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.

Network150.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
150.0.0.0
Broadcast address
151.255.255.255
First usable
150.0.0.1
Last usable
151.255.255.254
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 96000000 · Integer 2516582400 to 2550136831
Reverse DNS zones
150.in-addr.arpa
151.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
Address10010110.00000000.00000000.00000000150.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10010110.00000000.00000000.00000000150.0.0.0
Broadcast10010111.11111111.11111111.11111111151.255.255.255
Split into smaller subnets/15
/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)

150.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1150.0.0.0/15150.0.0.1 to 150.1.255.254150.1.255.255131,070
2150.2.0.0/15150.2.0.1 to 150.3.255.254150.3.255.255131,070
3150.4.0.0/15150.4.0.1 to 150.5.255.254150.5.255.255131,070
4150.6.0.0/15150.6.0.1 to 150.7.255.254150.7.255.255131,070
5150.8.0.0/15150.8.0.1 to 150.9.255.254150.9.255.255131,070
6150.10.0.0/15150.10.0.1 to 150.11.255.254150.11.255.255131,070
7150.12.0.0/15150.12.0.1 to 150.13.255.254150.13.255.255131,070
8150.14.0.0/15150.14.0.1 to 150.15.255.254150.15.255.255131,070
9150.16.0.0/15150.16.0.1 to 150.17.255.254150.17.255.255131,070
10150.18.0.0/15150.18.0.1 to 150.19.255.254150.19.255.255131,070
11150.20.0.0/15150.20.0.1 to 150.21.255.254150.21.255.255131,070
12150.22.0.0/15150.22.0.1 to 150.23.255.254150.23.255.255131,070
13150.24.0.0/15150.24.0.1 to 150.25.255.254150.25.255.255131,070
14150.26.0.0/15150.26.0.1 to 150.27.255.254150.27.255.255131,070
15150.28.0.0/15150.28.0.1 to 150.29.255.254150.29.255.255131,070
16150.30.0.0/15150.30.0.1 to 150.31.255.254150.31.255.255131,070
17150.32.0.0/15150.32.0.1 to 150.33.255.254150.33.255.255131,070
18150.34.0.0/15150.34.0.1 to 150.35.255.254150.35.255.255131,070
19150.36.0.0/15150.36.0.1 to 150.37.255.254150.37.255.255131,070
20150.38.0.0/15150.38.0.1 to 150.39.255.254150.39.255.255131,070
21150.40.0.0/15150.40.0.1 to 150.41.255.254150.41.255.255131,070
22150.42.0.0/15150.42.0.1 to 150.43.255.254150.43.255.255131,070
23150.44.0.0/15150.44.0.1 to 150.45.255.254150.45.255.255131,070
24150.46.0.0/15150.46.0.1 to 150.47.255.254150.47.255.255131,070
25150.48.0.0/15150.48.0.1 to 150.49.255.254150.49.255.255131,070
26150.50.0.0/15150.50.0.1 to 150.51.255.254150.51.255.255131,070
27150.52.0.0/15150.52.0.1 to 150.53.255.254150.53.255.255131,070
28150.54.0.0/15150.54.0.1 to 150.55.255.254150.55.255.255131,070
29150.56.0.0/15150.56.0.1 to 150.57.255.254150.57.255.255131,070
30150.58.0.0/15150.58.0.1 to 150.59.255.254150.59.255.255131,070
31150.60.0.0/15150.60.0.1 to 150.61.255.254150.61.255.255131,070
32150.62.0.0/15150.62.0.1 to 150.63.255.254150.63.255.255131,070
33150.64.0.0/15150.64.0.1 to 150.65.255.254150.65.255.255131,070
34150.66.0.0/15150.66.0.1 to 150.67.255.254150.67.255.255131,070
35150.68.0.0/15150.68.0.1 to 150.69.255.254150.69.255.255131,070
36150.70.0.0/15150.70.0.1 to 150.71.255.254150.71.255.255131,070
37150.72.0.0/15150.72.0.1 to 150.73.255.254150.73.255.255131,070
38150.74.0.0/15150.74.0.1 to 150.75.255.254150.75.255.255131,070
39150.76.0.0/15150.76.0.1 to 150.77.255.254150.77.255.255131,070
40150.78.0.0/15150.78.0.1 to 150.79.255.254150.79.255.255131,070
41150.80.0.0/15150.80.0.1 to 150.81.255.254150.81.255.255131,070
42150.82.0.0/15150.82.0.1 to 150.83.255.254150.83.255.255131,070
43150.84.0.0/15150.84.0.1 to 150.85.255.254150.85.255.255131,070
44150.86.0.0/15150.86.0.1 to 150.87.255.254150.87.255.255131,070
45150.88.0.0/15150.88.0.1 to 150.89.255.254150.89.255.255131,070
46150.90.0.0/15150.90.0.1 to 150.91.255.254150.91.255.255131,070
47150.92.0.0/15150.92.0.1 to 150.93.255.254150.93.255.255131,070
48150.94.0.0/15150.94.0.1 to 150.95.255.254150.95.255.255131,070
49150.96.0.0/15150.96.0.1 to 150.97.255.254150.97.255.255131,070
50150.98.0.0/15150.98.0.1 to 150.99.255.254150.99.255.255131,070
51150.100.0.0/15150.100.0.1 to 150.101.255.254150.101.255.255131,070
52150.102.0.0/15150.102.0.1 to 150.103.255.254150.103.255.255131,070
53150.104.0.0/15150.104.0.1 to 150.105.255.254150.105.255.255131,070
54150.106.0.0/15150.106.0.1 to 150.107.255.254150.107.255.255131,070
55150.108.0.0/15150.108.0.1 to 150.109.255.254150.109.255.255131,070
56150.110.0.0/15150.110.0.1 to 150.111.255.254150.111.255.255131,070
57150.112.0.0/15150.112.0.1 to 150.113.255.254150.113.255.255131,070
58150.114.0.0/15150.114.0.1 to 150.115.255.254150.115.255.255131,070
59150.116.0.0/15150.116.0.1 to 150.117.255.254150.117.255.255131,070
60150.118.0.0/15150.118.0.1 to 150.119.255.254150.119.255.255131,070
61150.120.0.0/15150.120.0.1 to 150.121.255.254150.121.255.255131,070
62150.122.0.0/15150.122.0.1 to 150.123.255.254150.123.255.255131,070
63150.124.0.0/15150.124.0.1 to 150.125.255.254150.125.255.255131,070
64150.126.0.0/15150.126.0.1 to 150.127.255.254150.127.255.255131,070
65150.128.0.0/15150.128.0.1 to 150.129.255.254150.129.255.255131,070
66150.130.0.0/15150.130.0.1 to 150.131.255.254150.131.255.255131,070
67150.132.0.0/15150.132.0.1 to 150.133.255.254150.133.255.255131,070
68150.134.0.0/15150.134.0.1 to 150.135.255.254150.135.255.255131,070
69150.136.0.0/15150.136.0.1 to 150.137.255.254150.137.255.255131,070
70150.138.0.0/15150.138.0.1 to 150.139.255.254150.139.255.255131,070
71150.140.0.0/15150.140.0.1 to 150.141.255.254150.141.255.255131,070
72150.142.0.0/15150.142.0.1 to 150.143.255.254150.143.255.255131,070
73150.144.0.0/15150.144.0.1 to 150.145.255.254150.145.255.255131,070
74150.146.0.0/15150.146.0.1 to 150.147.255.254150.147.255.255131,070
75150.148.0.0/15150.148.0.1 to 150.149.255.254150.149.255.255131,070
76150.150.0.0/15150.150.0.1 to 150.151.255.254150.151.255.255131,070
77150.152.0.0/15150.152.0.1 to 150.153.255.254150.153.255.255131,070
78150.154.0.0/15150.154.0.1 to 150.155.255.254150.155.255.255131,070
79150.156.0.0/15150.156.0.1 to 150.157.255.254150.157.255.255131,070
80150.158.0.0/15150.158.0.1 to 150.159.255.254150.159.255.255131,070
81150.160.0.0/15150.160.0.1 to 150.161.255.254150.161.255.255131,070
82150.162.0.0/15150.162.0.1 to 150.163.255.254150.163.255.255131,070
83150.164.0.0/15150.164.0.1 to 150.165.255.254150.165.255.255131,070
84150.166.0.0/15150.166.0.1 to 150.167.255.254150.167.255.255131,070
85150.168.0.0/15150.168.0.1 to 150.169.255.254150.169.255.255131,070
86150.170.0.0/15150.170.0.1 to 150.171.255.254150.171.255.255131,070
87150.172.0.0/15150.172.0.1 to 150.173.255.254150.173.255.255131,070
88150.174.0.0/15150.174.0.1 to 150.175.255.254150.175.255.255131,070
89150.176.0.0/15150.176.0.1 to 150.177.255.254150.177.255.255131,070
90150.178.0.0/15150.178.0.1 to 150.179.255.254150.179.255.255131,070
91150.180.0.0/15150.180.0.1 to 150.181.255.254150.181.255.255131,070
92150.182.0.0/15150.182.0.1 to 150.183.255.254150.183.255.255131,070
93150.184.0.0/15150.184.0.1 to 150.185.255.254150.185.255.255131,070
94150.186.0.0/15150.186.0.1 to 150.187.255.254150.187.255.255131,070
95150.188.0.0/15150.188.0.1 to 150.189.255.254150.189.255.255131,070
96150.190.0.0/15150.190.0.1 to 150.191.255.254150.191.255.255131,070
97150.192.0.0/15150.192.0.1 to 150.193.255.254150.193.255.255131,070
98150.194.0.0/15150.194.0.1 to 150.195.255.254150.195.255.255131,070
99150.196.0.0/15150.196.0.1 to 150.197.255.254150.197.255.255131,070
100150.198.0.0/15150.198.0.1 to 150.199.255.254150.199.255.255131,070
101150.200.0.0/15150.200.0.1 to 150.201.255.254150.201.255.255131,070
102150.202.0.0/15150.202.0.1 to 150.203.255.254150.203.255.255131,070
103150.204.0.0/15150.204.0.1 to 150.205.255.254150.205.255.255131,070
104150.206.0.0/15150.206.0.1 to 150.207.255.254150.207.255.255131,070
105150.208.0.0/15150.208.0.1 to 150.209.255.254150.209.255.255131,070
106150.210.0.0/15150.210.0.1 to 150.211.255.254150.211.255.255131,070
107150.212.0.0/15150.212.0.1 to 150.213.255.254150.213.255.255131,070
108150.214.0.0/15150.214.0.1 to 150.215.255.254150.215.255.255131,070
109150.216.0.0/15150.216.0.1 to 150.217.255.254150.217.255.255131,070
110150.218.0.0/15150.218.0.1 to 150.219.255.254150.219.255.255131,070
111150.220.0.0/15150.220.0.1 to 150.221.255.254150.221.255.255131,070
112150.222.0.0/15150.222.0.1 to 150.223.255.254150.223.255.255131,070
113150.224.0.0/15150.224.0.1 to 150.225.255.254150.225.255.255131,070
114150.226.0.0/15150.226.0.1 to 150.227.255.254150.227.255.255131,070
115150.228.0.0/15150.228.0.1 to 150.229.255.254150.229.255.255131,070
116150.230.0.0/15150.230.0.1 to 150.231.255.254150.231.255.255131,070
117150.232.0.0/15150.232.0.1 to 150.233.255.254150.233.255.255131,070
118150.234.0.0/15150.234.0.1 to 150.235.255.254150.235.255.255131,070
119150.236.0.0/15150.236.0.1 to 150.237.255.254150.237.255.255131,070
120150.238.0.0/15150.238.0.1 to 150.239.255.254150.239.255.255131,070
121150.240.0.0/15150.240.0.1 to 150.241.255.254150.241.255.255131,070
122150.242.0.0/15150.242.0.1 to 150.243.255.254150.243.255.255131,070
123150.244.0.0/15150.244.0.1 to 150.245.255.254150.245.255.255131,070
124150.246.0.0/15150.246.0.1 to 150.247.255.254150.247.255.255131,070
125150.248.0.0/15150.248.0.1 to 150.249.255.254150.249.255.255131,070
126150.250.0.0/15150.250.0.1 to 150.251.255.254150.251.255.255131,070
127150.252.0.0/15150.252.0.1 to 150.253.255.254150.253.255.255131,070
128150.254.0.0/15150.254.0.1 to 150.255.255.254150.255.255.255131,070
129151.0.0.0/15151.0.0.1 to 151.1.255.254151.1.255.255131,070
130151.2.0.0/15151.2.0.1 to 151.3.255.254151.3.255.255131,070
131151.4.0.0/15151.4.0.1 to 151.5.255.254151.5.255.255131,070
132151.6.0.0/15151.6.0.1 to 151.7.255.254151.7.255.255131,070
133151.8.0.0/15151.8.0.1 to 151.9.255.254151.9.255.255131,070
134151.10.0.0/15151.10.0.1 to 151.11.255.254151.11.255.255131,070
135151.12.0.0/15151.12.0.1 to 151.13.255.254151.13.255.255131,070
136151.14.0.0/15151.14.0.1 to 151.15.255.254151.15.255.255131,070
137151.16.0.0/15151.16.0.1 to 151.17.255.254151.17.255.255131,070
138151.18.0.0/15151.18.0.1 to 151.19.255.254151.19.255.255131,070
139151.20.0.0/15151.20.0.1 to 151.21.255.254151.21.255.255131,070
140151.22.0.0/15151.22.0.1 to 151.23.255.254151.23.255.255131,070
141151.24.0.0/15151.24.0.1 to 151.25.255.254151.25.255.255131,070
142151.26.0.0/15151.26.0.1 to 151.27.255.254151.27.255.255131,070
143151.28.0.0/15151.28.0.1 to 151.29.255.254151.29.255.255131,070
144151.30.0.0/15151.30.0.1 to 151.31.255.254151.31.255.255131,070
145151.32.0.0/15151.32.0.1 to 151.33.255.254151.33.255.255131,070
146151.34.0.0/15151.34.0.1 to 151.35.255.254151.35.255.255131,070
147151.36.0.0/15151.36.0.1 to 151.37.255.254151.37.255.255131,070
148151.38.0.0/15151.38.0.1 to 151.39.255.254151.39.255.255131,070
149151.40.0.0/15151.40.0.1 to 151.41.255.254151.41.255.255131,070
150151.42.0.0/15151.42.0.1 to 151.43.255.254151.43.255.255131,070
151151.44.0.0/15151.44.0.1 to 151.45.255.254151.45.255.255131,070
152151.46.0.0/15151.46.0.1 to 151.47.255.254151.47.255.255131,070
153151.48.0.0/15151.48.0.1 to 151.49.255.254151.49.255.255131,070
154151.50.0.0/15151.50.0.1 to 151.51.255.254151.51.255.255131,070
155151.52.0.0/15151.52.0.1 to 151.53.255.254151.53.255.255131,070
156151.54.0.0/15151.54.0.1 to 151.55.255.254151.55.255.255131,070
157151.56.0.0/15151.56.0.1 to 151.57.255.254151.57.255.255131,070
158151.58.0.0/15151.58.0.1 to 151.59.255.254151.59.255.255131,070
159151.60.0.0/15151.60.0.1 to 151.61.255.254151.61.255.255131,070
160151.62.0.0/15151.62.0.1 to 151.63.255.254151.63.255.255131,070
161151.64.0.0/15151.64.0.1 to 151.65.255.254151.65.255.255131,070
162151.66.0.0/15151.66.0.1 to 151.67.255.254151.67.255.255131,070
163151.68.0.0/15151.68.0.1 to 151.69.255.254151.69.255.255131,070
164151.70.0.0/15151.70.0.1 to 151.71.255.254151.71.255.255131,070
165151.72.0.0/15151.72.0.1 to 151.73.255.254151.73.255.255131,070
166151.74.0.0/15151.74.0.1 to 151.75.255.254151.75.255.255131,070
167151.76.0.0/15151.76.0.1 to 151.77.255.254151.77.255.255131,070
168151.78.0.0/15151.78.0.1 to 151.79.255.254151.79.255.255131,070
169151.80.0.0/15151.80.0.1 to 151.81.255.254151.81.255.255131,070
170151.82.0.0/15151.82.0.1 to 151.83.255.254151.83.255.255131,070
171151.84.0.0/15151.84.0.1 to 151.85.255.254151.85.255.255131,070
172151.86.0.0/15151.86.0.1 to 151.87.255.254151.87.255.255131,070
173151.88.0.0/15151.88.0.1 to 151.89.255.254151.89.255.255131,070
174151.90.0.0/15151.90.0.1 to 151.91.255.254151.91.255.255131,070
175151.92.0.0/15151.92.0.1 to 151.93.255.254151.93.255.255131,070
176151.94.0.0/15151.94.0.1 to 151.95.255.254151.95.255.255131,070
177151.96.0.0/15151.96.0.1 to 151.97.255.254151.97.255.255131,070
178151.98.0.0/15151.98.0.1 to 151.99.255.254151.99.255.255131,070
179151.100.0.0/15151.100.0.1 to 151.101.255.254151.101.255.255131,070
180151.102.0.0/15151.102.0.1 to 151.103.255.254151.103.255.255131,070
181151.104.0.0/15151.104.0.1 to 151.105.255.254151.105.255.255131,070
182151.106.0.0/15151.106.0.1 to 151.107.255.254151.107.255.255131,070
183151.108.0.0/15151.108.0.1 to 151.109.255.254151.109.255.255131,070
184151.110.0.0/15151.110.0.1 to 151.111.255.254151.111.255.255131,070
185151.112.0.0/15151.112.0.1 to 151.113.255.254151.113.255.255131,070
186151.114.0.0/15151.114.0.1 to 151.115.255.254151.115.255.255131,070
187151.116.0.0/15151.116.0.1 to 151.117.255.254151.117.255.255131,070
188151.118.0.0/15151.118.0.1 to 151.119.255.254151.119.255.255131,070
189151.120.0.0/15151.120.0.1 to 151.121.255.254151.121.255.255131,070
190151.122.0.0/15151.122.0.1 to 151.123.255.254151.123.255.255131,070
191151.124.0.0/15151.124.0.1 to 151.125.255.254151.125.255.255131,070
192151.126.0.0/15151.126.0.1 to 151.127.255.254151.127.255.255131,070
193151.128.0.0/15151.128.0.1 to 151.129.255.254151.129.255.255131,070
194151.130.0.0/15151.130.0.1 to 151.131.255.254151.131.255.255131,070
195151.132.0.0/15151.132.0.1 to 151.133.255.254151.133.255.255131,070
196151.134.0.0/15151.134.0.1 to 151.135.255.254151.135.255.255131,070
197151.136.0.0/15151.136.0.1 to 151.137.255.254151.137.255.255131,070
198151.138.0.0/15151.138.0.1 to 151.139.255.254151.139.255.255131,070
199151.140.0.0/15151.140.0.1 to 151.141.255.254151.141.255.255131,070
200151.142.0.0/15151.142.0.1 to 151.143.255.254151.143.255.255131,070
201151.144.0.0/15151.144.0.1 to 151.145.255.254151.145.255.255131,070
202151.146.0.0/15151.146.0.1 to 151.147.255.254151.147.255.255131,070
203151.148.0.0/15151.148.0.1 to 151.149.255.254151.149.255.255131,070
204151.150.0.0/15151.150.0.1 to 151.151.255.254151.151.255.255131,070
205151.152.0.0/15151.152.0.1 to 151.153.255.254151.153.255.255131,070
206151.154.0.0/15151.154.0.1 to 151.155.255.254151.155.255.255131,070
207151.156.0.0/15151.156.0.1 to 151.157.255.254151.157.255.255131,070
208151.158.0.0/15151.158.0.1 to 151.159.255.254151.159.255.255131,070
209151.160.0.0/15151.160.0.1 to 151.161.255.254151.161.255.255131,070
210151.162.0.0/15151.162.0.1 to 151.163.255.254151.163.255.255131,070
211151.164.0.0/15151.164.0.1 to 151.165.255.254151.165.255.255131,070
212151.166.0.0/15151.166.0.1 to 151.167.255.254151.167.255.255131,070
213151.168.0.0/15151.168.0.1 to 151.169.255.254151.169.255.255131,070
214151.170.0.0/15151.170.0.1 to 151.171.255.254151.171.255.255131,070
215151.172.0.0/15151.172.0.1 to 151.173.255.254151.173.255.255131,070
216151.174.0.0/15151.174.0.1 to 151.175.255.254151.175.255.255131,070
217151.176.0.0/15151.176.0.1 to 151.177.255.254151.177.255.255131,070
218151.178.0.0/15151.178.0.1 to 151.179.255.254151.179.255.255131,070
219151.180.0.0/15151.180.0.1 to 151.181.255.254151.181.255.255131,070
220151.182.0.0/15151.182.0.1 to 151.183.255.254151.183.255.255131,070
221151.184.0.0/15151.184.0.1 to 151.185.255.254151.185.255.255131,070
222151.186.0.0/15151.186.0.1 to 151.187.255.254151.187.255.255131,070
223151.188.0.0/15151.188.0.1 to 151.189.255.254151.189.255.255131,070
224151.190.0.0/15151.190.0.1 to 151.191.255.254151.191.255.255131,070
225151.192.0.0/15151.192.0.1 to 151.193.255.254151.193.255.255131,070
226151.194.0.0/15151.194.0.1 to 151.195.255.254151.195.255.255131,070
227151.196.0.0/15151.196.0.1 to 151.197.255.254151.197.255.255131,070
228151.198.0.0/15151.198.0.1 to 151.199.255.254151.199.255.255131,070
229151.200.0.0/15151.200.0.1 to 151.201.255.254151.201.255.255131,070
230151.202.0.0/15151.202.0.1 to 151.203.255.254151.203.255.255131,070
231151.204.0.0/15151.204.0.1 to 151.205.255.254151.205.255.255131,070
232151.206.0.0/15151.206.0.1 to 151.207.255.254151.207.255.255131,070
233151.208.0.0/15151.208.0.1 to 151.209.255.254151.209.255.255131,070
234151.210.0.0/15151.210.0.1 to 151.211.255.254151.211.255.255131,070
235151.212.0.0/15151.212.0.1 to 151.213.255.254151.213.255.255131,070
236151.214.0.0/15151.214.0.1 to 151.215.255.254151.215.255.255131,070
237151.216.0.0/15151.216.0.1 to 151.217.255.254151.217.255.255131,070
238151.218.0.0/15151.218.0.1 to 151.219.255.254151.219.255.255131,070
239151.220.0.0/15151.220.0.1 to 151.221.255.254151.221.255.255131,070
240151.222.0.0/15151.222.0.1 to 151.223.255.254151.223.255.255131,070
241151.224.0.0/15151.224.0.1 to 151.225.255.254151.225.255.255131,070
242151.226.0.0/15151.226.0.1 to 151.227.255.254151.227.255.255131,070
243151.228.0.0/15151.228.0.1 to 151.229.255.254151.229.255.255131,070
244151.230.0.0/15151.230.0.1 to 151.231.255.254151.231.255.255131,070
245151.232.0.0/15151.232.0.1 to 151.233.255.254151.233.255.255131,070
246151.234.0.0/15151.234.0.1 to 151.235.255.254151.235.255.255131,070
247151.236.0.0/15151.236.0.1 to 151.237.255.254151.237.255.255131,070
248151.238.0.0/15151.238.0.1 to 151.239.255.254151.239.255.255131,070
249151.240.0.0/15151.240.0.1 to 151.241.255.254151.241.255.255131,070
250151.242.0.0/15151.242.0.1 to 151.243.255.254151.243.255.255131,070
251151.244.0.0/15151.244.0.1 to 151.245.255.254151.245.255.255131,070
252151.246.0.0/15151.246.0.1 to 151.247.255.254151.247.255.255131,070
253151.248.0.0/15151.248.0.1 to 151.249.255.254151.249.255.255131,070
254151.250.0.0/15151.250.0.1 to 151.251.255.254151.251.255.255131,070
255151.252.0.0/15151.252.0.1 to 151.253.255.254151.253.255.255131,070
256151.254.0.0/15151.254.0.1 to 151.255.255.254151.255.255.255131,070

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.