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.

Network112.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
112.0.0.0
Broadcast address
127.255.255.255
First usable
112.0.0.1
Last usable
127.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
A (default /8)
As numbers
Hex 70000000 · Integer 1879048192 to 2147483647
Reverse DNS zones
112.in-addr.arpa
113.in-addr.arpa
114.in-addr.arpa
115.in-addr.arpa
116.in-addr.arpa
117.in-addr.arpa
118.in-addr.arpa
119.in-addr.arpa
120.in-addr.arpa
121.in-addr.arpa
122.in-addr.arpa
123.in-addr.arpa
124.in-addr.arpa
125.in-addr.arpa
126.in-addr.arpa
127.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01110000.00000000.00000000.00000000112.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network01110000.00000000.00000000.00000000112.0.0.0
Broadcast01111111.11111111.11111111.11111111127.255.255.255
Split into smaller subnets/15
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

112.0.0.0/4 makes 2,048 subnets of /15; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1112.0.0.0/15112.0.0.1 to 112.1.255.254112.1.255.255131,070
2112.2.0.0/15112.2.0.1 to 112.3.255.254112.3.255.255131,070
3112.4.0.0/15112.4.0.1 to 112.5.255.254112.5.255.255131,070
4112.6.0.0/15112.6.0.1 to 112.7.255.254112.7.255.255131,070
5112.8.0.0/15112.8.0.1 to 112.9.255.254112.9.255.255131,070
6112.10.0.0/15112.10.0.1 to 112.11.255.254112.11.255.255131,070
7112.12.0.0/15112.12.0.1 to 112.13.255.254112.13.255.255131,070
8112.14.0.0/15112.14.0.1 to 112.15.255.254112.15.255.255131,070
9112.16.0.0/15112.16.0.1 to 112.17.255.254112.17.255.255131,070
10112.18.0.0/15112.18.0.1 to 112.19.255.254112.19.255.255131,070
11112.20.0.0/15112.20.0.1 to 112.21.255.254112.21.255.255131,070
12112.22.0.0/15112.22.0.1 to 112.23.255.254112.23.255.255131,070
13112.24.0.0/15112.24.0.1 to 112.25.255.254112.25.255.255131,070
14112.26.0.0/15112.26.0.1 to 112.27.255.254112.27.255.255131,070
15112.28.0.0/15112.28.0.1 to 112.29.255.254112.29.255.255131,070
16112.30.0.0/15112.30.0.1 to 112.31.255.254112.31.255.255131,070
17112.32.0.0/15112.32.0.1 to 112.33.255.254112.33.255.255131,070
18112.34.0.0/15112.34.0.1 to 112.35.255.254112.35.255.255131,070
19112.36.0.0/15112.36.0.1 to 112.37.255.254112.37.255.255131,070
20112.38.0.0/15112.38.0.1 to 112.39.255.254112.39.255.255131,070
21112.40.0.0/15112.40.0.1 to 112.41.255.254112.41.255.255131,070
22112.42.0.0/15112.42.0.1 to 112.43.255.254112.43.255.255131,070
23112.44.0.0/15112.44.0.1 to 112.45.255.254112.45.255.255131,070
24112.46.0.0/15112.46.0.1 to 112.47.255.254112.47.255.255131,070
25112.48.0.0/15112.48.0.1 to 112.49.255.254112.49.255.255131,070
26112.50.0.0/15112.50.0.1 to 112.51.255.254112.51.255.255131,070
27112.52.0.0/15112.52.0.1 to 112.53.255.254112.53.255.255131,070
28112.54.0.0/15112.54.0.1 to 112.55.255.254112.55.255.255131,070
29112.56.0.0/15112.56.0.1 to 112.57.255.254112.57.255.255131,070
30112.58.0.0/15112.58.0.1 to 112.59.255.254112.59.255.255131,070
31112.60.0.0/15112.60.0.1 to 112.61.255.254112.61.255.255131,070
32112.62.0.0/15112.62.0.1 to 112.63.255.254112.63.255.255131,070
33112.64.0.0/15112.64.0.1 to 112.65.255.254112.65.255.255131,070
34112.66.0.0/15112.66.0.1 to 112.67.255.254112.67.255.255131,070
35112.68.0.0/15112.68.0.1 to 112.69.255.254112.69.255.255131,070
36112.70.0.0/15112.70.0.1 to 112.71.255.254112.71.255.255131,070
37112.72.0.0/15112.72.0.1 to 112.73.255.254112.73.255.255131,070
38112.74.0.0/15112.74.0.1 to 112.75.255.254112.75.255.255131,070
39112.76.0.0/15112.76.0.1 to 112.77.255.254112.77.255.255131,070
40112.78.0.0/15112.78.0.1 to 112.79.255.254112.79.255.255131,070
41112.80.0.0/15112.80.0.1 to 112.81.255.254112.81.255.255131,070
42112.82.0.0/15112.82.0.1 to 112.83.255.254112.83.255.255131,070
43112.84.0.0/15112.84.0.1 to 112.85.255.254112.85.255.255131,070
44112.86.0.0/15112.86.0.1 to 112.87.255.254112.87.255.255131,070
45112.88.0.0/15112.88.0.1 to 112.89.255.254112.89.255.255131,070
46112.90.0.0/15112.90.0.1 to 112.91.255.254112.91.255.255131,070
47112.92.0.0/15112.92.0.1 to 112.93.255.254112.93.255.255131,070
48112.94.0.0/15112.94.0.1 to 112.95.255.254112.95.255.255131,070
49112.96.0.0/15112.96.0.1 to 112.97.255.254112.97.255.255131,070
50112.98.0.0/15112.98.0.1 to 112.99.255.254112.99.255.255131,070
51112.100.0.0/15112.100.0.1 to 112.101.255.254112.101.255.255131,070
52112.102.0.0/15112.102.0.1 to 112.103.255.254112.103.255.255131,070
53112.104.0.0/15112.104.0.1 to 112.105.255.254112.105.255.255131,070
54112.106.0.0/15112.106.0.1 to 112.107.255.254112.107.255.255131,070
55112.108.0.0/15112.108.0.1 to 112.109.255.254112.109.255.255131,070
56112.110.0.0/15112.110.0.1 to 112.111.255.254112.111.255.255131,070
57112.112.0.0/15112.112.0.1 to 112.113.255.254112.113.255.255131,070
58112.114.0.0/15112.114.0.1 to 112.115.255.254112.115.255.255131,070
59112.116.0.0/15112.116.0.1 to 112.117.255.254112.117.255.255131,070
60112.118.0.0/15112.118.0.1 to 112.119.255.254112.119.255.255131,070
61112.120.0.0/15112.120.0.1 to 112.121.255.254112.121.255.255131,070
62112.122.0.0/15112.122.0.1 to 112.123.255.254112.123.255.255131,070
63112.124.0.0/15112.124.0.1 to 112.125.255.254112.125.255.255131,070
64112.126.0.0/15112.126.0.1 to 112.127.255.254112.127.255.255131,070
65112.128.0.0/15112.128.0.1 to 112.129.255.254112.129.255.255131,070
66112.130.0.0/15112.130.0.1 to 112.131.255.254112.131.255.255131,070
67112.132.0.0/15112.132.0.1 to 112.133.255.254112.133.255.255131,070
68112.134.0.0/15112.134.0.1 to 112.135.255.254112.135.255.255131,070
69112.136.0.0/15112.136.0.1 to 112.137.255.254112.137.255.255131,070
70112.138.0.0/15112.138.0.1 to 112.139.255.254112.139.255.255131,070
71112.140.0.0/15112.140.0.1 to 112.141.255.254112.141.255.255131,070
72112.142.0.0/15112.142.0.1 to 112.143.255.254112.143.255.255131,070
73112.144.0.0/15112.144.0.1 to 112.145.255.254112.145.255.255131,070
74112.146.0.0/15112.146.0.1 to 112.147.255.254112.147.255.255131,070
75112.148.0.0/15112.148.0.1 to 112.149.255.254112.149.255.255131,070
76112.150.0.0/15112.150.0.1 to 112.151.255.254112.151.255.255131,070
77112.152.0.0/15112.152.0.1 to 112.153.255.254112.153.255.255131,070
78112.154.0.0/15112.154.0.1 to 112.155.255.254112.155.255.255131,070
79112.156.0.0/15112.156.0.1 to 112.157.255.254112.157.255.255131,070
80112.158.0.0/15112.158.0.1 to 112.159.255.254112.159.255.255131,070
81112.160.0.0/15112.160.0.1 to 112.161.255.254112.161.255.255131,070
82112.162.0.0/15112.162.0.1 to 112.163.255.254112.163.255.255131,070
83112.164.0.0/15112.164.0.1 to 112.165.255.254112.165.255.255131,070
84112.166.0.0/15112.166.0.1 to 112.167.255.254112.167.255.255131,070
85112.168.0.0/15112.168.0.1 to 112.169.255.254112.169.255.255131,070
86112.170.0.0/15112.170.0.1 to 112.171.255.254112.171.255.255131,070
87112.172.0.0/15112.172.0.1 to 112.173.255.254112.173.255.255131,070
88112.174.0.0/15112.174.0.1 to 112.175.255.254112.175.255.255131,070
89112.176.0.0/15112.176.0.1 to 112.177.255.254112.177.255.255131,070
90112.178.0.0/15112.178.0.1 to 112.179.255.254112.179.255.255131,070
91112.180.0.0/15112.180.0.1 to 112.181.255.254112.181.255.255131,070
92112.182.0.0/15112.182.0.1 to 112.183.255.254112.183.255.255131,070
93112.184.0.0/15112.184.0.1 to 112.185.255.254112.185.255.255131,070
94112.186.0.0/15112.186.0.1 to 112.187.255.254112.187.255.255131,070
95112.188.0.0/15112.188.0.1 to 112.189.255.254112.189.255.255131,070
96112.190.0.0/15112.190.0.1 to 112.191.255.254112.191.255.255131,070
97112.192.0.0/15112.192.0.1 to 112.193.255.254112.193.255.255131,070
98112.194.0.0/15112.194.0.1 to 112.195.255.254112.195.255.255131,070
99112.196.0.0/15112.196.0.1 to 112.197.255.254112.197.255.255131,070
100112.198.0.0/15112.198.0.1 to 112.199.255.254112.199.255.255131,070
101112.200.0.0/15112.200.0.1 to 112.201.255.254112.201.255.255131,070
102112.202.0.0/15112.202.0.1 to 112.203.255.254112.203.255.255131,070
103112.204.0.0/15112.204.0.1 to 112.205.255.254112.205.255.255131,070
104112.206.0.0/15112.206.0.1 to 112.207.255.254112.207.255.255131,070
105112.208.0.0/15112.208.0.1 to 112.209.255.254112.209.255.255131,070
106112.210.0.0/15112.210.0.1 to 112.211.255.254112.211.255.255131,070
107112.212.0.0/15112.212.0.1 to 112.213.255.254112.213.255.255131,070
108112.214.0.0/15112.214.0.1 to 112.215.255.254112.215.255.255131,070
109112.216.0.0/15112.216.0.1 to 112.217.255.254112.217.255.255131,070
110112.218.0.0/15112.218.0.1 to 112.219.255.254112.219.255.255131,070
111112.220.0.0/15112.220.0.1 to 112.221.255.254112.221.255.255131,070
112112.222.0.0/15112.222.0.1 to 112.223.255.254112.223.255.255131,070
113112.224.0.0/15112.224.0.1 to 112.225.255.254112.225.255.255131,070
114112.226.0.0/15112.226.0.1 to 112.227.255.254112.227.255.255131,070
115112.228.0.0/15112.228.0.1 to 112.229.255.254112.229.255.255131,070
116112.230.0.0/15112.230.0.1 to 112.231.255.254112.231.255.255131,070
117112.232.0.0/15112.232.0.1 to 112.233.255.254112.233.255.255131,070
118112.234.0.0/15112.234.0.1 to 112.235.255.254112.235.255.255131,070
119112.236.0.0/15112.236.0.1 to 112.237.255.254112.237.255.255131,070
120112.238.0.0/15112.238.0.1 to 112.239.255.254112.239.255.255131,070
121112.240.0.0/15112.240.0.1 to 112.241.255.254112.241.255.255131,070
122112.242.0.0/15112.242.0.1 to 112.243.255.254112.243.255.255131,070
123112.244.0.0/15112.244.0.1 to 112.245.255.254112.245.255.255131,070
124112.246.0.0/15112.246.0.1 to 112.247.255.254112.247.255.255131,070
125112.248.0.0/15112.248.0.1 to 112.249.255.254112.249.255.255131,070
126112.250.0.0/15112.250.0.1 to 112.251.255.254112.251.255.255131,070
127112.252.0.0/15112.252.0.1 to 112.253.255.254112.253.255.255131,070
128112.254.0.0/15112.254.0.1 to 112.255.255.254112.255.255.255131,070
129113.0.0.0/15113.0.0.1 to 113.1.255.254113.1.255.255131,070
130113.2.0.0/15113.2.0.1 to 113.3.255.254113.3.255.255131,070
131113.4.0.0/15113.4.0.1 to 113.5.255.254113.5.255.255131,070
132113.6.0.0/15113.6.0.1 to 113.7.255.254113.7.255.255131,070
133113.8.0.0/15113.8.0.1 to 113.9.255.254113.9.255.255131,070
134113.10.0.0/15113.10.0.1 to 113.11.255.254113.11.255.255131,070
135113.12.0.0/15113.12.0.1 to 113.13.255.254113.13.255.255131,070
136113.14.0.0/15113.14.0.1 to 113.15.255.254113.15.255.255131,070
137113.16.0.0/15113.16.0.1 to 113.17.255.254113.17.255.255131,070
138113.18.0.0/15113.18.0.1 to 113.19.255.254113.19.255.255131,070
139113.20.0.0/15113.20.0.1 to 113.21.255.254113.21.255.255131,070
140113.22.0.0/15113.22.0.1 to 113.23.255.254113.23.255.255131,070
141113.24.0.0/15113.24.0.1 to 113.25.255.254113.25.255.255131,070
142113.26.0.0/15113.26.0.1 to 113.27.255.254113.27.255.255131,070
143113.28.0.0/15113.28.0.1 to 113.29.255.254113.29.255.255131,070
144113.30.0.0/15113.30.0.1 to 113.31.255.254113.31.255.255131,070
145113.32.0.0/15113.32.0.1 to 113.33.255.254113.33.255.255131,070
146113.34.0.0/15113.34.0.1 to 113.35.255.254113.35.255.255131,070
147113.36.0.0/15113.36.0.1 to 113.37.255.254113.37.255.255131,070
148113.38.0.0/15113.38.0.1 to 113.39.255.254113.39.255.255131,070
149113.40.0.0/15113.40.0.1 to 113.41.255.254113.41.255.255131,070
150113.42.0.0/15113.42.0.1 to 113.43.255.254113.43.255.255131,070
151113.44.0.0/15113.44.0.1 to 113.45.255.254113.45.255.255131,070
152113.46.0.0/15113.46.0.1 to 113.47.255.254113.47.255.255131,070
153113.48.0.0/15113.48.0.1 to 113.49.255.254113.49.255.255131,070
154113.50.0.0/15113.50.0.1 to 113.51.255.254113.51.255.255131,070
155113.52.0.0/15113.52.0.1 to 113.53.255.254113.53.255.255131,070
156113.54.0.0/15113.54.0.1 to 113.55.255.254113.55.255.255131,070
157113.56.0.0/15113.56.0.1 to 113.57.255.254113.57.255.255131,070
158113.58.0.0/15113.58.0.1 to 113.59.255.254113.59.255.255131,070
159113.60.0.0/15113.60.0.1 to 113.61.255.254113.61.255.255131,070
160113.62.0.0/15113.62.0.1 to 113.63.255.254113.63.255.255131,070
161113.64.0.0/15113.64.0.1 to 113.65.255.254113.65.255.255131,070
162113.66.0.0/15113.66.0.1 to 113.67.255.254113.67.255.255131,070
163113.68.0.0/15113.68.0.1 to 113.69.255.254113.69.255.255131,070
164113.70.0.0/15113.70.0.1 to 113.71.255.254113.71.255.255131,070
165113.72.0.0/15113.72.0.1 to 113.73.255.254113.73.255.255131,070
166113.74.0.0/15113.74.0.1 to 113.75.255.254113.75.255.255131,070
167113.76.0.0/15113.76.0.1 to 113.77.255.254113.77.255.255131,070
168113.78.0.0/15113.78.0.1 to 113.79.255.254113.79.255.255131,070
169113.80.0.0/15113.80.0.1 to 113.81.255.254113.81.255.255131,070
170113.82.0.0/15113.82.0.1 to 113.83.255.254113.83.255.255131,070
171113.84.0.0/15113.84.0.1 to 113.85.255.254113.85.255.255131,070
172113.86.0.0/15113.86.0.1 to 113.87.255.254113.87.255.255131,070
173113.88.0.0/15113.88.0.1 to 113.89.255.254113.89.255.255131,070
174113.90.0.0/15113.90.0.1 to 113.91.255.254113.91.255.255131,070
175113.92.0.0/15113.92.0.1 to 113.93.255.254113.93.255.255131,070
176113.94.0.0/15113.94.0.1 to 113.95.255.254113.95.255.255131,070
177113.96.0.0/15113.96.0.1 to 113.97.255.254113.97.255.255131,070
178113.98.0.0/15113.98.0.1 to 113.99.255.254113.99.255.255131,070
179113.100.0.0/15113.100.0.1 to 113.101.255.254113.101.255.255131,070
180113.102.0.0/15113.102.0.1 to 113.103.255.254113.103.255.255131,070
181113.104.0.0/15113.104.0.1 to 113.105.255.254113.105.255.255131,070
182113.106.0.0/15113.106.0.1 to 113.107.255.254113.107.255.255131,070
183113.108.0.0/15113.108.0.1 to 113.109.255.254113.109.255.255131,070
184113.110.0.0/15113.110.0.1 to 113.111.255.254113.111.255.255131,070
185113.112.0.0/15113.112.0.1 to 113.113.255.254113.113.255.255131,070
186113.114.0.0/15113.114.0.1 to 113.115.255.254113.115.255.255131,070
187113.116.0.0/15113.116.0.1 to 113.117.255.254113.117.255.255131,070
188113.118.0.0/15113.118.0.1 to 113.119.255.254113.119.255.255131,070
189113.120.0.0/15113.120.0.1 to 113.121.255.254113.121.255.255131,070
190113.122.0.0/15113.122.0.1 to 113.123.255.254113.123.255.255131,070
191113.124.0.0/15113.124.0.1 to 113.125.255.254113.125.255.255131,070
192113.126.0.0/15113.126.0.1 to 113.127.255.254113.127.255.255131,070
193113.128.0.0/15113.128.0.1 to 113.129.255.254113.129.255.255131,070
194113.130.0.0/15113.130.0.1 to 113.131.255.254113.131.255.255131,070
195113.132.0.0/15113.132.0.1 to 113.133.255.254113.133.255.255131,070
196113.134.0.0/15113.134.0.1 to 113.135.255.254113.135.255.255131,070
197113.136.0.0/15113.136.0.1 to 113.137.255.254113.137.255.255131,070
198113.138.0.0/15113.138.0.1 to 113.139.255.254113.139.255.255131,070
199113.140.0.0/15113.140.0.1 to 113.141.255.254113.141.255.255131,070
200113.142.0.0/15113.142.0.1 to 113.143.255.254113.143.255.255131,070
201113.144.0.0/15113.144.0.1 to 113.145.255.254113.145.255.255131,070
202113.146.0.0/15113.146.0.1 to 113.147.255.254113.147.255.255131,070
203113.148.0.0/15113.148.0.1 to 113.149.255.254113.149.255.255131,070
204113.150.0.0/15113.150.0.1 to 113.151.255.254113.151.255.255131,070
205113.152.0.0/15113.152.0.1 to 113.153.255.254113.153.255.255131,070
206113.154.0.0/15113.154.0.1 to 113.155.255.254113.155.255.255131,070
207113.156.0.0/15113.156.0.1 to 113.157.255.254113.157.255.255131,070
208113.158.0.0/15113.158.0.1 to 113.159.255.254113.159.255.255131,070
209113.160.0.0/15113.160.0.1 to 113.161.255.254113.161.255.255131,070
210113.162.0.0/15113.162.0.1 to 113.163.255.254113.163.255.255131,070
211113.164.0.0/15113.164.0.1 to 113.165.255.254113.165.255.255131,070
212113.166.0.0/15113.166.0.1 to 113.167.255.254113.167.255.255131,070
213113.168.0.0/15113.168.0.1 to 113.169.255.254113.169.255.255131,070
214113.170.0.0/15113.170.0.1 to 113.171.255.254113.171.255.255131,070
215113.172.0.0/15113.172.0.1 to 113.173.255.254113.173.255.255131,070
216113.174.0.0/15113.174.0.1 to 113.175.255.254113.175.255.255131,070
217113.176.0.0/15113.176.0.1 to 113.177.255.254113.177.255.255131,070
218113.178.0.0/15113.178.0.1 to 113.179.255.254113.179.255.255131,070
219113.180.0.0/15113.180.0.1 to 113.181.255.254113.181.255.255131,070
220113.182.0.0/15113.182.0.1 to 113.183.255.254113.183.255.255131,070
221113.184.0.0/15113.184.0.1 to 113.185.255.254113.185.255.255131,070
222113.186.0.0/15113.186.0.1 to 113.187.255.254113.187.255.255131,070
223113.188.0.0/15113.188.0.1 to 113.189.255.254113.189.255.255131,070
224113.190.0.0/15113.190.0.1 to 113.191.255.254113.191.255.255131,070
225113.192.0.0/15113.192.0.1 to 113.193.255.254113.193.255.255131,070
226113.194.0.0/15113.194.0.1 to 113.195.255.254113.195.255.255131,070
227113.196.0.0/15113.196.0.1 to 113.197.255.254113.197.255.255131,070
228113.198.0.0/15113.198.0.1 to 113.199.255.254113.199.255.255131,070
229113.200.0.0/15113.200.0.1 to 113.201.255.254113.201.255.255131,070
230113.202.0.0/15113.202.0.1 to 113.203.255.254113.203.255.255131,070
231113.204.0.0/15113.204.0.1 to 113.205.255.254113.205.255.255131,070
232113.206.0.0/15113.206.0.1 to 113.207.255.254113.207.255.255131,070
233113.208.0.0/15113.208.0.1 to 113.209.255.254113.209.255.255131,070
234113.210.0.0/15113.210.0.1 to 113.211.255.254113.211.255.255131,070
235113.212.0.0/15113.212.0.1 to 113.213.255.254113.213.255.255131,070
236113.214.0.0/15113.214.0.1 to 113.215.255.254113.215.255.255131,070
237113.216.0.0/15113.216.0.1 to 113.217.255.254113.217.255.255131,070
238113.218.0.0/15113.218.0.1 to 113.219.255.254113.219.255.255131,070
239113.220.0.0/15113.220.0.1 to 113.221.255.254113.221.255.255131,070
240113.222.0.0/15113.222.0.1 to 113.223.255.254113.223.255.255131,070
241113.224.0.0/15113.224.0.1 to 113.225.255.254113.225.255.255131,070
242113.226.0.0/15113.226.0.1 to 113.227.255.254113.227.255.255131,070
243113.228.0.0/15113.228.0.1 to 113.229.255.254113.229.255.255131,070
244113.230.0.0/15113.230.0.1 to 113.231.255.254113.231.255.255131,070
245113.232.0.0/15113.232.0.1 to 113.233.255.254113.233.255.255131,070
246113.234.0.0/15113.234.0.1 to 113.235.255.254113.235.255.255131,070
247113.236.0.0/15113.236.0.1 to 113.237.255.254113.237.255.255131,070
248113.238.0.0/15113.238.0.1 to 113.239.255.254113.239.255.255131,070
249113.240.0.0/15113.240.0.1 to 113.241.255.254113.241.255.255131,070
250113.242.0.0/15113.242.0.1 to 113.243.255.254113.243.255.255131,070
251113.244.0.0/15113.244.0.1 to 113.245.255.254113.245.255.255131,070
252113.246.0.0/15113.246.0.1 to 113.247.255.254113.247.255.255131,070
253113.248.0.0/15113.248.0.1 to 113.249.255.254113.249.255.255131,070
254113.250.0.0/15113.250.0.1 to 113.251.255.254113.251.255.255131,070
255113.252.0.0/15113.252.0.1 to 113.253.255.254113.253.255.255131,070
256113.254.0.0/15113.254.0.1 to 113.255.255.254113.255.255.255131,070

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.