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.

Network154.72.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
154.72.0.0
Broadcast address
154.79.255.255
First usable
154.72.0.1
Last usable
154.79.255.254
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 9A480000 · Integer 2588409856 to 2588934143
Reverse DNS zones
72.154.in-addr.arpa
73.154.in-addr.arpa
74.154.in-addr.arpa
75.154.in-addr.arpa
76.154.in-addr.arpa
77.154.in-addr.arpa
78.154.in-addr.arpa
79.154.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
Address10011010.01001000.00000000.00000000154.72.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10011010.01001000.00000000.00000000154.72.0.0
Broadcast10011010.01001111.11111111.11111111154.79.255.255
Split into smaller subnets/24
/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)

154.72.0.0/13 makes 2,048 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1154.72.0.0/24154.72.0.1 to 154.72.0.254154.72.0.255254
2154.72.1.0/24154.72.1.1 to 154.72.1.254154.72.1.255254
3154.72.2.0/24154.72.2.1 to 154.72.2.254154.72.2.255254
4154.72.3.0/24154.72.3.1 to 154.72.3.254154.72.3.255254
5154.72.4.0/24154.72.4.1 to 154.72.4.254154.72.4.255254
6154.72.5.0/24154.72.5.1 to 154.72.5.254154.72.5.255254
7154.72.6.0/24154.72.6.1 to 154.72.6.254154.72.6.255254
8154.72.7.0/24154.72.7.1 to 154.72.7.254154.72.7.255254
9154.72.8.0/24154.72.8.1 to 154.72.8.254154.72.8.255254
10154.72.9.0/24154.72.9.1 to 154.72.9.254154.72.9.255254
11154.72.10.0/24154.72.10.1 to 154.72.10.254154.72.10.255254
12154.72.11.0/24154.72.11.1 to 154.72.11.254154.72.11.255254
13154.72.12.0/24154.72.12.1 to 154.72.12.254154.72.12.255254
14154.72.13.0/24154.72.13.1 to 154.72.13.254154.72.13.255254
15154.72.14.0/24154.72.14.1 to 154.72.14.254154.72.14.255254
16154.72.15.0/24154.72.15.1 to 154.72.15.254154.72.15.255254
17154.72.16.0/24154.72.16.1 to 154.72.16.254154.72.16.255254
18154.72.17.0/24154.72.17.1 to 154.72.17.254154.72.17.255254
19154.72.18.0/24154.72.18.1 to 154.72.18.254154.72.18.255254
20154.72.19.0/24154.72.19.1 to 154.72.19.254154.72.19.255254
21154.72.20.0/24154.72.20.1 to 154.72.20.254154.72.20.255254
22154.72.21.0/24154.72.21.1 to 154.72.21.254154.72.21.255254
23154.72.22.0/24154.72.22.1 to 154.72.22.254154.72.22.255254
24154.72.23.0/24154.72.23.1 to 154.72.23.254154.72.23.255254
25154.72.24.0/24154.72.24.1 to 154.72.24.254154.72.24.255254
26154.72.25.0/24154.72.25.1 to 154.72.25.254154.72.25.255254
27154.72.26.0/24154.72.26.1 to 154.72.26.254154.72.26.255254
28154.72.27.0/24154.72.27.1 to 154.72.27.254154.72.27.255254
29154.72.28.0/24154.72.28.1 to 154.72.28.254154.72.28.255254
30154.72.29.0/24154.72.29.1 to 154.72.29.254154.72.29.255254
31154.72.30.0/24154.72.30.1 to 154.72.30.254154.72.30.255254
32154.72.31.0/24154.72.31.1 to 154.72.31.254154.72.31.255254
33154.72.32.0/24154.72.32.1 to 154.72.32.254154.72.32.255254
34154.72.33.0/24154.72.33.1 to 154.72.33.254154.72.33.255254
35154.72.34.0/24154.72.34.1 to 154.72.34.254154.72.34.255254
36154.72.35.0/24154.72.35.1 to 154.72.35.254154.72.35.255254
37154.72.36.0/24154.72.36.1 to 154.72.36.254154.72.36.255254
38154.72.37.0/24154.72.37.1 to 154.72.37.254154.72.37.255254
39154.72.38.0/24154.72.38.1 to 154.72.38.254154.72.38.255254
40154.72.39.0/24154.72.39.1 to 154.72.39.254154.72.39.255254
41154.72.40.0/24154.72.40.1 to 154.72.40.254154.72.40.255254
42154.72.41.0/24154.72.41.1 to 154.72.41.254154.72.41.255254
43154.72.42.0/24154.72.42.1 to 154.72.42.254154.72.42.255254
44154.72.43.0/24154.72.43.1 to 154.72.43.254154.72.43.255254
45154.72.44.0/24154.72.44.1 to 154.72.44.254154.72.44.255254
46154.72.45.0/24154.72.45.1 to 154.72.45.254154.72.45.255254
47154.72.46.0/24154.72.46.1 to 154.72.46.254154.72.46.255254
48154.72.47.0/24154.72.47.1 to 154.72.47.254154.72.47.255254
49154.72.48.0/24154.72.48.1 to 154.72.48.254154.72.48.255254
50154.72.49.0/24154.72.49.1 to 154.72.49.254154.72.49.255254
51154.72.50.0/24154.72.50.1 to 154.72.50.254154.72.50.255254
52154.72.51.0/24154.72.51.1 to 154.72.51.254154.72.51.255254
53154.72.52.0/24154.72.52.1 to 154.72.52.254154.72.52.255254
54154.72.53.0/24154.72.53.1 to 154.72.53.254154.72.53.255254
55154.72.54.0/24154.72.54.1 to 154.72.54.254154.72.54.255254
56154.72.55.0/24154.72.55.1 to 154.72.55.254154.72.55.255254
57154.72.56.0/24154.72.56.1 to 154.72.56.254154.72.56.255254
58154.72.57.0/24154.72.57.1 to 154.72.57.254154.72.57.255254
59154.72.58.0/24154.72.58.1 to 154.72.58.254154.72.58.255254
60154.72.59.0/24154.72.59.1 to 154.72.59.254154.72.59.255254
61154.72.60.0/24154.72.60.1 to 154.72.60.254154.72.60.255254
62154.72.61.0/24154.72.61.1 to 154.72.61.254154.72.61.255254
63154.72.62.0/24154.72.62.1 to 154.72.62.254154.72.62.255254
64154.72.63.0/24154.72.63.1 to 154.72.63.254154.72.63.255254
65154.72.64.0/24154.72.64.1 to 154.72.64.254154.72.64.255254
66154.72.65.0/24154.72.65.1 to 154.72.65.254154.72.65.255254
67154.72.66.0/24154.72.66.1 to 154.72.66.254154.72.66.255254
68154.72.67.0/24154.72.67.1 to 154.72.67.254154.72.67.255254
69154.72.68.0/24154.72.68.1 to 154.72.68.254154.72.68.255254
70154.72.69.0/24154.72.69.1 to 154.72.69.254154.72.69.255254
71154.72.70.0/24154.72.70.1 to 154.72.70.254154.72.70.255254
72154.72.71.0/24154.72.71.1 to 154.72.71.254154.72.71.255254
73154.72.72.0/24154.72.72.1 to 154.72.72.254154.72.72.255254
74154.72.73.0/24154.72.73.1 to 154.72.73.254154.72.73.255254
75154.72.74.0/24154.72.74.1 to 154.72.74.254154.72.74.255254
76154.72.75.0/24154.72.75.1 to 154.72.75.254154.72.75.255254
77154.72.76.0/24154.72.76.1 to 154.72.76.254154.72.76.255254
78154.72.77.0/24154.72.77.1 to 154.72.77.254154.72.77.255254
79154.72.78.0/24154.72.78.1 to 154.72.78.254154.72.78.255254
80154.72.79.0/24154.72.79.1 to 154.72.79.254154.72.79.255254
81154.72.80.0/24154.72.80.1 to 154.72.80.254154.72.80.255254
82154.72.81.0/24154.72.81.1 to 154.72.81.254154.72.81.255254
83154.72.82.0/24154.72.82.1 to 154.72.82.254154.72.82.255254
84154.72.83.0/24154.72.83.1 to 154.72.83.254154.72.83.255254
85154.72.84.0/24154.72.84.1 to 154.72.84.254154.72.84.255254
86154.72.85.0/24154.72.85.1 to 154.72.85.254154.72.85.255254
87154.72.86.0/24154.72.86.1 to 154.72.86.254154.72.86.255254
88154.72.87.0/24154.72.87.1 to 154.72.87.254154.72.87.255254
89154.72.88.0/24154.72.88.1 to 154.72.88.254154.72.88.255254
90154.72.89.0/24154.72.89.1 to 154.72.89.254154.72.89.255254
91154.72.90.0/24154.72.90.1 to 154.72.90.254154.72.90.255254
92154.72.91.0/24154.72.91.1 to 154.72.91.254154.72.91.255254
93154.72.92.0/24154.72.92.1 to 154.72.92.254154.72.92.255254
94154.72.93.0/24154.72.93.1 to 154.72.93.254154.72.93.255254
95154.72.94.0/24154.72.94.1 to 154.72.94.254154.72.94.255254
96154.72.95.0/24154.72.95.1 to 154.72.95.254154.72.95.255254
97154.72.96.0/24154.72.96.1 to 154.72.96.254154.72.96.255254
98154.72.97.0/24154.72.97.1 to 154.72.97.254154.72.97.255254
99154.72.98.0/24154.72.98.1 to 154.72.98.254154.72.98.255254
100154.72.99.0/24154.72.99.1 to 154.72.99.254154.72.99.255254
101154.72.100.0/24154.72.100.1 to 154.72.100.254154.72.100.255254
102154.72.101.0/24154.72.101.1 to 154.72.101.254154.72.101.255254
103154.72.102.0/24154.72.102.1 to 154.72.102.254154.72.102.255254
104154.72.103.0/24154.72.103.1 to 154.72.103.254154.72.103.255254
105154.72.104.0/24154.72.104.1 to 154.72.104.254154.72.104.255254
106154.72.105.0/24154.72.105.1 to 154.72.105.254154.72.105.255254
107154.72.106.0/24154.72.106.1 to 154.72.106.254154.72.106.255254
108154.72.107.0/24154.72.107.1 to 154.72.107.254154.72.107.255254
109154.72.108.0/24154.72.108.1 to 154.72.108.254154.72.108.255254
110154.72.109.0/24154.72.109.1 to 154.72.109.254154.72.109.255254
111154.72.110.0/24154.72.110.1 to 154.72.110.254154.72.110.255254
112154.72.111.0/24154.72.111.1 to 154.72.111.254154.72.111.255254
113154.72.112.0/24154.72.112.1 to 154.72.112.254154.72.112.255254
114154.72.113.0/24154.72.113.1 to 154.72.113.254154.72.113.255254
115154.72.114.0/24154.72.114.1 to 154.72.114.254154.72.114.255254
116154.72.115.0/24154.72.115.1 to 154.72.115.254154.72.115.255254
117154.72.116.0/24154.72.116.1 to 154.72.116.254154.72.116.255254
118154.72.117.0/24154.72.117.1 to 154.72.117.254154.72.117.255254
119154.72.118.0/24154.72.118.1 to 154.72.118.254154.72.118.255254
120154.72.119.0/24154.72.119.1 to 154.72.119.254154.72.119.255254
121154.72.120.0/24154.72.120.1 to 154.72.120.254154.72.120.255254
122154.72.121.0/24154.72.121.1 to 154.72.121.254154.72.121.255254
123154.72.122.0/24154.72.122.1 to 154.72.122.254154.72.122.255254
124154.72.123.0/24154.72.123.1 to 154.72.123.254154.72.123.255254
125154.72.124.0/24154.72.124.1 to 154.72.124.254154.72.124.255254
126154.72.125.0/24154.72.125.1 to 154.72.125.254154.72.125.255254
127154.72.126.0/24154.72.126.1 to 154.72.126.254154.72.126.255254
128154.72.127.0/24154.72.127.1 to 154.72.127.254154.72.127.255254
129154.72.128.0/24154.72.128.1 to 154.72.128.254154.72.128.255254
130154.72.129.0/24154.72.129.1 to 154.72.129.254154.72.129.255254
131154.72.130.0/24154.72.130.1 to 154.72.130.254154.72.130.255254
132154.72.131.0/24154.72.131.1 to 154.72.131.254154.72.131.255254
133154.72.132.0/24154.72.132.1 to 154.72.132.254154.72.132.255254
134154.72.133.0/24154.72.133.1 to 154.72.133.254154.72.133.255254
135154.72.134.0/24154.72.134.1 to 154.72.134.254154.72.134.255254
136154.72.135.0/24154.72.135.1 to 154.72.135.254154.72.135.255254
137154.72.136.0/24154.72.136.1 to 154.72.136.254154.72.136.255254
138154.72.137.0/24154.72.137.1 to 154.72.137.254154.72.137.255254
139154.72.138.0/24154.72.138.1 to 154.72.138.254154.72.138.255254
140154.72.139.0/24154.72.139.1 to 154.72.139.254154.72.139.255254
141154.72.140.0/24154.72.140.1 to 154.72.140.254154.72.140.255254
142154.72.141.0/24154.72.141.1 to 154.72.141.254154.72.141.255254
143154.72.142.0/24154.72.142.1 to 154.72.142.254154.72.142.255254
144154.72.143.0/24154.72.143.1 to 154.72.143.254154.72.143.255254
145154.72.144.0/24154.72.144.1 to 154.72.144.254154.72.144.255254
146154.72.145.0/24154.72.145.1 to 154.72.145.254154.72.145.255254
147154.72.146.0/24154.72.146.1 to 154.72.146.254154.72.146.255254
148154.72.147.0/24154.72.147.1 to 154.72.147.254154.72.147.255254
149154.72.148.0/24154.72.148.1 to 154.72.148.254154.72.148.255254
150154.72.149.0/24154.72.149.1 to 154.72.149.254154.72.149.255254
151154.72.150.0/24154.72.150.1 to 154.72.150.254154.72.150.255254
152154.72.151.0/24154.72.151.1 to 154.72.151.254154.72.151.255254
153154.72.152.0/24154.72.152.1 to 154.72.152.254154.72.152.255254
154154.72.153.0/24154.72.153.1 to 154.72.153.254154.72.153.255254
155154.72.154.0/24154.72.154.1 to 154.72.154.254154.72.154.255254
156154.72.155.0/24154.72.155.1 to 154.72.155.254154.72.155.255254
157154.72.156.0/24154.72.156.1 to 154.72.156.254154.72.156.255254
158154.72.157.0/24154.72.157.1 to 154.72.157.254154.72.157.255254
159154.72.158.0/24154.72.158.1 to 154.72.158.254154.72.158.255254
160154.72.159.0/24154.72.159.1 to 154.72.159.254154.72.159.255254
161154.72.160.0/24154.72.160.1 to 154.72.160.254154.72.160.255254
162154.72.161.0/24154.72.161.1 to 154.72.161.254154.72.161.255254
163154.72.162.0/24154.72.162.1 to 154.72.162.254154.72.162.255254
164154.72.163.0/24154.72.163.1 to 154.72.163.254154.72.163.255254
165154.72.164.0/24154.72.164.1 to 154.72.164.254154.72.164.255254
166154.72.165.0/24154.72.165.1 to 154.72.165.254154.72.165.255254
167154.72.166.0/24154.72.166.1 to 154.72.166.254154.72.166.255254
168154.72.167.0/24154.72.167.1 to 154.72.167.254154.72.167.255254
169154.72.168.0/24154.72.168.1 to 154.72.168.254154.72.168.255254
170154.72.169.0/24154.72.169.1 to 154.72.169.254154.72.169.255254
171154.72.170.0/24154.72.170.1 to 154.72.170.254154.72.170.255254
172154.72.171.0/24154.72.171.1 to 154.72.171.254154.72.171.255254
173154.72.172.0/24154.72.172.1 to 154.72.172.254154.72.172.255254
174154.72.173.0/24154.72.173.1 to 154.72.173.254154.72.173.255254
175154.72.174.0/24154.72.174.1 to 154.72.174.254154.72.174.255254
176154.72.175.0/24154.72.175.1 to 154.72.175.254154.72.175.255254
177154.72.176.0/24154.72.176.1 to 154.72.176.254154.72.176.255254
178154.72.177.0/24154.72.177.1 to 154.72.177.254154.72.177.255254
179154.72.178.0/24154.72.178.1 to 154.72.178.254154.72.178.255254
180154.72.179.0/24154.72.179.1 to 154.72.179.254154.72.179.255254
181154.72.180.0/24154.72.180.1 to 154.72.180.254154.72.180.255254
182154.72.181.0/24154.72.181.1 to 154.72.181.254154.72.181.255254
183154.72.182.0/24154.72.182.1 to 154.72.182.254154.72.182.255254
184154.72.183.0/24154.72.183.1 to 154.72.183.254154.72.183.255254
185154.72.184.0/24154.72.184.1 to 154.72.184.254154.72.184.255254
186154.72.185.0/24154.72.185.1 to 154.72.185.254154.72.185.255254
187154.72.186.0/24154.72.186.1 to 154.72.186.254154.72.186.255254
188154.72.187.0/24154.72.187.1 to 154.72.187.254154.72.187.255254
189154.72.188.0/24154.72.188.1 to 154.72.188.254154.72.188.255254
190154.72.189.0/24154.72.189.1 to 154.72.189.254154.72.189.255254
191154.72.190.0/24154.72.190.1 to 154.72.190.254154.72.190.255254
192154.72.191.0/24154.72.191.1 to 154.72.191.254154.72.191.255254
193154.72.192.0/24154.72.192.1 to 154.72.192.254154.72.192.255254
194154.72.193.0/24154.72.193.1 to 154.72.193.254154.72.193.255254
195154.72.194.0/24154.72.194.1 to 154.72.194.254154.72.194.255254
196154.72.195.0/24154.72.195.1 to 154.72.195.254154.72.195.255254
197154.72.196.0/24154.72.196.1 to 154.72.196.254154.72.196.255254
198154.72.197.0/24154.72.197.1 to 154.72.197.254154.72.197.255254
199154.72.198.0/24154.72.198.1 to 154.72.198.254154.72.198.255254
200154.72.199.0/24154.72.199.1 to 154.72.199.254154.72.199.255254
201154.72.200.0/24154.72.200.1 to 154.72.200.254154.72.200.255254
202154.72.201.0/24154.72.201.1 to 154.72.201.254154.72.201.255254
203154.72.202.0/24154.72.202.1 to 154.72.202.254154.72.202.255254
204154.72.203.0/24154.72.203.1 to 154.72.203.254154.72.203.255254
205154.72.204.0/24154.72.204.1 to 154.72.204.254154.72.204.255254
206154.72.205.0/24154.72.205.1 to 154.72.205.254154.72.205.255254
207154.72.206.0/24154.72.206.1 to 154.72.206.254154.72.206.255254
208154.72.207.0/24154.72.207.1 to 154.72.207.254154.72.207.255254
209154.72.208.0/24154.72.208.1 to 154.72.208.254154.72.208.255254
210154.72.209.0/24154.72.209.1 to 154.72.209.254154.72.209.255254
211154.72.210.0/24154.72.210.1 to 154.72.210.254154.72.210.255254
212154.72.211.0/24154.72.211.1 to 154.72.211.254154.72.211.255254
213154.72.212.0/24154.72.212.1 to 154.72.212.254154.72.212.255254
214154.72.213.0/24154.72.213.1 to 154.72.213.254154.72.213.255254
215154.72.214.0/24154.72.214.1 to 154.72.214.254154.72.214.255254
216154.72.215.0/24154.72.215.1 to 154.72.215.254154.72.215.255254
217154.72.216.0/24154.72.216.1 to 154.72.216.254154.72.216.255254
218154.72.217.0/24154.72.217.1 to 154.72.217.254154.72.217.255254
219154.72.218.0/24154.72.218.1 to 154.72.218.254154.72.218.255254
220154.72.219.0/24154.72.219.1 to 154.72.219.254154.72.219.255254
221154.72.220.0/24154.72.220.1 to 154.72.220.254154.72.220.255254
222154.72.221.0/24154.72.221.1 to 154.72.221.254154.72.221.255254
223154.72.222.0/24154.72.222.1 to 154.72.222.254154.72.222.255254
224154.72.223.0/24154.72.223.1 to 154.72.223.254154.72.223.255254
225154.72.224.0/24154.72.224.1 to 154.72.224.254154.72.224.255254
226154.72.225.0/24154.72.225.1 to 154.72.225.254154.72.225.255254
227154.72.226.0/24154.72.226.1 to 154.72.226.254154.72.226.255254
228154.72.227.0/24154.72.227.1 to 154.72.227.254154.72.227.255254
229154.72.228.0/24154.72.228.1 to 154.72.228.254154.72.228.255254
230154.72.229.0/24154.72.229.1 to 154.72.229.254154.72.229.255254
231154.72.230.0/24154.72.230.1 to 154.72.230.254154.72.230.255254
232154.72.231.0/24154.72.231.1 to 154.72.231.254154.72.231.255254
233154.72.232.0/24154.72.232.1 to 154.72.232.254154.72.232.255254
234154.72.233.0/24154.72.233.1 to 154.72.233.254154.72.233.255254
235154.72.234.0/24154.72.234.1 to 154.72.234.254154.72.234.255254
236154.72.235.0/24154.72.235.1 to 154.72.235.254154.72.235.255254
237154.72.236.0/24154.72.236.1 to 154.72.236.254154.72.236.255254
238154.72.237.0/24154.72.237.1 to 154.72.237.254154.72.237.255254
239154.72.238.0/24154.72.238.1 to 154.72.238.254154.72.238.255254
240154.72.239.0/24154.72.239.1 to 154.72.239.254154.72.239.255254
241154.72.240.0/24154.72.240.1 to 154.72.240.254154.72.240.255254
242154.72.241.0/24154.72.241.1 to 154.72.241.254154.72.241.255254
243154.72.242.0/24154.72.242.1 to 154.72.242.254154.72.242.255254
244154.72.243.0/24154.72.243.1 to 154.72.243.254154.72.243.255254
245154.72.244.0/24154.72.244.1 to 154.72.244.254154.72.244.255254
246154.72.245.0/24154.72.245.1 to 154.72.245.254154.72.245.255254
247154.72.246.0/24154.72.246.1 to 154.72.246.254154.72.246.255254
248154.72.247.0/24154.72.247.1 to 154.72.247.254154.72.247.255254
249154.72.248.0/24154.72.248.1 to 154.72.248.254154.72.248.255254
250154.72.249.0/24154.72.249.1 to 154.72.249.254154.72.249.255254
251154.72.250.0/24154.72.250.1 to 154.72.250.254154.72.250.255254
252154.72.251.0/24154.72.251.1 to 154.72.251.254154.72.251.255254
253154.72.252.0/24154.72.252.1 to 154.72.252.254154.72.252.255254
254154.72.253.0/24154.72.253.1 to 154.72.253.254154.72.253.255254
255154.72.254.0/24154.72.254.1 to 154.72.254.254154.72.254.255254
256154.72.255.0/24154.72.255.1 to 154.72.255.254154.72.255.255254

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.