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.

Network182.0.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
182.0.64.0
Broadcast address
182.0.95.255
First usable
182.0.64.1
Last usable
182.0.95.254
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 B6004000 · Integer 3053469696 to 3053477887
Reverse DNS zones
64.0.182.in-addr.arpa
65.0.182.in-addr.arpa
66.0.182.in-addr.arpa
67.0.182.in-addr.arpa
68.0.182.in-addr.arpa
69.0.182.in-addr.arpa
70.0.182.in-addr.arpa
71.0.182.in-addr.arpa
72.0.182.in-addr.arpa
73.0.182.in-addr.arpa
74.0.182.in-addr.arpa
75.0.182.in-addr.arpa
76.0.182.in-addr.arpa
77.0.182.in-addr.arpa
78.0.182.in-addr.arpa
79.0.182.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
Address10110110.00000000.01000000.00000000182.0.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10110110.00000000.01000000.00000000182.0.64.0
Broadcast10110110.00000000.01011111.11111111182.0.95.255
Split into smaller subnets/31
/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)

182.0.64.0/19 makes 4,096 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1182.0.64.0/31182.0.64.0 to 182.0.64.1—2
2182.0.64.2/31182.0.64.2 to 182.0.64.3—2
3182.0.64.4/31182.0.64.4 to 182.0.64.5—2
4182.0.64.6/31182.0.64.6 to 182.0.64.7—2
5182.0.64.8/31182.0.64.8 to 182.0.64.9—2
6182.0.64.10/31182.0.64.10 to 182.0.64.11—2
7182.0.64.12/31182.0.64.12 to 182.0.64.13—2
8182.0.64.14/31182.0.64.14 to 182.0.64.15—2
9182.0.64.16/31182.0.64.16 to 182.0.64.17—2
10182.0.64.18/31182.0.64.18 to 182.0.64.19—2
11182.0.64.20/31182.0.64.20 to 182.0.64.21—2
12182.0.64.22/31182.0.64.22 to 182.0.64.23—2
13182.0.64.24/31182.0.64.24 to 182.0.64.25—2
14182.0.64.26/31182.0.64.26 to 182.0.64.27—2
15182.0.64.28/31182.0.64.28 to 182.0.64.29—2
16182.0.64.30/31182.0.64.30 to 182.0.64.31—2
17182.0.64.32/31182.0.64.32 to 182.0.64.33—2
18182.0.64.34/31182.0.64.34 to 182.0.64.35—2
19182.0.64.36/31182.0.64.36 to 182.0.64.37—2
20182.0.64.38/31182.0.64.38 to 182.0.64.39—2
21182.0.64.40/31182.0.64.40 to 182.0.64.41—2
22182.0.64.42/31182.0.64.42 to 182.0.64.43—2
23182.0.64.44/31182.0.64.44 to 182.0.64.45—2
24182.0.64.46/31182.0.64.46 to 182.0.64.47—2
25182.0.64.48/31182.0.64.48 to 182.0.64.49—2
26182.0.64.50/31182.0.64.50 to 182.0.64.51—2
27182.0.64.52/31182.0.64.52 to 182.0.64.53—2
28182.0.64.54/31182.0.64.54 to 182.0.64.55—2
29182.0.64.56/31182.0.64.56 to 182.0.64.57—2
30182.0.64.58/31182.0.64.58 to 182.0.64.59—2
31182.0.64.60/31182.0.64.60 to 182.0.64.61—2
32182.0.64.62/31182.0.64.62 to 182.0.64.63—2
33182.0.64.64/31182.0.64.64 to 182.0.64.65—2
34182.0.64.66/31182.0.64.66 to 182.0.64.67—2
35182.0.64.68/31182.0.64.68 to 182.0.64.69—2
36182.0.64.70/31182.0.64.70 to 182.0.64.71—2
37182.0.64.72/31182.0.64.72 to 182.0.64.73—2
38182.0.64.74/31182.0.64.74 to 182.0.64.75—2
39182.0.64.76/31182.0.64.76 to 182.0.64.77—2
40182.0.64.78/31182.0.64.78 to 182.0.64.79—2
41182.0.64.80/31182.0.64.80 to 182.0.64.81—2
42182.0.64.82/31182.0.64.82 to 182.0.64.83—2
43182.0.64.84/31182.0.64.84 to 182.0.64.85—2
44182.0.64.86/31182.0.64.86 to 182.0.64.87—2
45182.0.64.88/31182.0.64.88 to 182.0.64.89—2
46182.0.64.90/31182.0.64.90 to 182.0.64.91—2
47182.0.64.92/31182.0.64.92 to 182.0.64.93—2
48182.0.64.94/31182.0.64.94 to 182.0.64.95—2
49182.0.64.96/31182.0.64.96 to 182.0.64.97—2
50182.0.64.98/31182.0.64.98 to 182.0.64.99—2
51182.0.64.100/31182.0.64.100 to 182.0.64.101—2
52182.0.64.102/31182.0.64.102 to 182.0.64.103—2
53182.0.64.104/31182.0.64.104 to 182.0.64.105—2
54182.0.64.106/31182.0.64.106 to 182.0.64.107—2
55182.0.64.108/31182.0.64.108 to 182.0.64.109—2
56182.0.64.110/31182.0.64.110 to 182.0.64.111—2
57182.0.64.112/31182.0.64.112 to 182.0.64.113—2
58182.0.64.114/31182.0.64.114 to 182.0.64.115—2
59182.0.64.116/31182.0.64.116 to 182.0.64.117—2
60182.0.64.118/31182.0.64.118 to 182.0.64.119—2
61182.0.64.120/31182.0.64.120 to 182.0.64.121—2
62182.0.64.122/31182.0.64.122 to 182.0.64.123—2
63182.0.64.124/31182.0.64.124 to 182.0.64.125—2
64182.0.64.126/31182.0.64.126 to 182.0.64.127—2
65182.0.64.128/31182.0.64.128 to 182.0.64.129—2
66182.0.64.130/31182.0.64.130 to 182.0.64.131—2
67182.0.64.132/31182.0.64.132 to 182.0.64.133—2
68182.0.64.134/31182.0.64.134 to 182.0.64.135—2
69182.0.64.136/31182.0.64.136 to 182.0.64.137—2
70182.0.64.138/31182.0.64.138 to 182.0.64.139—2
71182.0.64.140/31182.0.64.140 to 182.0.64.141—2
72182.0.64.142/31182.0.64.142 to 182.0.64.143—2
73182.0.64.144/31182.0.64.144 to 182.0.64.145—2
74182.0.64.146/31182.0.64.146 to 182.0.64.147—2
75182.0.64.148/31182.0.64.148 to 182.0.64.149—2
76182.0.64.150/31182.0.64.150 to 182.0.64.151—2
77182.0.64.152/31182.0.64.152 to 182.0.64.153—2
78182.0.64.154/31182.0.64.154 to 182.0.64.155—2
79182.0.64.156/31182.0.64.156 to 182.0.64.157—2
80182.0.64.158/31182.0.64.158 to 182.0.64.159—2
81182.0.64.160/31182.0.64.160 to 182.0.64.161—2
82182.0.64.162/31182.0.64.162 to 182.0.64.163—2
83182.0.64.164/31182.0.64.164 to 182.0.64.165—2
84182.0.64.166/31182.0.64.166 to 182.0.64.167—2
85182.0.64.168/31182.0.64.168 to 182.0.64.169—2
86182.0.64.170/31182.0.64.170 to 182.0.64.171—2
87182.0.64.172/31182.0.64.172 to 182.0.64.173—2
88182.0.64.174/31182.0.64.174 to 182.0.64.175—2
89182.0.64.176/31182.0.64.176 to 182.0.64.177—2
90182.0.64.178/31182.0.64.178 to 182.0.64.179—2
91182.0.64.180/31182.0.64.180 to 182.0.64.181—2
92182.0.64.182/31182.0.64.182 to 182.0.64.183—2
93182.0.64.184/31182.0.64.184 to 182.0.64.185—2
94182.0.64.186/31182.0.64.186 to 182.0.64.187—2
95182.0.64.188/31182.0.64.188 to 182.0.64.189—2
96182.0.64.190/31182.0.64.190 to 182.0.64.191—2
97182.0.64.192/31182.0.64.192 to 182.0.64.193—2
98182.0.64.194/31182.0.64.194 to 182.0.64.195—2
99182.0.64.196/31182.0.64.196 to 182.0.64.197—2
100182.0.64.198/31182.0.64.198 to 182.0.64.199—2
101182.0.64.200/31182.0.64.200 to 182.0.64.201—2
102182.0.64.202/31182.0.64.202 to 182.0.64.203—2
103182.0.64.204/31182.0.64.204 to 182.0.64.205—2
104182.0.64.206/31182.0.64.206 to 182.0.64.207—2
105182.0.64.208/31182.0.64.208 to 182.0.64.209—2
106182.0.64.210/31182.0.64.210 to 182.0.64.211—2
107182.0.64.212/31182.0.64.212 to 182.0.64.213—2
108182.0.64.214/31182.0.64.214 to 182.0.64.215—2
109182.0.64.216/31182.0.64.216 to 182.0.64.217—2
110182.0.64.218/31182.0.64.218 to 182.0.64.219—2
111182.0.64.220/31182.0.64.220 to 182.0.64.221—2
112182.0.64.222/31182.0.64.222 to 182.0.64.223—2
113182.0.64.224/31182.0.64.224 to 182.0.64.225—2
114182.0.64.226/31182.0.64.226 to 182.0.64.227—2
115182.0.64.228/31182.0.64.228 to 182.0.64.229—2
116182.0.64.230/31182.0.64.230 to 182.0.64.231—2
117182.0.64.232/31182.0.64.232 to 182.0.64.233—2
118182.0.64.234/31182.0.64.234 to 182.0.64.235—2
119182.0.64.236/31182.0.64.236 to 182.0.64.237—2
120182.0.64.238/31182.0.64.238 to 182.0.64.239—2
121182.0.64.240/31182.0.64.240 to 182.0.64.241—2
122182.0.64.242/31182.0.64.242 to 182.0.64.243—2
123182.0.64.244/31182.0.64.244 to 182.0.64.245—2
124182.0.64.246/31182.0.64.246 to 182.0.64.247—2
125182.0.64.248/31182.0.64.248 to 182.0.64.249—2
126182.0.64.250/31182.0.64.250 to 182.0.64.251—2
127182.0.64.252/31182.0.64.252 to 182.0.64.253—2
128182.0.64.254/31182.0.64.254 to 182.0.64.255—2
129182.0.65.0/31182.0.65.0 to 182.0.65.1—2
130182.0.65.2/31182.0.65.2 to 182.0.65.3—2
131182.0.65.4/31182.0.65.4 to 182.0.65.5—2
132182.0.65.6/31182.0.65.6 to 182.0.65.7—2
133182.0.65.8/31182.0.65.8 to 182.0.65.9—2
134182.0.65.10/31182.0.65.10 to 182.0.65.11—2
135182.0.65.12/31182.0.65.12 to 182.0.65.13—2
136182.0.65.14/31182.0.65.14 to 182.0.65.15—2
137182.0.65.16/31182.0.65.16 to 182.0.65.17—2
138182.0.65.18/31182.0.65.18 to 182.0.65.19—2
139182.0.65.20/31182.0.65.20 to 182.0.65.21—2
140182.0.65.22/31182.0.65.22 to 182.0.65.23—2
141182.0.65.24/31182.0.65.24 to 182.0.65.25—2
142182.0.65.26/31182.0.65.26 to 182.0.65.27—2
143182.0.65.28/31182.0.65.28 to 182.0.65.29—2
144182.0.65.30/31182.0.65.30 to 182.0.65.31—2
145182.0.65.32/31182.0.65.32 to 182.0.65.33—2
146182.0.65.34/31182.0.65.34 to 182.0.65.35—2
147182.0.65.36/31182.0.65.36 to 182.0.65.37—2
148182.0.65.38/31182.0.65.38 to 182.0.65.39—2
149182.0.65.40/31182.0.65.40 to 182.0.65.41—2
150182.0.65.42/31182.0.65.42 to 182.0.65.43—2
151182.0.65.44/31182.0.65.44 to 182.0.65.45—2
152182.0.65.46/31182.0.65.46 to 182.0.65.47—2
153182.0.65.48/31182.0.65.48 to 182.0.65.49—2
154182.0.65.50/31182.0.65.50 to 182.0.65.51—2
155182.0.65.52/31182.0.65.52 to 182.0.65.53—2
156182.0.65.54/31182.0.65.54 to 182.0.65.55—2
157182.0.65.56/31182.0.65.56 to 182.0.65.57—2
158182.0.65.58/31182.0.65.58 to 182.0.65.59—2
159182.0.65.60/31182.0.65.60 to 182.0.65.61—2
160182.0.65.62/31182.0.65.62 to 182.0.65.63—2
161182.0.65.64/31182.0.65.64 to 182.0.65.65—2
162182.0.65.66/31182.0.65.66 to 182.0.65.67—2
163182.0.65.68/31182.0.65.68 to 182.0.65.69—2
164182.0.65.70/31182.0.65.70 to 182.0.65.71—2
165182.0.65.72/31182.0.65.72 to 182.0.65.73—2
166182.0.65.74/31182.0.65.74 to 182.0.65.75—2
167182.0.65.76/31182.0.65.76 to 182.0.65.77—2
168182.0.65.78/31182.0.65.78 to 182.0.65.79—2
169182.0.65.80/31182.0.65.80 to 182.0.65.81—2
170182.0.65.82/31182.0.65.82 to 182.0.65.83—2
171182.0.65.84/31182.0.65.84 to 182.0.65.85—2
172182.0.65.86/31182.0.65.86 to 182.0.65.87—2
173182.0.65.88/31182.0.65.88 to 182.0.65.89—2
174182.0.65.90/31182.0.65.90 to 182.0.65.91—2
175182.0.65.92/31182.0.65.92 to 182.0.65.93—2
176182.0.65.94/31182.0.65.94 to 182.0.65.95—2
177182.0.65.96/31182.0.65.96 to 182.0.65.97—2
178182.0.65.98/31182.0.65.98 to 182.0.65.99—2
179182.0.65.100/31182.0.65.100 to 182.0.65.101—2
180182.0.65.102/31182.0.65.102 to 182.0.65.103—2
181182.0.65.104/31182.0.65.104 to 182.0.65.105—2
182182.0.65.106/31182.0.65.106 to 182.0.65.107—2
183182.0.65.108/31182.0.65.108 to 182.0.65.109—2
184182.0.65.110/31182.0.65.110 to 182.0.65.111—2
185182.0.65.112/31182.0.65.112 to 182.0.65.113—2
186182.0.65.114/31182.0.65.114 to 182.0.65.115—2
187182.0.65.116/31182.0.65.116 to 182.0.65.117—2
188182.0.65.118/31182.0.65.118 to 182.0.65.119—2
189182.0.65.120/31182.0.65.120 to 182.0.65.121—2
190182.0.65.122/31182.0.65.122 to 182.0.65.123—2
191182.0.65.124/31182.0.65.124 to 182.0.65.125—2
192182.0.65.126/31182.0.65.126 to 182.0.65.127—2
193182.0.65.128/31182.0.65.128 to 182.0.65.129—2
194182.0.65.130/31182.0.65.130 to 182.0.65.131—2
195182.0.65.132/31182.0.65.132 to 182.0.65.133—2
196182.0.65.134/31182.0.65.134 to 182.0.65.135—2
197182.0.65.136/31182.0.65.136 to 182.0.65.137—2
198182.0.65.138/31182.0.65.138 to 182.0.65.139—2
199182.0.65.140/31182.0.65.140 to 182.0.65.141—2
200182.0.65.142/31182.0.65.142 to 182.0.65.143—2
201182.0.65.144/31182.0.65.144 to 182.0.65.145—2
202182.0.65.146/31182.0.65.146 to 182.0.65.147—2
203182.0.65.148/31182.0.65.148 to 182.0.65.149—2
204182.0.65.150/31182.0.65.150 to 182.0.65.151—2
205182.0.65.152/31182.0.65.152 to 182.0.65.153—2
206182.0.65.154/31182.0.65.154 to 182.0.65.155—2
207182.0.65.156/31182.0.65.156 to 182.0.65.157—2
208182.0.65.158/31182.0.65.158 to 182.0.65.159—2
209182.0.65.160/31182.0.65.160 to 182.0.65.161—2
210182.0.65.162/31182.0.65.162 to 182.0.65.163—2
211182.0.65.164/31182.0.65.164 to 182.0.65.165—2
212182.0.65.166/31182.0.65.166 to 182.0.65.167—2
213182.0.65.168/31182.0.65.168 to 182.0.65.169—2
214182.0.65.170/31182.0.65.170 to 182.0.65.171—2
215182.0.65.172/31182.0.65.172 to 182.0.65.173—2
216182.0.65.174/31182.0.65.174 to 182.0.65.175—2
217182.0.65.176/31182.0.65.176 to 182.0.65.177—2
218182.0.65.178/31182.0.65.178 to 182.0.65.179—2
219182.0.65.180/31182.0.65.180 to 182.0.65.181—2
220182.0.65.182/31182.0.65.182 to 182.0.65.183—2
221182.0.65.184/31182.0.65.184 to 182.0.65.185—2
222182.0.65.186/31182.0.65.186 to 182.0.65.187—2
223182.0.65.188/31182.0.65.188 to 182.0.65.189—2
224182.0.65.190/31182.0.65.190 to 182.0.65.191—2
225182.0.65.192/31182.0.65.192 to 182.0.65.193—2
226182.0.65.194/31182.0.65.194 to 182.0.65.195—2
227182.0.65.196/31182.0.65.196 to 182.0.65.197—2
228182.0.65.198/31182.0.65.198 to 182.0.65.199—2
229182.0.65.200/31182.0.65.200 to 182.0.65.201—2
230182.0.65.202/31182.0.65.202 to 182.0.65.203—2
231182.0.65.204/31182.0.65.204 to 182.0.65.205—2
232182.0.65.206/31182.0.65.206 to 182.0.65.207—2
233182.0.65.208/31182.0.65.208 to 182.0.65.209—2
234182.0.65.210/31182.0.65.210 to 182.0.65.211—2
235182.0.65.212/31182.0.65.212 to 182.0.65.213—2
236182.0.65.214/31182.0.65.214 to 182.0.65.215—2
237182.0.65.216/31182.0.65.216 to 182.0.65.217—2
238182.0.65.218/31182.0.65.218 to 182.0.65.219—2
239182.0.65.220/31182.0.65.220 to 182.0.65.221—2
240182.0.65.222/31182.0.65.222 to 182.0.65.223—2
241182.0.65.224/31182.0.65.224 to 182.0.65.225—2
242182.0.65.226/31182.0.65.226 to 182.0.65.227—2
243182.0.65.228/31182.0.65.228 to 182.0.65.229—2
244182.0.65.230/31182.0.65.230 to 182.0.65.231—2
245182.0.65.232/31182.0.65.232 to 182.0.65.233—2
246182.0.65.234/31182.0.65.234 to 182.0.65.235—2
247182.0.65.236/31182.0.65.236 to 182.0.65.237—2
248182.0.65.238/31182.0.65.238 to 182.0.65.239—2
249182.0.65.240/31182.0.65.240 to 182.0.65.241—2
250182.0.65.242/31182.0.65.242 to 182.0.65.243—2
251182.0.65.244/31182.0.65.244 to 182.0.65.245—2
252182.0.65.246/31182.0.65.246 to 182.0.65.247—2
253182.0.65.248/31182.0.65.248 to 182.0.65.249—2
254182.0.65.250/31182.0.65.250 to 182.0.65.251—2
255182.0.65.252/31182.0.65.252 to 182.0.65.253—2
256182.0.65.254/31182.0.65.254 to 182.0.65.255—2

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.