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.

Network201.148.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
201.148.0.0
Broadcast address
201.151.255.255
First usable
201.148.0.1
Last usable
201.151.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
C (default /24)
As numbers
Hex C9940000 · Integer 3381919744 to 3382181887
Reverse DNS zones
148.201.in-addr.arpa
149.201.in-addr.arpa
150.201.in-addr.arpa
151.201.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001001.10010100.00000000.00000000201.148.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network11001001.10010100.00000000.00000000201.148.0.0
Broadcast11001001.10010111.11111111.11111111201.151.255.255
Split into smaller subnets/25
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

201.148.0.0/14 makes 2,048 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1201.148.0.0/25201.148.0.1 to 201.148.0.126201.148.0.127126
2201.148.0.128/25201.148.0.129 to 201.148.0.254201.148.0.255126
3201.148.1.0/25201.148.1.1 to 201.148.1.126201.148.1.127126
4201.148.1.128/25201.148.1.129 to 201.148.1.254201.148.1.255126
5201.148.2.0/25201.148.2.1 to 201.148.2.126201.148.2.127126
6201.148.2.128/25201.148.2.129 to 201.148.2.254201.148.2.255126
7201.148.3.0/25201.148.3.1 to 201.148.3.126201.148.3.127126
8201.148.3.128/25201.148.3.129 to 201.148.3.254201.148.3.255126
9201.148.4.0/25201.148.4.1 to 201.148.4.126201.148.4.127126
10201.148.4.128/25201.148.4.129 to 201.148.4.254201.148.4.255126
11201.148.5.0/25201.148.5.1 to 201.148.5.126201.148.5.127126
12201.148.5.128/25201.148.5.129 to 201.148.5.254201.148.5.255126
13201.148.6.0/25201.148.6.1 to 201.148.6.126201.148.6.127126
14201.148.6.128/25201.148.6.129 to 201.148.6.254201.148.6.255126
15201.148.7.0/25201.148.7.1 to 201.148.7.126201.148.7.127126
16201.148.7.128/25201.148.7.129 to 201.148.7.254201.148.7.255126
17201.148.8.0/25201.148.8.1 to 201.148.8.126201.148.8.127126
18201.148.8.128/25201.148.8.129 to 201.148.8.254201.148.8.255126
19201.148.9.0/25201.148.9.1 to 201.148.9.126201.148.9.127126
20201.148.9.128/25201.148.9.129 to 201.148.9.254201.148.9.255126
21201.148.10.0/25201.148.10.1 to 201.148.10.126201.148.10.127126
22201.148.10.128/25201.148.10.129 to 201.148.10.254201.148.10.255126
23201.148.11.0/25201.148.11.1 to 201.148.11.126201.148.11.127126
24201.148.11.128/25201.148.11.129 to 201.148.11.254201.148.11.255126
25201.148.12.0/25201.148.12.1 to 201.148.12.126201.148.12.127126
26201.148.12.128/25201.148.12.129 to 201.148.12.254201.148.12.255126
27201.148.13.0/25201.148.13.1 to 201.148.13.126201.148.13.127126
28201.148.13.128/25201.148.13.129 to 201.148.13.254201.148.13.255126
29201.148.14.0/25201.148.14.1 to 201.148.14.126201.148.14.127126
30201.148.14.128/25201.148.14.129 to 201.148.14.254201.148.14.255126
31201.148.15.0/25201.148.15.1 to 201.148.15.126201.148.15.127126
32201.148.15.128/25201.148.15.129 to 201.148.15.254201.148.15.255126
33201.148.16.0/25201.148.16.1 to 201.148.16.126201.148.16.127126
34201.148.16.128/25201.148.16.129 to 201.148.16.254201.148.16.255126
35201.148.17.0/25201.148.17.1 to 201.148.17.126201.148.17.127126
36201.148.17.128/25201.148.17.129 to 201.148.17.254201.148.17.255126
37201.148.18.0/25201.148.18.1 to 201.148.18.126201.148.18.127126
38201.148.18.128/25201.148.18.129 to 201.148.18.254201.148.18.255126
39201.148.19.0/25201.148.19.1 to 201.148.19.126201.148.19.127126
40201.148.19.128/25201.148.19.129 to 201.148.19.254201.148.19.255126
41201.148.20.0/25201.148.20.1 to 201.148.20.126201.148.20.127126
42201.148.20.128/25201.148.20.129 to 201.148.20.254201.148.20.255126
43201.148.21.0/25201.148.21.1 to 201.148.21.126201.148.21.127126
44201.148.21.128/25201.148.21.129 to 201.148.21.254201.148.21.255126
45201.148.22.0/25201.148.22.1 to 201.148.22.126201.148.22.127126
46201.148.22.128/25201.148.22.129 to 201.148.22.254201.148.22.255126
47201.148.23.0/25201.148.23.1 to 201.148.23.126201.148.23.127126
48201.148.23.128/25201.148.23.129 to 201.148.23.254201.148.23.255126
49201.148.24.0/25201.148.24.1 to 201.148.24.126201.148.24.127126
50201.148.24.128/25201.148.24.129 to 201.148.24.254201.148.24.255126
51201.148.25.0/25201.148.25.1 to 201.148.25.126201.148.25.127126
52201.148.25.128/25201.148.25.129 to 201.148.25.254201.148.25.255126
53201.148.26.0/25201.148.26.1 to 201.148.26.126201.148.26.127126
54201.148.26.128/25201.148.26.129 to 201.148.26.254201.148.26.255126
55201.148.27.0/25201.148.27.1 to 201.148.27.126201.148.27.127126
56201.148.27.128/25201.148.27.129 to 201.148.27.254201.148.27.255126
57201.148.28.0/25201.148.28.1 to 201.148.28.126201.148.28.127126
58201.148.28.128/25201.148.28.129 to 201.148.28.254201.148.28.255126
59201.148.29.0/25201.148.29.1 to 201.148.29.126201.148.29.127126
60201.148.29.128/25201.148.29.129 to 201.148.29.254201.148.29.255126
61201.148.30.0/25201.148.30.1 to 201.148.30.126201.148.30.127126
62201.148.30.128/25201.148.30.129 to 201.148.30.254201.148.30.255126
63201.148.31.0/25201.148.31.1 to 201.148.31.126201.148.31.127126
64201.148.31.128/25201.148.31.129 to 201.148.31.254201.148.31.255126
65201.148.32.0/25201.148.32.1 to 201.148.32.126201.148.32.127126
66201.148.32.128/25201.148.32.129 to 201.148.32.254201.148.32.255126
67201.148.33.0/25201.148.33.1 to 201.148.33.126201.148.33.127126
68201.148.33.128/25201.148.33.129 to 201.148.33.254201.148.33.255126
69201.148.34.0/25201.148.34.1 to 201.148.34.126201.148.34.127126
70201.148.34.128/25201.148.34.129 to 201.148.34.254201.148.34.255126
71201.148.35.0/25201.148.35.1 to 201.148.35.126201.148.35.127126
72201.148.35.128/25201.148.35.129 to 201.148.35.254201.148.35.255126
73201.148.36.0/25201.148.36.1 to 201.148.36.126201.148.36.127126
74201.148.36.128/25201.148.36.129 to 201.148.36.254201.148.36.255126
75201.148.37.0/25201.148.37.1 to 201.148.37.126201.148.37.127126
76201.148.37.128/25201.148.37.129 to 201.148.37.254201.148.37.255126
77201.148.38.0/25201.148.38.1 to 201.148.38.126201.148.38.127126
78201.148.38.128/25201.148.38.129 to 201.148.38.254201.148.38.255126
79201.148.39.0/25201.148.39.1 to 201.148.39.126201.148.39.127126
80201.148.39.128/25201.148.39.129 to 201.148.39.254201.148.39.255126
81201.148.40.0/25201.148.40.1 to 201.148.40.126201.148.40.127126
82201.148.40.128/25201.148.40.129 to 201.148.40.254201.148.40.255126
83201.148.41.0/25201.148.41.1 to 201.148.41.126201.148.41.127126
84201.148.41.128/25201.148.41.129 to 201.148.41.254201.148.41.255126
85201.148.42.0/25201.148.42.1 to 201.148.42.126201.148.42.127126
86201.148.42.128/25201.148.42.129 to 201.148.42.254201.148.42.255126
87201.148.43.0/25201.148.43.1 to 201.148.43.126201.148.43.127126
88201.148.43.128/25201.148.43.129 to 201.148.43.254201.148.43.255126
89201.148.44.0/25201.148.44.1 to 201.148.44.126201.148.44.127126
90201.148.44.128/25201.148.44.129 to 201.148.44.254201.148.44.255126
91201.148.45.0/25201.148.45.1 to 201.148.45.126201.148.45.127126
92201.148.45.128/25201.148.45.129 to 201.148.45.254201.148.45.255126
93201.148.46.0/25201.148.46.1 to 201.148.46.126201.148.46.127126
94201.148.46.128/25201.148.46.129 to 201.148.46.254201.148.46.255126
95201.148.47.0/25201.148.47.1 to 201.148.47.126201.148.47.127126
96201.148.47.128/25201.148.47.129 to 201.148.47.254201.148.47.255126
97201.148.48.0/25201.148.48.1 to 201.148.48.126201.148.48.127126
98201.148.48.128/25201.148.48.129 to 201.148.48.254201.148.48.255126
99201.148.49.0/25201.148.49.1 to 201.148.49.126201.148.49.127126
100201.148.49.128/25201.148.49.129 to 201.148.49.254201.148.49.255126
101201.148.50.0/25201.148.50.1 to 201.148.50.126201.148.50.127126
102201.148.50.128/25201.148.50.129 to 201.148.50.254201.148.50.255126
103201.148.51.0/25201.148.51.1 to 201.148.51.126201.148.51.127126
104201.148.51.128/25201.148.51.129 to 201.148.51.254201.148.51.255126
105201.148.52.0/25201.148.52.1 to 201.148.52.126201.148.52.127126
106201.148.52.128/25201.148.52.129 to 201.148.52.254201.148.52.255126
107201.148.53.0/25201.148.53.1 to 201.148.53.126201.148.53.127126
108201.148.53.128/25201.148.53.129 to 201.148.53.254201.148.53.255126
109201.148.54.0/25201.148.54.1 to 201.148.54.126201.148.54.127126
110201.148.54.128/25201.148.54.129 to 201.148.54.254201.148.54.255126
111201.148.55.0/25201.148.55.1 to 201.148.55.126201.148.55.127126
112201.148.55.128/25201.148.55.129 to 201.148.55.254201.148.55.255126
113201.148.56.0/25201.148.56.1 to 201.148.56.126201.148.56.127126
114201.148.56.128/25201.148.56.129 to 201.148.56.254201.148.56.255126
115201.148.57.0/25201.148.57.1 to 201.148.57.126201.148.57.127126
116201.148.57.128/25201.148.57.129 to 201.148.57.254201.148.57.255126
117201.148.58.0/25201.148.58.1 to 201.148.58.126201.148.58.127126
118201.148.58.128/25201.148.58.129 to 201.148.58.254201.148.58.255126
119201.148.59.0/25201.148.59.1 to 201.148.59.126201.148.59.127126
120201.148.59.128/25201.148.59.129 to 201.148.59.254201.148.59.255126
121201.148.60.0/25201.148.60.1 to 201.148.60.126201.148.60.127126
122201.148.60.128/25201.148.60.129 to 201.148.60.254201.148.60.255126
123201.148.61.0/25201.148.61.1 to 201.148.61.126201.148.61.127126
124201.148.61.128/25201.148.61.129 to 201.148.61.254201.148.61.255126
125201.148.62.0/25201.148.62.1 to 201.148.62.126201.148.62.127126
126201.148.62.128/25201.148.62.129 to 201.148.62.254201.148.62.255126
127201.148.63.0/25201.148.63.1 to 201.148.63.126201.148.63.127126
128201.148.63.128/25201.148.63.129 to 201.148.63.254201.148.63.255126
129201.148.64.0/25201.148.64.1 to 201.148.64.126201.148.64.127126
130201.148.64.128/25201.148.64.129 to 201.148.64.254201.148.64.255126
131201.148.65.0/25201.148.65.1 to 201.148.65.126201.148.65.127126
132201.148.65.128/25201.148.65.129 to 201.148.65.254201.148.65.255126
133201.148.66.0/25201.148.66.1 to 201.148.66.126201.148.66.127126
134201.148.66.128/25201.148.66.129 to 201.148.66.254201.148.66.255126
135201.148.67.0/25201.148.67.1 to 201.148.67.126201.148.67.127126
136201.148.67.128/25201.148.67.129 to 201.148.67.254201.148.67.255126
137201.148.68.0/25201.148.68.1 to 201.148.68.126201.148.68.127126
138201.148.68.128/25201.148.68.129 to 201.148.68.254201.148.68.255126
139201.148.69.0/25201.148.69.1 to 201.148.69.126201.148.69.127126
140201.148.69.128/25201.148.69.129 to 201.148.69.254201.148.69.255126
141201.148.70.0/25201.148.70.1 to 201.148.70.126201.148.70.127126
142201.148.70.128/25201.148.70.129 to 201.148.70.254201.148.70.255126
143201.148.71.0/25201.148.71.1 to 201.148.71.126201.148.71.127126
144201.148.71.128/25201.148.71.129 to 201.148.71.254201.148.71.255126
145201.148.72.0/25201.148.72.1 to 201.148.72.126201.148.72.127126
146201.148.72.128/25201.148.72.129 to 201.148.72.254201.148.72.255126
147201.148.73.0/25201.148.73.1 to 201.148.73.126201.148.73.127126
148201.148.73.128/25201.148.73.129 to 201.148.73.254201.148.73.255126
149201.148.74.0/25201.148.74.1 to 201.148.74.126201.148.74.127126
150201.148.74.128/25201.148.74.129 to 201.148.74.254201.148.74.255126
151201.148.75.0/25201.148.75.1 to 201.148.75.126201.148.75.127126
152201.148.75.128/25201.148.75.129 to 201.148.75.254201.148.75.255126
153201.148.76.0/25201.148.76.1 to 201.148.76.126201.148.76.127126
154201.148.76.128/25201.148.76.129 to 201.148.76.254201.148.76.255126
155201.148.77.0/25201.148.77.1 to 201.148.77.126201.148.77.127126
156201.148.77.128/25201.148.77.129 to 201.148.77.254201.148.77.255126
157201.148.78.0/25201.148.78.1 to 201.148.78.126201.148.78.127126
158201.148.78.128/25201.148.78.129 to 201.148.78.254201.148.78.255126
159201.148.79.0/25201.148.79.1 to 201.148.79.126201.148.79.127126
160201.148.79.128/25201.148.79.129 to 201.148.79.254201.148.79.255126
161201.148.80.0/25201.148.80.1 to 201.148.80.126201.148.80.127126
162201.148.80.128/25201.148.80.129 to 201.148.80.254201.148.80.255126
163201.148.81.0/25201.148.81.1 to 201.148.81.126201.148.81.127126
164201.148.81.128/25201.148.81.129 to 201.148.81.254201.148.81.255126
165201.148.82.0/25201.148.82.1 to 201.148.82.126201.148.82.127126
166201.148.82.128/25201.148.82.129 to 201.148.82.254201.148.82.255126
167201.148.83.0/25201.148.83.1 to 201.148.83.126201.148.83.127126
168201.148.83.128/25201.148.83.129 to 201.148.83.254201.148.83.255126
169201.148.84.0/25201.148.84.1 to 201.148.84.126201.148.84.127126
170201.148.84.128/25201.148.84.129 to 201.148.84.254201.148.84.255126
171201.148.85.0/25201.148.85.1 to 201.148.85.126201.148.85.127126
172201.148.85.128/25201.148.85.129 to 201.148.85.254201.148.85.255126
173201.148.86.0/25201.148.86.1 to 201.148.86.126201.148.86.127126
174201.148.86.128/25201.148.86.129 to 201.148.86.254201.148.86.255126
175201.148.87.0/25201.148.87.1 to 201.148.87.126201.148.87.127126
176201.148.87.128/25201.148.87.129 to 201.148.87.254201.148.87.255126
177201.148.88.0/25201.148.88.1 to 201.148.88.126201.148.88.127126
178201.148.88.128/25201.148.88.129 to 201.148.88.254201.148.88.255126
179201.148.89.0/25201.148.89.1 to 201.148.89.126201.148.89.127126
180201.148.89.128/25201.148.89.129 to 201.148.89.254201.148.89.255126
181201.148.90.0/25201.148.90.1 to 201.148.90.126201.148.90.127126
182201.148.90.128/25201.148.90.129 to 201.148.90.254201.148.90.255126
183201.148.91.0/25201.148.91.1 to 201.148.91.126201.148.91.127126
184201.148.91.128/25201.148.91.129 to 201.148.91.254201.148.91.255126
185201.148.92.0/25201.148.92.1 to 201.148.92.126201.148.92.127126
186201.148.92.128/25201.148.92.129 to 201.148.92.254201.148.92.255126
187201.148.93.0/25201.148.93.1 to 201.148.93.126201.148.93.127126
188201.148.93.128/25201.148.93.129 to 201.148.93.254201.148.93.255126
189201.148.94.0/25201.148.94.1 to 201.148.94.126201.148.94.127126
190201.148.94.128/25201.148.94.129 to 201.148.94.254201.148.94.255126
191201.148.95.0/25201.148.95.1 to 201.148.95.126201.148.95.127126
192201.148.95.128/25201.148.95.129 to 201.148.95.254201.148.95.255126
193201.148.96.0/25201.148.96.1 to 201.148.96.126201.148.96.127126
194201.148.96.128/25201.148.96.129 to 201.148.96.254201.148.96.255126
195201.148.97.0/25201.148.97.1 to 201.148.97.126201.148.97.127126
196201.148.97.128/25201.148.97.129 to 201.148.97.254201.148.97.255126
197201.148.98.0/25201.148.98.1 to 201.148.98.126201.148.98.127126
198201.148.98.128/25201.148.98.129 to 201.148.98.254201.148.98.255126
199201.148.99.0/25201.148.99.1 to 201.148.99.126201.148.99.127126
200201.148.99.128/25201.148.99.129 to 201.148.99.254201.148.99.255126
201201.148.100.0/25201.148.100.1 to 201.148.100.126201.148.100.127126
202201.148.100.128/25201.148.100.129 to 201.148.100.254201.148.100.255126
203201.148.101.0/25201.148.101.1 to 201.148.101.126201.148.101.127126
204201.148.101.128/25201.148.101.129 to 201.148.101.254201.148.101.255126
205201.148.102.0/25201.148.102.1 to 201.148.102.126201.148.102.127126
206201.148.102.128/25201.148.102.129 to 201.148.102.254201.148.102.255126
207201.148.103.0/25201.148.103.1 to 201.148.103.126201.148.103.127126
208201.148.103.128/25201.148.103.129 to 201.148.103.254201.148.103.255126
209201.148.104.0/25201.148.104.1 to 201.148.104.126201.148.104.127126
210201.148.104.128/25201.148.104.129 to 201.148.104.254201.148.104.255126
211201.148.105.0/25201.148.105.1 to 201.148.105.126201.148.105.127126
212201.148.105.128/25201.148.105.129 to 201.148.105.254201.148.105.255126
213201.148.106.0/25201.148.106.1 to 201.148.106.126201.148.106.127126
214201.148.106.128/25201.148.106.129 to 201.148.106.254201.148.106.255126
215201.148.107.0/25201.148.107.1 to 201.148.107.126201.148.107.127126
216201.148.107.128/25201.148.107.129 to 201.148.107.254201.148.107.255126
217201.148.108.0/25201.148.108.1 to 201.148.108.126201.148.108.127126
218201.148.108.128/25201.148.108.129 to 201.148.108.254201.148.108.255126
219201.148.109.0/25201.148.109.1 to 201.148.109.126201.148.109.127126
220201.148.109.128/25201.148.109.129 to 201.148.109.254201.148.109.255126
221201.148.110.0/25201.148.110.1 to 201.148.110.126201.148.110.127126
222201.148.110.128/25201.148.110.129 to 201.148.110.254201.148.110.255126
223201.148.111.0/25201.148.111.1 to 201.148.111.126201.148.111.127126
224201.148.111.128/25201.148.111.129 to 201.148.111.254201.148.111.255126
225201.148.112.0/25201.148.112.1 to 201.148.112.126201.148.112.127126
226201.148.112.128/25201.148.112.129 to 201.148.112.254201.148.112.255126
227201.148.113.0/25201.148.113.1 to 201.148.113.126201.148.113.127126
228201.148.113.128/25201.148.113.129 to 201.148.113.254201.148.113.255126
229201.148.114.0/25201.148.114.1 to 201.148.114.126201.148.114.127126
230201.148.114.128/25201.148.114.129 to 201.148.114.254201.148.114.255126
231201.148.115.0/25201.148.115.1 to 201.148.115.126201.148.115.127126
232201.148.115.128/25201.148.115.129 to 201.148.115.254201.148.115.255126
233201.148.116.0/25201.148.116.1 to 201.148.116.126201.148.116.127126
234201.148.116.128/25201.148.116.129 to 201.148.116.254201.148.116.255126
235201.148.117.0/25201.148.117.1 to 201.148.117.126201.148.117.127126
236201.148.117.128/25201.148.117.129 to 201.148.117.254201.148.117.255126
237201.148.118.0/25201.148.118.1 to 201.148.118.126201.148.118.127126
238201.148.118.128/25201.148.118.129 to 201.148.118.254201.148.118.255126
239201.148.119.0/25201.148.119.1 to 201.148.119.126201.148.119.127126
240201.148.119.128/25201.148.119.129 to 201.148.119.254201.148.119.255126
241201.148.120.0/25201.148.120.1 to 201.148.120.126201.148.120.127126
242201.148.120.128/25201.148.120.129 to 201.148.120.254201.148.120.255126
243201.148.121.0/25201.148.121.1 to 201.148.121.126201.148.121.127126
244201.148.121.128/25201.148.121.129 to 201.148.121.254201.148.121.255126
245201.148.122.0/25201.148.122.1 to 201.148.122.126201.148.122.127126
246201.148.122.128/25201.148.122.129 to 201.148.122.254201.148.122.255126
247201.148.123.0/25201.148.123.1 to 201.148.123.126201.148.123.127126
248201.148.123.128/25201.148.123.129 to 201.148.123.254201.148.123.255126
249201.148.124.0/25201.148.124.1 to 201.148.124.126201.148.124.127126
250201.148.124.128/25201.148.124.129 to 201.148.124.254201.148.124.255126
251201.148.125.0/25201.148.125.1 to 201.148.125.126201.148.125.127126
252201.148.125.128/25201.148.125.129 to 201.148.125.254201.148.125.255126
253201.148.126.0/25201.148.126.1 to 201.148.126.126201.148.126.127126
254201.148.126.128/25201.148.126.129 to 201.148.126.254201.148.126.255126
255201.148.127.0/25201.148.127.1 to 201.148.127.126201.148.127.127126
256201.148.127.128/25201.148.127.129 to 201.148.127.254201.148.127.255126

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.