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.

Network240.167.232.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
240.167.232.0
Broadcast address
240.167.233.255
First usable
240.167.232.1
Last usable
240.167.233.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F0A7E800 · Integer 4037535744 to 4037536255
Reverse DNS zones
232.167.240.in-addr.arpa
233.167.240.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110000.10100111.11101000.00000000240.167.232.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network11110000.10100111.11101000.00000000240.167.232.0
Broadcast11110000.10100111.11101001.11111111240.167.233.255
Split into smaller subnets/32
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

240.167.232.0/23 makes 512 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.167.232.0/32240.167.232.0 to 240.167.232.0—1
2240.167.232.1/32240.167.232.1 to 240.167.232.1—1
3240.167.232.2/32240.167.232.2 to 240.167.232.2—1
4240.167.232.3/32240.167.232.3 to 240.167.232.3—1
5240.167.232.4/32240.167.232.4 to 240.167.232.4—1
6240.167.232.5/32240.167.232.5 to 240.167.232.5—1
7240.167.232.6/32240.167.232.6 to 240.167.232.6—1
8240.167.232.7/32240.167.232.7 to 240.167.232.7—1
9240.167.232.8/32240.167.232.8 to 240.167.232.8—1
10240.167.232.9/32240.167.232.9 to 240.167.232.9—1
11240.167.232.10/32240.167.232.10 to 240.167.232.10—1
12240.167.232.11/32240.167.232.11 to 240.167.232.11—1
13240.167.232.12/32240.167.232.12 to 240.167.232.12—1
14240.167.232.13/32240.167.232.13 to 240.167.232.13—1
15240.167.232.14/32240.167.232.14 to 240.167.232.14—1
16240.167.232.15/32240.167.232.15 to 240.167.232.15—1
17240.167.232.16/32240.167.232.16 to 240.167.232.16—1
18240.167.232.17/32240.167.232.17 to 240.167.232.17—1
19240.167.232.18/32240.167.232.18 to 240.167.232.18—1
20240.167.232.19/32240.167.232.19 to 240.167.232.19—1
21240.167.232.20/32240.167.232.20 to 240.167.232.20—1
22240.167.232.21/32240.167.232.21 to 240.167.232.21—1
23240.167.232.22/32240.167.232.22 to 240.167.232.22—1
24240.167.232.23/32240.167.232.23 to 240.167.232.23—1
25240.167.232.24/32240.167.232.24 to 240.167.232.24—1
26240.167.232.25/32240.167.232.25 to 240.167.232.25—1
27240.167.232.26/32240.167.232.26 to 240.167.232.26—1
28240.167.232.27/32240.167.232.27 to 240.167.232.27—1
29240.167.232.28/32240.167.232.28 to 240.167.232.28—1
30240.167.232.29/32240.167.232.29 to 240.167.232.29—1
31240.167.232.30/32240.167.232.30 to 240.167.232.30—1
32240.167.232.31/32240.167.232.31 to 240.167.232.31—1
33240.167.232.32/32240.167.232.32 to 240.167.232.32—1
34240.167.232.33/32240.167.232.33 to 240.167.232.33—1
35240.167.232.34/32240.167.232.34 to 240.167.232.34—1
36240.167.232.35/32240.167.232.35 to 240.167.232.35—1
37240.167.232.36/32240.167.232.36 to 240.167.232.36—1
38240.167.232.37/32240.167.232.37 to 240.167.232.37—1
39240.167.232.38/32240.167.232.38 to 240.167.232.38—1
40240.167.232.39/32240.167.232.39 to 240.167.232.39—1
41240.167.232.40/32240.167.232.40 to 240.167.232.40—1
42240.167.232.41/32240.167.232.41 to 240.167.232.41—1
43240.167.232.42/32240.167.232.42 to 240.167.232.42—1
44240.167.232.43/32240.167.232.43 to 240.167.232.43—1
45240.167.232.44/32240.167.232.44 to 240.167.232.44—1
46240.167.232.45/32240.167.232.45 to 240.167.232.45—1
47240.167.232.46/32240.167.232.46 to 240.167.232.46—1
48240.167.232.47/32240.167.232.47 to 240.167.232.47—1
49240.167.232.48/32240.167.232.48 to 240.167.232.48—1
50240.167.232.49/32240.167.232.49 to 240.167.232.49—1
51240.167.232.50/32240.167.232.50 to 240.167.232.50—1
52240.167.232.51/32240.167.232.51 to 240.167.232.51—1
53240.167.232.52/32240.167.232.52 to 240.167.232.52—1
54240.167.232.53/32240.167.232.53 to 240.167.232.53—1
55240.167.232.54/32240.167.232.54 to 240.167.232.54—1
56240.167.232.55/32240.167.232.55 to 240.167.232.55—1
57240.167.232.56/32240.167.232.56 to 240.167.232.56—1
58240.167.232.57/32240.167.232.57 to 240.167.232.57—1
59240.167.232.58/32240.167.232.58 to 240.167.232.58—1
60240.167.232.59/32240.167.232.59 to 240.167.232.59—1
61240.167.232.60/32240.167.232.60 to 240.167.232.60—1
62240.167.232.61/32240.167.232.61 to 240.167.232.61—1
63240.167.232.62/32240.167.232.62 to 240.167.232.62—1
64240.167.232.63/32240.167.232.63 to 240.167.232.63—1
65240.167.232.64/32240.167.232.64 to 240.167.232.64—1
66240.167.232.65/32240.167.232.65 to 240.167.232.65—1
67240.167.232.66/32240.167.232.66 to 240.167.232.66—1
68240.167.232.67/32240.167.232.67 to 240.167.232.67—1
69240.167.232.68/32240.167.232.68 to 240.167.232.68—1
70240.167.232.69/32240.167.232.69 to 240.167.232.69—1
71240.167.232.70/32240.167.232.70 to 240.167.232.70—1
72240.167.232.71/32240.167.232.71 to 240.167.232.71—1
73240.167.232.72/32240.167.232.72 to 240.167.232.72—1
74240.167.232.73/32240.167.232.73 to 240.167.232.73—1
75240.167.232.74/32240.167.232.74 to 240.167.232.74—1
76240.167.232.75/32240.167.232.75 to 240.167.232.75—1
77240.167.232.76/32240.167.232.76 to 240.167.232.76—1
78240.167.232.77/32240.167.232.77 to 240.167.232.77—1
79240.167.232.78/32240.167.232.78 to 240.167.232.78—1
80240.167.232.79/32240.167.232.79 to 240.167.232.79—1
81240.167.232.80/32240.167.232.80 to 240.167.232.80—1
82240.167.232.81/32240.167.232.81 to 240.167.232.81—1
83240.167.232.82/32240.167.232.82 to 240.167.232.82—1
84240.167.232.83/32240.167.232.83 to 240.167.232.83—1
85240.167.232.84/32240.167.232.84 to 240.167.232.84—1
86240.167.232.85/32240.167.232.85 to 240.167.232.85—1
87240.167.232.86/32240.167.232.86 to 240.167.232.86—1
88240.167.232.87/32240.167.232.87 to 240.167.232.87—1
89240.167.232.88/32240.167.232.88 to 240.167.232.88—1
90240.167.232.89/32240.167.232.89 to 240.167.232.89—1
91240.167.232.90/32240.167.232.90 to 240.167.232.90—1
92240.167.232.91/32240.167.232.91 to 240.167.232.91—1
93240.167.232.92/32240.167.232.92 to 240.167.232.92—1
94240.167.232.93/32240.167.232.93 to 240.167.232.93—1
95240.167.232.94/32240.167.232.94 to 240.167.232.94—1
96240.167.232.95/32240.167.232.95 to 240.167.232.95—1
97240.167.232.96/32240.167.232.96 to 240.167.232.96—1
98240.167.232.97/32240.167.232.97 to 240.167.232.97—1
99240.167.232.98/32240.167.232.98 to 240.167.232.98—1
100240.167.232.99/32240.167.232.99 to 240.167.232.99—1
101240.167.232.100/32240.167.232.100 to 240.167.232.100—1
102240.167.232.101/32240.167.232.101 to 240.167.232.101—1
103240.167.232.102/32240.167.232.102 to 240.167.232.102—1
104240.167.232.103/32240.167.232.103 to 240.167.232.103—1
105240.167.232.104/32240.167.232.104 to 240.167.232.104—1
106240.167.232.105/32240.167.232.105 to 240.167.232.105—1
107240.167.232.106/32240.167.232.106 to 240.167.232.106—1
108240.167.232.107/32240.167.232.107 to 240.167.232.107—1
109240.167.232.108/32240.167.232.108 to 240.167.232.108—1
110240.167.232.109/32240.167.232.109 to 240.167.232.109—1
111240.167.232.110/32240.167.232.110 to 240.167.232.110—1
112240.167.232.111/32240.167.232.111 to 240.167.232.111—1
113240.167.232.112/32240.167.232.112 to 240.167.232.112—1
114240.167.232.113/32240.167.232.113 to 240.167.232.113—1
115240.167.232.114/32240.167.232.114 to 240.167.232.114—1
116240.167.232.115/32240.167.232.115 to 240.167.232.115—1
117240.167.232.116/32240.167.232.116 to 240.167.232.116—1
118240.167.232.117/32240.167.232.117 to 240.167.232.117—1
119240.167.232.118/32240.167.232.118 to 240.167.232.118—1
120240.167.232.119/32240.167.232.119 to 240.167.232.119—1
121240.167.232.120/32240.167.232.120 to 240.167.232.120—1
122240.167.232.121/32240.167.232.121 to 240.167.232.121—1
123240.167.232.122/32240.167.232.122 to 240.167.232.122—1
124240.167.232.123/32240.167.232.123 to 240.167.232.123—1
125240.167.232.124/32240.167.232.124 to 240.167.232.124—1
126240.167.232.125/32240.167.232.125 to 240.167.232.125—1
127240.167.232.126/32240.167.232.126 to 240.167.232.126—1
128240.167.232.127/32240.167.232.127 to 240.167.232.127—1
129240.167.232.128/32240.167.232.128 to 240.167.232.128—1
130240.167.232.129/32240.167.232.129 to 240.167.232.129—1
131240.167.232.130/32240.167.232.130 to 240.167.232.130—1
132240.167.232.131/32240.167.232.131 to 240.167.232.131—1
133240.167.232.132/32240.167.232.132 to 240.167.232.132—1
134240.167.232.133/32240.167.232.133 to 240.167.232.133—1
135240.167.232.134/32240.167.232.134 to 240.167.232.134—1
136240.167.232.135/32240.167.232.135 to 240.167.232.135—1
137240.167.232.136/32240.167.232.136 to 240.167.232.136—1
138240.167.232.137/32240.167.232.137 to 240.167.232.137—1
139240.167.232.138/32240.167.232.138 to 240.167.232.138—1
140240.167.232.139/32240.167.232.139 to 240.167.232.139—1
141240.167.232.140/32240.167.232.140 to 240.167.232.140—1
142240.167.232.141/32240.167.232.141 to 240.167.232.141—1
143240.167.232.142/32240.167.232.142 to 240.167.232.142—1
144240.167.232.143/32240.167.232.143 to 240.167.232.143—1
145240.167.232.144/32240.167.232.144 to 240.167.232.144—1
146240.167.232.145/32240.167.232.145 to 240.167.232.145—1
147240.167.232.146/32240.167.232.146 to 240.167.232.146—1
148240.167.232.147/32240.167.232.147 to 240.167.232.147—1
149240.167.232.148/32240.167.232.148 to 240.167.232.148—1
150240.167.232.149/32240.167.232.149 to 240.167.232.149—1
151240.167.232.150/32240.167.232.150 to 240.167.232.150—1
152240.167.232.151/32240.167.232.151 to 240.167.232.151—1
153240.167.232.152/32240.167.232.152 to 240.167.232.152—1
154240.167.232.153/32240.167.232.153 to 240.167.232.153—1
155240.167.232.154/32240.167.232.154 to 240.167.232.154—1
156240.167.232.155/32240.167.232.155 to 240.167.232.155—1
157240.167.232.156/32240.167.232.156 to 240.167.232.156—1
158240.167.232.157/32240.167.232.157 to 240.167.232.157—1
159240.167.232.158/32240.167.232.158 to 240.167.232.158—1
160240.167.232.159/32240.167.232.159 to 240.167.232.159—1
161240.167.232.160/32240.167.232.160 to 240.167.232.160—1
162240.167.232.161/32240.167.232.161 to 240.167.232.161—1
163240.167.232.162/32240.167.232.162 to 240.167.232.162—1
164240.167.232.163/32240.167.232.163 to 240.167.232.163—1
165240.167.232.164/32240.167.232.164 to 240.167.232.164—1
166240.167.232.165/32240.167.232.165 to 240.167.232.165—1
167240.167.232.166/32240.167.232.166 to 240.167.232.166—1
168240.167.232.167/32240.167.232.167 to 240.167.232.167—1
169240.167.232.168/32240.167.232.168 to 240.167.232.168—1
170240.167.232.169/32240.167.232.169 to 240.167.232.169—1
171240.167.232.170/32240.167.232.170 to 240.167.232.170—1
172240.167.232.171/32240.167.232.171 to 240.167.232.171—1
173240.167.232.172/32240.167.232.172 to 240.167.232.172—1
174240.167.232.173/32240.167.232.173 to 240.167.232.173—1
175240.167.232.174/32240.167.232.174 to 240.167.232.174—1
176240.167.232.175/32240.167.232.175 to 240.167.232.175—1
177240.167.232.176/32240.167.232.176 to 240.167.232.176—1
178240.167.232.177/32240.167.232.177 to 240.167.232.177—1
179240.167.232.178/32240.167.232.178 to 240.167.232.178—1
180240.167.232.179/32240.167.232.179 to 240.167.232.179—1
181240.167.232.180/32240.167.232.180 to 240.167.232.180—1
182240.167.232.181/32240.167.232.181 to 240.167.232.181—1
183240.167.232.182/32240.167.232.182 to 240.167.232.182—1
184240.167.232.183/32240.167.232.183 to 240.167.232.183—1
185240.167.232.184/32240.167.232.184 to 240.167.232.184—1
186240.167.232.185/32240.167.232.185 to 240.167.232.185—1
187240.167.232.186/32240.167.232.186 to 240.167.232.186—1
188240.167.232.187/32240.167.232.187 to 240.167.232.187—1
189240.167.232.188/32240.167.232.188 to 240.167.232.188—1
190240.167.232.189/32240.167.232.189 to 240.167.232.189—1
191240.167.232.190/32240.167.232.190 to 240.167.232.190—1
192240.167.232.191/32240.167.232.191 to 240.167.232.191—1
193240.167.232.192/32240.167.232.192 to 240.167.232.192—1
194240.167.232.193/32240.167.232.193 to 240.167.232.193—1
195240.167.232.194/32240.167.232.194 to 240.167.232.194—1
196240.167.232.195/32240.167.232.195 to 240.167.232.195—1
197240.167.232.196/32240.167.232.196 to 240.167.232.196—1
198240.167.232.197/32240.167.232.197 to 240.167.232.197—1
199240.167.232.198/32240.167.232.198 to 240.167.232.198—1
200240.167.232.199/32240.167.232.199 to 240.167.232.199—1
201240.167.232.200/32240.167.232.200 to 240.167.232.200—1
202240.167.232.201/32240.167.232.201 to 240.167.232.201—1
203240.167.232.202/32240.167.232.202 to 240.167.232.202—1
204240.167.232.203/32240.167.232.203 to 240.167.232.203—1
205240.167.232.204/32240.167.232.204 to 240.167.232.204—1
206240.167.232.205/32240.167.232.205 to 240.167.232.205—1
207240.167.232.206/32240.167.232.206 to 240.167.232.206—1
208240.167.232.207/32240.167.232.207 to 240.167.232.207—1
209240.167.232.208/32240.167.232.208 to 240.167.232.208—1
210240.167.232.209/32240.167.232.209 to 240.167.232.209—1
211240.167.232.210/32240.167.232.210 to 240.167.232.210—1
212240.167.232.211/32240.167.232.211 to 240.167.232.211—1
213240.167.232.212/32240.167.232.212 to 240.167.232.212—1
214240.167.232.213/32240.167.232.213 to 240.167.232.213—1
215240.167.232.214/32240.167.232.214 to 240.167.232.214—1
216240.167.232.215/32240.167.232.215 to 240.167.232.215—1
217240.167.232.216/32240.167.232.216 to 240.167.232.216—1
218240.167.232.217/32240.167.232.217 to 240.167.232.217—1
219240.167.232.218/32240.167.232.218 to 240.167.232.218—1
220240.167.232.219/32240.167.232.219 to 240.167.232.219—1
221240.167.232.220/32240.167.232.220 to 240.167.232.220—1
222240.167.232.221/32240.167.232.221 to 240.167.232.221—1
223240.167.232.222/32240.167.232.222 to 240.167.232.222—1
224240.167.232.223/32240.167.232.223 to 240.167.232.223—1
225240.167.232.224/32240.167.232.224 to 240.167.232.224—1
226240.167.232.225/32240.167.232.225 to 240.167.232.225—1
227240.167.232.226/32240.167.232.226 to 240.167.232.226—1
228240.167.232.227/32240.167.232.227 to 240.167.232.227—1
229240.167.232.228/32240.167.232.228 to 240.167.232.228—1
230240.167.232.229/32240.167.232.229 to 240.167.232.229—1
231240.167.232.230/32240.167.232.230 to 240.167.232.230—1
232240.167.232.231/32240.167.232.231 to 240.167.232.231—1
233240.167.232.232/32240.167.232.232 to 240.167.232.232—1
234240.167.232.233/32240.167.232.233 to 240.167.232.233—1
235240.167.232.234/32240.167.232.234 to 240.167.232.234—1
236240.167.232.235/32240.167.232.235 to 240.167.232.235—1
237240.167.232.236/32240.167.232.236 to 240.167.232.236—1
238240.167.232.237/32240.167.232.237 to 240.167.232.237—1
239240.167.232.238/32240.167.232.238 to 240.167.232.238—1
240240.167.232.239/32240.167.232.239 to 240.167.232.239—1
241240.167.232.240/32240.167.232.240 to 240.167.232.240—1
242240.167.232.241/32240.167.232.241 to 240.167.232.241—1
243240.167.232.242/32240.167.232.242 to 240.167.232.242—1
244240.167.232.243/32240.167.232.243 to 240.167.232.243—1
245240.167.232.244/32240.167.232.244 to 240.167.232.244—1
246240.167.232.245/32240.167.232.245 to 240.167.232.245—1
247240.167.232.246/32240.167.232.246 to 240.167.232.246—1
248240.167.232.247/32240.167.232.247 to 240.167.232.247—1
249240.167.232.248/32240.167.232.248 to 240.167.232.248—1
250240.167.232.249/32240.167.232.249 to 240.167.232.249—1
251240.167.232.250/32240.167.232.250 to 240.167.232.250—1
252240.167.232.251/32240.167.232.251 to 240.167.232.251—1
253240.167.232.252/32240.167.232.252 to 240.167.232.252—1
254240.167.232.253/32240.167.232.253 to 240.167.232.253—1
255240.167.232.254/32240.167.232.254 to 240.167.232.254—1
256240.167.232.255/32240.167.232.255 to 240.167.232.255—1

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.