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.

Network179.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
179.0.0.0
Broadcast address
179.255.255.255
First usable
179.0.0.1
Last usable
179.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex B3000000 · Integer 3003121664 to 3019898879
Reverse DNS zone
179.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110011..00000000.00000000.00000000179.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10110011..00000000.00000000.00000000179.0.0.0
Broadcast10110011..11111111.11111111.11111111179.255.255.255
Split into smaller subnets/16
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

179.0.0.0/8 makes 256 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1179.0.0.0/16179.0.0.1 to 179.0.255.254179.0.255.25565,534
2179.1.0.0/16179.1.0.1 to 179.1.255.254179.1.255.25565,534
3179.2.0.0/16179.2.0.1 to 179.2.255.254179.2.255.25565,534
4179.3.0.0/16179.3.0.1 to 179.3.255.254179.3.255.25565,534
5179.4.0.0/16179.4.0.1 to 179.4.255.254179.4.255.25565,534
6179.5.0.0/16179.5.0.1 to 179.5.255.254179.5.255.25565,534
7179.6.0.0/16179.6.0.1 to 179.6.255.254179.6.255.25565,534
8179.7.0.0/16179.7.0.1 to 179.7.255.254179.7.255.25565,534
9179.8.0.0/16179.8.0.1 to 179.8.255.254179.8.255.25565,534
10179.9.0.0/16179.9.0.1 to 179.9.255.254179.9.255.25565,534
11179.10.0.0/16179.10.0.1 to 179.10.255.254179.10.255.25565,534
12179.11.0.0/16179.11.0.1 to 179.11.255.254179.11.255.25565,534
13179.12.0.0/16179.12.0.1 to 179.12.255.254179.12.255.25565,534
14179.13.0.0/16179.13.0.1 to 179.13.255.254179.13.255.25565,534
15179.14.0.0/16179.14.0.1 to 179.14.255.254179.14.255.25565,534
16179.15.0.0/16179.15.0.1 to 179.15.255.254179.15.255.25565,534
17179.16.0.0/16179.16.0.1 to 179.16.255.254179.16.255.25565,534
18179.17.0.0/16179.17.0.1 to 179.17.255.254179.17.255.25565,534
19179.18.0.0/16179.18.0.1 to 179.18.255.254179.18.255.25565,534
20179.19.0.0/16179.19.0.1 to 179.19.255.254179.19.255.25565,534
21179.20.0.0/16179.20.0.1 to 179.20.255.254179.20.255.25565,534
22179.21.0.0/16179.21.0.1 to 179.21.255.254179.21.255.25565,534
23179.22.0.0/16179.22.0.1 to 179.22.255.254179.22.255.25565,534
24179.23.0.0/16179.23.0.1 to 179.23.255.254179.23.255.25565,534
25179.24.0.0/16179.24.0.1 to 179.24.255.254179.24.255.25565,534
26179.25.0.0/16179.25.0.1 to 179.25.255.254179.25.255.25565,534
27179.26.0.0/16179.26.0.1 to 179.26.255.254179.26.255.25565,534
28179.27.0.0/16179.27.0.1 to 179.27.255.254179.27.255.25565,534
29179.28.0.0/16179.28.0.1 to 179.28.255.254179.28.255.25565,534
30179.29.0.0/16179.29.0.1 to 179.29.255.254179.29.255.25565,534
31179.30.0.0/16179.30.0.1 to 179.30.255.254179.30.255.25565,534
32179.31.0.0/16179.31.0.1 to 179.31.255.254179.31.255.25565,534
33179.32.0.0/16179.32.0.1 to 179.32.255.254179.32.255.25565,534
34179.33.0.0/16179.33.0.1 to 179.33.255.254179.33.255.25565,534
35179.34.0.0/16179.34.0.1 to 179.34.255.254179.34.255.25565,534
36179.35.0.0/16179.35.0.1 to 179.35.255.254179.35.255.25565,534
37179.36.0.0/16179.36.0.1 to 179.36.255.254179.36.255.25565,534
38179.37.0.0/16179.37.0.1 to 179.37.255.254179.37.255.25565,534
39179.38.0.0/16179.38.0.1 to 179.38.255.254179.38.255.25565,534
40179.39.0.0/16179.39.0.1 to 179.39.255.254179.39.255.25565,534
41179.40.0.0/16179.40.0.1 to 179.40.255.254179.40.255.25565,534
42179.41.0.0/16179.41.0.1 to 179.41.255.254179.41.255.25565,534
43179.42.0.0/16179.42.0.1 to 179.42.255.254179.42.255.25565,534
44179.43.0.0/16179.43.0.1 to 179.43.255.254179.43.255.25565,534
45179.44.0.0/16179.44.0.1 to 179.44.255.254179.44.255.25565,534
46179.45.0.0/16179.45.0.1 to 179.45.255.254179.45.255.25565,534
47179.46.0.0/16179.46.0.1 to 179.46.255.254179.46.255.25565,534
48179.47.0.0/16179.47.0.1 to 179.47.255.254179.47.255.25565,534
49179.48.0.0/16179.48.0.1 to 179.48.255.254179.48.255.25565,534
50179.49.0.0/16179.49.0.1 to 179.49.255.254179.49.255.25565,534
51179.50.0.0/16179.50.0.1 to 179.50.255.254179.50.255.25565,534
52179.51.0.0/16179.51.0.1 to 179.51.255.254179.51.255.25565,534
53179.52.0.0/16179.52.0.1 to 179.52.255.254179.52.255.25565,534
54179.53.0.0/16179.53.0.1 to 179.53.255.254179.53.255.25565,534
55179.54.0.0/16179.54.0.1 to 179.54.255.254179.54.255.25565,534
56179.55.0.0/16179.55.0.1 to 179.55.255.254179.55.255.25565,534
57179.56.0.0/16179.56.0.1 to 179.56.255.254179.56.255.25565,534
58179.57.0.0/16179.57.0.1 to 179.57.255.254179.57.255.25565,534
59179.58.0.0/16179.58.0.1 to 179.58.255.254179.58.255.25565,534
60179.59.0.0/16179.59.0.1 to 179.59.255.254179.59.255.25565,534
61179.60.0.0/16179.60.0.1 to 179.60.255.254179.60.255.25565,534
62179.61.0.0/16179.61.0.1 to 179.61.255.254179.61.255.25565,534
63179.62.0.0/16179.62.0.1 to 179.62.255.254179.62.255.25565,534
64179.63.0.0/16179.63.0.1 to 179.63.255.254179.63.255.25565,534
65179.64.0.0/16179.64.0.1 to 179.64.255.254179.64.255.25565,534
66179.65.0.0/16179.65.0.1 to 179.65.255.254179.65.255.25565,534
67179.66.0.0/16179.66.0.1 to 179.66.255.254179.66.255.25565,534
68179.67.0.0/16179.67.0.1 to 179.67.255.254179.67.255.25565,534
69179.68.0.0/16179.68.0.1 to 179.68.255.254179.68.255.25565,534
70179.69.0.0/16179.69.0.1 to 179.69.255.254179.69.255.25565,534
71179.70.0.0/16179.70.0.1 to 179.70.255.254179.70.255.25565,534
72179.71.0.0/16179.71.0.1 to 179.71.255.254179.71.255.25565,534
73179.72.0.0/16179.72.0.1 to 179.72.255.254179.72.255.25565,534
74179.73.0.0/16179.73.0.1 to 179.73.255.254179.73.255.25565,534
75179.74.0.0/16179.74.0.1 to 179.74.255.254179.74.255.25565,534
76179.75.0.0/16179.75.0.1 to 179.75.255.254179.75.255.25565,534
77179.76.0.0/16179.76.0.1 to 179.76.255.254179.76.255.25565,534
78179.77.0.0/16179.77.0.1 to 179.77.255.254179.77.255.25565,534
79179.78.0.0/16179.78.0.1 to 179.78.255.254179.78.255.25565,534
80179.79.0.0/16179.79.0.1 to 179.79.255.254179.79.255.25565,534
81179.80.0.0/16179.80.0.1 to 179.80.255.254179.80.255.25565,534
82179.81.0.0/16179.81.0.1 to 179.81.255.254179.81.255.25565,534
83179.82.0.0/16179.82.0.1 to 179.82.255.254179.82.255.25565,534
84179.83.0.0/16179.83.0.1 to 179.83.255.254179.83.255.25565,534
85179.84.0.0/16179.84.0.1 to 179.84.255.254179.84.255.25565,534
86179.85.0.0/16179.85.0.1 to 179.85.255.254179.85.255.25565,534
87179.86.0.0/16179.86.0.1 to 179.86.255.254179.86.255.25565,534
88179.87.0.0/16179.87.0.1 to 179.87.255.254179.87.255.25565,534
89179.88.0.0/16179.88.0.1 to 179.88.255.254179.88.255.25565,534
90179.89.0.0/16179.89.0.1 to 179.89.255.254179.89.255.25565,534
91179.90.0.0/16179.90.0.1 to 179.90.255.254179.90.255.25565,534
92179.91.0.0/16179.91.0.1 to 179.91.255.254179.91.255.25565,534
93179.92.0.0/16179.92.0.1 to 179.92.255.254179.92.255.25565,534
94179.93.0.0/16179.93.0.1 to 179.93.255.254179.93.255.25565,534
95179.94.0.0/16179.94.0.1 to 179.94.255.254179.94.255.25565,534
96179.95.0.0/16179.95.0.1 to 179.95.255.254179.95.255.25565,534
97179.96.0.0/16179.96.0.1 to 179.96.255.254179.96.255.25565,534
98179.97.0.0/16179.97.0.1 to 179.97.255.254179.97.255.25565,534
99179.98.0.0/16179.98.0.1 to 179.98.255.254179.98.255.25565,534
100179.99.0.0/16179.99.0.1 to 179.99.255.254179.99.255.25565,534
101179.100.0.0/16179.100.0.1 to 179.100.255.254179.100.255.25565,534
102179.101.0.0/16179.101.0.1 to 179.101.255.254179.101.255.25565,534
103179.102.0.0/16179.102.0.1 to 179.102.255.254179.102.255.25565,534
104179.103.0.0/16179.103.0.1 to 179.103.255.254179.103.255.25565,534
105179.104.0.0/16179.104.0.1 to 179.104.255.254179.104.255.25565,534
106179.105.0.0/16179.105.0.1 to 179.105.255.254179.105.255.25565,534
107179.106.0.0/16179.106.0.1 to 179.106.255.254179.106.255.25565,534
108179.107.0.0/16179.107.0.1 to 179.107.255.254179.107.255.25565,534
109179.108.0.0/16179.108.0.1 to 179.108.255.254179.108.255.25565,534
110179.109.0.0/16179.109.0.1 to 179.109.255.254179.109.255.25565,534
111179.110.0.0/16179.110.0.1 to 179.110.255.254179.110.255.25565,534
112179.111.0.0/16179.111.0.1 to 179.111.255.254179.111.255.25565,534
113179.112.0.0/16179.112.0.1 to 179.112.255.254179.112.255.25565,534
114179.113.0.0/16179.113.0.1 to 179.113.255.254179.113.255.25565,534
115179.114.0.0/16179.114.0.1 to 179.114.255.254179.114.255.25565,534
116179.115.0.0/16179.115.0.1 to 179.115.255.254179.115.255.25565,534
117179.116.0.0/16179.116.0.1 to 179.116.255.254179.116.255.25565,534
118179.117.0.0/16179.117.0.1 to 179.117.255.254179.117.255.25565,534
119179.118.0.0/16179.118.0.1 to 179.118.255.254179.118.255.25565,534
120179.119.0.0/16179.119.0.1 to 179.119.255.254179.119.255.25565,534
121179.120.0.0/16179.120.0.1 to 179.120.255.254179.120.255.25565,534
122179.121.0.0/16179.121.0.1 to 179.121.255.254179.121.255.25565,534
123179.122.0.0/16179.122.0.1 to 179.122.255.254179.122.255.25565,534
124179.123.0.0/16179.123.0.1 to 179.123.255.254179.123.255.25565,534
125179.124.0.0/16179.124.0.1 to 179.124.255.254179.124.255.25565,534
126179.125.0.0/16179.125.0.1 to 179.125.255.254179.125.255.25565,534
127179.126.0.0/16179.126.0.1 to 179.126.255.254179.126.255.25565,534
128179.127.0.0/16179.127.0.1 to 179.127.255.254179.127.255.25565,534
129179.128.0.0/16179.128.0.1 to 179.128.255.254179.128.255.25565,534
130179.129.0.0/16179.129.0.1 to 179.129.255.254179.129.255.25565,534
131179.130.0.0/16179.130.0.1 to 179.130.255.254179.130.255.25565,534
132179.131.0.0/16179.131.0.1 to 179.131.255.254179.131.255.25565,534
133179.132.0.0/16179.132.0.1 to 179.132.255.254179.132.255.25565,534
134179.133.0.0/16179.133.0.1 to 179.133.255.254179.133.255.25565,534
135179.134.0.0/16179.134.0.1 to 179.134.255.254179.134.255.25565,534
136179.135.0.0/16179.135.0.1 to 179.135.255.254179.135.255.25565,534
137179.136.0.0/16179.136.0.1 to 179.136.255.254179.136.255.25565,534
138179.137.0.0/16179.137.0.1 to 179.137.255.254179.137.255.25565,534
139179.138.0.0/16179.138.0.1 to 179.138.255.254179.138.255.25565,534
140179.139.0.0/16179.139.0.1 to 179.139.255.254179.139.255.25565,534
141179.140.0.0/16179.140.0.1 to 179.140.255.254179.140.255.25565,534
142179.141.0.0/16179.141.0.1 to 179.141.255.254179.141.255.25565,534
143179.142.0.0/16179.142.0.1 to 179.142.255.254179.142.255.25565,534
144179.143.0.0/16179.143.0.1 to 179.143.255.254179.143.255.25565,534
145179.144.0.0/16179.144.0.1 to 179.144.255.254179.144.255.25565,534
146179.145.0.0/16179.145.0.1 to 179.145.255.254179.145.255.25565,534
147179.146.0.0/16179.146.0.1 to 179.146.255.254179.146.255.25565,534
148179.147.0.0/16179.147.0.1 to 179.147.255.254179.147.255.25565,534
149179.148.0.0/16179.148.0.1 to 179.148.255.254179.148.255.25565,534
150179.149.0.0/16179.149.0.1 to 179.149.255.254179.149.255.25565,534
151179.150.0.0/16179.150.0.1 to 179.150.255.254179.150.255.25565,534
152179.151.0.0/16179.151.0.1 to 179.151.255.254179.151.255.25565,534
153179.152.0.0/16179.152.0.1 to 179.152.255.254179.152.255.25565,534
154179.153.0.0/16179.153.0.1 to 179.153.255.254179.153.255.25565,534
155179.154.0.0/16179.154.0.1 to 179.154.255.254179.154.255.25565,534
156179.155.0.0/16179.155.0.1 to 179.155.255.254179.155.255.25565,534
157179.156.0.0/16179.156.0.1 to 179.156.255.254179.156.255.25565,534
158179.157.0.0/16179.157.0.1 to 179.157.255.254179.157.255.25565,534
159179.158.0.0/16179.158.0.1 to 179.158.255.254179.158.255.25565,534
160179.159.0.0/16179.159.0.1 to 179.159.255.254179.159.255.25565,534
161179.160.0.0/16179.160.0.1 to 179.160.255.254179.160.255.25565,534
162179.161.0.0/16179.161.0.1 to 179.161.255.254179.161.255.25565,534
163179.162.0.0/16179.162.0.1 to 179.162.255.254179.162.255.25565,534
164179.163.0.0/16179.163.0.1 to 179.163.255.254179.163.255.25565,534
165179.164.0.0/16179.164.0.1 to 179.164.255.254179.164.255.25565,534
166179.165.0.0/16179.165.0.1 to 179.165.255.254179.165.255.25565,534
167179.166.0.0/16179.166.0.1 to 179.166.255.254179.166.255.25565,534
168179.167.0.0/16179.167.0.1 to 179.167.255.254179.167.255.25565,534
169179.168.0.0/16179.168.0.1 to 179.168.255.254179.168.255.25565,534
170179.169.0.0/16179.169.0.1 to 179.169.255.254179.169.255.25565,534
171179.170.0.0/16179.170.0.1 to 179.170.255.254179.170.255.25565,534
172179.171.0.0/16179.171.0.1 to 179.171.255.254179.171.255.25565,534
173179.172.0.0/16179.172.0.1 to 179.172.255.254179.172.255.25565,534
174179.173.0.0/16179.173.0.1 to 179.173.255.254179.173.255.25565,534
175179.174.0.0/16179.174.0.1 to 179.174.255.254179.174.255.25565,534
176179.175.0.0/16179.175.0.1 to 179.175.255.254179.175.255.25565,534
177179.176.0.0/16179.176.0.1 to 179.176.255.254179.176.255.25565,534
178179.177.0.0/16179.177.0.1 to 179.177.255.254179.177.255.25565,534
179179.178.0.0/16179.178.0.1 to 179.178.255.254179.178.255.25565,534
180179.179.0.0/16179.179.0.1 to 179.179.255.254179.179.255.25565,534
181179.180.0.0/16179.180.0.1 to 179.180.255.254179.180.255.25565,534
182179.181.0.0/16179.181.0.1 to 179.181.255.254179.181.255.25565,534
183179.182.0.0/16179.182.0.1 to 179.182.255.254179.182.255.25565,534
184179.183.0.0/16179.183.0.1 to 179.183.255.254179.183.255.25565,534
185179.184.0.0/16179.184.0.1 to 179.184.255.254179.184.255.25565,534
186179.185.0.0/16179.185.0.1 to 179.185.255.254179.185.255.25565,534
187179.186.0.0/16179.186.0.1 to 179.186.255.254179.186.255.25565,534
188179.187.0.0/16179.187.0.1 to 179.187.255.254179.187.255.25565,534
189179.188.0.0/16179.188.0.1 to 179.188.255.254179.188.255.25565,534
190179.189.0.0/16179.189.0.1 to 179.189.255.254179.189.255.25565,534
191179.190.0.0/16179.190.0.1 to 179.190.255.254179.190.255.25565,534
192179.191.0.0/16179.191.0.1 to 179.191.255.254179.191.255.25565,534
193179.192.0.0/16179.192.0.1 to 179.192.255.254179.192.255.25565,534
194179.193.0.0/16179.193.0.1 to 179.193.255.254179.193.255.25565,534
195179.194.0.0/16179.194.0.1 to 179.194.255.254179.194.255.25565,534
196179.195.0.0/16179.195.0.1 to 179.195.255.254179.195.255.25565,534
197179.196.0.0/16179.196.0.1 to 179.196.255.254179.196.255.25565,534
198179.197.0.0/16179.197.0.1 to 179.197.255.254179.197.255.25565,534
199179.198.0.0/16179.198.0.1 to 179.198.255.254179.198.255.25565,534
200179.199.0.0/16179.199.0.1 to 179.199.255.254179.199.255.25565,534
201179.200.0.0/16179.200.0.1 to 179.200.255.254179.200.255.25565,534
202179.201.0.0/16179.201.0.1 to 179.201.255.254179.201.255.25565,534
203179.202.0.0/16179.202.0.1 to 179.202.255.254179.202.255.25565,534
204179.203.0.0/16179.203.0.1 to 179.203.255.254179.203.255.25565,534
205179.204.0.0/16179.204.0.1 to 179.204.255.254179.204.255.25565,534
206179.205.0.0/16179.205.0.1 to 179.205.255.254179.205.255.25565,534
207179.206.0.0/16179.206.0.1 to 179.206.255.254179.206.255.25565,534
208179.207.0.0/16179.207.0.1 to 179.207.255.254179.207.255.25565,534
209179.208.0.0/16179.208.0.1 to 179.208.255.254179.208.255.25565,534
210179.209.0.0/16179.209.0.1 to 179.209.255.254179.209.255.25565,534
211179.210.0.0/16179.210.0.1 to 179.210.255.254179.210.255.25565,534
212179.211.0.0/16179.211.0.1 to 179.211.255.254179.211.255.25565,534
213179.212.0.0/16179.212.0.1 to 179.212.255.254179.212.255.25565,534
214179.213.0.0/16179.213.0.1 to 179.213.255.254179.213.255.25565,534
215179.214.0.0/16179.214.0.1 to 179.214.255.254179.214.255.25565,534
216179.215.0.0/16179.215.0.1 to 179.215.255.254179.215.255.25565,534
217179.216.0.0/16179.216.0.1 to 179.216.255.254179.216.255.25565,534
218179.217.0.0/16179.217.0.1 to 179.217.255.254179.217.255.25565,534
219179.218.0.0/16179.218.0.1 to 179.218.255.254179.218.255.25565,534
220179.219.0.0/16179.219.0.1 to 179.219.255.254179.219.255.25565,534
221179.220.0.0/16179.220.0.1 to 179.220.255.254179.220.255.25565,534
222179.221.0.0/16179.221.0.1 to 179.221.255.254179.221.255.25565,534
223179.222.0.0/16179.222.0.1 to 179.222.255.254179.222.255.25565,534
224179.223.0.0/16179.223.0.1 to 179.223.255.254179.223.255.25565,534
225179.224.0.0/16179.224.0.1 to 179.224.255.254179.224.255.25565,534
226179.225.0.0/16179.225.0.1 to 179.225.255.254179.225.255.25565,534
227179.226.0.0/16179.226.0.1 to 179.226.255.254179.226.255.25565,534
228179.227.0.0/16179.227.0.1 to 179.227.255.254179.227.255.25565,534
229179.228.0.0/16179.228.0.1 to 179.228.255.254179.228.255.25565,534
230179.229.0.0/16179.229.0.1 to 179.229.255.254179.229.255.25565,534
231179.230.0.0/16179.230.0.1 to 179.230.255.254179.230.255.25565,534
232179.231.0.0/16179.231.0.1 to 179.231.255.254179.231.255.25565,534
233179.232.0.0/16179.232.0.1 to 179.232.255.254179.232.255.25565,534
234179.233.0.0/16179.233.0.1 to 179.233.255.254179.233.255.25565,534
235179.234.0.0/16179.234.0.1 to 179.234.255.254179.234.255.25565,534
236179.235.0.0/16179.235.0.1 to 179.235.255.254179.235.255.25565,534
237179.236.0.0/16179.236.0.1 to 179.236.255.254179.236.255.25565,534
238179.237.0.0/16179.237.0.1 to 179.237.255.254179.237.255.25565,534
239179.238.0.0/16179.238.0.1 to 179.238.255.254179.238.255.25565,534
240179.239.0.0/16179.239.0.1 to 179.239.255.254179.239.255.25565,534
241179.240.0.0/16179.240.0.1 to 179.240.255.254179.240.255.25565,534
242179.241.0.0/16179.241.0.1 to 179.241.255.254179.241.255.25565,534
243179.242.0.0/16179.242.0.1 to 179.242.255.254179.242.255.25565,534
244179.243.0.0/16179.243.0.1 to 179.243.255.254179.243.255.25565,534
245179.244.0.0/16179.244.0.1 to 179.244.255.254179.244.255.25565,534
246179.245.0.0/16179.245.0.1 to 179.245.255.254179.245.255.25565,534
247179.246.0.0/16179.246.0.1 to 179.246.255.254179.246.255.25565,534
248179.247.0.0/16179.247.0.1 to 179.247.255.254179.247.255.25565,534
249179.248.0.0/16179.248.0.1 to 179.248.255.254179.248.255.25565,534
250179.249.0.0/16179.249.0.1 to 179.249.255.254179.249.255.25565,534
251179.250.0.0/16179.250.0.1 to 179.250.255.254179.250.255.25565,534
252179.251.0.0/16179.251.0.1 to 179.251.255.254179.251.255.25565,534
253179.252.0.0/16179.252.0.1 to 179.252.255.254179.252.255.25565,534
254179.253.0.0/16179.253.0.1 to 179.253.255.254179.253.255.25565,534
255179.254.0.0/16179.254.0.1 to 179.254.255.254179.254.255.25565,534
256179.255.0.0/16179.255.0.1 to 179.255.255.254179.255.255.25565,534

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.