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001001.01010000.00000000.00000000201.80.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network11001001.01010000.00000000.00000000201.80.0.0
Broadcast11001001.01010011.11111111.11111111201.83.255.255
Split into smaller subnets/23
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

201.80.0.0/14 makes 512 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1201.80.0.0/23201.80.0.1 to 201.80.1.254201.80.1.255510
2201.80.2.0/23201.80.2.1 to 201.80.3.254201.80.3.255510
3201.80.4.0/23201.80.4.1 to 201.80.5.254201.80.5.255510
4201.80.6.0/23201.80.6.1 to 201.80.7.254201.80.7.255510
5201.80.8.0/23201.80.8.1 to 201.80.9.254201.80.9.255510
6201.80.10.0/23201.80.10.1 to 201.80.11.254201.80.11.255510
7201.80.12.0/23201.80.12.1 to 201.80.13.254201.80.13.255510
8201.80.14.0/23201.80.14.1 to 201.80.15.254201.80.15.255510
9201.80.16.0/23201.80.16.1 to 201.80.17.254201.80.17.255510
10201.80.18.0/23201.80.18.1 to 201.80.19.254201.80.19.255510
11201.80.20.0/23201.80.20.1 to 201.80.21.254201.80.21.255510
12201.80.22.0/23201.80.22.1 to 201.80.23.254201.80.23.255510
13201.80.24.0/23201.80.24.1 to 201.80.25.254201.80.25.255510
14201.80.26.0/23201.80.26.1 to 201.80.27.254201.80.27.255510
15201.80.28.0/23201.80.28.1 to 201.80.29.254201.80.29.255510
16201.80.30.0/23201.80.30.1 to 201.80.31.254201.80.31.255510
17201.80.32.0/23201.80.32.1 to 201.80.33.254201.80.33.255510
18201.80.34.0/23201.80.34.1 to 201.80.35.254201.80.35.255510
19201.80.36.0/23201.80.36.1 to 201.80.37.254201.80.37.255510
20201.80.38.0/23201.80.38.1 to 201.80.39.254201.80.39.255510
21201.80.40.0/23201.80.40.1 to 201.80.41.254201.80.41.255510
22201.80.42.0/23201.80.42.1 to 201.80.43.254201.80.43.255510
23201.80.44.0/23201.80.44.1 to 201.80.45.254201.80.45.255510
24201.80.46.0/23201.80.46.1 to 201.80.47.254201.80.47.255510
25201.80.48.0/23201.80.48.1 to 201.80.49.254201.80.49.255510
26201.80.50.0/23201.80.50.1 to 201.80.51.254201.80.51.255510
27201.80.52.0/23201.80.52.1 to 201.80.53.254201.80.53.255510
28201.80.54.0/23201.80.54.1 to 201.80.55.254201.80.55.255510
29201.80.56.0/23201.80.56.1 to 201.80.57.254201.80.57.255510
30201.80.58.0/23201.80.58.1 to 201.80.59.254201.80.59.255510
31201.80.60.0/23201.80.60.1 to 201.80.61.254201.80.61.255510
32201.80.62.0/23201.80.62.1 to 201.80.63.254201.80.63.255510
33201.80.64.0/23201.80.64.1 to 201.80.65.254201.80.65.255510
34201.80.66.0/23201.80.66.1 to 201.80.67.254201.80.67.255510
35201.80.68.0/23201.80.68.1 to 201.80.69.254201.80.69.255510
36201.80.70.0/23201.80.70.1 to 201.80.71.254201.80.71.255510
37201.80.72.0/23201.80.72.1 to 201.80.73.254201.80.73.255510
38201.80.74.0/23201.80.74.1 to 201.80.75.254201.80.75.255510
39201.80.76.0/23201.80.76.1 to 201.80.77.254201.80.77.255510
40201.80.78.0/23201.80.78.1 to 201.80.79.254201.80.79.255510
41201.80.80.0/23201.80.80.1 to 201.80.81.254201.80.81.255510
42201.80.82.0/23201.80.82.1 to 201.80.83.254201.80.83.255510
43201.80.84.0/23201.80.84.1 to 201.80.85.254201.80.85.255510
44201.80.86.0/23201.80.86.1 to 201.80.87.254201.80.87.255510
45201.80.88.0/23201.80.88.1 to 201.80.89.254201.80.89.255510
46201.80.90.0/23201.80.90.1 to 201.80.91.254201.80.91.255510
47201.80.92.0/23201.80.92.1 to 201.80.93.254201.80.93.255510
48201.80.94.0/23201.80.94.1 to 201.80.95.254201.80.95.255510
49201.80.96.0/23201.80.96.1 to 201.80.97.254201.80.97.255510
50201.80.98.0/23201.80.98.1 to 201.80.99.254201.80.99.255510
51201.80.100.0/23201.80.100.1 to 201.80.101.254201.80.101.255510
52201.80.102.0/23201.80.102.1 to 201.80.103.254201.80.103.255510
53201.80.104.0/23201.80.104.1 to 201.80.105.254201.80.105.255510
54201.80.106.0/23201.80.106.1 to 201.80.107.254201.80.107.255510
55201.80.108.0/23201.80.108.1 to 201.80.109.254201.80.109.255510
56201.80.110.0/23201.80.110.1 to 201.80.111.254201.80.111.255510
57201.80.112.0/23201.80.112.1 to 201.80.113.254201.80.113.255510
58201.80.114.0/23201.80.114.1 to 201.80.115.254201.80.115.255510
59201.80.116.0/23201.80.116.1 to 201.80.117.254201.80.117.255510
60201.80.118.0/23201.80.118.1 to 201.80.119.254201.80.119.255510
61201.80.120.0/23201.80.120.1 to 201.80.121.254201.80.121.255510
62201.80.122.0/23201.80.122.1 to 201.80.123.254201.80.123.255510
63201.80.124.0/23201.80.124.1 to 201.80.125.254201.80.125.255510
64201.80.126.0/23201.80.126.1 to 201.80.127.254201.80.127.255510
65201.80.128.0/23201.80.128.1 to 201.80.129.254201.80.129.255510
66201.80.130.0/23201.80.130.1 to 201.80.131.254201.80.131.255510
67201.80.132.0/23201.80.132.1 to 201.80.133.254201.80.133.255510
68201.80.134.0/23201.80.134.1 to 201.80.135.254201.80.135.255510
69201.80.136.0/23201.80.136.1 to 201.80.137.254201.80.137.255510
70201.80.138.0/23201.80.138.1 to 201.80.139.254201.80.139.255510
71201.80.140.0/23201.80.140.1 to 201.80.141.254201.80.141.255510
72201.80.142.0/23201.80.142.1 to 201.80.143.254201.80.143.255510
73201.80.144.0/23201.80.144.1 to 201.80.145.254201.80.145.255510
74201.80.146.0/23201.80.146.1 to 201.80.147.254201.80.147.255510
75201.80.148.0/23201.80.148.1 to 201.80.149.254201.80.149.255510
76201.80.150.0/23201.80.150.1 to 201.80.151.254201.80.151.255510
77201.80.152.0/23201.80.152.1 to 201.80.153.254201.80.153.255510
78201.80.154.0/23201.80.154.1 to 201.80.155.254201.80.155.255510
79201.80.156.0/23201.80.156.1 to 201.80.157.254201.80.157.255510
80201.80.158.0/23201.80.158.1 to 201.80.159.254201.80.159.255510
81201.80.160.0/23201.80.160.1 to 201.80.161.254201.80.161.255510
82201.80.162.0/23201.80.162.1 to 201.80.163.254201.80.163.255510
83201.80.164.0/23201.80.164.1 to 201.80.165.254201.80.165.255510
84201.80.166.0/23201.80.166.1 to 201.80.167.254201.80.167.255510
85201.80.168.0/23201.80.168.1 to 201.80.169.254201.80.169.255510
86201.80.170.0/23201.80.170.1 to 201.80.171.254201.80.171.255510
87201.80.172.0/23201.80.172.1 to 201.80.173.254201.80.173.255510
88201.80.174.0/23201.80.174.1 to 201.80.175.254201.80.175.255510
89201.80.176.0/23201.80.176.1 to 201.80.177.254201.80.177.255510
90201.80.178.0/23201.80.178.1 to 201.80.179.254201.80.179.255510
91201.80.180.0/23201.80.180.1 to 201.80.181.254201.80.181.255510
92201.80.182.0/23201.80.182.1 to 201.80.183.254201.80.183.255510
93201.80.184.0/23201.80.184.1 to 201.80.185.254201.80.185.255510
94201.80.186.0/23201.80.186.1 to 201.80.187.254201.80.187.255510
95201.80.188.0/23201.80.188.1 to 201.80.189.254201.80.189.255510
96201.80.190.0/23201.80.190.1 to 201.80.191.254201.80.191.255510
97201.80.192.0/23201.80.192.1 to 201.80.193.254201.80.193.255510
98201.80.194.0/23201.80.194.1 to 201.80.195.254201.80.195.255510
99201.80.196.0/23201.80.196.1 to 201.80.197.254201.80.197.255510
100201.80.198.0/23201.80.198.1 to 201.80.199.254201.80.199.255510
101201.80.200.0/23201.80.200.1 to 201.80.201.254201.80.201.255510
102201.80.202.0/23201.80.202.1 to 201.80.203.254201.80.203.255510
103201.80.204.0/23201.80.204.1 to 201.80.205.254201.80.205.255510
104201.80.206.0/23201.80.206.1 to 201.80.207.254201.80.207.255510
105201.80.208.0/23201.80.208.1 to 201.80.209.254201.80.209.255510
106201.80.210.0/23201.80.210.1 to 201.80.211.254201.80.211.255510
107201.80.212.0/23201.80.212.1 to 201.80.213.254201.80.213.255510
108201.80.214.0/23201.80.214.1 to 201.80.215.254201.80.215.255510
109201.80.216.0/23201.80.216.1 to 201.80.217.254201.80.217.255510
110201.80.218.0/23201.80.218.1 to 201.80.219.254201.80.219.255510
111201.80.220.0/23201.80.220.1 to 201.80.221.254201.80.221.255510
112201.80.222.0/23201.80.222.1 to 201.80.223.254201.80.223.255510
113201.80.224.0/23201.80.224.1 to 201.80.225.254201.80.225.255510
114201.80.226.0/23201.80.226.1 to 201.80.227.254201.80.227.255510
115201.80.228.0/23201.80.228.1 to 201.80.229.254201.80.229.255510
116201.80.230.0/23201.80.230.1 to 201.80.231.254201.80.231.255510
117201.80.232.0/23201.80.232.1 to 201.80.233.254201.80.233.255510
118201.80.234.0/23201.80.234.1 to 201.80.235.254201.80.235.255510
119201.80.236.0/23201.80.236.1 to 201.80.237.254201.80.237.255510
120201.80.238.0/23201.80.238.1 to 201.80.239.254201.80.239.255510
121201.80.240.0/23201.80.240.1 to 201.80.241.254201.80.241.255510
122201.80.242.0/23201.80.242.1 to 201.80.243.254201.80.243.255510
123201.80.244.0/23201.80.244.1 to 201.80.245.254201.80.245.255510
124201.80.246.0/23201.80.246.1 to 201.80.247.254201.80.247.255510
125201.80.248.0/23201.80.248.1 to 201.80.249.254201.80.249.255510
126201.80.250.0/23201.80.250.1 to 201.80.251.254201.80.251.255510
127201.80.252.0/23201.80.252.1 to 201.80.253.254201.80.253.255510
128201.80.254.0/23201.80.254.1 to 201.80.255.254201.80.255.255510
129201.81.0.0/23201.81.0.1 to 201.81.1.254201.81.1.255510
130201.81.2.0/23201.81.2.1 to 201.81.3.254201.81.3.255510
131201.81.4.0/23201.81.4.1 to 201.81.5.254201.81.5.255510
132201.81.6.0/23201.81.6.1 to 201.81.7.254201.81.7.255510
133201.81.8.0/23201.81.8.1 to 201.81.9.254201.81.9.255510
134201.81.10.0/23201.81.10.1 to 201.81.11.254201.81.11.255510
135201.81.12.0/23201.81.12.1 to 201.81.13.254201.81.13.255510
136201.81.14.0/23201.81.14.1 to 201.81.15.254201.81.15.255510
137201.81.16.0/23201.81.16.1 to 201.81.17.254201.81.17.255510
138201.81.18.0/23201.81.18.1 to 201.81.19.254201.81.19.255510
139201.81.20.0/23201.81.20.1 to 201.81.21.254201.81.21.255510
140201.81.22.0/23201.81.22.1 to 201.81.23.254201.81.23.255510
141201.81.24.0/23201.81.24.1 to 201.81.25.254201.81.25.255510
142201.81.26.0/23201.81.26.1 to 201.81.27.254201.81.27.255510
143201.81.28.0/23201.81.28.1 to 201.81.29.254201.81.29.255510
144201.81.30.0/23201.81.30.1 to 201.81.31.254201.81.31.255510
145201.81.32.0/23201.81.32.1 to 201.81.33.254201.81.33.255510
146201.81.34.0/23201.81.34.1 to 201.81.35.254201.81.35.255510
147201.81.36.0/23201.81.36.1 to 201.81.37.254201.81.37.255510
148201.81.38.0/23201.81.38.1 to 201.81.39.254201.81.39.255510
149201.81.40.0/23201.81.40.1 to 201.81.41.254201.81.41.255510
150201.81.42.0/23201.81.42.1 to 201.81.43.254201.81.43.255510
151201.81.44.0/23201.81.44.1 to 201.81.45.254201.81.45.255510
152201.81.46.0/23201.81.46.1 to 201.81.47.254201.81.47.255510
153201.81.48.0/23201.81.48.1 to 201.81.49.254201.81.49.255510
154201.81.50.0/23201.81.50.1 to 201.81.51.254201.81.51.255510
155201.81.52.0/23201.81.52.1 to 201.81.53.254201.81.53.255510
156201.81.54.0/23201.81.54.1 to 201.81.55.254201.81.55.255510
157201.81.56.0/23201.81.56.1 to 201.81.57.254201.81.57.255510
158201.81.58.0/23201.81.58.1 to 201.81.59.254201.81.59.255510
159201.81.60.0/23201.81.60.1 to 201.81.61.254201.81.61.255510
160201.81.62.0/23201.81.62.1 to 201.81.63.254201.81.63.255510
161201.81.64.0/23201.81.64.1 to 201.81.65.254201.81.65.255510
162201.81.66.0/23201.81.66.1 to 201.81.67.254201.81.67.255510
163201.81.68.0/23201.81.68.1 to 201.81.69.254201.81.69.255510
164201.81.70.0/23201.81.70.1 to 201.81.71.254201.81.71.255510
165201.81.72.0/23201.81.72.1 to 201.81.73.254201.81.73.255510
166201.81.74.0/23201.81.74.1 to 201.81.75.254201.81.75.255510
167201.81.76.0/23201.81.76.1 to 201.81.77.254201.81.77.255510
168201.81.78.0/23201.81.78.1 to 201.81.79.254201.81.79.255510
169201.81.80.0/23201.81.80.1 to 201.81.81.254201.81.81.255510
170201.81.82.0/23201.81.82.1 to 201.81.83.254201.81.83.255510
171201.81.84.0/23201.81.84.1 to 201.81.85.254201.81.85.255510
172201.81.86.0/23201.81.86.1 to 201.81.87.254201.81.87.255510
173201.81.88.0/23201.81.88.1 to 201.81.89.254201.81.89.255510
174201.81.90.0/23201.81.90.1 to 201.81.91.254201.81.91.255510
175201.81.92.0/23201.81.92.1 to 201.81.93.254201.81.93.255510
176201.81.94.0/23201.81.94.1 to 201.81.95.254201.81.95.255510
177201.81.96.0/23201.81.96.1 to 201.81.97.254201.81.97.255510
178201.81.98.0/23201.81.98.1 to 201.81.99.254201.81.99.255510
179201.81.100.0/23201.81.100.1 to 201.81.101.254201.81.101.255510
180201.81.102.0/23201.81.102.1 to 201.81.103.254201.81.103.255510
181201.81.104.0/23201.81.104.1 to 201.81.105.254201.81.105.255510
182201.81.106.0/23201.81.106.1 to 201.81.107.254201.81.107.255510
183201.81.108.0/23201.81.108.1 to 201.81.109.254201.81.109.255510
184201.81.110.0/23201.81.110.1 to 201.81.111.254201.81.111.255510
185201.81.112.0/23201.81.112.1 to 201.81.113.254201.81.113.255510
186201.81.114.0/23201.81.114.1 to 201.81.115.254201.81.115.255510
187201.81.116.0/23201.81.116.1 to 201.81.117.254201.81.117.255510
188201.81.118.0/23201.81.118.1 to 201.81.119.254201.81.119.255510
189201.81.120.0/23201.81.120.1 to 201.81.121.254201.81.121.255510
190201.81.122.0/23201.81.122.1 to 201.81.123.254201.81.123.255510
191201.81.124.0/23201.81.124.1 to 201.81.125.254201.81.125.255510
192201.81.126.0/23201.81.126.1 to 201.81.127.254201.81.127.255510
193201.81.128.0/23201.81.128.1 to 201.81.129.254201.81.129.255510
194201.81.130.0/23201.81.130.1 to 201.81.131.254201.81.131.255510
195201.81.132.0/23201.81.132.1 to 201.81.133.254201.81.133.255510
196201.81.134.0/23201.81.134.1 to 201.81.135.254201.81.135.255510
197201.81.136.0/23201.81.136.1 to 201.81.137.254201.81.137.255510
198201.81.138.0/23201.81.138.1 to 201.81.139.254201.81.139.255510
199201.81.140.0/23201.81.140.1 to 201.81.141.254201.81.141.255510
200201.81.142.0/23201.81.142.1 to 201.81.143.254201.81.143.255510
201201.81.144.0/23201.81.144.1 to 201.81.145.254201.81.145.255510
202201.81.146.0/23201.81.146.1 to 201.81.147.254201.81.147.255510
203201.81.148.0/23201.81.148.1 to 201.81.149.254201.81.149.255510
204201.81.150.0/23201.81.150.1 to 201.81.151.254201.81.151.255510
205201.81.152.0/23201.81.152.1 to 201.81.153.254201.81.153.255510
206201.81.154.0/23201.81.154.1 to 201.81.155.254201.81.155.255510
207201.81.156.0/23201.81.156.1 to 201.81.157.254201.81.157.255510
208201.81.158.0/23201.81.158.1 to 201.81.159.254201.81.159.255510
209201.81.160.0/23201.81.160.1 to 201.81.161.254201.81.161.255510
210201.81.162.0/23201.81.162.1 to 201.81.163.254201.81.163.255510
211201.81.164.0/23201.81.164.1 to 201.81.165.254201.81.165.255510
212201.81.166.0/23201.81.166.1 to 201.81.167.254201.81.167.255510
213201.81.168.0/23201.81.168.1 to 201.81.169.254201.81.169.255510
214201.81.170.0/23201.81.170.1 to 201.81.171.254201.81.171.255510
215201.81.172.0/23201.81.172.1 to 201.81.173.254201.81.173.255510
216201.81.174.0/23201.81.174.1 to 201.81.175.254201.81.175.255510
217201.81.176.0/23201.81.176.1 to 201.81.177.254201.81.177.255510
218201.81.178.0/23201.81.178.1 to 201.81.179.254201.81.179.255510
219201.81.180.0/23201.81.180.1 to 201.81.181.254201.81.181.255510
220201.81.182.0/23201.81.182.1 to 201.81.183.254201.81.183.255510
221201.81.184.0/23201.81.184.1 to 201.81.185.254201.81.185.255510
222201.81.186.0/23201.81.186.1 to 201.81.187.254201.81.187.255510
223201.81.188.0/23201.81.188.1 to 201.81.189.254201.81.189.255510
224201.81.190.0/23201.81.190.1 to 201.81.191.254201.81.191.255510
225201.81.192.0/23201.81.192.1 to 201.81.193.254201.81.193.255510
226201.81.194.0/23201.81.194.1 to 201.81.195.254201.81.195.255510
227201.81.196.0/23201.81.196.1 to 201.81.197.254201.81.197.255510
228201.81.198.0/23201.81.198.1 to 201.81.199.254201.81.199.255510
229201.81.200.0/23201.81.200.1 to 201.81.201.254201.81.201.255510
230201.81.202.0/23201.81.202.1 to 201.81.203.254201.81.203.255510
231201.81.204.0/23201.81.204.1 to 201.81.205.254201.81.205.255510
232201.81.206.0/23201.81.206.1 to 201.81.207.254201.81.207.255510
233201.81.208.0/23201.81.208.1 to 201.81.209.254201.81.209.255510
234201.81.210.0/23201.81.210.1 to 201.81.211.254201.81.211.255510
235201.81.212.0/23201.81.212.1 to 201.81.213.254201.81.213.255510
236201.81.214.0/23201.81.214.1 to 201.81.215.254201.81.215.255510
237201.81.216.0/23201.81.216.1 to 201.81.217.254201.81.217.255510
238201.81.218.0/23201.81.218.1 to 201.81.219.254201.81.219.255510
239201.81.220.0/23201.81.220.1 to 201.81.221.254201.81.221.255510
240201.81.222.0/23201.81.222.1 to 201.81.223.254201.81.223.255510
241201.81.224.0/23201.81.224.1 to 201.81.225.254201.81.225.255510
242201.81.226.0/23201.81.226.1 to 201.81.227.254201.81.227.255510
243201.81.228.0/23201.81.228.1 to 201.81.229.254201.81.229.255510
244201.81.230.0/23201.81.230.1 to 201.81.231.254201.81.231.255510
245201.81.232.0/23201.81.232.1 to 201.81.233.254201.81.233.255510
246201.81.234.0/23201.81.234.1 to 201.81.235.254201.81.235.255510
247201.81.236.0/23201.81.236.1 to 201.81.237.254201.81.237.255510
248201.81.238.0/23201.81.238.1 to 201.81.239.254201.81.239.255510
249201.81.240.0/23201.81.240.1 to 201.81.241.254201.81.241.255510
250201.81.242.0/23201.81.242.1 to 201.81.243.254201.81.243.255510
251201.81.244.0/23201.81.244.1 to 201.81.245.254201.81.245.255510
252201.81.246.0/23201.81.246.1 to 201.81.247.254201.81.247.255510
253201.81.248.0/23201.81.248.1 to 201.81.249.254201.81.249.255510
254201.81.250.0/23201.81.250.1 to 201.81.251.254201.81.251.255510
255201.81.252.0/23201.81.252.1 to 201.81.253.254201.81.253.255510
256201.81.254.0/23201.81.254.1 to 201.81.255.254201.81.255.255510

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.