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.

Network176.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
176.0.0.0
Broadcast address
177.255.255.255
First usable
176.0.0.1
Last usable
177.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex B0000000 · Integer 2952790016 to 2986344447
Reverse DNS zones
176.in-addr.arpa
177.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110000.00000000.00000000.00000000176.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10110000.00000000.00000000.00000000176.0.0.0
Broadcast10110001.11111111.11111111.11111111177.255.255.255
Split into smaller subnets/16
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

176.0.0.0/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1176.0.0.0/16176.0.0.1 to 176.0.255.254176.0.255.25565,534
2176.1.0.0/16176.1.0.1 to 176.1.255.254176.1.255.25565,534
3176.2.0.0/16176.2.0.1 to 176.2.255.254176.2.255.25565,534
4176.3.0.0/16176.3.0.1 to 176.3.255.254176.3.255.25565,534
5176.4.0.0/16176.4.0.1 to 176.4.255.254176.4.255.25565,534
6176.5.0.0/16176.5.0.1 to 176.5.255.254176.5.255.25565,534
7176.6.0.0/16176.6.0.1 to 176.6.255.254176.6.255.25565,534
8176.7.0.0/16176.7.0.1 to 176.7.255.254176.7.255.25565,534
9176.8.0.0/16176.8.0.1 to 176.8.255.254176.8.255.25565,534
10176.9.0.0/16176.9.0.1 to 176.9.255.254176.9.255.25565,534
11176.10.0.0/16176.10.0.1 to 176.10.255.254176.10.255.25565,534
12176.11.0.0/16176.11.0.1 to 176.11.255.254176.11.255.25565,534
13176.12.0.0/16176.12.0.1 to 176.12.255.254176.12.255.25565,534
14176.13.0.0/16176.13.0.1 to 176.13.255.254176.13.255.25565,534
15176.14.0.0/16176.14.0.1 to 176.14.255.254176.14.255.25565,534
16176.15.0.0/16176.15.0.1 to 176.15.255.254176.15.255.25565,534
17176.16.0.0/16176.16.0.1 to 176.16.255.254176.16.255.25565,534
18176.17.0.0/16176.17.0.1 to 176.17.255.254176.17.255.25565,534
19176.18.0.0/16176.18.0.1 to 176.18.255.254176.18.255.25565,534
20176.19.0.0/16176.19.0.1 to 176.19.255.254176.19.255.25565,534
21176.20.0.0/16176.20.0.1 to 176.20.255.254176.20.255.25565,534
22176.21.0.0/16176.21.0.1 to 176.21.255.254176.21.255.25565,534
23176.22.0.0/16176.22.0.1 to 176.22.255.254176.22.255.25565,534
24176.23.0.0/16176.23.0.1 to 176.23.255.254176.23.255.25565,534
25176.24.0.0/16176.24.0.1 to 176.24.255.254176.24.255.25565,534
26176.25.0.0/16176.25.0.1 to 176.25.255.254176.25.255.25565,534
27176.26.0.0/16176.26.0.1 to 176.26.255.254176.26.255.25565,534
28176.27.0.0/16176.27.0.1 to 176.27.255.254176.27.255.25565,534
29176.28.0.0/16176.28.0.1 to 176.28.255.254176.28.255.25565,534
30176.29.0.0/16176.29.0.1 to 176.29.255.254176.29.255.25565,534
31176.30.0.0/16176.30.0.1 to 176.30.255.254176.30.255.25565,534
32176.31.0.0/16176.31.0.1 to 176.31.255.254176.31.255.25565,534
33176.32.0.0/16176.32.0.1 to 176.32.255.254176.32.255.25565,534
34176.33.0.0/16176.33.0.1 to 176.33.255.254176.33.255.25565,534
35176.34.0.0/16176.34.0.1 to 176.34.255.254176.34.255.25565,534
36176.35.0.0/16176.35.0.1 to 176.35.255.254176.35.255.25565,534
37176.36.0.0/16176.36.0.1 to 176.36.255.254176.36.255.25565,534
38176.37.0.0/16176.37.0.1 to 176.37.255.254176.37.255.25565,534
39176.38.0.0/16176.38.0.1 to 176.38.255.254176.38.255.25565,534
40176.39.0.0/16176.39.0.1 to 176.39.255.254176.39.255.25565,534
41176.40.0.0/16176.40.0.1 to 176.40.255.254176.40.255.25565,534
42176.41.0.0/16176.41.0.1 to 176.41.255.254176.41.255.25565,534
43176.42.0.0/16176.42.0.1 to 176.42.255.254176.42.255.25565,534
44176.43.0.0/16176.43.0.1 to 176.43.255.254176.43.255.25565,534
45176.44.0.0/16176.44.0.1 to 176.44.255.254176.44.255.25565,534
46176.45.0.0/16176.45.0.1 to 176.45.255.254176.45.255.25565,534
47176.46.0.0/16176.46.0.1 to 176.46.255.254176.46.255.25565,534
48176.47.0.0/16176.47.0.1 to 176.47.255.254176.47.255.25565,534
49176.48.0.0/16176.48.0.1 to 176.48.255.254176.48.255.25565,534
50176.49.0.0/16176.49.0.1 to 176.49.255.254176.49.255.25565,534
51176.50.0.0/16176.50.0.1 to 176.50.255.254176.50.255.25565,534
52176.51.0.0/16176.51.0.1 to 176.51.255.254176.51.255.25565,534
53176.52.0.0/16176.52.0.1 to 176.52.255.254176.52.255.25565,534
54176.53.0.0/16176.53.0.1 to 176.53.255.254176.53.255.25565,534
55176.54.0.0/16176.54.0.1 to 176.54.255.254176.54.255.25565,534
56176.55.0.0/16176.55.0.1 to 176.55.255.254176.55.255.25565,534
57176.56.0.0/16176.56.0.1 to 176.56.255.254176.56.255.25565,534
58176.57.0.0/16176.57.0.1 to 176.57.255.254176.57.255.25565,534
59176.58.0.0/16176.58.0.1 to 176.58.255.254176.58.255.25565,534
60176.59.0.0/16176.59.0.1 to 176.59.255.254176.59.255.25565,534
61176.60.0.0/16176.60.0.1 to 176.60.255.254176.60.255.25565,534
62176.61.0.0/16176.61.0.1 to 176.61.255.254176.61.255.25565,534
63176.62.0.0/16176.62.0.1 to 176.62.255.254176.62.255.25565,534
64176.63.0.0/16176.63.0.1 to 176.63.255.254176.63.255.25565,534
65176.64.0.0/16176.64.0.1 to 176.64.255.254176.64.255.25565,534
66176.65.0.0/16176.65.0.1 to 176.65.255.254176.65.255.25565,534
67176.66.0.0/16176.66.0.1 to 176.66.255.254176.66.255.25565,534
68176.67.0.0/16176.67.0.1 to 176.67.255.254176.67.255.25565,534
69176.68.0.0/16176.68.0.1 to 176.68.255.254176.68.255.25565,534
70176.69.0.0/16176.69.0.1 to 176.69.255.254176.69.255.25565,534
71176.70.0.0/16176.70.0.1 to 176.70.255.254176.70.255.25565,534
72176.71.0.0/16176.71.0.1 to 176.71.255.254176.71.255.25565,534
73176.72.0.0/16176.72.0.1 to 176.72.255.254176.72.255.25565,534
74176.73.0.0/16176.73.0.1 to 176.73.255.254176.73.255.25565,534
75176.74.0.0/16176.74.0.1 to 176.74.255.254176.74.255.25565,534
76176.75.0.0/16176.75.0.1 to 176.75.255.254176.75.255.25565,534
77176.76.0.0/16176.76.0.1 to 176.76.255.254176.76.255.25565,534
78176.77.0.0/16176.77.0.1 to 176.77.255.254176.77.255.25565,534
79176.78.0.0/16176.78.0.1 to 176.78.255.254176.78.255.25565,534
80176.79.0.0/16176.79.0.1 to 176.79.255.254176.79.255.25565,534
81176.80.0.0/16176.80.0.1 to 176.80.255.254176.80.255.25565,534
82176.81.0.0/16176.81.0.1 to 176.81.255.254176.81.255.25565,534
83176.82.0.0/16176.82.0.1 to 176.82.255.254176.82.255.25565,534
84176.83.0.0/16176.83.0.1 to 176.83.255.254176.83.255.25565,534
85176.84.0.0/16176.84.0.1 to 176.84.255.254176.84.255.25565,534
86176.85.0.0/16176.85.0.1 to 176.85.255.254176.85.255.25565,534
87176.86.0.0/16176.86.0.1 to 176.86.255.254176.86.255.25565,534
88176.87.0.0/16176.87.0.1 to 176.87.255.254176.87.255.25565,534
89176.88.0.0/16176.88.0.1 to 176.88.255.254176.88.255.25565,534
90176.89.0.0/16176.89.0.1 to 176.89.255.254176.89.255.25565,534
91176.90.0.0/16176.90.0.1 to 176.90.255.254176.90.255.25565,534
92176.91.0.0/16176.91.0.1 to 176.91.255.254176.91.255.25565,534
93176.92.0.0/16176.92.0.1 to 176.92.255.254176.92.255.25565,534
94176.93.0.0/16176.93.0.1 to 176.93.255.254176.93.255.25565,534
95176.94.0.0/16176.94.0.1 to 176.94.255.254176.94.255.25565,534
96176.95.0.0/16176.95.0.1 to 176.95.255.254176.95.255.25565,534
97176.96.0.0/16176.96.0.1 to 176.96.255.254176.96.255.25565,534
98176.97.0.0/16176.97.0.1 to 176.97.255.254176.97.255.25565,534
99176.98.0.0/16176.98.0.1 to 176.98.255.254176.98.255.25565,534
100176.99.0.0/16176.99.0.1 to 176.99.255.254176.99.255.25565,534
101176.100.0.0/16176.100.0.1 to 176.100.255.254176.100.255.25565,534
102176.101.0.0/16176.101.0.1 to 176.101.255.254176.101.255.25565,534
103176.102.0.0/16176.102.0.1 to 176.102.255.254176.102.255.25565,534
104176.103.0.0/16176.103.0.1 to 176.103.255.254176.103.255.25565,534
105176.104.0.0/16176.104.0.1 to 176.104.255.254176.104.255.25565,534
106176.105.0.0/16176.105.0.1 to 176.105.255.254176.105.255.25565,534
107176.106.0.0/16176.106.0.1 to 176.106.255.254176.106.255.25565,534
108176.107.0.0/16176.107.0.1 to 176.107.255.254176.107.255.25565,534
109176.108.0.0/16176.108.0.1 to 176.108.255.254176.108.255.25565,534
110176.109.0.0/16176.109.0.1 to 176.109.255.254176.109.255.25565,534
111176.110.0.0/16176.110.0.1 to 176.110.255.254176.110.255.25565,534
112176.111.0.0/16176.111.0.1 to 176.111.255.254176.111.255.25565,534
113176.112.0.0/16176.112.0.1 to 176.112.255.254176.112.255.25565,534
114176.113.0.0/16176.113.0.1 to 176.113.255.254176.113.255.25565,534
115176.114.0.0/16176.114.0.1 to 176.114.255.254176.114.255.25565,534
116176.115.0.0/16176.115.0.1 to 176.115.255.254176.115.255.25565,534
117176.116.0.0/16176.116.0.1 to 176.116.255.254176.116.255.25565,534
118176.117.0.0/16176.117.0.1 to 176.117.255.254176.117.255.25565,534
119176.118.0.0/16176.118.0.1 to 176.118.255.254176.118.255.25565,534
120176.119.0.0/16176.119.0.1 to 176.119.255.254176.119.255.25565,534
121176.120.0.0/16176.120.0.1 to 176.120.255.254176.120.255.25565,534
122176.121.0.0/16176.121.0.1 to 176.121.255.254176.121.255.25565,534
123176.122.0.0/16176.122.0.1 to 176.122.255.254176.122.255.25565,534
124176.123.0.0/16176.123.0.1 to 176.123.255.254176.123.255.25565,534
125176.124.0.0/16176.124.0.1 to 176.124.255.254176.124.255.25565,534
126176.125.0.0/16176.125.0.1 to 176.125.255.254176.125.255.25565,534
127176.126.0.0/16176.126.0.1 to 176.126.255.254176.126.255.25565,534
128176.127.0.0/16176.127.0.1 to 176.127.255.254176.127.255.25565,534
129176.128.0.0/16176.128.0.1 to 176.128.255.254176.128.255.25565,534
130176.129.0.0/16176.129.0.1 to 176.129.255.254176.129.255.25565,534
131176.130.0.0/16176.130.0.1 to 176.130.255.254176.130.255.25565,534
132176.131.0.0/16176.131.0.1 to 176.131.255.254176.131.255.25565,534
133176.132.0.0/16176.132.0.1 to 176.132.255.254176.132.255.25565,534
134176.133.0.0/16176.133.0.1 to 176.133.255.254176.133.255.25565,534
135176.134.0.0/16176.134.0.1 to 176.134.255.254176.134.255.25565,534
136176.135.0.0/16176.135.0.1 to 176.135.255.254176.135.255.25565,534
137176.136.0.0/16176.136.0.1 to 176.136.255.254176.136.255.25565,534
138176.137.0.0/16176.137.0.1 to 176.137.255.254176.137.255.25565,534
139176.138.0.0/16176.138.0.1 to 176.138.255.254176.138.255.25565,534
140176.139.0.0/16176.139.0.1 to 176.139.255.254176.139.255.25565,534
141176.140.0.0/16176.140.0.1 to 176.140.255.254176.140.255.25565,534
142176.141.0.0/16176.141.0.1 to 176.141.255.254176.141.255.25565,534
143176.142.0.0/16176.142.0.1 to 176.142.255.254176.142.255.25565,534
144176.143.0.0/16176.143.0.1 to 176.143.255.254176.143.255.25565,534
145176.144.0.0/16176.144.0.1 to 176.144.255.254176.144.255.25565,534
146176.145.0.0/16176.145.0.1 to 176.145.255.254176.145.255.25565,534
147176.146.0.0/16176.146.0.1 to 176.146.255.254176.146.255.25565,534
148176.147.0.0/16176.147.0.1 to 176.147.255.254176.147.255.25565,534
149176.148.0.0/16176.148.0.1 to 176.148.255.254176.148.255.25565,534
150176.149.0.0/16176.149.0.1 to 176.149.255.254176.149.255.25565,534
151176.150.0.0/16176.150.0.1 to 176.150.255.254176.150.255.25565,534
152176.151.0.0/16176.151.0.1 to 176.151.255.254176.151.255.25565,534
153176.152.0.0/16176.152.0.1 to 176.152.255.254176.152.255.25565,534
154176.153.0.0/16176.153.0.1 to 176.153.255.254176.153.255.25565,534
155176.154.0.0/16176.154.0.1 to 176.154.255.254176.154.255.25565,534
156176.155.0.0/16176.155.0.1 to 176.155.255.254176.155.255.25565,534
157176.156.0.0/16176.156.0.1 to 176.156.255.254176.156.255.25565,534
158176.157.0.0/16176.157.0.1 to 176.157.255.254176.157.255.25565,534
159176.158.0.0/16176.158.0.1 to 176.158.255.254176.158.255.25565,534
160176.159.0.0/16176.159.0.1 to 176.159.255.254176.159.255.25565,534
161176.160.0.0/16176.160.0.1 to 176.160.255.254176.160.255.25565,534
162176.161.0.0/16176.161.0.1 to 176.161.255.254176.161.255.25565,534
163176.162.0.0/16176.162.0.1 to 176.162.255.254176.162.255.25565,534
164176.163.0.0/16176.163.0.1 to 176.163.255.254176.163.255.25565,534
165176.164.0.0/16176.164.0.1 to 176.164.255.254176.164.255.25565,534
166176.165.0.0/16176.165.0.1 to 176.165.255.254176.165.255.25565,534
167176.166.0.0/16176.166.0.1 to 176.166.255.254176.166.255.25565,534
168176.167.0.0/16176.167.0.1 to 176.167.255.254176.167.255.25565,534
169176.168.0.0/16176.168.0.1 to 176.168.255.254176.168.255.25565,534
170176.169.0.0/16176.169.0.1 to 176.169.255.254176.169.255.25565,534
171176.170.0.0/16176.170.0.1 to 176.170.255.254176.170.255.25565,534
172176.171.0.0/16176.171.0.1 to 176.171.255.254176.171.255.25565,534
173176.172.0.0/16176.172.0.1 to 176.172.255.254176.172.255.25565,534
174176.173.0.0/16176.173.0.1 to 176.173.255.254176.173.255.25565,534
175176.174.0.0/16176.174.0.1 to 176.174.255.254176.174.255.25565,534
176176.175.0.0/16176.175.0.1 to 176.175.255.254176.175.255.25565,534
177176.176.0.0/16176.176.0.1 to 176.176.255.254176.176.255.25565,534
178176.177.0.0/16176.177.0.1 to 176.177.255.254176.177.255.25565,534
179176.178.0.0/16176.178.0.1 to 176.178.255.254176.178.255.25565,534
180176.179.0.0/16176.179.0.1 to 176.179.255.254176.179.255.25565,534
181176.180.0.0/16176.180.0.1 to 176.180.255.254176.180.255.25565,534
182176.181.0.0/16176.181.0.1 to 176.181.255.254176.181.255.25565,534
183176.182.0.0/16176.182.0.1 to 176.182.255.254176.182.255.25565,534
184176.183.0.0/16176.183.0.1 to 176.183.255.254176.183.255.25565,534
185176.184.0.0/16176.184.0.1 to 176.184.255.254176.184.255.25565,534
186176.185.0.0/16176.185.0.1 to 176.185.255.254176.185.255.25565,534
187176.186.0.0/16176.186.0.1 to 176.186.255.254176.186.255.25565,534
188176.187.0.0/16176.187.0.1 to 176.187.255.254176.187.255.25565,534
189176.188.0.0/16176.188.0.1 to 176.188.255.254176.188.255.25565,534
190176.189.0.0/16176.189.0.1 to 176.189.255.254176.189.255.25565,534
191176.190.0.0/16176.190.0.1 to 176.190.255.254176.190.255.25565,534
192176.191.0.0/16176.191.0.1 to 176.191.255.254176.191.255.25565,534
193176.192.0.0/16176.192.0.1 to 176.192.255.254176.192.255.25565,534
194176.193.0.0/16176.193.0.1 to 176.193.255.254176.193.255.25565,534
195176.194.0.0/16176.194.0.1 to 176.194.255.254176.194.255.25565,534
196176.195.0.0/16176.195.0.1 to 176.195.255.254176.195.255.25565,534
197176.196.0.0/16176.196.0.1 to 176.196.255.254176.196.255.25565,534
198176.197.0.0/16176.197.0.1 to 176.197.255.254176.197.255.25565,534
199176.198.0.0/16176.198.0.1 to 176.198.255.254176.198.255.25565,534
200176.199.0.0/16176.199.0.1 to 176.199.255.254176.199.255.25565,534
201176.200.0.0/16176.200.0.1 to 176.200.255.254176.200.255.25565,534
202176.201.0.0/16176.201.0.1 to 176.201.255.254176.201.255.25565,534
203176.202.0.0/16176.202.0.1 to 176.202.255.254176.202.255.25565,534
204176.203.0.0/16176.203.0.1 to 176.203.255.254176.203.255.25565,534
205176.204.0.0/16176.204.0.1 to 176.204.255.254176.204.255.25565,534
206176.205.0.0/16176.205.0.1 to 176.205.255.254176.205.255.25565,534
207176.206.0.0/16176.206.0.1 to 176.206.255.254176.206.255.25565,534
208176.207.0.0/16176.207.0.1 to 176.207.255.254176.207.255.25565,534
209176.208.0.0/16176.208.0.1 to 176.208.255.254176.208.255.25565,534
210176.209.0.0/16176.209.0.1 to 176.209.255.254176.209.255.25565,534
211176.210.0.0/16176.210.0.1 to 176.210.255.254176.210.255.25565,534
212176.211.0.0/16176.211.0.1 to 176.211.255.254176.211.255.25565,534
213176.212.0.0/16176.212.0.1 to 176.212.255.254176.212.255.25565,534
214176.213.0.0/16176.213.0.1 to 176.213.255.254176.213.255.25565,534
215176.214.0.0/16176.214.0.1 to 176.214.255.254176.214.255.25565,534
216176.215.0.0/16176.215.0.1 to 176.215.255.254176.215.255.25565,534
217176.216.0.0/16176.216.0.1 to 176.216.255.254176.216.255.25565,534
218176.217.0.0/16176.217.0.1 to 176.217.255.254176.217.255.25565,534
219176.218.0.0/16176.218.0.1 to 176.218.255.254176.218.255.25565,534
220176.219.0.0/16176.219.0.1 to 176.219.255.254176.219.255.25565,534
221176.220.0.0/16176.220.0.1 to 176.220.255.254176.220.255.25565,534
222176.221.0.0/16176.221.0.1 to 176.221.255.254176.221.255.25565,534
223176.222.0.0/16176.222.0.1 to 176.222.255.254176.222.255.25565,534
224176.223.0.0/16176.223.0.1 to 176.223.255.254176.223.255.25565,534
225176.224.0.0/16176.224.0.1 to 176.224.255.254176.224.255.25565,534
226176.225.0.0/16176.225.0.1 to 176.225.255.254176.225.255.25565,534
227176.226.0.0/16176.226.0.1 to 176.226.255.254176.226.255.25565,534
228176.227.0.0/16176.227.0.1 to 176.227.255.254176.227.255.25565,534
229176.228.0.0/16176.228.0.1 to 176.228.255.254176.228.255.25565,534
230176.229.0.0/16176.229.0.1 to 176.229.255.254176.229.255.25565,534
231176.230.0.0/16176.230.0.1 to 176.230.255.254176.230.255.25565,534
232176.231.0.0/16176.231.0.1 to 176.231.255.254176.231.255.25565,534
233176.232.0.0/16176.232.0.1 to 176.232.255.254176.232.255.25565,534
234176.233.0.0/16176.233.0.1 to 176.233.255.254176.233.255.25565,534
235176.234.0.0/16176.234.0.1 to 176.234.255.254176.234.255.25565,534
236176.235.0.0/16176.235.0.1 to 176.235.255.254176.235.255.25565,534
237176.236.0.0/16176.236.0.1 to 176.236.255.254176.236.255.25565,534
238176.237.0.0/16176.237.0.1 to 176.237.255.254176.237.255.25565,534
239176.238.0.0/16176.238.0.1 to 176.238.255.254176.238.255.25565,534
240176.239.0.0/16176.239.0.1 to 176.239.255.254176.239.255.25565,534
241176.240.0.0/16176.240.0.1 to 176.240.255.254176.240.255.25565,534
242176.241.0.0/16176.241.0.1 to 176.241.255.254176.241.255.25565,534
243176.242.0.0/16176.242.0.1 to 176.242.255.254176.242.255.25565,534
244176.243.0.0/16176.243.0.1 to 176.243.255.254176.243.255.25565,534
245176.244.0.0/16176.244.0.1 to 176.244.255.254176.244.255.25565,534
246176.245.0.0/16176.245.0.1 to 176.245.255.254176.245.255.25565,534
247176.246.0.0/16176.246.0.1 to 176.246.255.254176.246.255.25565,534
248176.247.0.0/16176.247.0.1 to 176.247.255.254176.247.255.25565,534
249176.248.0.0/16176.248.0.1 to 176.248.255.254176.248.255.25565,534
250176.249.0.0/16176.249.0.1 to 176.249.255.254176.249.255.25565,534
251176.250.0.0/16176.250.0.1 to 176.250.255.254176.250.255.25565,534
252176.251.0.0/16176.251.0.1 to 176.251.255.254176.251.255.25565,534
253176.252.0.0/16176.252.0.1 to 176.252.255.254176.252.255.25565,534
254176.253.0.0/16176.253.0.1 to 176.253.255.254176.253.255.25565,534
255176.254.0.0/16176.254.0.1 to 176.254.255.254176.254.255.25565,534
256176.255.0.0/16176.255.0.1 to 176.255.255.254176.255.255.25565,534

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.