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.

Network129.2.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
129.2.0.0
Broadcast address
129.2.31.255
First usable
129.2.0.1
Last usable
129.2.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
B (default /16)
As numbers
Hex 81020000 · Integer 2164391936 to 2164400127
Reverse DNS zones
0.2.129.in-addr.arpa
1.2.129.in-addr.arpa
2.2.129.in-addr.arpa
3.2.129.in-addr.arpa
4.2.129.in-addr.arpa
5.2.129.in-addr.arpa
6.2.129.in-addr.arpa
7.2.129.in-addr.arpa
8.2.129.in-addr.arpa
9.2.129.in-addr.arpa
10.2.129.in-addr.arpa
11.2.129.in-addr.arpa
12.2.129.in-addr.arpa
13.2.129.in-addr.arpa
14.2.129.in-addr.arpa
15.2.129.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000001.00000010.00000000.00000000129.2.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10000001.00000010.00000000.00000000129.2.0.0
Broadcast10000001.00000010.00011111.11111111129.2.31.255
Split into smaller subnets/29
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

129.2.0.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1129.2.0.0/29129.2.0.1 to 129.2.0.6129.2.0.76
2129.2.0.8/29129.2.0.9 to 129.2.0.14129.2.0.156
3129.2.0.16/29129.2.0.17 to 129.2.0.22129.2.0.236
4129.2.0.24/29129.2.0.25 to 129.2.0.30129.2.0.316
5129.2.0.32/29129.2.0.33 to 129.2.0.38129.2.0.396
6129.2.0.40/29129.2.0.41 to 129.2.0.46129.2.0.476
7129.2.0.48/29129.2.0.49 to 129.2.0.54129.2.0.556
8129.2.0.56/29129.2.0.57 to 129.2.0.62129.2.0.636
9129.2.0.64/29129.2.0.65 to 129.2.0.70129.2.0.716
10129.2.0.72/29129.2.0.73 to 129.2.0.78129.2.0.796
11129.2.0.80/29129.2.0.81 to 129.2.0.86129.2.0.876
12129.2.0.88/29129.2.0.89 to 129.2.0.94129.2.0.956
13129.2.0.96/29129.2.0.97 to 129.2.0.102129.2.0.1036
14129.2.0.104/29129.2.0.105 to 129.2.0.110129.2.0.1116
15129.2.0.112/29129.2.0.113 to 129.2.0.118129.2.0.1196
16129.2.0.120/29129.2.0.121 to 129.2.0.126129.2.0.1276
17129.2.0.128/29129.2.0.129 to 129.2.0.134129.2.0.1356
18129.2.0.136/29129.2.0.137 to 129.2.0.142129.2.0.1436
19129.2.0.144/29129.2.0.145 to 129.2.0.150129.2.0.1516
20129.2.0.152/29129.2.0.153 to 129.2.0.158129.2.0.1596
21129.2.0.160/29129.2.0.161 to 129.2.0.166129.2.0.1676
22129.2.0.168/29129.2.0.169 to 129.2.0.174129.2.0.1756
23129.2.0.176/29129.2.0.177 to 129.2.0.182129.2.0.1836
24129.2.0.184/29129.2.0.185 to 129.2.0.190129.2.0.1916
25129.2.0.192/29129.2.0.193 to 129.2.0.198129.2.0.1996
26129.2.0.200/29129.2.0.201 to 129.2.0.206129.2.0.2076
27129.2.0.208/29129.2.0.209 to 129.2.0.214129.2.0.2156
28129.2.0.216/29129.2.0.217 to 129.2.0.222129.2.0.2236
29129.2.0.224/29129.2.0.225 to 129.2.0.230129.2.0.2316
30129.2.0.232/29129.2.0.233 to 129.2.0.238129.2.0.2396
31129.2.0.240/29129.2.0.241 to 129.2.0.246129.2.0.2476
32129.2.0.248/29129.2.0.249 to 129.2.0.254129.2.0.2556
33129.2.1.0/29129.2.1.1 to 129.2.1.6129.2.1.76
34129.2.1.8/29129.2.1.9 to 129.2.1.14129.2.1.156
35129.2.1.16/29129.2.1.17 to 129.2.1.22129.2.1.236
36129.2.1.24/29129.2.1.25 to 129.2.1.30129.2.1.316
37129.2.1.32/29129.2.1.33 to 129.2.1.38129.2.1.396
38129.2.1.40/29129.2.1.41 to 129.2.1.46129.2.1.476
39129.2.1.48/29129.2.1.49 to 129.2.1.54129.2.1.556
40129.2.1.56/29129.2.1.57 to 129.2.1.62129.2.1.636
41129.2.1.64/29129.2.1.65 to 129.2.1.70129.2.1.716
42129.2.1.72/29129.2.1.73 to 129.2.1.78129.2.1.796
43129.2.1.80/29129.2.1.81 to 129.2.1.86129.2.1.876
44129.2.1.88/29129.2.1.89 to 129.2.1.94129.2.1.956
45129.2.1.96/29129.2.1.97 to 129.2.1.102129.2.1.1036
46129.2.1.104/29129.2.1.105 to 129.2.1.110129.2.1.1116
47129.2.1.112/29129.2.1.113 to 129.2.1.118129.2.1.1196
48129.2.1.120/29129.2.1.121 to 129.2.1.126129.2.1.1276
49129.2.1.128/29129.2.1.129 to 129.2.1.134129.2.1.1356
50129.2.1.136/29129.2.1.137 to 129.2.1.142129.2.1.1436
51129.2.1.144/29129.2.1.145 to 129.2.1.150129.2.1.1516
52129.2.1.152/29129.2.1.153 to 129.2.1.158129.2.1.1596
53129.2.1.160/29129.2.1.161 to 129.2.1.166129.2.1.1676
54129.2.1.168/29129.2.1.169 to 129.2.1.174129.2.1.1756
55129.2.1.176/29129.2.1.177 to 129.2.1.182129.2.1.1836
56129.2.1.184/29129.2.1.185 to 129.2.1.190129.2.1.1916
57129.2.1.192/29129.2.1.193 to 129.2.1.198129.2.1.1996
58129.2.1.200/29129.2.1.201 to 129.2.1.206129.2.1.2076
59129.2.1.208/29129.2.1.209 to 129.2.1.214129.2.1.2156
60129.2.1.216/29129.2.1.217 to 129.2.1.222129.2.1.2236
61129.2.1.224/29129.2.1.225 to 129.2.1.230129.2.1.2316
62129.2.1.232/29129.2.1.233 to 129.2.1.238129.2.1.2396
63129.2.1.240/29129.2.1.241 to 129.2.1.246129.2.1.2476
64129.2.1.248/29129.2.1.249 to 129.2.1.254129.2.1.2556
65129.2.2.0/29129.2.2.1 to 129.2.2.6129.2.2.76
66129.2.2.8/29129.2.2.9 to 129.2.2.14129.2.2.156
67129.2.2.16/29129.2.2.17 to 129.2.2.22129.2.2.236
68129.2.2.24/29129.2.2.25 to 129.2.2.30129.2.2.316
69129.2.2.32/29129.2.2.33 to 129.2.2.38129.2.2.396
70129.2.2.40/29129.2.2.41 to 129.2.2.46129.2.2.476
71129.2.2.48/29129.2.2.49 to 129.2.2.54129.2.2.556
72129.2.2.56/29129.2.2.57 to 129.2.2.62129.2.2.636
73129.2.2.64/29129.2.2.65 to 129.2.2.70129.2.2.716
74129.2.2.72/29129.2.2.73 to 129.2.2.78129.2.2.796
75129.2.2.80/29129.2.2.81 to 129.2.2.86129.2.2.876
76129.2.2.88/29129.2.2.89 to 129.2.2.94129.2.2.956
77129.2.2.96/29129.2.2.97 to 129.2.2.102129.2.2.1036
78129.2.2.104/29129.2.2.105 to 129.2.2.110129.2.2.1116
79129.2.2.112/29129.2.2.113 to 129.2.2.118129.2.2.1196
80129.2.2.120/29129.2.2.121 to 129.2.2.126129.2.2.1276
81129.2.2.128/29129.2.2.129 to 129.2.2.134129.2.2.1356
82129.2.2.136/29129.2.2.137 to 129.2.2.142129.2.2.1436
83129.2.2.144/29129.2.2.145 to 129.2.2.150129.2.2.1516
84129.2.2.152/29129.2.2.153 to 129.2.2.158129.2.2.1596
85129.2.2.160/29129.2.2.161 to 129.2.2.166129.2.2.1676
86129.2.2.168/29129.2.2.169 to 129.2.2.174129.2.2.1756
87129.2.2.176/29129.2.2.177 to 129.2.2.182129.2.2.1836
88129.2.2.184/29129.2.2.185 to 129.2.2.190129.2.2.1916
89129.2.2.192/29129.2.2.193 to 129.2.2.198129.2.2.1996
90129.2.2.200/29129.2.2.201 to 129.2.2.206129.2.2.2076
91129.2.2.208/29129.2.2.209 to 129.2.2.214129.2.2.2156
92129.2.2.216/29129.2.2.217 to 129.2.2.222129.2.2.2236
93129.2.2.224/29129.2.2.225 to 129.2.2.230129.2.2.2316
94129.2.2.232/29129.2.2.233 to 129.2.2.238129.2.2.2396
95129.2.2.240/29129.2.2.241 to 129.2.2.246129.2.2.2476
96129.2.2.248/29129.2.2.249 to 129.2.2.254129.2.2.2556
97129.2.3.0/29129.2.3.1 to 129.2.3.6129.2.3.76
98129.2.3.8/29129.2.3.9 to 129.2.3.14129.2.3.156
99129.2.3.16/29129.2.3.17 to 129.2.3.22129.2.3.236
100129.2.3.24/29129.2.3.25 to 129.2.3.30129.2.3.316
101129.2.3.32/29129.2.3.33 to 129.2.3.38129.2.3.396
102129.2.3.40/29129.2.3.41 to 129.2.3.46129.2.3.476
103129.2.3.48/29129.2.3.49 to 129.2.3.54129.2.3.556
104129.2.3.56/29129.2.3.57 to 129.2.3.62129.2.3.636
105129.2.3.64/29129.2.3.65 to 129.2.3.70129.2.3.716
106129.2.3.72/29129.2.3.73 to 129.2.3.78129.2.3.796
107129.2.3.80/29129.2.3.81 to 129.2.3.86129.2.3.876
108129.2.3.88/29129.2.3.89 to 129.2.3.94129.2.3.956
109129.2.3.96/29129.2.3.97 to 129.2.3.102129.2.3.1036
110129.2.3.104/29129.2.3.105 to 129.2.3.110129.2.3.1116
111129.2.3.112/29129.2.3.113 to 129.2.3.118129.2.3.1196
112129.2.3.120/29129.2.3.121 to 129.2.3.126129.2.3.1276
113129.2.3.128/29129.2.3.129 to 129.2.3.134129.2.3.1356
114129.2.3.136/29129.2.3.137 to 129.2.3.142129.2.3.1436
115129.2.3.144/29129.2.3.145 to 129.2.3.150129.2.3.1516
116129.2.3.152/29129.2.3.153 to 129.2.3.158129.2.3.1596
117129.2.3.160/29129.2.3.161 to 129.2.3.166129.2.3.1676
118129.2.3.168/29129.2.3.169 to 129.2.3.174129.2.3.1756
119129.2.3.176/29129.2.3.177 to 129.2.3.182129.2.3.1836
120129.2.3.184/29129.2.3.185 to 129.2.3.190129.2.3.1916
121129.2.3.192/29129.2.3.193 to 129.2.3.198129.2.3.1996
122129.2.3.200/29129.2.3.201 to 129.2.3.206129.2.3.2076
123129.2.3.208/29129.2.3.209 to 129.2.3.214129.2.3.2156
124129.2.3.216/29129.2.3.217 to 129.2.3.222129.2.3.2236
125129.2.3.224/29129.2.3.225 to 129.2.3.230129.2.3.2316
126129.2.3.232/29129.2.3.233 to 129.2.3.238129.2.3.2396
127129.2.3.240/29129.2.3.241 to 129.2.3.246129.2.3.2476
128129.2.3.248/29129.2.3.249 to 129.2.3.254129.2.3.2556
129129.2.4.0/29129.2.4.1 to 129.2.4.6129.2.4.76
130129.2.4.8/29129.2.4.9 to 129.2.4.14129.2.4.156
131129.2.4.16/29129.2.4.17 to 129.2.4.22129.2.4.236
132129.2.4.24/29129.2.4.25 to 129.2.4.30129.2.4.316
133129.2.4.32/29129.2.4.33 to 129.2.4.38129.2.4.396
134129.2.4.40/29129.2.4.41 to 129.2.4.46129.2.4.476
135129.2.4.48/29129.2.4.49 to 129.2.4.54129.2.4.556
136129.2.4.56/29129.2.4.57 to 129.2.4.62129.2.4.636
137129.2.4.64/29129.2.4.65 to 129.2.4.70129.2.4.716
138129.2.4.72/29129.2.4.73 to 129.2.4.78129.2.4.796
139129.2.4.80/29129.2.4.81 to 129.2.4.86129.2.4.876
140129.2.4.88/29129.2.4.89 to 129.2.4.94129.2.4.956
141129.2.4.96/29129.2.4.97 to 129.2.4.102129.2.4.1036
142129.2.4.104/29129.2.4.105 to 129.2.4.110129.2.4.1116
143129.2.4.112/29129.2.4.113 to 129.2.4.118129.2.4.1196
144129.2.4.120/29129.2.4.121 to 129.2.4.126129.2.4.1276
145129.2.4.128/29129.2.4.129 to 129.2.4.134129.2.4.1356
146129.2.4.136/29129.2.4.137 to 129.2.4.142129.2.4.1436
147129.2.4.144/29129.2.4.145 to 129.2.4.150129.2.4.1516
148129.2.4.152/29129.2.4.153 to 129.2.4.158129.2.4.1596
149129.2.4.160/29129.2.4.161 to 129.2.4.166129.2.4.1676
150129.2.4.168/29129.2.4.169 to 129.2.4.174129.2.4.1756
151129.2.4.176/29129.2.4.177 to 129.2.4.182129.2.4.1836
152129.2.4.184/29129.2.4.185 to 129.2.4.190129.2.4.1916
153129.2.4.192/29129.2.4.193 to 129.2.4.198129.2.4.1996
154129.2.4.200/29129.2.4.201 to 129.2.4.206129.2.4.2076
155129.2.4.208/29129.2.4.209 to 129.2.4.214129.2.4.2156
156129.2.4.216/29129.2.4.217 to 129.2.4.222129.2.4.2236
157129.2.4.224/29129.2.4.225 to 129.2.4.230129.2.4.2316
158129.2.4.232/29129.2.4.233 to 129.2.4.238129.2.4.2396
159129.2.4.240/29129.2.4.241 to 129.2.4.246129.2.4.2476
160129.2.4.248/29129.2.4.249 to 129.2.4.254129.2.4.2556
161129.2.5.0/29129.2.5.1 to 129.2.5.6129.2.5.76
162129.2.5.8/29129.2.5.9 to 129.2.5.14129.2.5.156
163129.2.5.16/29129.2.5.17 to 129.2.5.22129.2.5.236
164129.2.5.24/29129.2.5.25 to 129.2.5.30129.2.5.316
165129.2.5.32/29129.2.5.33 to 129.2.5.38129.2.5.396
166129.2.5.40/29129.2.5.41 to 129.2.5.46129.2.5.476
167129.2.5.48/29129.2.5.49 to 129.2.5.54129.2.5.556
168129.2.5.56/29129.2.5.57 to 129.2.5.62129.2.5.636
169129.2.5.64/29129.2.5.65 to 129.2.5.70129.2.5.716
170129.2.5.72/29129.2.5.73 to 129.2.5.78129.2.5.796
171129.2.5.80/29129.2.5.81 to 129.2.5.86129.2.5.876
172129.2.5.88/29129.2.5.89 to 129.2.5.94129.2.5.956
173129.2.5.96/29129.2.5.97 to 129.2.5.102129.2.5.1036
174129.2.5.104/29129.2.5.105 to 129.2.5.110129.2.5.1116
175129.2.5.112/29129.2.5.113 to 129.2.5.118129.2.5.1196
176129.2.5.120/29129.2.5.121 to 129.2.5.126129.2.5.1276
177129.2.5.128/29129.2.5.129 to 129.2.5.134129.2.5.1356
178129.2.5.136/29129.2.5.137 to 129.2.5.142129.2.5.1436
179129.2.5.144/29129.2.5.145 to 129.2.5.150129.2.5.1516
180129.2.5.152/29129.2.5.153 to 129.2.5.158129.2.5.1596
181129.2.5.160/29129.2.5.161 to 129.2.5.166129.2.5.1676
182129.2.5.168/29129.2.5.169 to 129.2.5.174129.2.5.1756
183129.2.5.176/29129.2.5.177 to 129.2.5.182129.2.5.1836
184129.2.5.184/29129.2.5.185 to 129.2.5.190129.2.5.1916
185129.2.5.192/29129.2.5.193 to 129.2.5.198129.2.5.1996
186129.2.5.200/29129.2.5.201 to 129.2.5.206129.2.5.2076
187129.2.5.208/29129.2.5.209 to 129.2.5.214129.2.5.2156
188129.2.5.216/29129.2.5.217 to 129.2.5.222129.2.5.2236
189129.2.5.224/29129.2.5.225 to 129.2.5.230129.2.5.2316
190129.2.5.232/29129.2.5.233 to 129.2.5.238129.2.5.2396
191129.2.5.240/29129.2.5.241 to 129.2.5.246129.2.5.2476
192129.2.5.248/29129.2.5.249 to 129.2.5.254129.2.5.2556
193129.2.6.0/29129.2.6.1 to 129.2.6.6129.2.6.76
194129.2.6.8/29129.2.6.9 to 129.2.6.14129.2.6.156
195129.2.6.16/29129.2.6.17 to 129.2.6.22129.2.6.236
196129.2.6.24/29129.2.6.25 to 129.2.6.30129.2.6.316
197129.2.6.32/29129.2.6.33 to 129.2.6.38129.2.6.396
198129.2.6.40/29129.2.6.41 to 129.2.6.46129.2.6.476
199129.2.6.48/29129.2.6.49 to 129.2.6.54129.2.6.556
200129.2.6.56/29129.2.6.57 to 129.2.6.62129.2.6.636
201129.2.6.64/29129.2.6.65 to 129.2.6.70129.2.6.716
202129.2.6.72/29129.2.6.73 to 129.2.6.78129.2.6.796
203129.2.6.80/29129.2.6.81 to 129.2.6.86129.2.6.876
204129.2.6.88/29129.2.6.89 to 129.2.6.94129.2.6.956
205129.2.6.96/29129.2.6.97 to 129.2.6.102129.2.6.1036
206129.2.6.104/29129.2.6.105 to 129.2.6.110129.2.6.1116
207129.2.6.112/29129.2.6.113 to 129.2.6.118129.2.6.1196
208129.2.6.120/29129.2.6.121 to 129.2.6.126129.2.6.1276
209129.2.6.128/29129.2.6.129 to 129.2.6.134129.2.6.1356
210129.2.6.136/29129.2.6.137 to 129.2.6.142129.2.6.1436
211129.2.6.144/29129.2.6.145 to 129.2.6.150129.2.6.1516
212129.2.6.152/29129.2.6.153 to 129.2.6.158129.2.6.1596
213129.2.6.160/29129.2.6.161 to 129.2.6.166129.2.6.1676
214129.2.6.168/29129.2.6.169 to 129.2.6.174129.2.6.1756
215129.2.6.176/29129.2.6.177 to 129.2.6.182129.2.6.1836
216129.2.6.184/29129.2.6.185 to 129.2.6.190129.2.6.1916
217129.2.6.192/29129.2.6.193 to 129.2.6.198129.2.6.1996
218129.2.6.200/29129.2.6.201 to 129.2.6.206129.2.6.2076
219129.2.6.208/29129.2.6.209 to 129.2.6.214129.2.6.2156
220129.2.6.216/29129.2.6.217 to 129.2.6.222129.2.6.2236
221129.2.6.224/29129.2.6.225 to 129.2.6.230129.2.6.2316
222129.2.6.232/29129.2.6.233 to 129.2.6.238129.2.6.2396
223129.2.6.240/29129.2.6.241 to 129.2.6.246129.2.6.2476
224129.2.6.248/29129.2.6.249 to 129.2.6.254129.2.6.2556
225129.2.7.0/29129.2.7.1 to 129.2.7.6129.2.7.76
226129.2.7.8/29129.2.7.9 to 129.2.7.14129.2.7.156
227129.2.7.16/29129.2.7.17 to 129.2.7.22129.2.7.236
228129.2.7.24/29129.2.7.25 to 129.2.7.30129.2.7.316
229129.2.7.32/29129.2.7.33 to 129.2.7.38129.2.7.396
230129.2.7.40/29129.2.7.41 to 129.2.7.46129.2.7.476
231129.2.7.48/29129.2.7.49 to 129.2.7.54129.2.7.556
232129.2.7.56/29129.2.7.57 to 129.2.7.62129.2.7.636
233129.2.7.64/29129.2.7.65 to 129.2.7.70129.2.7.716
234129.2.7.72/29129.2.7.73 to 129.2.7.78129.2.7.796
235129.2.7.80/29129.2.7.81 to 129.2.7.86129.2.7.876
236129.2.7.88/29129.2.7.89 to 129.2.7.94129.2.7.956
237129.2.7.96/29129.2.7.97 to 129.2.7.102129.2.7.1036
238129.2.7.104/29129.2.7.105 to 129.2.7.110129.2.7.1116
239129.2.7.112/29129.2.7.113 to 129.2.7.118129.2.7.1196
240129.2.7.120/29129.2.7.121 to 129.2.7.126129.2.7.1276
241129.2.7.128/29129.2.7.129 to 129.2.7.134129.2.7.1356
242129.2.7.136/29129.2.7.137 to 129.2.7.142129.2.7.1436
243129.2.7.144/29129.2.7.145 to 129.2.7.150129.2.7.1516
244129.2.7.152/29129.2.7.153 to 129.2.7.158129.2.7.1596
245129.2.7.160/29129.2.7.161 to 129.2.7.166129.2.7.1676
246129.2.7.168/29129.2.7.169 to 129.2.7.174129.2.7.1756
247129.2.7.176/29129.2.7.177 to 129.2.7.182129.2.7.1836
248129.2.7.184/29129.2.7.185 to 129.2.7.190129.2.7.1916
249129.2.7.192/29129.2.7.193 to 129.2.7.198129.2.7.1996
250129.2.7.200/29129.2.7.201 to 129.2.7.206129.2.7.2076
251129.2.7.208/29129.2.7.209 to 129.2.7.214129.2.7.2156
252129.2.7.216/29129.2.7.217 to 129.2.7.222129.2.7.2236
253129.2.7.224/29129.2.7.225 to 129.2.7.230129.2.7.2316
254129.2.7.232/29129.2.7.233 to 129.2.7.238129.2.7.2396
255129.2.7.240/29129.2.7.241 to 129.2.7.246129.2.7.2476
256129.2.7.248/29129.2.7.249 to 129.2.7.254129.2.7.2556

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.