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.

Network145.80.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
145.80.0.0
Broadcast address
145.80.255.255
First usable
145.80.0.1
Last usable
145.80.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
B (default /16)
As numbers
Hex 91500000 · Integer 2437939200 to 2438004735
Reverse DNS zone
80.145.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010001.01010000..00000000.00000000145.80.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10010001.01010000..00000000.00000000145.80.0.0
Broadcast10010001.01010000..11111111.11111111145.80.255.255
Split into smaller subnets/25
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

145.80.0.0/16 makes 512 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.80.0.0/25145.80.0.1 to 145.80.0.126145.80.0.127126
2145.80.0.128/25145.80.0.129 to 145.80.0.254145.80.0.255126
3145.80.1.0/25145.80.1.1 to 145.80.1.126145.80.1.127126
4145.80.1.128/25145.80.1.129 to 145.80.1.254145.80.1.255126
5145.80.2.0/25145.80.2.1 to 145.80.2.126145.80.2.127126
6145.80.2.128/25145.80.2.129 to 145.80.2.254145.80.2.255126
7145.80.3.0/25145.80.3.1 to 145.80.3.126145.80.3.127126
8145.80.3.128/25145.80.3.129 to 145.80.3.254145.80.3.255126
9145.80.4.0/25145.80.4.1 to 145.80.4.126145.80.4.127126
10145.80.4.128/25145.80.4.129 to 145.80.4.254145.80.4.255126
11145.80.5.0/25145.80.5.1 to 145.80.5.126145.80.5.127126
12145.80.5.128/25145.80.5.129 to 145.80.5.254145.80.5.255126
13145.80.6.0/25145.80.6.1 to 145.80.6.126145.80.6.127126
14145.80.6.128/25145.80.6.129 to 145.80.6.254145.80.6.255126
15145.80.7.0/25145.80.7.1 to 145.80.7.126145.80.7.127126
16145.80.7.128/25145.80.7.129 to 145.80.7.254145.80.7.255126
17145.80.8.0/25145.80.8.1 to 145.80.8.126145.80.8.127126
18145.80.8.128/25145.80.8.129 to 145.80.8.254145.80.8.255126
19145.80.9.0/25145.80.9.1 to 145.80.9.126145.80.9.127126
20145.80.9.128/25145.80.9.129 to 145.80.9.254145.80.9.255126
21145.80.10.0/25145.80.10.1 to 145.80.10.126145.80.10.127126
22145.80.10.128/25145.80.10.129 to 145.80.10.254145.80.10.255126
23145.80.11.0/25145.80.11.1 to 145.80.11.126145.80.11.127126
24145.80.11.128/25145.80.11.129 to 145.80.11.254145.80.11.255126
25145.80.12.0/25145.80.12.1 to 145.80.12.126145.80.12.127126
26145.80.12.128/25145.80.12.129 to 145.80.12.254145.80.12.255126
27145.80.13.0/25145.80.13.1 to 145.80.13.126145.80.13.127126
28145.80.13.128/25145.80.13.129 to 145.80.13.254145.80.13.255126
29145.80.14.0/25145.80.14.1 to 145.80.14.126145.80.14.127126
30145.80.14.128/25145.80.14.129 to 145.80.14.254145.80.14.255126
31145.80.15.0/25145.80.15.1 to 145.80.15.126145.80.15.127126
32145.80.15.128/25145.80.15.129 to 145.80.15.254145.80.15.255126
33145.80.16.0/25145.80.16.1 to 145.80.16.126145.80.16.127126
34145.80.16.128/25145.80.16.129 to 145.80.16.254145.80.16.255126
35145.80.17.0/25145.80.17.1 to 145.80.17.126145.80.17.127126
36145.80.17.128/25145.80.17.129 to 145.80.17.254145.80.17.255126
37145.80.18.0/25145.80.18.1 to 145.80.18.126145.80.18.127126
38145.80.18.128/25145.80.18.129 to 145.80.18.254145.80.18.255126
39145.80.19.0/25145.80.19.1 to 145.80.19.126145.80.19.127126
40145.80.19.128/25145.80.19.129 to 145.80.19.254145.80.19.255126
41145.80.20.0/25145.80.20.1 to 145.80.20.126145.80.20.127126
42145.80.20.128/25145.80.20.129 to 145.80.20.254145.80.20.255126
43145.80.21.0/25145.80.21.1 to 145.80.21.126145.80.21.127126
44145.80.21.128/25145.80.21.129 to 145.80.21.254145.80.21.255126
45145.80.22.0/25145.80.22.1 to 145.80.22.126145.80.22.127126
46145.80.22.128/25145.80.22.129 to 145.80.22.254145.80.22.255126
47145.80.23.0/25145.80.23.1 to 145.80.23.126145.80.23.127126
48145.80.23.128/25145.80.23.129 to 145.80.23.254145.80.23.255126
49145.80.24.0/25145.80.24.1 to 145.80.24.126145.80.24.127126
50145.80.24.128/25145.80.24.129 to 145.80.24.254145.80.24.255126
51145.80.25.0/25145.80.25.1 to 145.80.25.126145.80.25.127126
52145.80.25.128/25145.80.25.129 to 145.80.25.254145.80.25.255126
53145.80.26.0/25145.80.26.1 to 145.80.26.126145.80.26.127126
54145.80.26.128/25145.80.26.129 to 145.80.26.254145.80.26.255126
55145.80.27.0/25145.80.27.1 to 145.80.27.126145.80.27.127126
56145.80.27.128/25145.80.27.129 to 145.80.27.254145.80.27.255126
57145.80.28.0/25145.80.28.1 to 145.80.28.126145.80.28.127126
58145.80.28.128/25145.80.28.129 to 145.80.28.254145.80.28.255126
59145.80.29.0/25145.80.29.1 to 145.80.29.126145.80.29.127126
60145.80.29.128/25145.80.29.129 to 145.80.29.254145.80.29.255126
61145.80.30.0/25145.80.30.1 to 145.80.30.126145.80.30.127126
62145.80.30.128/25145.80.30.129 to 145.80.30.254145.80.30.255126
63145.80.31.0/25145.80.31.1 to 145.80.31.126145.80.31.127126
64145.80.31.128/25145.80.31.129 to 145.80.31.254145.80.31.255126
65145.80.32.0/25145.80.32.1 to 145.80.32.126145.80.32.127126
66145.80.32.128/25145.80.32.129 to 145.80.32.254145.80.32.255126
67145.80.33.0/25145.80.33.1 to 145.80.33.126145.80.33.127126
68145.80.33.128/25145.80.33.129 to 145.80.33.254145.80.33.255126
69145.80.34.0/25145.80.34.1 to 145.80.34.126145.80.34.127126
70145.80.34.128/25145.80.34.129 to 145.80.34.254145.80.34.255126
71145.80.35.0/25145.80.35.1 to 145.80.35.126145.80.35.127126
72145.80.35.128/25145.80.35.129 to 145.80.35.254145.80.35.255126
73145.80.36.0/25145.80.36.1 to 145.80.36.126145.80.36.127126
74145.80.36.128/25145.80.36.129 to 145.80.36.254145.80.36.255126
75145.80.37.0/25145.80.37.1 to 145.80.37.126145.80.37.127126
76145.80.37.128/25145.80.37.129 to 145.80.37.254145.80.37.255126
77145.80.38.0/25145.80.38.1 to 145.80.38.126145.80.38.127126
78145.80.38.128/25145.80.38.129 to 145.80.38.254145.80.38.255126
79145.80.39.0/25145.80.39.1 to 145.80.39.126145.80.39.127126
80145.80.39.128/25145.80.39.129 to 145.80.39.254145.80.39.255126
81145.80.40.0/25145.80.40.1 to 145.80.40.126145.80.40.127126
82145.80.40.128/25145.80.40.129 to 145.80.40.254145.80.40.255126
83145.80.41.0/25145.80.41.1 to 145.80.41.126145.80.41.127126
84145.80.41.128/25145.80.41.129 to 145.80.41.254145.80.41.255126
85145.80.42.0/25145.80.42.1 to 145.80.42.126145.80.42.127126
86145.80.42.128/25145.80.42.129 to 145.80.42.254145.80.42.255126
87145.80.43.0/25145.80.43.1 to 145.80.43.126145.80.43.127126
88145.80.43.128/25145.80.43.129 to 145.80.43.254145.80.43.255126
89145.80.44.0/25145.80.44.1 to 145.80.44.126145.80.44.127126
90145.80.44.128/25145.80.44.129 to 145.80.44.254145.80.44.255126
91145.80.45.0/25145.80.45.1 to 145.80.45.126145.80.45.127126
92145.80.45.128/25145.80.45.129 to 145.80.45.254145.80.45.255126
93145.80.46.0/25145.80.46.1 to 145.80.46.126145.80.46.127126
94145.80.46.128/25145.80.46.129 to 145.80.46.254145.80.46.255126
95145.80.47.0/25145.80.47.1 to 145.80.47.126145.80.47.127126
96145.80.47.128/25145.80.47.129 to 145.80.47.254145.80.47.255126
97145.80.48.0/25145.80.48.1 to 145.80.48.126145.80.48.127126
98145.80.48.128/25145.80.48.129 to 145.80.48.254145.80.48.255126
99145.80.49.0/25145.80.49.1 to 145.80.49.126145.80.49.127126
100145.80.49.128/25145.80.49.129 to 145.80.49.254145.80.49.255126
101145.80.50.0/25145.80.50.1 to 145.80.50.126145.80.50.127126
102145.80.50.128/25145.80.50.129 to 145.80.50.254145.80.50.255126
103145.80.51.0/25145.80.51.1 to 145.80.51.126145.80.51.127126
104145.80.51.128/25145.80.51.129 to 145.80.51.254145.80.51.255126
105145.80.52.0/25145.80.52.1 to 145.80.52.126145.80.52.127126
106145.80.52.128/25145.80.52.129 to 145.80.52.254145.80.52.255126
107145.80.53.0/25145.80.53.1 to 145.80.53.126145.80.53.127126
108145.80.53.128/25145.80.53.129 to 145.80.53.254145.80.53.255126
109145.80.54.0/25145.80.54.1 to 145.80.54.126145.80.54.127126
110145.80.54.128/25145.80.54.129 to 145.80.54.254145.80.54.255126
111145.80.55.0/25145.80.55.1 to 145.80.55.126145.80.55.127126
112145.80.55.128/25145.80.55.129 to 145.80.55.254145.80.55.255126
113145.80.56.0/25145.80.56.1 to 145.80.56.126145.80.56.127126
114145.80.56.128/25145.80.56.129 to 145.80.56.254145.80.56.255126
115145.80.57.0/25145.80.57.1 to 145.80.57.126145.80.57.127126
116145.80.57.128/25145.80.57.129 to 145.80.57.254145.80.57.255126
117145.80.58.0/25145.80.58.1 to 145.80.58.126145.80.58.127126
118145.80.58.128/25145.80.58.129 to 145.80.58.254145.80.58.255126
119145.80.59.0/25145.80.59.1 to 145.80.59.126145.80.59.127126
120145.80.59.128/25145.80.59.129 to 145.80.59.254145.80.59.255126
121145.80.60.0/25145.80.60.1 to 145.80.60.126145.80.60.127126
122145.80.60.128/25145.80.60.129 to 145.80.60.254145.80.60.255126
123145.80.61.0/25145.80.61.1 to 145.80.61.126145.80.61.127126
124145.80.61.128/25145.80.61.129 to 145.80.61.254145.80.61.255126
125145.80.62.0/25145.80.62.1 to 145.80.62.126145.80.62.127126
126145.80.62.128/25145.80.62.129 to 145.80.62.254145.80.62.255126
127145.80.63.0/25145.80.63.1 to 145.80.63.126145.80.63.127126
128145.80.63.128/25145.80.63.129 to 145.80.63.254145.80.63.255126
129145.80.64.0/25145.80.64.1 to 145.80.64.126145.80.64.127126
130145.80.64.128/25145.80.64.129 to 145.80.64.254145.80.64.255126
131145.80.65.0/25145.80.65.1 to 145.80.65.126145.80.65.127126
132145.80.65.128/25145.80.65.129 to 145.80.65.254145.80.65.255126
133145.80.66.0/25145.80.66.1 to 145.80.66.126145.80.66.127126
134145.80.66.128/25145.80.66.129 to 145.80.66.254145.80.66.255126
135145.80.67.0/25145.80.67.1 to 145.80.67.126145.80.67.127126
136145.80.67.128/25145.80.67.129 to 145.80.67.254145.80.67.255126
137145.80.68.0/25145.80.68.1 to 145.80.68.126145.80.68.127126
138145.80.68.128/25145.80.68.129 to 145.80.68.254145.80.68.255126
139145.80.69.0/25145.80.69.1 to 145.80.69.126145.80.69.127126
140145.80.69.128/25145.80.69.129 to 145.80.69.254145.80.69.255126
141145.80.70.0/25145.80.70.1 to 145.80.70.126145.80.70.127126
142145.80.70.128/25145.80.70.129 to 145.80.70.254145.80.70.255126
143145.80.71.0/25145.80.71.1 to 145.80.71.126145.80.71.127126
144145.80.71.128/25145.80.71.129 to 145.80.71.254145.80.71.255126
145145.80.72.0/25145.80.72.1 to 145.80.72.126145.80.72.127126
146145.80.72.128/25145.80.72.129 to 145.80.72.254145.80.72.255126
147145.80.73.0/25145.80.73.1 to 145.80.73.126145.80.73.127126
148145.80.73.128/25145.80.73.129 to 145.80.73.254145.80.73.255126
149145.80.74.0/25145.80.74.1 to 145.80.74.126145.80.74.127126
150145.80.74.128/25145.80.74.129 to 145.80.74.254145.80.74.255126
151145.80.75.0/25145.80.75.1 to 145.80.75.126145.80.75.127126
152145.80.75.128/25145.80.75.129 to 145.80.75.254145.80.75.255126
153145.80.76.0/25145.80.76.1 to 145.80.76.126145.80.76.127126
154145.80.76.128/25145.80.76.129 to 145.80.76.254145.80.76.255126
155145.80.77.0/25145.80.77.1 to 145.80.77.126145.80.77.127126
156145.80.77.128/25145.80.77.129 to 145.80.77.254145.80.77.255126
157145.80.78.0/25145.80.78.1 to 145.80.78.126145.80.78.127126
158145.80.78.128/25145.80.78.129 to 145.80.78.254145.80.78.255126
159145.80.79.0/25145.80.79.1 to 145.80.79.126145.80.79.127126
160145.80.79.128/25145.80.79.129 to 145.80.79.254145.80.79.255126
161145.80.80.0/25145.80.80.1 to 145.80.80.126145.80.80.127126
162145.80.80.128/25145.80.80.129 to 145.80.80.254145.80.80.255126
163145.80.81.0/25145.80.81.1 to 145.80.81.126145.80.81.127126
164145.80.81.128/25145.80.81.129 to 145.80.81.254145.80.81.255126
165145.80.82.0/25145.80.82.1 to 145.80.82.126145.80.82.127126
166145.80.82.128/25145.80.82.129 to 145.80.82.254145.80.82.255126
167145.80.83.0/25145.80.83.1 to 145.80.83.126145.80.83.127126
168145.80.83.128/25145.80.83.129 to 145.80.83.254145.80.83.255126
169145.80.84.0/25145.80.84.1 to 145.80.84.126145.80.84.127126
170145.80.84.128/25145.80.84.129 to 145.80.84.254145.80.84.255126
171145.80.85.0/25145.80.85.1 to 145.80.85.126145.80.85.127126
172145.80.85.128/25145.80.85.129 to 145.80.85.254145.80.85.255126
173145.80.86.0/25145.80.86.1 to 145.80.86.126145.80.86.127126
174145.80.86.128/25145.80.86.129 to 145.80.86.254145.80.86.255126
175145.80.87.0/25145.80.87.1 to 145.80.87.126145.80.87.127126
176145.80.87.128/25145.80.87.129 to 145.80.87.254145.80.87.255126
177145.80.88.0/25145.80.88.1 to 145.80.88.126145.80.88.127126
178145.80.88.128/25145.80.88.129 to 145.80.88.254145.80.88.255126
179145.80.89.0/25145.80.89.1 to 145.80.89.126145.80.89.127126
180145.80.89.128/25145.80.89.129 to 145.80.89.254145.80.89.255126
181145.80.90.0/25145.80.90.1 to 145.80.90.126145.80.90.127126
182145.80.90.128/25145.80.90.129 to 145.80.90.254145.80.90.255126
183145.80.91.0/25145.80.91.1 to 145.80.91.126145.80.91.127126
184145.80.91.128/25145.80.91.129 to 145.80.91.254145.80.91.255126
185145.80.92.0/25145.80.92.1 to 145.80.92.126145.80.92.127126
186145.80.92.128/25145.80.92.129 to 145.80.92.254145.80.92.255126
187145.80.93.0/25145.80.93.1 to 145.80.93.126145.80.93.127126
188145.80.93.128/25145.80.93.129 to 145.80.93.254145.80.93.255126
189145.80.94.0/25145.80.94.1 to 145.80.94.126145.80.94.127126
190145.80.94.128/25145.80.94.129 to 145.80.94.254145.80.94.255126
191145.80.95.0/25145.80.95.1 to 145.80.95.126145.80.95.127126
192145.80.95.128/25145.80.95.129 to 145.80.95.254145.80.95.255126
193145.80.96.0/25145.80.96.1 to 145.80.96.126145.80.96.127126
194145.80.96.128/25145.80.96.129 to 145.80.96.254145.80.96.255126
195145.80.97.0/25145.80.97.1 to 145.80.97.126145.80.97.127126
196145.80.97.128/25145.80.97.129 to 145.80.97.254145.80.97.255126
197145.80.98.0/25145.80.98.1 to 145.80.98.126145.80.98.127126
198145.80.98.128/25145.80.98.129 to 145.80.98.254145.80.98.255126
199145.80.99.0/25145.80.99.1 to 145.80.99.126145.80.99.127126
200145.80.99.128/25145.80.99.129 to 145.80.99.254145.80.99.255126
201145.80.100.0/25145.80.100.1 to 145.80.100.126145.80.100.127126
202145.80.100.128/25145.80.100.129 to 145.80.100.254145.80.100.255126
203145.80.101.0/25145.80.101.1 to 145.80.101.126145.80.101.127126
204145.80.101.128/25145.80.101.129 to 145.80.101.254145.80.101.255126
205145.80.102.0/25145.80.102.1 to 145.80.102.126145.80.102.127126
206145.80.102.128/25145.80.102.129 to 145.80.102.254145.80.102.255126
207145.80.103.0/25145.80.103.1 to 145.80.103.126145.80.103.127126
208145.80.103.128/25145.80.103.129 to 145.80.103.254145.80.103.255126
209145.80.104.0/25145.80.104.1 to 145.80.104.126145.80.104.127126
210145.80.104.128/25145.80.104.129 to 145.80.104.254145.80.104.255126
211145.80.105.0/25145.80.105.1 to 145.80.105.126145.80.105.127126
212145.80.105.128/25145.80.105.129 to 145.80.105.254145.80.105.255126
213145.80.106.0/25145.80.106.1 to 145.80.106.126145.80.106.127126
214145.80.106.128/25145.80.106.129 to 145.80.106.254145.80.106.255126
215145.80.107.0/25145.80.107.1 to 145.80.107.126145.80.107.127126
216145.80.107.128/25145.80.107.129 to 145.80.107.254145.80.107.255126
217145.80.108.0/25145.80.108.1 to 145.80.108.126145.80.108.127126
218145.80.108.128/25145.80.108.129 to 145.80.108.254145.80.108.255126
219145.80.109.0/25145.80.109.1 to 145.80.109.126145.80.109.127126
220145.80.109.128/25145.80.109.129 to 145.80.109.254145.80.109.255126
221145.80.110.0/25145.80.110.1 to 145.80.110.126145.80.110.127126
222145.80.110.128/25145.80.110.129 to 145.80.110.254145.80.110.255126
223145.80.111.0/25145.80.111.1 to 145.80.111.126145.80.111.127126
224145.80.111.128/25145.80.111.129 to 145.80.111.254145.80.111.255126
225145.80.112.0/25145.80.112.1 to 145.80.112.126145.80.112.127126
226145.80.112.128/25145.80.112.129 to 145.80.112.254145.80.112.255126
227145.80.113.0/25145.80.113.1 to 145.80.113.126145.80.113.127126
228145.80.113.128/25145.80.113.129 to 145.80.113.254145.80.113.255126
229145.80.114.0/25145.80.114.1 to 145.80.114.126145.80.114.127126
230145.80.114.128/25145.80.114.129 to 145.80.114.254145.80.114.255126
231145.80.115.0/25145.80.115.1 to 145.80.115.126145.80.115.127126
232145.80.115.128/25145.80.115.129 to 145.80.115.254145.80.115.255126
233145.80.116.0/25145.80.116.1 to 145.80.116.126145.80.116.127126
234145.80.116.128/25145.80.116.129 to 145.80.116.254145.80.116.255126
235145.80.117.0/25145.80.117.1 to 145.80.117.126145.80.117.127126
236145.80.117.128/25145.80.117.129 to 145.80.117.254145.80.117.255126
237145.80.118.0/25145.80.118.1 to 145.80.118.126145.80.118.127126
238145.80.118.128/25145.80.118.129 to 145.80.118.254145.80.118.255126
239145.80.119.0/25145.80.119.1 to 145.80.119.126145.80.119.127126
240145.80.119.128/25145.80.119.129 to 145.80.119.254145.80.119.255126
241145.80.120.0/25145.80.120.1 to 145.80.120.126145.80.120.127126
242145.80.120.128/25145.80.120.129 to 145.80.120.254145.80.120.255126
243145.80.121.0/25145.80.121.1 to 145.80.121.126145.80.121.127126
244145.80.121.128/25145.80.121.129 to 145.80.121.254145.80.121.255126
245145.80.122.0/25145.80.122.1 to 145.80.122.126145.80.122.127126
246145.80.122.128/25145.80.122.129 to 145.80.122.254145.80.122.255126
247145.80.123.0/25145.80.123.1 to 145.80.123.126145.80.123.127126
248145.80.123.128/25145.80.123.129 to 145.80.123.254145.80.123.255126
249145.80.124.0/25145.80.124.1 to 145.80.124.126145.80.124.127126
250145.80.124.128/25145.80.124.129 to 145.80.124.254145.80.124.255126
251145.80.125.0/25145.80.125.1 to 145.80.125.126145.80.125.127126
252145.80.125.128/25145.80.125.129 to 145.80.125.254145.80.125.255126
253145.80.126.0/25145.80.126.1 to 145.80.126.126145.80.126.127126
254145.80.126.128/25145.80.126.129 to 145.80.126.254145.80.126.255126
255145.80.127.0/25145.80.127.1 to 145.80.127.126145.80.127.127126
256145.80.127.128/25145.80.127.129 to 145.80.127.254145.80.127.255126

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.