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.

Network180.2.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
180.2.0.0
Broadcast address
180.2.127.255
First usable
180.2.0.1
Last usable
180.2.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex B4020000 · Integer 3020029952 to 3020062719
Reverse DNS zones
0.2.180.in-addr.arpa
1.2.180.in-addr.arpa
2.2.180.in-addr.arpa
3.2.180.in-addr.arpa
4.2.180.in-addr.arpa
5.2.180.in-addr.arpa
6.2.180.in-addr.arpa
7.2.180.in-addr.arpa
8.2.180.in-addr.arpa
9.2.180.in-addr.arpa
10.2.180.in-addr.arpa
11.2.180.in-addr.arpa
12.2.180.in-addr.arpa
13.2.180.in-addr.arpa
14.2.180.in-addr.arpa
15.2.180.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110100.00000010.00000000.00000000180.2.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10110100.00000010.00000000.00000000180.2.0.0
Broadcast10110100.00000010.01111111.11111111180.2.127.255
Split into smaller subnets/29
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

180.2.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1180.2.0.0/29180.2.0.1 to 180.2.0.6180.2.0.76
2180.2.0.8/29180.2.0.9 to 180.2.0.14180.2.0.156
3180.2.0.16/29180.2.0.17 to 180.2.0.22180.2.0.236
4180.2.0.24/29180.2.0.25 to 180.2.0.30180.2.0.316
5180.2.0.32/29180.2.0.33 to 180.2.0.38180.2.0.396
6180.2.0.40/29180.2.0.41 to 180.2.0.46180.2.0.476
7180.2.0.48/29180.2.0.49 to 180.2.0.54180.2.0.556
8180.2.0.56/29180.2.0.57 to 180.2.0.62180.2.0.636
9180.2.0.64/29180.2.0.65 to 180.2.0.70180.2.0.716
10180.2.0.72/29180.2.0.73 to 180.2.0.78180.2.0.796
11180.2.0.80/29180.2.0.81 to 180.2.0.86180.2.0.876
12180.2.0.88/29180.2.0.89 to 180.2.0.94180.2.0.956
13180.2.0.96/29180.2.0.97 to 180.2.0.102180.2.0.1036
14180.2.0.104/29180.2.0.105 to 180.2.0.110180.2.0.1116
15180.2.0.112/29180.2.0.113 to 180.2.0.118180.2.0.1196
16180.2.0.120/29180.2.0.121 to 180.2.0.126180.2.0.1276
17180.2.0.128/29180.2.0.129 to 180.2.0.134180.2.0.1356
18180.2.0.136/29180.2.0.137 to 180.2.0.142180.2.0.1436
19180.2.0.144/29180.2.0.145 to 180.2.0.150180.2.0.1516
20180.2.0.152/29180.2.0.153 to 180.2.0.158180.2.0.1596
21180.2.0.160/29180.2.0.161 to 180.2.0.166180.2.0.1676
22180.2.0.168/29180.2.0.169 to 180.2.0.174180.2.0.1756
23180.2.0.176/29180.2.0.177 to 180.2.0.182180.2.0.1836
24180.2.0.184/29180.2.0.185 to 180.2.0.190180.2.0.1916
25180.2.0.192/29180.2.0.193 to 180.2.0.198180.2.0.1996
26180.2.0.200/29180.2.0.201 to 180.2.0.206180.2.0.2076
27180.2.0.208/29180.2.0.209 to 180.2.0.214180.2.0.2156
28180.2.0.216/29180.2.0.217 to 180.2.0.222180.2.0.2236
29180.2.0.224/29180.2.0.225 to 180.2.0.230180.2.0.2316
30180.2.0.232/29180.2.0.233 to 180.2.0.238180.2.0.2396
31180.2.0.240/29180.2.0.241 to 180.2.0.246180.2.0.2476
32180.2.0.248/29180.2.0.249 to 180.2.0.254180.2.0.2556
33180.2.1.0/29180.2.1.1 to 180.2.1.6180.2.1.76
34180.2.1.8/29180.2.1.9 to 180.2.1.14180.2.1.156
35180.2.1.16/29180.2.1.17 to 180.2.1.22180.2.1.236
36180.2.1.24/29180.2.1.25 to 180.2.1.30180.2.1.316
37180.2.1.32/29180.2.1.33 to 180.2.1.38180.2.1.396
38180.2.1.40/29180.2.1.41 to 180.2.1.46180.2.1.476
39180.2.1.48/29180.2.1.49 to 180.2.1.54180.2.1.556
40180.2.1.56/29180.2.1.57 to 180.2.1.62180.2.1.636
41180.2.1.64/29180.2.1.65 to 180.2.1.70180.2.1.716
42180.2.1.72/29180.2.1.73 to 180.2.1.78180.2.1.796
43180.2.1.80/29180.2.1.81 to 180.2.1.86180.2.1.876
44180.2.1.88/29180.2.1.89 to 180.2.1.94180.2.1.956
45180.2.1.96/29180.2.1.97 to 180.2.1.102180.2.1.1036
46180.2.1.104/29180.2.1.105 to 180.2.1.110180.2.1.1116
47180.2.1.112/29180.2.1.113 to 180.2.1.118180.2.1.1196
48180.2.1.120/29180.2.1.121 to 180.2.1.126180.2.1.1276
49180.2.1.128/29180.2.1.129 to 180.2.1.134180.2.1.1356
50180.2.1.136/29180.2.1.137 to 180.2.1.142180.2.1.1436
51180.2.1.144/29180.2.1.145 to 180.2.1.150180.2.1.1516
52180.2.1.152/29180.2.1.153 to 180.2.1.158180.2.1.1596
53180.2.1.160/29180.2.1.161 to 180.2.1.166180.2.1.1676
54180.2.1.168/29180.2.1.169 to 180.2.1.174180.2.1.1756
55180.2.1.176/29180.2.1.177 to 180.2.1.182180.2.1.1836
56180.2.1.184/29180.2.1.185 to 180.2.1.190180.2.1.1916
57180.2.1.192/29180.2.1.193 to 180.2.1.198180.2.1.1996
58180.2.1.200/29180.2.1.201 to 180.2.1.206180.2.1.2076
59180.2.1.208/29180.2.1.209 to 180.2.1.214180.2.1.2156
60180.2.1.216/29180.2.1.217 to 180.2.1.222180.2.1.2236
61180.2.1.224/29180.2.1.225 to 180.2.1.230180.2.1.2316
62180.2.1.232/29180.2.1.233 to 180.2.1.238180.2.1.2396
63180.2.1.240/29180.2.1.241 to 180.2.1.246180.2.1.2476
64180.2.1.248/29180.2.1.249 to 180.2.1.254180.2.1.2556
65180.2.2.0/29180.2.2.1 to 180.2.2.6180.2.2.76
66180.2.2.8/29180.2.2.9 to 180.2.2.14180.2.2.156
67180.2.2.16/29180.2.2.17 to 180.2.2.22180.2.2.236
68180.2.2.24/29180.2.2.25 to 180.2.2.30180.2.2.316
69180.2.2.32/29180.2.2.33 to 180.2.2.38180.2.2.396
70180.2.2.40/29180.2.2.41 to 180.2.2.46180.2.2.476
71180.2.2.48/29180.2.2.49 to 180.2.2.54180.2.2.556
72180.2.2.56/29180.2.2.57 to 180.2.2.62180.2.2.636
73180.2.2.64/29180.2.2.65 to 180.2.2.70180.2.2.716
74180.2.2.72/29180.2.2.73 to 180.2.2.78180.2.2.796
75180.2.2.80/29180.2.2.81 to 180.2.2.86180.2.2.876
76180.2.2.88/29180.2.2.89 to 180.2.2.94180.2.2.956
77180.2.2.96/29180.2.2.97 to 180.2.2.102180.2.2.1036
78180.2.2.104/29180.2.2.105 to 180.2.2.110180.2.2.1116
79180.2.2.112/29180.2.2.113 to 180.2.2.118180.2.2.1196
80180.2.2.120/29180.2.2.121 to 180.2.2.126180.2.2.1276
81180.2.2.128/29180.2.2.129 to 180.2.2.134180.2.2.1356
82180.2.2.136/29180.2.2.137 to 180.2.2.142180.2.2.1436
83180.2.2.144/29180.2.2.145 to 180.2.2.150180.2.2.1516
84180.2.2.152/29180.2.2.153 to 180.2.2.158180.2.2.1596
85180.2.2.160/29180.2.2.161 to 180.2.2.166180.2.2.1676
86180.2.2.168/29180.2.2.169 to 180.2.2.174180.2.2.1756
87180.2.2.176/29180.2.2.177 to 180.2.2.182180.2.2.1836
88180.2.2.184/29180.2.2.185 to 180.2.2.190180.2.2.1916
89180.2.2.192/29180.2.2.193 to 180.2.2.198180.2.2.1996
90180.2.2.200/29180.2.2.201 to 180.2.2.206180.2.2.2076
91180.2.2.208/29180.2.2.209 to 180.2.2.214180.2.2.2156
92180.2.2.216/29180.2.2.217 to 180.2.2.222180.2.2.2236
93180.2.2.224/29180.2.2.225 to 180.2.2.230180.2.2.2316
94180.2.2.232/29180.2.2.233 to 180.2.2.238180.2.2.2396
95180.2.2.240/29180.2.2.241 to 180.2.2.246180.2.2.2476
96180.2.2.248/29180.2.2.249 to 180.2.2.254180.2.2.2556
97180.2.3.0/29180.2.3.1 to 180.2.3.6180.2.3.76
98180.2.3.8/29180.2.3.9 to 180.2.3.14180.2.3.156
99180.2.3.16/29180.2.3.17 to 180.2.3.22180.2.3.236
100180.2.3.24/29180.2.3.25 to 180.2.3.30180.2.3.316
101180.2.3.32/29180.2.3.33 to 180.2.3.38180.2.3.396
102180.2.3.40/29180.2.3.41 to 180.2.3.46180.2.3.476
103180.2.3.48/29180.2.3.49 to 180.2.3.54180.2.3.556
104180.2.3.56/29180.2.3.57 to 180.2.3.62180.2.3.636
105180.2.3.64/29180.2.3.65 to 180.2.3.70180.2.3.716
106180.2.3.72/29180.2.3.73 to 180.2.3.78180.2.3.796
107180.2.3.80/29180.2.3.81 to 180.2.3.86180.2.3.876
108180.2.3.88/29180.2.3.89 to 180.2.3.94180.2.3.956
109180.2.3.96/29180.2.3.97 to 180.2.3.102180.2.3.1036
110180.2.3.104/29180.2.3.105 to 180.2.3.110180.2.3.1116
111180.2.3.112/29180.2.3.113 to 180.2.3.118180.2.3.1196
112180.2.3.120/29180.2.3.121 to 180.2.3.126180.2.3.1276
113180.2.3.128/29180.2.3.129 to 180.2.3.134180.2.3.1356
114180.2.3.136/29180.2.3.137 to 180.2.3.142180.2.3.1436
115180.2.3.144/29180.2.3.145 to 180.2.3.150180.2.3.1516
116180.2.3.152/29180.2.3.153 to 180.2.3.158180.2.3.1596
117180.2.3.160/29180.2.3.161 to 180.2.3.166180.2.3.1676
118180.2.3.168/29180.2.3.169 to 180.2.3.174180.2.3.1756
119180.2.3.176/29180.2.3.177 to 180.2.3.182180.2.3.1836
120180.2.3.184/29180.2.3.185 to 180.2.3.190180.2.3.1916
121180.2.3.192/29180.2.3.193 to 180.2.3.198180.2.3.1996
122180.2.3.200/29180.2.3.201 to 180.2.3.206180.2.3.2076
123180.2.3.208/29180.2.3.209 to 180.2.3.214180.2.3.2156
124180.2.3.216/29180.2.3.217 to 180.2.3.222180.2.3.2236
125180.2.3.224/29180.2.3.225 to 180.2.3.230180.2.3.2316
126180.2.3.232/29180.2.3.233 to 180.2.3.238180.2.3.2396
127180.2.3.240/29180.2.3.241 to 180.2.3.246180.2.3.2476
128180.2.3.248/29180.2.3.249 to 180.2.3.254180.2.3.2556
129180.2.4.0/29180.2.4.1 to 180.2.4.6180.2.4.76
130180.2.4.8/29180.2.4.9 to 180.2.4.14180.2.4.156
131180.2.4.16/29180.2.4.17 to 180.2.4.22180.2.4.236
132180.2.4.24/29180.2.4.25 to 180.2.4.30180.2.4.316
133180.2.4.32/29180.2.4.33 to 180.2.4.38180.2.4.396
134180.2.4.40/29180.2.4.41 to 180.2.4.46180.2.4.476
135180.2.4.48/29180.2.4.49 to 180.2.4.54180.2.4.556
136180.2.4.56/29180.2.4.57 to 180.2.4.62180.2.4.636
137180.2.4.64/29180.2.4.65 to 180.2.4.70180.2.4.716
138180.2.4.72/29180.2.4.73 to 180.2.4.78180.2.4.796
139180.2.4.80/29180.2.4.81 to 180.2.4.86180.2.4.876
140180.2.4.88/29180.2.4.89 to 180.2.4.94180.2.4.956
141180.2.4.96/29180.2.4.97 to 180.2.4.102180.2.4.1036
142180.2.4.104/29180.2.4.105 to 180.2.4.110180.2.4.1116
143180.2.4.112/29180.2.4.113 to 180.2.4.118180.2.4.1196
144180.2.4.120/29180.2.4.121 to 180.2.4.126180.2.4.1276
145180.2.4.128/29180.2.4.129 to 180.2.4.134180.2.4.1356
146180.2.4.136/29180.2.4.137 to 180.2.4.142180.2.4.1436
147180.2.4.144/29180.2.4.145 to 180.2.4.150180.2.4.1516
148180.2.4.152/29180.2.4.153 to 180.2.4.158180.2.4.1596
149180.2.4.160/29180.2.4.161 to 180.2.4.166180.2.4.1676
150180.2.4.168/29180.2.4.169 to 180.2.4.174180.2.4.1756
151180.2.4.176/29180.2.4.177 to 180.2.4.182180.2.4.1836
152180.2.4.184/29180.2.4.185 to 180.2.4.190180.2.4.1916
153180.2.4.192/29180.2.4.193 to 180.2.4.198180.2.4.1996
154180.2.4.200/29180.2.4.201 to 180.2.4.206180.2.4.2076
155180.2.4.208/29180.2.4.209 to 180.2.4.214180.2.4.2156
156180.2.4.216/29180.2.4.217 to 180.2.4.222180.2.4.2236
157180.2.4.224/29180.2.4.225 to 180.2.4.230180.2.4.2316
158180.2.4.232/29180.2.4.233 to 180.2.4.238180.2.4.2396
159180.2.4.240/29180.2.4.241 to 180.2.4.246180.2.4.2476
160180.2.4.248/29180.2.4.249 to 180.2.4.254180.2.4.2556
161180.2.5.0/29180.2.5.1 to 180.2.5.6180.2.5.76
162180.2.5.8/29180.2.5.9 to 180.2.5.14180.2.5.156
163180.2.5.16/29180.2.5.17 to 180.2.5.22180.2.5.236
164180.2.5.24/29180.2.5.25 to 180.2.5.30180.2.5.316
165180.2.5.32/29180.2.5.33 to 180.2.5.38180.2.5.396
166180.2.5.40/29180.2.5.41 to 180.2.5.46180.2.5.476
167180.2.5.48/29180.2.5.49 to 180.2.5.54180.2.5.556
168180.2.5.56/29180.2.5.57 to 180.2.5.62180.2.5.636
169180.2.5.64/29180.2.5.65 to 180.2.5.70180.2.5.716
170180.2.5.72/29180.2.5.73 to 180.2.5.78180.2.5.796
171180.2.5.80/29180.2.5.81 to 180.2.5.86180.2.5.876
172180.2.5.88/29180.2.5.89 to 180.2.5.94180.2.5.956
173180.2.5.96/29180.2.5.97 to 180.2.5.102180.2.5.1036
174180.2.5.104/29180.2.5.105 to 180.2.5.110180.2.5.1116
175180.2.5.112/29180.2.5.113 to 180.2.5.118180.2.5.1196
176180.2.5.120/29180.2.5.121 to 180.2.5.126180.2.5.1276
177180.2.5.128/29180.2.5.129 to 180.2.5.134180.2.5.1356
178180.2.5.136/29180.2.5.137 to 180.2.5.142180.2.5.1436
179180.2.5.144/29180.2.5.145 to 180.2.5.150180.2.5.1516
180180.2.5.152/29180.2.5.153 to 180.2.5.158180.2.5.1596
181180.2.5.160/29180.2.5.161 to 180.2.5.166180.2.5.1676
182180.2.5.168/29180.2.5.169 to 180.2.5.174180.2.5.1756
183180.2.5.176/29180.2.5.177 to 180.2.5.182180.2.5.1836
184180.2.5.184/29180.2.5.185 to 180.2.5.190180.2.5.1916
185180.2.5.192/29180.2.5.193 to 180.2.5.198180.2.5.1996
186180.2.5.200/29180.2.5.201 to 180.2.5.206180.2.5.2076
187180.2.5.208/29180.2.5.209 to 180.2.5.214180.2.5.2156
188180.2.5.216/29180.2.5.217 to 180.2.5.222180.2.5.2236
189180.2.5.224/29180.2.5.225 to 180.2.5.230180.2.5.2316
190180.2.5.232/29180.2.5.233 to 180.2.5.238180.2.5.2396
191180.2.5.240/29180.2.5.241 to 180.2.5.246180.2.5.2476
192180.2.5.248/29180.2.5.249 to 180.2.5.254180.2.5.2556
193180.2.6.0/29180.2.6.1 to 180.2.6.6180.2.6.76
194180.2.6.8/29180.2.6.9 to 180.2.6.14180.2.6.156
195180.2.6.16/29180.2.6.17 to 180.2.6.22180.2.6.236
196180.2.6.24/29180.2.6.25 to 180.2.6.30180.2.6.316
197180.2.6.32/29180.2.6.33 to 180.2.6.38180.2.6.396
198180.2.6.40/29180.2.6.41 to 180.2.6.46180.2.6.476
199180.2.6.48/29180.2.6.49 to 180.2.6.54180.2.6.556
200180.2.6.56/29180.2.6.57 to 180.2.6.62180.2.6.636
201180.2.6.64/29180.2.6.65 to 180.2.6.70180.2.6.716
202180.2.6.72/29180.2.6.73 to 180.2.6.78180.2.6.796
203180.2.6.80/29180.2.6.81 to 180.2.6.86180.2.6.876
204180.2.6.88/29180.2.6.89 to 180.2.6.94180.2.6.956
205180.2.6.96/29180.2.6.97 to 180.2.6.102180.2.6.1036
206180.2.6.104/29180.2.6.105 to 180.2.6.110180.2.6.1116
207180.2.6.112/29180.2.6.113 to 180.2.6.118180.2.6.1196
208180.2.6.120/29180.2.6.121 to 180.2.6.126180.2.6.1276
209180.2.6.128/29180.2.6.129 to 180.2.6.134180.2.6.1356
210180.2.6.136/29180.2.6.137 to 180.2.6.142180.2.6.1436
211180.2.6.144/29180.2.6.145 to 180.2.6.150180.2.6.1516
212180.2.6.152/29180.2.6.153 to 180.2.6.158180.2.6.1596
213180.2.6.160/29180.2.6.161 to 180.2.6.166180.2.6.1676
214180.2.6.168/29180.2.6.169 to 180.2.6.174180.2.6.1756
215180.2.6.176/29180.2.6.177 to 180.2.6.182180.2.6.1836
216180.2.6.184/29180.2.6.185 to 180.2.6.190180.2.6.1916
217180.2.6.192/29180.2.6.193 to 180.2.6.198180.2.6.1996
218180.2.6.200/29180.2.6.201 to 180.2.6.206180.2.6.2076
219180.2.6.208/29180.2.6.209 to 180.2.6.214180.2.6.2156
220180.2.6.216/29180.2.6.217 to 180.2.6.222180.2.6.2236
221180.2.6.224/29180.2.6.225 to 180.2.6.230180.2.6.2316
222180.2.6.232/29180.2.6.233 to 180.2.6.238180.2.6.2396
223180.2.6.240/29180.2.6.241 to 180.2.6.246180.2.6.2476
224180.2.6.248/29180.2.6.249 to 180.2.6.254180.2.6.2556
225180.2.7.0/29180.2.7.1 to 180.2.7.6180.2.7.76
226180.2.7.8/29180.2.7.9 to 180.2.7.14180.2.7.156
227180.2.7.16/29180.2.7.17 to 180.2.7.22180.2.7.236
228180.2.7.24/29180.2.7.25 to 180.2.7.30180.2.7.316
229180.2.7.32/29180.2.7.33 to 180.2.7.38180.2.7.396
230180.2.7.40/29180.2.7.41 to 180.2.7.46180.2.7.476
231180.2.7.48/29180.2.7.49 to 180.2.7.54180.2.7.556
232180.2.7.56/29180.2.7.57 to 180.2.7.62180.2.7.636
233180.2.7.64/29180.2.7.65 to 180.2.7.70180.2.7.716
234180.2.7.72/29180.2.7.73 to 180.2.7.78180.2.7.796
235180.2.7.80/29180.2.7.81 to 180.2.7.86180.2.7.876
236180.2.7.88/29180.2.7.89 to 180.2.7.94180.2.7.956
237180.2.7.96/29180.2.7.97 to 180.2.7.102180.2.7.1036
238180.2.7.104/29180.2.7.105 to 180.2.7.110180.2.7.1116
239180.2.7.112/29180.2.7.113 to 180.2.7.118180.2.7.1196
240180.2.7.120/29180.2.7.121 to 180.2.7.126180.2.7.1276
241180.2.7.128/29180.2.7.129 to 180.2.7.134180.2.7.1356
242180.2.7.136/29180.2.7.137 to 180.2.7.142180.2.7.1436
243180.2.7.144/29180.2.7.145 to 180.2.7.150180.2.7.1516
244180.2.7.152/29180.2.7.153 to 180.2.7.158180.2.7.1596
245180.2.7.160/29180.2.7.161 to 180.2.7.166180.2.7.1676
246180.2.7.168/29180.2.7.169 to 180.2.7.174180.2.7.1756
247180.2.7.176/29180.2.7.177 to 180.2.7.182180.2.7.1836
248180.2.7.184/29180.2.7.185 to 180.2.7.190180.2.7.1916
249180.2.7.192/29180.2.7.193 to 180.2.7.198180.2.7.1996
250180.2.7.200/29180.2.7.201 to 180.2.7.206180.2.7.2076
251180.2.7.208/29180.2.7.209 to 180.2.7.214180.2.7.2156
252180.2.7.216/29180.2.7.217 to 180.2.7.222180.2.7.2236
253180.2.7.224/29180.2.7.225 to 180.2.7.230180.2.7.2316
254180.2.7.232/29180.2.7.233 to 180.2.7.238180.2.7.2396
255180.2.7.240/29180.2.7.241 to 180.2.7.246180.2.7.2476
256180.2.7.248/29180.2.7.249 to 180.2.7.254180.2.7.2556

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.