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.

Network148.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
148.0.0.0
Broadcast address
149.255.255.255
First usable
148.0.0.1
Last usable
149.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 94000000 · Integer 2483027968 to 2516582399
Reverse DNS zones
148.in-addr.arpa
149.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010100.00000000.00000000.00000000148.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10010100.00000000.00000000.00000000148.0.0.0
Broadcast10010101.11111111.11111111.11111111149.255.255.255
Split into smaller subnets/18
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

148.0.0.0/7 makes 2,048 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1148.0.0.0/18148.0.0.1 to 148.0.63.254148.0.63.25516,382
2148.0.64.0/18148.0.64.1 to 148.0.127.254148.0.127.25516,382
3148.0.128.0/18148.0.128.1 to 148.0.191.254148.0.191.25516,382
4148.0.192.0/18148.0.192.1 to 148.0.255.254148.0.255.25516,382
5148.1.0.0/18148.1.0.1 to 148.1.63.254148.1.63.25516,382
6148.1.64.0/18148.1.64.1 to 148.1.127.254148.1.127.25516,382
7148.1.128.0/18148.1.128.1 to 148.1.191.254148.1.191.25516,382
8148.1.192.0/18148.1.192.1 to 148.1.255.254148.1.255.25516,382
9148.2.0.0/18148.2.0.1 to 148.2.63.254148.2.63.25516,382
10148.2.64.0/18148.2.64.1 to 148.2.127.254148.2.127.25516,382
11148.2.128.0/18148.2.128.1 to 148.2.191.254148.2.191.25516,382
12148.2.192.0/18148.2.192.1 to 148.2.255.254148.2.255.25516,382
13148.3.0.0/18148.3.0.1 to 148.3.63.254148.3.63.25516,382
14148.3.64.0/18148.3.64.1 to 148.3.127.254148.3.127.25516,382
15148.3.128.0/18148.3.128.1 to 148.3.191.254148.3.191.25516,382
16148.3.192.0/18148.3.192.1 to 148.3.255.254148.3.255.25516,382
17148.4.0.0/18148.4.0.1 to 148.4.63.254148.4.63.25516,382
18148.4.64.0/18148.4.64.1 to 148.4.127.254148.4.127.25516,382
19148.4.128.0/18148.4.128.1 to 148.4.191.254148.4.191.25516,382
20148.4.192.0/18148.4.192.1 to 148.4.255.254148.4.255.25516,382
21148.5.0.0/18148.5.0.1 to 148.5.63.254148.5.63.25516,382
22148.5.64.0/18148.5.64.1 to 148.5.127.254148.5.127.25516,382
23148.5.128.0/18148.5.128.1 to 148.5.191.254148.5.191.25516,382
24148.5.192.0/18148.5.192.1 to 148.5.255.254148.5.255.25516,382
25148.6.0.0/18148.6.0.1 to 148.6.63.254148.6.63.25516,382
26148.6.64.0/18148.6.64.1 to 148.6.127.254148.6.127.25516,382
27148.6.128.0/18148.6.128.1 to 148.6.191.254148.6.191.25516,382
28148.6.192.0/18148.6.192.1 to 148.6.255.254148.6.255.25516,382
29148.7.0.0/18148.7.0.1 to 148.7.63.254148.7.63.25516,382
30148.7.64.0/18148.7.64.1 to 148.7.127.254148.7.127.25516,382
31148.7.128.0/18148.7.128.1 to 148.7.191.254148.7.191.25516,382
32148.7.192.0/18148.7.192.1 to 148.7.255.254148.7.255.25516,382
33148.8.0.0/18148.8.0.1 to 148.8.63.254148.8.63.25516,382
34148.8.64.0/18148.8.64.1 to 148.8.127.254148.8.127.25516,382
35148.8.128.0/18148.8.128.1 to 148.8.191.254148.8.191.25516,382
36148.8.192.0/18148.8.192.1 to 148.8.255.254148.8.255.25516,382
37148.9.0.0/18148.9.0.1 to 148.9.63.254148.9.63.25516,382
38148.9.64.0/18148.9.64.1 to 148.9.127.254148.9.127.25516,382
39148.9.128.0/18148.9.128.1 to 148.9.191.254148.9.191.25516,382
40148.9.192.0/18148.9.192.1 to 148.9.255.254148.9.255.25516,382
41148.10.0.0/18148.10.0.1 to 148.10.63.254148.10.63.25516,382
42148.10.64.0/18148.10.64.1 to 148.10.127.254148.10.127.25516,382
43148.10.128.0/18148.10.128.1 to 148.10.191.254148.10.191.25516,382
44148.10.192.0/18148.10.192.1 to 148.10.255.254148.10.255.25516,382
45148.11.0.0/18148.11.0.1 to 148.11.63.254148.11.63.25516,382
46148.11.64.0/18148.11.64.1 to 148.11.127.254148.11.127.25516,382
47148.11.128.0/18148.11.128.1 to 148.11.191.254148.11.191.25516,382
48148.11.192.0/18148.11.192.1 to 148.11.255.254148.11.255.25516,382
49148.12.0.0/18148.12.0.1 to 148.12.63.254148.12.63.25516,382
50148.12.64.0/18148.12.64.1 to 148.12.127.254148.12.127.25516,382
51148.12.128.0/18148.12.128.1 to 148.12.191.254148.12.191.25516,382
52148.12.192.0/18148.12.192.1 to 148.12.255.254148.12.255.25516,382
53148.13.0.0/18148.13.0.1 to 148.13.63.254148.13.63.25516,382
54148.13.64.0/18148.13.64.1 to 148.13.127.254148.13.127.25516,382
55148.13.128.0/18148.13.128.1 to 148.13.191.254148.13.191.25516,382
56148.13.192.0/18148.13.192.1 to 148.13.255.254148.13.255.25516,382
57148.14.0.0/18148.14.0.1 to 148.14.63.254148.14.63.25516,382
58148.14.64.0/18148.14.64.1 to 148.14.127.254148.14.127.25516,382
59148.14.128.0/18148.14.128.1 to 148.14.191.254148.14.191.25516,382
60148.14.192.0/18148.14.192.1 to 148.14.255.254148.14.255.25516,382
61148.15.0.0/18148.15.0.1 to 148.15.63.254148.15.63.25516,382
62148.15.64.0/18148.15.64.1 to 148.15.127.254148.15.127.25516,382
63148.15.128.0/18148.15.128.1 to 148.15.191.254148.15.191.25516,382
64148.15.192.0/18148.15.192.1 to 148.15.255.254148.15.255.25516,382
65148.16.0.0/18148.16.0.1 to 148.16.63.254148.16.63.25516,382
66148.16.64.0/18148.16.64.1 to 148.16.127.254148.16.127.25516,382
67148.16.128.0/18148.16.128.1 to 148.16.191.254148.16.191.25516,382
68148.16.192.0/18148.16.192.1 to 148.16.255.254148.16.255.25516,382
69148.17.0.0/18148.17.0.1 to 148.17.63.254148.17.63.25516,382
70148.17.64.0/18148.17.64.1 to 148.17.127.254148.17.127.25516,382
71148.17.128.0/18148.17.128.1 to 148.17.191.254148.17.191.25516,382
72148.17.192.0/18148.17.192.1 to 148.17.255.254148.17.255.25516,382
73148.18.0.0/18148.18.0.1 to 148.18.63.254148.18.63.25516,382
74148.18.64.0/18148.18.64.1 to 148.18.127.254148.18.127.25516,382
75148.18.128.0/18148.18.128.1 to 148.18.191.254148.18.191.25516,382
76148.18.192.0/18148.18.192.1 to 148.18.255.254148.18.255.25516,382
77148.19.0.0/18148.19.0.1 to 148.19.63.254148.19.63.25516,382
78148.19.64.0/18148.19.64.1 to 148.19.127.254148.19.127.25516,382
79148.19.128.0/18148.19.128.1 to 148.19.191.254148.19.191.25516,382
80148.19.192.0/18148.19.192.1 to 148.19.255.254148.19.255.25516,382
81148.20.0.0/18148.20.0.1 to 148.20.63.254148.20.63.25516,382
82148.20.64.0/18148.20.64.1 to 148.20.127.254148.20.127.25516,382
83148.20.128.0/18148.20.128.1 to 148.20.191.254148.20.191.25516,382
84148.20.192.0/18148.20.192.1 to 148.20.255.254148.20.255.25516,382
85148.21.0.0/18148.21.0.1 to 148.21.63.254148.21.63.25516,382
86148.21.64.0/18148.21.64.1 to 148.21.127.254148.21.127.25516,382
87148.21.128.0/18148.21.128.1 to 148.21.191.254148.21.191.25516,382
88148.21.192.0/18148.21.192.1 to 148.21.255.254148.21.255.25516,382
89148.22.0.0/18148.22.0.1 to 148.22.63.254148.22.63.25516,382
90148.22.64.0/18148.22.64.1 to 148.22.127.254148.22.127.25516,382
91148.22.128.0/18148.22.128.1 to 148.22.191.254148.22.191.25516,382
92148.22.192.0/18148.22.192.1 to 148.22.255.254148.22.255.25516,382
93148.23.0.0/18148.23.0.1 to 148.23.63.254148.23.63.25516,382
94148.23.64.0/18148.23.64.1 to 148.23.127.254148.23.127.25516,382
95148.23.128.0/18148.23.128.1 to 148.23.191.254148.23.191.25516,382
96148.23.192.0/18148.23.192.1 to 148.23.255.254148.23.255.25516,382
97148.24.0.0/18148.24.0.1 to 148.24.63.254148.24.63.25516,382
98148.24.64.0/18148.24.64.1 to 148.24.127.254148.24.127.25516,382
99148.24.128.0/18148.24.128.1 to 148.24.191.254148.24.191.25516,382
100148.24.192.0/18148.24.192.1 to 148.24.255.254148.24.255.25516,382
101148.25.0.0/18148.25.0.1 to 148.25.63.254148.25.63.25516,382
102148.25.64.0/18148.25.64.1 to 148.25.127.254148.25.127.25516,382
103148.25.128.0/18148.25.128.1 to 148.25.191.254148.25.191.25516,382
104148.25.192.0/18148.25.192.1 to 148.25.255.254148.25.255.25516,382
105148.26.0.0/18148.26.0.1 to 148.26.63.254148.26.63.25516,382
106148.26.64.0/18148.26.64.1 to 148.26.127.254148.26.127.25516,382
107148.26.128.0/18148.26.128.1 to 148.26.191.254148.26.191.25516,382
108148.26.192.0/18148.26.192.1 to 148.26.255.254148.26.255.25516,382
109148.27.0.0/18148.27.0.1 to 148.27.63.254148.27.63.25516,382
110148.27.64.0/18148.27.64.1 to 148.27.127.254148.27.127.25516,382
111148.27.128.0/18148.27.128.1 to 148.27.191.254148.27.191.25516,382
112148.27.192.0/18148.27.192.1 to 148.27.255.254148.27.255.25516,382
113148.28.0.0/18148.28.0.1 to 148.28.63.254148.28.63.25516,382
114148.28.64.0/18148.28.64.1 to 148.28.127.254148.28.127.25516,382
115148.28.128.0/18148.28.128.1 to 148.28.191.254148.28.191.25516,382
116148.28.192.0/18148.28.192.1 to 148.28.255.254148.28.255.25516,382
117148.29.0.0/18148.29.0.1 to 148.29.63.254148.29.63.25516,382
118148.29.64.0/18148.29.64.1 to 148.29.127.254148.29.127.25516,382
119148.29.128.0/18148.29.128.1 to 148.29.191.254148.29.191.25516,382
120148.29.192.0/18148.29.192.1 to 148.29.255.254148.29.255.25516,382
121148.30.0.0/18148.30.0.1 to 148.30.63.254148.30.63.25516,382
122148.30.64.0/18148.30.64.1 to 148.30.127.254148.30.127.25516,382
123148.30.128.0/18148.30.128.1 to 148.30.191.254148.30.191.25516,382
124148.30.192.0/18148.30.192.1 to 148.30.255.254148.30.255.25516,382
125148.31.0.0/18148.31.0.1 to 148.31.63.254148.31.63.25516,382
126148.31.64.0/18148.31.64.1 to 148.31.127.254148.31.127.25516,382
127148.31.128.0/18148.31.128.1 to 148.31.191.254148.31.191.25516,382
128148.31.192.0/18148.31.192.1 to 148.31.255.254148.31.255.25516,382
129148.32.0.0/18148.32.0.1 to 148.32.63.254148.32.63.25516,382
130148.32.64.0/18148.32.64.1 to 148.32.127.254148.32.127.25516,382
131148.32.128.0/18148.32.128.1 to 148.32.191.254148.32.191.25516,382
132148.32.192.0/18148.32.192.1 to 148.32.255.254148.32.255.25516,382
133148.33.0.0/18148.33.0.1 to 148.33.63.254148.33.63.25516,382
134148.33.64.0/18148.33.64.1 to 148.33.127.254148.33.127.25516,382
135148.33.128.0/18148.33.128.1 to 148.33.191.254148.33.191.25516,382
136148.33.192.0/18148.33.192.1 to 148.33.255.254148.33.255.25516,382
137148.34.0.0/18148.34.0.1 to 148.34.63.254148.34.63.25516,382
138148.34.64.0/18148.34.64.1 to 148.34.127.254148.34.127.25516,382
139148.34.128.0/18148.34.128.1 to 148.34.191.254148.34.191.25516,382
140148.34.192.0/18148.34.192.1 to 148.34.255.254148.34.255.25516,382
141148.35.0.0/18148.35.0.1 to 148.35.63.254148.35.63.25516,382
142148.35.64.0/18148.35.64.1 to 148.35.127.254148.35.127.25516,382
143148.35.128.0/18148.35.128.1 to 148.35.191.254148.35.191.25516,382
144148.35.192.0/18148.35.192.1 to 148.35.255.254148.35.255.25516,382
145148.36.0.0/18148.36.0.1 to 148.36.63.254148.36.63.25516,382
146148.36.64.0/18148.36.64.1 to 148.36.127.254148.36.127.25516,382
147148.36.128.0/18148.36.128.1 to 148.36.191.254148.36.191.25516,382
148148.36.192.0/18148.36.192.1 to 148.36.255.254148.36.255.25516,382
149148.37.0.0/18148.37.0.1 to 148.37.63.254148.37.63.25516,382
150148.37.64.0/18148.37.64.1 to 148.37.127.254148.37.127.25516,382
151148.37.128.0/18148.37.128.1 to 148.37.191.254148.37.191.25516,382
152148.37.192.0/18148.37.192.1 to 148.37.255.254148.37.255.25516,382
153148.38.0.0/18148.38.0.1 to 148.38.63.254148.38.63.25516,382
154148.38.64.0/18148.38.64.1 to 148.38.127.254148.38.127.25516,382
155148.38.128.0/18148.38.128.1 to 148.38.191.254148.38.191.25516,382
156148.38.192.0/18148.38.192.1 to 148.38.255.254148.38.255.25516,382
157148.39.0.0/18148.39.0.1 to 148.39.63.254148.39.63.25516,382
158148.39.64.0/18148.39.64.1 to 148.39.127.254148.39.127.25516,382
159148.39.128.0/18148.39.128.1 to 148.39.191.254148.39.191.25516,382
160148.39.192.0/18148.39.192.1 to 148.39.255.254148.39.255.25516,382
161148.40.0.0/18148.40.0.1 to 148.40.63.254148.40.63.25516,382
162148.40.64.0/18148.40.64.1 to 148.40.127.254148.40.127.25516,382
163148.40.128.0/18148.40.128.1 to 148.40.191.254148.40.191.25516,382
164148.40.192.0/18148.40.192.1 to 148.40.255.254148.40.255.25516,382
165148.41.0.0/18148.41.0.1 to 148.41.63.254148.41.63.25516,382
166148.41.64.0/18148.41.64.1 to 148.41.127.254148.41.127.25516,382
167148.41.128.0/18148.41.128.1 to 148.41.191.254148.41.191.25516,382
168148.41.192.0/18148.41.192.1 to 148.41.255.254148.41.255.25516,382
169148.42.0.0/18148.42.0.1 to 148.42.63.254148.42.63.25516,382
170148.42.64.0/18148.42.64.1 to 148.42.127.254148.42.127.25516,382
171148.42.128.0/18148.42.128.1 to 148.42.191.254148.42.191.25516,382
172148.42.192.0/18148.42.192.1 to 148.42.255.254148.42.255.25516,382
173148.43.0.0/18148.43.0.1 to 148.43.63.254148.43.63.25516,382
174148.43.64.0/18148.43.64.1 to 148.43.127.254148.43.127.25516,382
175148.43.128.0/18148.43.128.1 to 148.43.191.254148.43.191.25516,382
176148.43.192.0/18148.43.192.1 to 148.43.255.254148.43.255.25516,382
177148.44.0.0/18148.44.0.1 to 148.44.63.254148.44.63.25516,382
178148.44.64.0/18148.44.64.1 to 148.44.127.254148.44.127.25516,382
179148.44.128.0/18148.44.128.1 to 148.44.191.254148.44.191.25516,382
180148.44.192.0/18148.44.192.1 to 148.44.255.254148.44.255.25516,382
181148.45.0.0/18148.45.0.1 to 148.45.63.254148.45.63.25516,382
182148.45.64.0/18148.45.64.1 to 148.45.127.254148.45.127.25516,382
183148.45.128.0/18148.45.128.1 to 148.45.191.254148.45.191.25516,382
184148.45.192.0/18148.45.192.1 to 148.45.255.254148.45.255.25516,382
185148.46.0.0/18148.46.0.1 to 148.46.63.254148.46.63.25516,382
186148.46.64.0/18148.46.64.1 to 148.46.127.254148.46.127.25516,382
187148.46.128.0/18148.46.128.1 to 148.46.191.254148.46.191.25516,382
188148.46.192.0/18148.46.192.1 to 148.46.255.254148.46.255.25516,382
189148.47.0.0/18148.47.0.1 to 148.47.63.254148.47.63.25516,382
190148.47.64.0/18148.47.64.1 to 148.47.127.254148.47.127.25516,382
191148.47.128.0/18148.47.128.1 to 148.47.191.254148.47.191.25516,382
192148.47.192.0/18148.47.192.1 to 148.47.255.254148.47.255.25516,382
193148.48.0.0/18148.48.0.1 to 148.48.63.254148.48.63.25516,382
194148.48.64.0/18148.48.64.1 to 148.48.127.254148.48.127.25516,382
195148.48.128.0/18148.48.128.1 to 148.48.191.254148.48.191.25516,382
196148.48.192.0/18148.48.192.1 to 148.48.255.254148.48.255.25516,382
197148.49.0.0/18148.49.0.1 to 148.49.63.254148.49.63.25516,382
198148.49.64.0/18148.49.64.1 to 148.49.127.254148.49.127.25516,382
199148.49.128.0/18148.49.128.1 to 148.49.191.254148.49.191.25516,382
200148.49.192.0/18148.49.192.1 to 148.49.255.254148.49.255.25516,382
201148.50.0.0/18148.50.0.1 to 148.50.63.254148.50.63.25516,382
202148.50.64.0/18148.50.64.1 to 148.50.127.254148.50.127.25516,382
203148.50.128.0/18148.50.128.1 to 148.50.191.254148.50.191.25516,382
204148.50.192.0/18148.50.192.1 to 148.50.255.254148.50.255.25516,382
205148.51.0.0/18148.51.0.1 to 148.51.63.254148.51.63.25516,382
206148.51.64.0/18148.51.64.1 to 148.51.127.254148.51.127.25516,382
207148.51.128.0/18148.51.128.1 to 148.51.191.254148.51.191.25516,382
208148.51.192.0/18148.51.192.1 to 148.51.255.254148.51.255.25516,382
209148.52.0.0/18148.52.0.1 to 148.52.63.254148.52.63.25516,382
210148.52.64.0/18148.52.64.1 to 148.52.127.254148.52.127.25516,382
211148.52.128.0/18148.52.128.1 to 148.52.191.254148.52.191.25516,382
212148.52.192.0/18148.52.192.1 to 148.52.255.254148.52.255.25516,382
213148.53.0.0/18148.53.0.1 to 148.53.63.254148.53.63.25516,382
214148.53.64.0/18148.53.64.1 to 148.53.127.254148.53.127.25516,382
215148.53.128.0/18148.53.128.1 to 148.53.191.254148.53.191.25516,382
216148.53.192.0/18148.53.192.1 to 148.53.255.254148.53.255.25516,382
217148.54.0.0/18148.54.0.1 to 148.54.63.254148.54.63.25516,382
218148.54.64.0/18148.54.64.1 to 148.54.127.254148.54.127.25516,382
219148.54.128.0/18148.54.128.1 to 148.54.191.254148.54.191.25516,382
220148.54.192.0/18148.54.192.1 to 148.54.255.254148.54.255.25516,382
221148.55.0.0/18148.55.0.1 to 148.55.63.254148.55.63.25516,382
222148.55.64.0/18148.55.64.1 to 148.55.127.254148.55.127.25516,382
223148.55.128.0/18148.55.128.1 to 148.55.191.254148.55.191.25516,382
224148.55.192.0/18148.55.192.1 to 148.55.255.254148.55.255.25516,382
225148.56.0.0/18148.56.0.1 to 148.56.63.254148.56.63.25516,382
226148.56.64.0/18148.56.64.1 to 148.56.127.254148.56.127.25516,382
227148.56.128.0/18148.56.128.1 to 148.56.191.254148.56.191.25516,382
228148.56.192.0/18148.56.192.1 to 148.56.255.254148.56.255.25516,382
229148.57.0.0/18148.57.0.1 to 148.57.63.254148.57.63.25516,382
230148.57.64.0/18148.57.64.1 to 148.57.127.254148.57.127.25516,382
231148.57.128.0/18148.57.128.1 to 148.57.191.254148.57.191.25516,382
232148.57.192.0/18148.57.192.1 to 148.57.255.254148.57.255.25516,382
233148.58.0.0/18148.58.0.1 to 148.58.63.254148.58.63.25516,382
234148.58.64.0/18148.58.64.1 to 148.58.127.254148.58.127.25516,382
235148.58.128.0/18148.58.128.1 to 148.58.191.254148.58.191.25516,382
236148.58.192.0/18148.58.192.1 to 148.58.255.254148.58.255.25516,382
237148.59.0.0/18148.59.0.1 to 148.59.63.254148.59.63.25516,382
238148.59.64.0/18148.59.64.1 to 148.59.127.254148.59.127.25516,382
239148.59.128.0/18148.59.128.1 to 148.59.191.254148.59.191.25516,382
240148.59.192.0/18148.59.192.1 to 148.59.255.254148.59.255.25516,382
241148.60.0.0/18148.60.0.1 to 148.60.63.254148.60.63.25516,382
242148.60.64.0/18148.60.64.1 to 148.60.127.254148.60.127.25516,382
243148.60.128.0/18148.60.128.1 to 148.60.191.254148.60.191.25516,382
244148.60.192.0/18148.60.192.1 to 148.60.255.254148.60.255.25516,382
245148.61.0.0/18148.61.0.1 to 148.61.63.254148.61.63.25516,382
246148.61.64.0/18148.61.64.1 to 148.61.127.254148.61.127.25516,382
247148.61.128.0/18148.61.128.1 to 148.61.191.254148.61.191.25516,382
248148.61.192.0/18148.61.192.1 to 148.61.255.254148.61.255.25516,382
249148.62.0.0/18148.62.0.1 to 148.62.63.254148.62.63.25516,382
250148.62.64.0/18148.62.64.1 to 148.62.127.254148.62.127.25516,382
251148.62.128.0/18148.62.128.1 to 148.62.191.254148.62.191.25516,382
252148.62.192.0/18148.62.192.1 to 148.62.255.254148.62.255.25516,382
253148.63.0.0/18148.63.0.1 to 148.63.63.254148.63.63.25516,382
254148.63.64.0/18148.63.64.1 to 148.63.127.254148.63.127.25516,382
255148.63.128.0/18148.63.128.1 to 148.63.191.254148.63.191.25516,382
256148.63.192.0/18148.63.192.1 to 148.63.255.254148.63.255.25516,382

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.