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.

Network218.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
218.0.0.0
Broadcast address
219.255.255.255
First usable
218.0.0.1
Last usable
219.255.255.254
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
C (default /24)
As numbers
Hex DA000000 · Integer 3657433088 to 3690987519
Reverse DNS zones
218.in-addr.arpa
219.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
Address11011010.00000000.00000000.00000000218.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11011010.00000000.00000000.00000000218.0.0.0
Broadcast11011011.11111111.11111111.11111111219.255.255.255
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)

218.0.0.0/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1218.0.0.0/16218.0.0.1 to 218.0.255.254218.0.255.25565,534
2218.1.0.0/16218.1.0.1 to 218.1.255.254218.1.255.25565,534
3218.2.0.0/16218.2.0.1 to 218.2.255.254218.2.255.25565,534
4218.3.0.0/16218.3.0.1 to 218.3.255.254218.3.255.25565,534
5218.4.0.0/16218.4.0.1 to 218.4.255.254218.4.255.25565,534
6218.5.0.0/16218.5.0.1 to 218.5.255.254218.5.255.25565,534
7218.6.0.0/16218.6.0.1 to 218.6.255.254218.6.255.25565,534
8218.7.0.0/16218.7.0.1 to 218.7.255.254218.7.255.25565,534
9218.8.0.0/16218.8.0.1 to 218.8.255.254218.8.255.25565,534
10218.9.0.0/16218.9.0.1 to 218.9.255.254218.9.255.25565,534
11218.10.0.0/16218.10.0.1 to 218.10.255.254218.10.255.25565,534
12218.11.0.0/16218.11.0.1 to 218.11.255.254218.11.255.25565,534
13218.12.0.0/16218.12.0.1 to 218.12.255.254218.12.255.25565,534
14218.13.0.0/16218.13.0.1 to 218.13.255.254218.13.255.25565,534
15218.14.0.0/16218.14.0.1 to 218.14.255.254218.14.255.25565,534
16218.15.0.0/16218.15.0.1 to 218.15.255.254218.15.255.25565,534
17218.16.0.0/16218.16.0.1 to 218.16.255.254218.16.255.25565,534
18218.17.0.0/16218.17.0.1 to 218.17.255.254218.17.255.25565,534
19218.18.0.0/16218.18.0.1 to 218.18.255.254218.18.255.25565,534
20218.19.0.0/16218.19.0.1 to 218.19.255.254218.19.255.25565,534
21218.20.0.0/16218.20.0.1 to 218.20.255.254218.20.255.25565,534
22218.21.0.0/16218.21.0.1 to 218.21.255.254218.21.255.25565,534
23218.22.0.0/16218.22.0.1 to 218.22.255.254218.22.255.25565,534
24218.23.0.0/16218.23.0.1 to 218.23.255.254218.23.255.25565,534
25218.24.0.0/16218.24.0.1 to 218.24.255.254218.24.255.25565,534
26218.25.0.0/16218.25.0.1 to 218.25.255.254218.25.255.25565,534
27218.26.0.0/16218.26.0.1 to 218.26.255.254218.26.255.25565,534
28218.27.0.0/16218.27.0.1 to 218.27.255.254218.27.255.25565,534
29218.28.0.0/16218.28.0.1 to 218.28.255.254218.28.255.25565,534
30218.29.0.0/16218.29.0.1 to 218.29.255.254218.29.255.25565,534
31218.30.0.0/16218.30.0.1 to 218.30.255.254218.30.255.25565,534
32218.31.0.0/16218.31.0.1 to 218.31.255.254218.31.255.25565,534
33218.32.0.0/16218.32.0.1 to 218.32.255.254218.32.255.25565,534
34218.33.0.0/16218.33.0.1 to 218.33.255.254218.33.255.25565,534
35218.34.0.0/16218.34.0.1 to 218.34.255.254218.34.255.25565,534
36218.35.0.0/16218.35.0.1 to 218.35.255.254218.35.255.25565,534
37218.36.0.0/16218.36.0.1 to 218.36.255.254218.36.255.25565,534
38218.37.0.0/16218.37.0.1 to 218.37.255.254218.37.255.25565,534
39218.38.0.0/16218.38.0.1 to 218.38.255.254218.38.255.25565,534
40218.39.0.0/16218.39.0.1 to 218.39.255.254218.39.255.25565,534
41218.40.0.0/16218.40.0.1 to 218.40.255.254218.40.255.25565,534
42218.41.0.0/16218.41.0.1 to 218.41.255.254218.41.255.25565,534
43218.42.0.0/16218.42.0.1 to 218.42.255.254218.42.255.25565,534
44218.43.0.0/16218.43.0.1 to 218.43.255.254218.43.255.25565,534
45218.44.0.0/16218.44.0.1 to 218.44.255.254218.44.255.25565,534
46218.45.0.0/16218.45.0.1 to 218.45.255.254218.45.255.25565,534
47218.46.0.0/16218.46.0.1 to 218.46.255.254218.46.255.25565,534
48218.47.0.0/16218.47.0.1 to 218.47.255.254218.47.255.25565,534
49218.48.0.0/16218.48.0.1 to 218.48.255.254218.48.255.25565,534
50218.49.0.0/16218.49.0.1 to 218.49.255.254218.49.255.25565,534
51218.50.0.0/16218.50.0.1 to 218.50.255.254218.50.255.25565,534
52218.51.0.0/16218.51.0.1 to 218.51.255.254218.51.255.25565,534
53218.52.0.0/16218.52.0.1 to 218.52.255.254218.52.255.25565,534
54218.53.0.0/16218.53.0.1 to 218.53.255.254218.53.255.25565,534
55218.54.0.0/16218.54.0.1 to 218.54.255.254218.54.255.25565,534
56218.55.0.0/16218.55.0.1 to 218.55.255.254218.55.255.25565,534
57218.56.0.0/16218.56.0.1 to 218.56.255.254218.56.255.25565,534
58218.57.0.0/16218.57.0.1 to 218.57.255.254218.57.255.25565,534
59218.58.0.0/16218.58.0.1 to 218.58.255.254218.58.255.25565,534
60218.59.0.0/16218.59.0.1 to 218.59.255.254218.59.255.25565,534
61218.60.0.0/16218.60.0.1 to 218.60.255.254218.60.255.25565,534
62218.61.0.0/16218.61.0.1 to 218.61.255.254218.61.255.25565,534
63218.62.0.0/16218.62.0.1 to 218.62.255.254218.62.255.25565,534
64218.63.0.0/16218.63.0.1 to 218.63.255.254218.63.255.25565,534
65218.64.0.0/16218.64.0.1 to 218.64.255.254218.64.255.25565,534
66218.65.0.0/16218.65.0.1 to 218.65.255.254218.65.255.25565,534
67218.66.0.0/16218.66.0.1 to 218.66.255.254218.66.255.25565,534
68218.67.0.0/16218.67.0.1 to 218.67.255.254218.67.255.25565,534
69218.68.0.0/16218.68.0.1 to 218.68.255.254218.68.255.25565,534
70218.69.0.0/16218.69.0.1 to 218.69.255.254218.69.255.25565,534
71218.70.0.0/16218.70.0.1 to 218.70.255.254218.70.255.25565,534
72218.71.0.0/16218.71.0.1 to 218.71.255.254218.71.255.25565,534
73218.72.0.0/16218.72.0.1 to 218.72.255.254218.72.255.25565,534
74218.73.0.0/16218.73.0.1 to 218.73.255.254218.73.255.25565,534
75218.74.0.0/16218.74.0.1 to 218.74.255.254218.74.255.25565,534
76218.75.0.0/16218.75.0.1 to 218.75.255.254218.75.255.25565,534
77218.76.0.0/16218.76.0.1 to 218.76.255.254218.76.255.25565,534
78218.77.0.0/16218.77.0.1 to 218.77.255.254218.77.255.25565,534
79218.78.0.0/16218.78.0.1 to 218.78.255.254218.78.255.25565,534
80218.79.0.0/16218.79.0.1 to 218.79.255.254218.79.255.25565,534
81218.80.0.0/16218.80.0.1 to 218.80.255.254218.80.255.25565,534
82218.81.0.0/16218.81.0.1 to 218.81.255.254218.81.255.25565,534
83218.82.0.0/16218.82.0.1 to 218.82.255.254218.82.255.25565,534
84218.83.0.0/16218.83.0.1 to 218.83.255.254218.83.255.25565,534
85218.84.0.0/16218.84.0.1 to 218.84.255.254218.84.255.25565,534
86218.85.0.0/16218.85.0.1 to 218.85.255.254218.85.255.25565,534
87218.86.0.0/16218.86.0.1 to 218.86.255.254218.86.255.25565,534
88218.87.0.0/16218.87.0.1 to 218.87.255.254218.87.255.25565,534
89218.88.0.0/16218.88.0.1 to 218.88.255.254218.88.255.25565,534
90218.89.0.0/16218.89.0.1 to 218.89.255.254218.89.255.25565,534
91218.90.0.0/16218.90.0.1 to 218.90.255.254218.90.255.25565,534
92218.91.0.0/16218.91.0.1 to 218.91.255.254218.91.255.25565,534
93218.92.0.0/16218.92.0.1 to 218.92.255.254218.92.255.25565,534
94218.93.0.0/16218.93.0.1 to 218.93.255.254218.93.255.25565,534
95218.94.0.0/16218.94.0.1 to 218.94.255.254218.94.255.25565,534
96218.95.0.0/16218.95.0.1 to 218.95.255.254218.95.255.25565,534
97218.96.0.0/16218.96.0.1 to 218.96.255.254218.96.255.25565,534
98218.97.0.0/16218.97.0.1 to 218.97.255.254218.97.255.25565,534
99218.98.0.0/16218.98.0.1 to 218.98.255.254218.98.255.25565,534
100218.99.0.0/16218.99.0.1 to 218.99.255.254218.99.255.25565,534
101218.100.0.0/16218.100.0.1 to 218.100.255.254218.100.255.25565,534
102218.101.0.0/16218.101.0.1 to 218.101.255.254218.101.255.25565,534
103218.102.0.0/16218.102.0.1 to 218.102.255.254218.102.255.25565,534
104218.103.0.0/16218.103.0.1 to 218.103.255.254218.103.255.25565,534
105218.104.0.0/16218.104.0.1 to 218.104.255.254218.104.255.25565,534
106218.105.0.0/16218.105.0.1 to 218.105.255.254218.105.255.25565,534
107218.106.0.0/16218.106.0.1 to 218.106.255.254218.106.255.25565,534
108218.107.0.0/16218.107.0.1 to 218.107.255.254218.107.255.25565,534
109218.108.0.0/16218.108.0.1 to 218.108.255.254218.108.255.25565,534
110218.109.0.0/16218.109.0.1 to 218.109.255.254218.109.255.25565,534
111218.110.0.0/16218.110.0.1 to 218.110.255.254218.110.255.25565,534
112218.111.0.0/16218.111.0.1 to 218.111.255.254218.111.255.25565,534
113218.112.0.0/16218.112.0.1 to 218.112.255.254218.112.255.25565,534
114218.113.0.0/16218.113.0.1 to 218.113.255.254218.113.255.25565,534
115218.114.0.0/16218.114.0.1 to 218.114.255.254218.114.255.25565,534
116218.115.0.0/16218.115.0.1 to 218.115.255.254218.115.255.25565,534
117218.116.0.0/16218.116.0.1 to 218.116.255.254218.116.255.25565,534
118218.117.0.0/16218.117.0.1 to 218.117.255.254218.117.255.25565,534
119218.118.0.0/16218.118.0.1 to 218.118.255.254218.118.255.25565,534
120218.119.0.0/16218.119.0.1 to 218.119.255.254218.119.255.25565,534
121218.120.0.0/16218.120.0.1 to 218.120.255.254218.120.255.25565,534
122218.121.0.0/16218.121.0.1 to 218.121.255.254218.121.255.25565,534
123218.122.0.0/16218.122.0.1 to 218.122.255.254218.122.255.25565,534
124218.123.0.0/16218.123.0.1 to 218.123.255.254218.123.255.25565,534
125218.124.0.0/16218.124.0.1 to 218.124.255.254218.124.255.25565,534
126218.125.0.0/16218.125.0.1 to 218.125.255.254218.125.255.25565,534
127218.126.0.0/16218.126.0.1 to 218.126.255.254218.126.255.25565,534
128218.127.0.0/16218.127.0.1 to 218.127.255.254218.127.255.25565,534
129218.128.0.0/16218.128.0.1 to 218.128.255.254218.128.255.25565,534
130218.129.0.0/16218.129.0.1 to 218.129.255.254218.129.255.25565,534
131218.130.0.0/16218.130.0.1 to 218.130.255.254218.130.255.25565,534
132218.131.0.0/16218.131.0.1 to 218.131.255.254218.131.255.25565,534
133218.132.0.0/16218.132.0.1 to 218.132.255.254218.132.255.25565,534
134218.133.0.0/16218.133.0.1 to 218.133.255.254218.133.255.25565,534
135218.134.0.0/16218.134.0.1 to 218.134.255.254218.134.255.25565,534
136218.135.0.0/16218.135.0.1 to 218.135.255.254218.135.255.25565,534
137218.136.0.0/16218.136.0.1 to 218.136.255.254218.136.255.25565,534
138218.137.0.0/16218.137.0.1 to 218.137.255.254218.137.255.25565,534
139218.138.0.0/16218.138.0.1 to 218.138.255.254218.138.255.25565,534
140218.139.0.0/16218.139.0.1 to 218.139.255.254218.139.255.25565,534
141218.140.0.0/16218.140.0.1 to 218.140.255.254218.140.255.25565,534
142218.141.0.0/16218.141.0.1 to 218.141.255.254218.141.255.25565,534
143218.142.0.0/16218.142.0.1 to 218.142.255.254218.142.255.25565,534
144218.143.0.0/16218.143.0.1 to 218.143.255.254218.143.255.25565,534
145218.144.0.0/16218.144.0.1 to 218.144.255.254218.144.255.25565,534
146218.145.0.0/16218.145.0.1 to 218.145.255.254218.145.255.25565,534
147218.146.0.0/16218.146.0.1 to 218.146.255.254218.146.255.25565,534
148218.147.0.0/16218.147.0.1 to 218.147.255.254218.147.255.25565,534
149218.148.0.0/16218.148.0.1 to 218.148.255.254218.148.255.25565,534
150218.149.0.0/16218.149.0.1 to 218.149.255.254218.149.255.25565,534
151218.150.0.0/16218.150.0.1 to 218.150.255.254218.150.255.25565,534
152218.151.0.0/16218.151.0.1 to 218.151.255.254218.151.255.25565,534
153218.152.0.0/16218.152.0.1 to 218.152.255.254218.152.255.25565,534
154218.153.0.0/16218.153.0.1 to 218.153.255.254218.153.255.25565,534
155218.154.0.0/16218.154.0.1 to 218.154.255.254218.154.255.25565,534
156218.155.0.0/16218.155.0.1 to 218.155.255.254218.155.255.25565,534
157218.156.0.0/16218.156.0.1 to 218.156.255.254218.156.255.25565,534
158218.157.0.0/16218.157.0.1 to 218.157.255.254218.157.255.25565,534
159218.158.0.0/16218.158.0.1 to 218.158.255.254218.158.255.25565,534
160218.159.0.0/16218.159.0.1 to 218.159.255.254218.159.255.25565,534
161218.160.0.0/16218.160.0.1 to 218.160.255.254218.160.255.25565,534
162218.161.0.0/16218.161.0.1 to 218.161.255.254218.161.255.25565,534
163218.162.0.0/16218.162.0.1 to 218.162.255.254218.162.255.25565,534
164218.163.0.0/16218.163.0.1 to 218.163.255.254218.163.255.25565,534
165218.164.0.0/16218.164.0.1 to 218.164.255.254218.164.255.25565,534
166218.165.0.0/16218.165.0.1 to 218.165.255.254218.165.255.25565,534
167218.166.0.0/16218.166.0.1 to 218.166.255.254218.166.255.25565,534
168218.167.0.0/16218.167.0.1 to 218.167.255.254218.167.255.25565,534
169218.168.0.0/16218.168.0.1 to 218.168.255.254218.168.255.25565,534
170218.169.0.0/16218.169.0.1 to 218.169.255.254218.169.255.25565,534
171218.170.0.0/16218.170.0.1 to 218.170.255.254218.170.255.25565,534
172218.171.0.0/16218.171.0.1 to 218.171.255.254218.171.255.25565,534
173218.172.0.0/16218.172.0.1 to 218.172.255.254218.172.255.25565,534
174218.173.0.0/16218.173.0.1 to 218.173.255.254218.173.255.25565,534
175218.174.0.0/16218.174.0.1 to 218.174.255.254218.174.255.25565,534
176218.175.0.0/16218.175.0.1 to 218.175.255.254218.175.255.25565,534
177218.176.0.0/16218.176.0.1 to 218.176.255.254218.176.255.25565,534
178218.177.0.0/16218.177.0.1 to 218.177.255.254218.177.255.25565,534
179218.178.0.0/16218.178.0.1 to 218.178.255.254218.178.255.25565,534
180218.179.0.0/16218.179.0.1 to 218.179.255.254218.179.255.25565,534
181218.180.0.0/16218.180.0.1 to 218.180.255.254218.180.255.25565,534
182218.181.0.0/16218.181.0.1 to 218.181.255.254218.181.255.25565,534
183218.182.0.0/16218.182.0.1 to 218.182.255.254218.182.255.25565,534
184218.183.0.0/16218.183.0.1 to 218.183.255.254218.183.255.25565,534
185218.184.0.0/16218.184.0.1 to 218.184.255.254218.184.255.25565,534
186218.185.0.0/16218.185.0.1 to 218.185.255.254218.185.255.25565,534
187218.186.0.0/16218.186.0.1 to 218.186.255.254218.186.255.25565,534
188218.187.0.0/16218.187.0.1 to 218.187.255.254218.187.255.25565,534
189218.188.0.0/16218.188.0.1 to 218.188.255.254218.188.255.25565,534
190218.189.0.0/16218.189.0.1 to 218.189.255.254218.189.255.25565,534
191218.190.0.0/16218.190.0.1 to 218.190.255.254218.190.255.25565,534
192218.191.0.0/16218.191.0.1 to 218.191.255.254218.191.255.25565,534
193218.192.0.0/16218.192.0.1 to 218.192.255.254218.192.255.25565,534
194218.193.0.0/16218.193.0.1 to 218.193.255.254218.193.255.25565,534
195218.194.0.0/16218.194.0.1 to 218.194.255.254218.194.255.25565,534
196218.195.0.0/16218.195.0.1 to 218.195.255.254218.195.255.25565,534
197218.196.0.0/16218.196.0.1 to 218.196.255.254218.196.255.25565,534
198218.197.0.0/16218.197.0.1 to 218.197.255.254218.197.255.25565,534
199218.198.0.0/16218.198.0.1 to 218.198.255.254218.198.255.25565,534
200218.199.0.0/16218.199.0.1 to 218.199.255.254218.199.255.25565,534
201218.200.0.0/16218.200.0.1 to 218.200.255.254218.200.255.25565,534
202218.201.0.0/16218.201.0.1 to 218.201.255.254218.201.255.25565,534
203218.202.0.0/16218.202.0.1 to 218.202.255.254218.202.255.25565,534
204218.203.0.0/16218.203.0.1 to 218.203.255.254218.203.255.25565,534
205218.204.0.0/16218.204.0.1 to 218.204.255.254218.204.255.25565,534
206218.205.0.0/16218.205.0.1 to 218.205.255.254218.205.255.25565,534
207218.206.0.0/16218.206.0.1 to 218.206.255.254218.206.255.25565,534
208218.207.0.0/16218.207.0.1 to 218.207.255.254218.207.255.25565,534
209218.208.0.0/16218.208.0.1 to 218.208.255.254218.208.255.25565,534
210218.209.0.0/16218.209.0.1 to 218.209.255.254218.209.255.25565,534
211218.210.0.0/16218.210.0.1 to 218.210.255.254218.210.255.25565,534
212218.211.0.0/16218.211.0.1 to 218.211.255.254218.211.255.25565,534
213218.212.0.0/16218.212.0.1 to 218.212.255.254218.212.255.25565,534
214218.213.0.0/16218.213.0.1 to 218.213.255.254218.213.255.25565,534
215218.214.0.0/16218.214.0.1 to 218.214.255.254218.214.255.25565,534
216218.215.0.0/16218.215.0.1 to 218.215.255.254218.215.255.25565,534
217218.216.0.0/16218.216.0.1 to 218.216.255.254218.216.255.25565,534
218218.217.0.0/16218.217.0.1 to 218.217.255.254218.217.255.25565,534
219218.218.0.0/16218.218.0.1 to 218.218.255.254218.218.255.25565,534
220218.219.0.0/16218.219.0.1 to 218.219.255.254218.219.255.25565,534
221218.220.0.0/16218.220.0.1 to 218.220.255.254218.220.255.25565,534
222218.221.0.0/16218.221.0.1 to 218.221.255.254218.221.255.25565,534
223218.222.0.0/16218.222.0.1 to 218.222.255.254218.222.255.25565,534
224218.223.0.0/16218.223.0.1 to 218.223.255.254218.223.255.25565,534
225218.224.0.0/16218.224.0.1 to 218.224.255.254218.224.255.25565,534
226218.225.0.0/16218.225.0.1 to 218.225.255.254218.225.255.25565,534
227218.226.0.0/16218.226.0.1 to 218.226.255.254218.226.255.25565,534
228218.227.0.0/16218.227.0.1 to 218.227.255.254218.227.255.25565,534
229218.228.0.0/16218.228.0.1 to 218.228.255.254218.228.255.25565,534
230218.229.0.0/16218.229.0.1 to 218.229.255.254218.229.255.25565,534
231218.230.0.0/16218.230.0.1 to 218.230.255.254218.230.255.25565,534
232218.231.0.0/16218.231.0.1 to 218.231.255.254218.231.255.25565,534
233218.232.0.0/16218.232.0.1 to 218.232.255.254218.232.255.25565,534
234218.233.0.0/16218.233.0.1 to 218.233.255.254218.233.255.25565,534
235218.234.0.0/16218.234.0.1 to 218.234.255.254218.234.255.25565,534
236218.235.0.0/16218.235.0.1 to 218.235.255.254218.235.255.25565,534
237218.236.0.0/16218.236.0.1 to 218.236.255.254218.236.255.25565,534
238218.237.0.0/16218.237.0.1 to 218.237.255.254218.237.255.25565,534
239218.238.0.0/16218.238.0.1 to 218.238.255.254218.238.255.25565,534
240218.239.0.0/16218.239.0.1 to 218.239.255.254218.239.255.25565,534
241218.240.0.0/16218.240.0.1 to 218.240.255.254218.240.255.25565,534
242218.241.0.0/16218.241.0.1 to 218.241.255.254218.241.255.25565,534
243218.242.0.0/16218.242.0.1 to 218.242.255.254218.242.255.25565,534
244218.243.0.0/16218.243.0.1 to 218.243.255.254218.243.255.25565,534
245218.244.0.0/16218.244.0.1 to 218.244.255.254218.244.255.25565,534
246218.245.0.0/16218.245.0.1 to 218.245.255.254218.245.255.25565,534
247218.246.0.0/16218.246.0.1 to 218.246.255.254218.246.255.25565,534
248218.247.0.0/16218.247.0.1 to 218.247.255.254218.247.255.25565,534
249218.248.0.0/16218.248.0.1 to 218.248.255.254218.248.255.25565,534
250218.249.0.0/16218.249.0.1 to 218.249.255.254218.249.255.25565,534
251218.250.0.0/16218.250.0.1 to 218.250.255.254218.250.255.25565,534
252218.251.0.0/16218.251.0.1 to 218.251.255.254218.251.255.25565,534
253218.252.0.0/16218.252.0.1 to 218.252.255.254218.252.255.25565,534
254218.253.0.0/16218.253.0.1 to 218.253.255.254218.253.255.25565,534
255218.254.0.0/16218.254.0.1 to 218.254.255.254218.254.255.25565,534
256218.255.0.0/16218.255.0.1 to 218.255.255.254218.255.255.25565,534

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.