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.

Network225.132.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
225.132.0.0
Broadcast address
225.133.255.255
First usable
225.132.0.1
Last usable
225.133.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E1840000 · Integer 3783524352 to 3783655423
Reverse DNS zones
132.225.in-addr.arpa
133.225.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100001.10000100.00000000.00000000225.132.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11100001.10000100.00000000.00000000225.132.0.0
Broadcast11100001.10000101.11111111.11111111225.133.255.255
Split into smaller subnets/24
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

225.132.0.0/15 makes 512 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1225.132.0.0/24225.132.0.1 to 225.132.0.254225.132.0.255254
2225.132.1.0/24225.132.1.1 to 225.132.1.254225.132.1.255254
3225.132.2.0/24225.132.2.1 to 225.132.2.254225.132.2.255254
4225.132.3.0/24225.132.3.1 to 225.132.3.254225.132.3.255254
5225.132.4.0/24225.132.4.1 to 225.132.4.254225.132.4.255254
6225.132.5.0/24225.132.5.1 to 225.132.5.254225.132.5.255254
7225.132.6.0/24225.132.6.1 to 225.132.6.254225.132.6.255254
8225.132.7.0/24225.132.7.1 to 225.132.7.254225.132.7.255254
9225.132.8.0/24225.132.8.1 to 225.132.8.254225.132.8.255254
10225.132.9.0/24225.132.9.1 to 225.132.9.254225.132.9.255254
11225.132.10.0/24225.132.10.1 to 225.132.10.254225.132.10.255254
12225.132.11.0/24225.132.11.1 to 225.132.11.254225.132.11.255254
13225.132.12.0/24225.132.12.1 to 225.132.12.254225.132.12.255254
14225.132.13.0/24225.132.13.1 to 225.132.13.254225.132.13.255254
15225.132.14.0/24225.132.14.1 to 225.132.14.254225.132.14.255254
16225.132.15.0/24225.132.15.1 to 225.132.15.254225.132.15.255254
17225.132.16.0/24225.132.16.1 to 225.132.16.254225.132.16.255254
18225.132.17.0/24225.132.17.1 to 225.132.17.254225.132.17.255254
19225.132.18.0/24225.132.18.1 to 225.132.18.254225.132.18.255254
20225.132.19.0/24225.132.19.1 to 225.132.19.254225.132.19.255254
21225.132.20.0/24225.132.20.1 to 225.132.20.254225.132.20.255254
22225.132.21.0/24225.132.21.1 to 225.132.21.254225.132.21.255254
23225.132.22.0/24225.132.22.1 to 225.132.22.254225.132.22.255254
24225.132.23.0/24225.132.23.1 to 225.132.23.254225.132.23.255254
25225.132.24.0/24225.132.24.1 to 225.132.24.254225.132.24.255254
26225.132.25.0/24225.132.25.1 to 225.132.25.254225.132.25.255254
27225.132.26.0/24225.132.26.1 to 225.132.26.254225.132.26.255254
28225.132.27.0/24225.132.27.1 to 225.132.27.254225.132.27.255254
29225.132.28.0/24225.132.28.1 to 225.132.28.254225.132.28.255254
30225.132.29.0/24225.132.29.1 to 225.132.29.254225.132.29.255254
31225.132.30.0/24225.132.30.1 to 225.132.30.254225.132.30.255254
32225.132.31.0/24225.132.31.1 to 225.132.31.254225.132.31.255254
33225.132.32.0/24225.132.32.1 to 225.132.32.254225.132.32.255254
34225.132.33.0/24225.132.33.1 to 225.132.33.254225.132.33.255254
35225.132.34.0/24225.132.34.1 to 225.132.34.254225.132.34.255254
36225.132.35.0/24225.132.35.1 to 225.132.35.254225.132.35.255254
37225.132.36.0/24225.132.36.1 to 225.132.36.254225.132.36.255254
38225.132.37.0/24225.132.37.1 to 225.132.37.254225.132.37.255254
39225.132.38.0/24225.132.38.1 to 225.132.38.254225.132.38.255254
40225.132.39.0/24225.132.39.1 to 225.132.39.254225.132.39.255254
41225.132.40.0/24225.132.40.1 to 225.132.40.254225.132.40.255254
42225.132.41.0/24225.132.41.1 to 225.132.41.254225.132.41.255254
43225.132.42.0/24225.132.42.1 to 225.132.42.254225.132.42.255254
44225.132.43.0/24225.132.43.1 to 225.132.43.254225.132.43.255254
45225.132.44.0/24225.132.44.1 to 225.132.44.254225.132.44.255254
46225.132.45.0/24225.132.45.1 to 225.132.45.254225.132.45.255254
47225.132.46.0/24225.132.46.1 to 225.132.46.254225.132.46.255254
48225.132.47.0/24225.132.47.1 to 225.132.47.254225.132.47.255254
49225.132.48.0/24225.132.48.1 to 225.132.48.254225.132.48.255254
50225.132.49.0/24225.132.49.1 to 225.132.49.254225.132.49.255254
51225.132.50.0/24225.132.50.1 to 225.132.50.254225.132.50.255254
52225.132.51.0/24225.132.51.1 to 225.132.51.254225.132.51.255254
53225.132.52.0/24225.132.52.1 to 225.132.52.254225.132.52.255254
54225.132.53.0/24225.132.53.1 to 225.132.53.254225.132.53.255254
55225.132.54.0/24225.132.54.1 to 225.132.54.254225.132.54.255254
56225.132.55.0/24225.132.55.1 to 225.132.55.254225.132.55.255254
57225.132.56.0/24225.132.56.1 to 225.132.56.254225.132.56.255254
58225.132.57.0/24225.132.57.1 to 225.132.57.254225.132.57.255254
59225.132.58.0/24225.132.58.1 to 225.132.58.254225.132.58.255254
60225.132.59.0/24225.132.59.1 to 225.132.59.254225.132.59.255254
61225.132.60.0/24225.132.60.1 to 225.132.60.254225.132.60.255254
62225.132.61.0/24225.132.61.1 to 225.132.61.254225.132.61.255254
63225.132.62.0/24225.132.62.1 to 225.132.62.254225.132.62.255254
64225.132.63.0/24225.132.63.1 to 225.132.63.254225.132.63.255254
65225.132.64.0/24225.132.64.1 to 225.132.64.254225.132.64.255254
66225.132.65.0/24225.132.65.1 to 225.132.65.254225.132.65.255254
67225.132.66.0/24225.132.66.1 to 225.132.66.254225.132.66.255254
68225.132.67.0/24225.132.67.1 to 225.132.67.254225.132.67.255254
69225.132.68.0/24225.132.68.1 to 225.132.68.254225.132.68.255254
70225.132.69.0/24225.132.69.1 to 225.132.69.254225.132.69.255254
71225.132.70.0/24225.132.70.1 to 225.132.70.254225.132.70.255254
72225.132.71.0/24225.132.71.1 to 225.132.71.254225.132.71.255254
73225.132.72.0/24225.132.72.1 to 225.132.72.254225.132.72.255254
74225.132.73.0/24225.132.73.1 to 225.132.73.254225.132.73.255254
75225.132.74.0/24225.132.74.1 to 225.132.74.254225.132.74.255254
76225.132.75.0/24225.132.75.1 to 225.132.75.254225.132.75.255254
77225.132.76.0/24225.132.76.1 to 225.132.76.254225.132.76.255254
78225.132.77.0/24225.132.77.1 to 225.132.77.254225.132.77.255254
79225.132.78.0/24225.132.78.1 to 225.132.78.254225.132.78.255254
80225.132.79.0/24225.132.79.1 to 225.132.79.254225.132.79.255254
81225.132.80.0/24225.132.80.1 to 225.132.80.254225.132.80.255254
82225.132.81.0/24225.132.81.1 to 225.132.81.254225.132.81.255254
83225.132.82.0/24225.132.82.1 to 225.132.82.254225.132.82.255254
84225.132.83.0/24225.132.83.1 to 225.132.83.254225.132.83.255254
85225.132.84.0/24225.132.84.1 to 225.132.84.254225.132.84.255254
86225.132.85.0/24225.132.85.1 to 225.132.85.254225.132.85.255254
87225.132.86.0/24225.132.86.1 to 225.132.86.254225.132.86.255254
88225.132.87.0/24225.132.87.1 to 225.132.87.254225.132.87.255254
89225.132.88.0/24225.132.88.1 to 225.132.88.254225.132.88.255254
90225.132.89.0/24225.132.89.1 to 225.132.89.254225.132.89.255254
91225.132.90.0/24225.132.90.1 to 225.132.90.254225.132.90.255254
92225.132.91.0/24225.132.91.1 to 225.132.91.254225.132.91.255254
93225.132.92.0/24225.132.92.1 to 225.132.92.254225.132.92.255254
94225.132.93.0/24225.132.93.1 to 225.132.93.254225.132.93.255254
95225.132.94.0/24225.132.94.1 to 225.132.94.254225.132.94.255254
96225.132.95.0/24225.132.95.1 to 225.132.95.254225.132.95.255254
97225.132.96.0/24225.132.96.1 to 225.132.96.254225.132.96.255254
98225.132.97.0/24225.132.97.1 to 225.132.97.254225.132.97.255254
99225.132.98.0/24225.132.98.1 to 225.132.98.254225.132.98.255254
100225.132.99.0/24225.132.99.1 to 225.132.99.254225.132.99.255254
101225.132.100.0/24225.132.100.1 to 225.132.100.254225.132.100.255254
102225.132.101.0/24225.132.101.1 to 225.132.101.254225.132.101.255254
103225.132.102.0/24225.132.102.1 to 225.132.102.254225.132.102.255254
104225.132.103.0/24225.132.103.1 to 225.132.103.254225.132.103.255254
105225.132.104.0/24225.132.104.1 to 225.132.104.254225.132.104.255254
106225.132.105.0/24225.132.105.1 to 225.132.105.254225.132.105.255254
107225.132.106.0/24225.132.106.1 to 225.132.106.254225.132.106.255254
108225.132.107.0/24225.132.107.1 to 225.132.107.254225.132.107.255254
109225.132.108.0/24225.132.108.1 to 225.132.108.254225.132.108.255254
110225.132.109.0/24225.132.109.1 to 225.132.109.254225.132.109.255254
111225.132.110.0/24225.132.110.1 to 225.132.110.254225.132.110.255254
112225.132.111.0/24225.132.111.1 to 225.132.111.254225.132.111.255254
113225.132.112.0/24225.132.112.1 to 225.132.112.254225.132.112.255254
114225.132.113.0/24225.132.113.1 to 225.132.113.254225.132.113.255254
115225.132.114.0/24225.132.114.1 to 225.132.114.254225.132.114.255254
116225.132.115.0/24225.132.115.1 to 225.132.115.254225.132.115.255254
117225.132.116.0/24225.132.116.1 to 225.132.116.254225.132.116.255254
118225.132.117.0/24225.132.117.1 to 225.132.117.254225.132.117.255254
119225.132.118.0/24225.132.118.1 to 225.132.118.254225.132.118.255254
120225.132.119.0/24225.132.119.1 to 225.132.119.254225.132.119.255254
121225.132.120.0/24225.132.120.1 to 225.132.120.254225.132.120.255254
122225.132.121.0/24225.132.121.1 to 225.132.121.254225.132.121.255254
123225.132.122.0/24225.132.122.1 to 225.132.122.254225.132.122.255254
124225.132.123.0/24225.132.123.1 to 225.132.123.254225.132.123.255254
125225.132.124.0/24225.132.124.1 to 225.132.124.254225.132.124.255254
126225.132.125.0/24225.132.125.1 to 225.132.125.254225.132.125.255254
127225.132.126.0/24225.132.126.1 to 225.132.126.254225.132.126.255254
128225.132.127.0/24225.132.127.1 to 225.132.127.254225.132.127.255254
129225.132.128.0/24225.132.128.1 to 225.132.128.254225.132.128.255254
130225.132.129.0/24225.132.129.1 to 225.132.129.254225.132.129.255254
131225.132.130.0/24225.132.130.1 to 225.132.130.254225.132.130.255254
132225.132.131.0/24225.132.131.1 to 225.132.131.254225.132.131.255254
133225.132.132.0/24225.132.132.1 to 225.132.132.254225.132.132.255254
134225.132.133.0/24225.132.133.1 to 225.132.133.254225.132.133.255254
135225.132.134.0/24225.132.134.1 to 225.132.134.254225.132.134.255254
136225.132.135.0/24225.132.135.1 to 225.132.135.254225.132.135.255254
137225.132.136.0/24225.132.136.1 to 225.132.136.254225.132.136.255254
138225.132.137.0/24225.132.137.1 to 225.132.137.254225.132.137.255254
139225.132.138.0/24225.132.138.1 to 225.132.138.254225.132.138.255254
140225.132.139.0/24225.132.139.1 to 225.132.139.254225.132.139.255254
141225.132.140.0/24225.132.140.1 to 225.132.140.254225.132.140.255254
142225.132.141.0/24225.132.141.1 to 225.132.141.254225.132.141.255254
143225.132.142.0/24225.132.142.1 to 225.132.142.254225.132.142.255254
144225.132.143.0/24225.132.143.1 to 225.132.143.254225.132.143.255254
145225.132.144.0/24225.132.144.1 to 225.132.144.254225.132.144.255254
146225.132.145.0/24225.132.145.1 to 225.132.145.254225.132.145.255254
147225.132.146.0/24225.132.146.1 to 225.132.146.254225.132.146.255254
148225.132.147.0/24225.132.147.1 to 225.132.147.254225.132.147.255254
149225.132.148.0/24225.132.148.1 to 225.132.148.254225.132.148.255254
150225.132.149.0/24225.132.149.1 to 225.132.149.254225.132.149.255254
151225.132.150.0/24225.132.150.1 to 225.132.150.254225.132.150.255254
152225.132.151.0/24225.132.151.1 to 225.132.151.254225.132.151.255254
153225.132.152.0/24225.132.152.1 to 225.132.152.254225.132.152.255254
154225.132.153.0/24225.132.153.1 to 225.132.153.254225.132.153.255254
155225.132.154.0/24225.132.154.1 to 225.132.154.254225.132.154.255254
156225.132.155.0/24225.132.155.1 to 225.132.155.254225.132.155.255254
157225.132.156.0/24225.132.156.1 to 225.132.156.254225.132.156.255254
158225.132.157.0/24225.132.157.1 to 225.132.157.254225.132.157.255254
159225.132.158.0/24225.132.158.1 to 225.132.158.254225.132.158.255254
160225.132.159.0/24225.132.159.1 to 225.132.159.254225.132.159.255254
161225.132.160.0/24225.132.160.1 to 225.132.160.254225.132.160.255254
162225.132.161.0/24225.132.161.1 to 225.132.161.254225.132.161.255254
163225.132.162.0/24225.132.162.1 to 225.132.162.254225.132.162.255254
164225.132.163.0/24225.132.163.1 to 225.132.163.254225.132.163.255254
165225.132.164.0/24225.132.164.1 to 225.132.164.254225.132.164.255254
166225.132.165.0/24225.132.165.1 to 225.132.165.254225.132.165.255254
167225.132.166.0/24225.132.166.1 to 225.132.166.254225.132.166.255254
168225.132.167.0/24225.132.167.1 to 225.132.167.254225.132.167.255254
169225.132.168.0/24225.132.168.1 to 225.132.168.254225.132.168.255254
170225.132.169.0/24225.132.169.1 to 225.132.169.254225.132.169.255254
171225.132.170.0/24225.132.170.1 to 225.132.170.254225.132.170.255254
172225.132.171.0/24225.132.171.1 to 225.132.171.254225.132.171.255254
173225.132.172.0/24225.132.172.1 to 225.132.172.254225.132.172.255254
174225.132.173.0/24225.132.173.1 to 225.132.173.254225.132.173.255254
175225.132.174.0/24225.132.174.1 to 225.132.174.254225.132.174.255254
176225.132.175.0/24225.132.175.1 to 225.132.175.254225.132.175.255254
177225.132.176.0/24225.132.176.1 to 225.132.176.254225.132.176.255254
178225.132.177.0/24225.132.177.1 to 225.132.177.254225.132.177.255254
179225.132.178.0/24225.132.178.1 to 225.132.178.254225.132.178.255254
180225.132.179.0/24225.132.179.1 to 225.132.179.254225.132.179.255254
181225.132.180.0/24225.132.180.1 to 225.132.180.254225.132.180.255254
182225.132.181.0/24225.132.181.1 to 225.132.181.254225.132.181.255254
183225.132.182.0/24225.132.182.1 to 225.132.182.254225.132.182.255254
184225.132.183.0/24225.132.183.1 to 225.132.183.254225.132.183.255254
185225.132.184.0/24225.132.184.1 to 225.132.184.254225.132.184.255254
186225.132.185.0/24225.132.185.1 to 225.132.185.254225.132.185.255254
187225.132.186.0/24225.132.186.1 to 225.132.186.254225.132.186.255254
188225.132.187.0/24225.132.187.1 to 225.132.187.254225.132.187.255254
189225.132.188.0/24225.132.188.1 to 225.132.188.254225.132.188.255254
190225.132.189.0/24225.132.189.1 to 225.132.189.254225.132.189.255254
191225.132.190.0/24225.132.190.1 to 225.132.190.254225.132.190.255254
192225.132.191.0/24225.132.191.1 to 225.132.191.254225.132.191.255254
193225.132.192.0/24225.132.192.1 to 225.132.192.254225.132.192.255254
194225.132.193.0/24225.132.193.1 to 225.132.193.254225.132.193.255254
195225.132.194.0/24225.132.194.1 to 225.132.194.254225.132.194.255254
196225.132.195.0/24225.132.195.1 to 225.132.195.254225.132.195.255254
197225.132.196.0/24225.132.196.1 to 225.132.196.254225.132.196.255254
198225.132.197.0/24225.132.197.1 to 225.132.197.254225.132.197.255254
199225.132.198.0/24225.132.198.1 to 225.132.198.254225.132.198.255254
200225.132.199.0/24225.132.199.1 to 225.132.199.254225.132.199.255254
201225.132.200.0/24225.132.200.1 to 225.132.200.254225.132.200.255254
202225.132.201.0/24225.132.201.1 to 225.132.201.254225.132.201.255254
203225.132.202.0/24225.132.202.1 to 225.132.202.254225.132.202.255254
204225.132.203.0/24225.132.203.1 to 225.132.203.254225.132.203.255254
205225.132.204.0/24225.132.204.1 to 225.132.204.254225.132.204.255254
206225.132.205.0/24225.132.205.1 to 225.132.205.254225.132.205.255254
207225.132.206.0/24225.132.206.1 to 225.132.206.254225.132.206.255254
208225.132.207.0/24225.132.207.1 to 225.132.207.254225.132.207.255254
209225.132.208.0/24225.132.208.1 to 225.132.208.254225.132.208.255254
210225.132.209.0/24225.132.209.1 to 225.132.209.254225.132.209.255254
211225.132.210.0/24225.132.210.1 to 225.132.210.254225.132.210.255254
212225.132.211.0/24225.132.211.1 to 225.132.211.254225.132.211.255254
213225.132.212.0/24225.132.212.1 to 225.132.212.254225.132.212.255254
214225.132.213.0/24225.132.213.1 to 225.132.213.254225.132.213.255254
215225.132.214.0/24225.132.214.1 to 225.132.214.254225.132.214.255254
216225.132.215.0/24225.132.215.1 to 225.132.215.254225.132.215.255254
217225.132.216.0/24225.132.216.1 to 225.132.216.254225.132.216.255254
218225.132.217.0/24225.132.217.1 to 225.132.217.254225.132.217.255254
219225.132.218.0/24225.132.218.1 to 225.132.218.254225.132.218.255254
220225.132.219.0/24225.132.219.1 to 225.132.219.254225.132.219.255254
221225.132.220.0/24225.132.220.1 to 225.132.220.254225.132.220.255254
222225.132.221.0/24225.132.221.1 to 225.132.221.254225.132.221.255254
223225.132.222.0/24225.132.222.1 to 225.132.222.254225.132.222.255254
224225.132.223.0/24225.132.223.1 to 225.132.223.254225.132.223.255254
225225.132.224.0/24225.132.224.1 to 225.132.224.254225.132.224.255254
226225.132.225.0/24225.132.225.1 to 225.132.225.254225.132.225.255254
227225.132.226.0/24225.132.226.1 to 225.132.226.254225.132.226.255254
228225.132.227.0/24225.132.227.1 to 225.132.227.254225.132.227.255254
229225.132.228.0/24225.132.228.1 to 225.132.228.254225.132.228.255254
230225.132.229.0/24225.132.229.1 to 225.132.229.254225.132.229.255254
231225.132.230.0/24225.132.230.1 to 225.132.230.254225.132.230.255254
232225.132.231.0/24225.132.231.1 to 225.132.231.254225.132.231.255254
233225.132.232.0/24225.132.232.1 to 225.132.232.254225.132.232.255254
234225.132.233.0/24225.132.233.1 to 225.132.233.254225.132.233.255254
235225.132.234.0/24225.132.234.1 to 225.132.234.254225.132.234.255254
236225.132.235.0/24225.132.235.1 to 225.132.235.254225.132.235.255254
237225.132.236.0/24225.132.236.1 to 225.132.236.254225.132.236.255254
238225.132.237.0/24225.132.237.1 to 225.132.237.254225.132.237.255254
239225.132.238.0/24225.132.238.1 to 225.132.238.254225.132.238.255254
240225.132.239.0/24225.132.239.1 to 225.132.239.254225.132.239.255254
241225.132.240.0/24225.132.240.1 to 225.132.240.254225.132.240.255254
242225.132.241.0/24225.132.241.1 to 225.132.241.254225.132.241.255254
243225.132.242.0/24225.132.242.1 to 225.132.242.254225.132.242.255254
244225.132.243.0/24225.132.243.1 to 225.132.243.254225.132.243.255254
245225.132.244.0/24225.132.244.1 to 225.132.244.254225.132.244.255254
246225.132.245.0/24225.132.245.1 to 225.132.245.254225.132.245.255254
247225.132.246.0/24225.132.246.1 to 225.132.246.254225.132.246.255254
248225.132.247.0/24225.132.247.1 to 225.132.247.254225.132.247.255254
249225.132.248.0/24225.132.248.1 to 225.132.248.254225.132.248.255254
250225.132.249.0/24225.132.249.1 to 225.132.249.254225.132.249.255254
251225.132.250.0/24225.132.250.1 to 225.132.250.254225.132.250.255254
252225.132.251.0/24225.132.251.1 to 225.132.251.254225.132.251.255254
253225.132.252.0/24225.132.252.1 to 225.132.252.254225.132.252.255254
254225.132.253.0/24225.132.253.1 to 225.132.253.254225.132.253.255254
255225.132.254.0/24225.132.254.1 to 225.132.254.254225.132.254.255254
256225.132.255.0/24225.132.255.1 to 225.132.255.254225.132.255.255254

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.