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.

Network224.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
224.128.0.0
Broadcast address
224.191.255.255
First usable
224.128.0.1
Last usable
224.191.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E0800000 · Integer 3766484992 to 3770679295
Reverse DNS zones
128.224.in-addr.arpa
129.224.in-addr.arpa
130.224.in-addr.arpa
131.224.in-addr.arpa
132.224.in-addr.arpa
133.224.in-addr.arpa
134.224.in-addr.arpa
135.224.in-addr.arpa
136.224.in-addr.arpa
137.224.in-addr.arpa
138.224.in-addr.arpa
139.224.in-addr.arpa
140.224.in-addr.arpa
141.224.in-addr.arpa
142.224.in-addr.arpa
143.224.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100000.10000000.00000000.00000000224.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11100000.10000000.00000000.00000000224.128.0.0
Broadcast11100000.10111111.11111111.11111111224.191.255.255
Split into smaller subnets/22
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

224.128.0.0/10 makes 4,096 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1224.128.0.0/22224.128.0.1 to 224.128.3.254224.128.3.2551,022
2224.128.4.0/22224.128.4.1 to 224.128.7.254224.128.7.2551,022
3224.128.8.0/22224.128.8.1 to 224.128.11.254224.128.11.2551,022
4224.128.12.0/22224.128.12.1 to 224.128.15.254224.128.15.2551,022
5224.128.16.0/22224.128.16.1 to 224.128.19.254224.128.19.2551,022
6224.128.20.0/22224.128.20.1 to 224.128.23.254224.128.23.2551,022
7224.128.24.0/22224.128.24.1 to 224.128.27.254224.128.27.2551,022
8224.128.28.0/22224.128.28.1 to 224.128.31.254224.128.31.2551,022
9224.128.32.0/22224.128.32.1 to 224.128.35.254224.128.35.2551,022
10224.128.36.0/22224.128.36.1 to 224.128.39.254224.128.39.2551,022
11224.128.40.0/22224.128.40.1 to 224.128.43.254224.128.43.2551,022
12224.128.44.0/22224.128.44.1 to 224.128.47.254224.128.47.2551,022
13224.128.48.0/22224.128.48.1 to 224.128.51.254224.128.51.2551,022
14224.128.52.0/22224.128.52.1 to 224.128.55.254224.128.55.2551,022
15224.128.56.0/22224.128.56.1 to 224.128.59.254224.128.59.2551,022
16224.128.60.0/22224.128.60.1 to 224.128.63.254224.128.63.2551,022
17224.128.64.0/22224.128.64.1 to 224.128.67.254224.128.67.2551,022
18224.128.68.0/22224.128.68.1 to 224.128.71.254224.128.71.2551,022
19224.128.72.0/22224.128.72.1 to 224.128.75.254224.128.75.2551,022
20224.128.76.0/22224.128.76.1 to 224.128.79.254224.128.79.2551,022
21224.128.80.0/22224.128.80.1 to 224.128.83.254224.128.83.2551,022
22224.128.84.0/22224.128.84.1 to 224.128.87.254224.128.87.2551,022
23224.128.88.0/22224.128.88.1 to 224.128.91.254224.128.91.2551,022
24224.128.92.0/22224.128.92.1 to 224.128.95.254224.128.95.2551,022
25224.128.96.0/22224.128.96.1 to 224.128.99.254224.128.99.2551,022
26224.128.100.0/22224.128.100.1 to 224.128.103.254224.128.103.2551,022
27224.128.104.0/22224.128.104.1 to 224.128.107.254224.128.107.2551,022
28224.128.108.0/22224.128.108.1 to 224.128.111.254224.128.111.2551,022
29224.128.112.0/22224.128.112.1 to 224.128.115.254224.128.115.2551,022
30224.128.116.0/22224.128.116.1 to 224.128.119.254224.128.119.2551,022
31224.128.120.0/22224.128.120.1 to 224.128.123.254224.128.123.2551,022
32224.128.124.0/22224.128.124.1 to 224.128.127.254224.128.127.2551,022
33224.128.128.0/22224.128.128.1 to 224.128.131.254224.128.131.2551,022
34224.128.132.0/22224.128.132.1 to 224.128.135.254224.128.135.2551,022
35224.128.136.0/22224.128.136.1 to 224.128.139.254224.128.139.2551,022
36224.128.140.0/22224.128.140.1 to 224.128.143.254224.128.143.2551,022
37224.128.144.0/22224.128.144.1 to 224.128.147.254224.128.147.2551,022
38224.128.148.0/22224.128.148.1 to 224.128.151.254224.128.151.2551,022
39224.128.152.0/22224.128.152.1 to 224.128.155.254224.128.155.2551,022
40224.128.156.0/22224.128.156.1 to 224.128.159.254224.128.159.2551,022
41224.128.160.0/22224.128.160.1 to 224.128.163.254224.128.163.2551,022
42224.128.164.0/22224.128.164.1 to 224.128.167.254224.128.167.2551,022
43224.128.168.0/22224.128.168.1 to 224.128.171.254224.128.171.2551,022
44224.128.172.0/22224.128.172.1 to 224.128.175.254224.128.175.2551,022
45224.128.176.0/22224.128.176.1 to 224.128.179.254224.128.179.2551,022
46224.128.180.0/22224.128.180.1 to 224.128.183.254224.128.183.2551,022
47224.128.184.0/22224.128.184.1 to 224.128.187.254224.128.187.2551,022
48224.128.188.0/22224.128.188.1 to 224.128.191.254224.128.191.2551,022
49224.128.192.0/22224.128.192.1 to 224.128.195.254224.128.195.2551,022
50224.128.196.0/22224.128.196.1 to 224.128.199.254224.128.199.2551,022
51224.128.200.0/22224.128.200.1 to 224.128.203.254224.128.203.2551,022
52224.128.204.0/22224.128.204.1 to 224.128.207.254224.128.207.2551,022
53224.128.208.0/22224.128.208.1 to 224.128.211.254224.128.211.2551,022
54224.128.212.0/22224.128.212.1 to 224.128.215.254224.128.215.2551,022
55224.128.216.0/22224.128.216.1 to 224.128.219.254224.128.219.2551,022
56224.128.220.0/22224.128.220.1 to 224.128.223.254224.128.223.2551,022
57224.128.224.0/22224.128.224.1 to 224.128.227.254224.128.227.2551,022
58224.128.228.0/22224.128.228.1 to 224.128.231.254224.128.231.2551,022
59224.128.232.0/22224.128.232.1 to 224.128.235.254224.128.235.2551,022
60224.128.236.0/22224.128.236.1 to 224.128.239.254224.128.239.2551,022
61224.128.240.0/22224.128.240.1 to 224.128.243.254224.128.243.2551,022
62224.128.244.0/22224.128.244.1 to 224.128.247.254224.128.247.2551,022
63224.128.248.0/22224.128.248.1 to 224.128.251.254224.128.251.2551,022
64224.128.252.0/22224.128.252.1 to 224.128.255.254224.128.255.2551,022
65224.129.0.0/22224.129.0.1 to 224.129.3.254224.129.3.2551,022
66224.129.4.0/22224.129.4.1 to 224.129.7.254224.129.7.2551,022
67224.129.8.0/22224.129.8.1 to 224.129.11.254224.129.11.2551,022
68224.129.12.0/22224.129.12.1 to 224.129.15.254224.129.15.2551,022
69224.129.16.0/22224.129.16.1 to 224.129.19.254224.129.19.2551,022
70224.129.20.0/22224.129.20.1 to 224.129.23.254224.129.23.2551,022
71224.129.24.0/22224.129.24.1 to 224.129.27.254224.129.27.2551,022
72224.129.28.0/22224.129.28.1 to 224.129.31.254224.129.31.2551,022
73224.129.32.0/22224.129.32.1 to 224.129.35.254224.129.35.2551,022
74224.129.36.0/22224.129.36.1 to 224.129.39.254224.129.39.2551,022
75224.129.40.0/22224.129.40.1 to 224.129.43.254224.129.43.2551,022
76224.129.44.0/22224.129.44.1 to 224.129.47.254224.129.47.2551,022
77224.129.48.0/22224.129.48.1 to 224.129.51.254224.129.51.2551,022
78224.129.52.0/22224.129.52.1 to 224.129.55.254224.129.55.2551,022
79224.129.56.0/22224.129.56.1 to 224.129.59.254224.129.59.2551,022
80224.129.60.0/22224.129.60.1 to 224.129.63.254224.129.63.2551,022
81224.129.64.0/22224.129.64.1 to 224.129.67.254224.129.67.2551,022
82224.129.68.0/22224.129.68.1 to 224.129.71.254224.129.71.2551,022
83224.129.72.0/22224.129.72.1 to 224.129.75.254224.129.75.2551,022
84224.129.76.0/22224.129.76.1 to 224.129.79.254224.129.79.2551,022
85224.129.80.0/22224.129.80.1 to 224.129.83.254224.129.83.2551,022
86224.129.84.0/22224.129.84.1 to 224.129.87.254224.129.87.2551,022
87224.129.88.0/22224.129.88.1 to 224.129.91.254224.129.91.2551,022
88224.129.92.0/22224.129.92.1 to 224.129.95.254224.129.95.2551,022
89224.129.96.0/22224.129.96.1 to 224.129.99.254224.129.99.2551,022
90224.129.100.0/22224.129.100.1 to 224.129.103.254224.129.103.2551,022
91224.129.104.0/22224.129.104.1 to 224.129.107.254224.129.107.2551,022
92224.129.108.0/22224.129.108.1 to 224.129.111.254224.129.111.2551,022
93224.129.112.0/22224.129.112.1 to 224.129.115.254224.129.115.2551,022
94224.129.116.0/22224.129.116.1 to 224.129.119.254224.129.119.2551,022
95224.129.120.0/22224.129.120.1 to 224.129.123.254224.129.123.2551,022
96224.129.124.0/22224.129.124.1 to 224.129.127.254224.129.127.2551,022
97224.129.128.0/22224.129.128.1 to 224.129.131.254224.129.131.2551,022
98224.129.132.0/22224.129.132.1 to 224.129.135.254224.129.135.2551,022
99224.129.136.0/22224.129.136.1 to 224.129.139.254224.129.139.2551,022
100224.129.140.0/22224.129.140.1 to 224.129.143.254224.129.143.2551,022
101224.129.144.0/22224.129.144.1 to 224.129.147.254224.129.147.2551,022
102224.129.148.0/22224.129.148.1 to 224.129.151.254224.129.151.2551,022
103224.129.152.0/22224.129.152.1 to 224.129.155.254224.129.155.2551,022
104224.129.156.0/22224.129.156.1 to 224.129.159.254224.129.159.2551,022
105224.129.160.0/22224.129.160.1 to 224.129.163.254224.129.163.2551,022
106224.129.164.0/22224.129.164.1 to 224.129.167.254224.129.167.2551,022
107224.129.168.0/22224.129.168.1 to 224.129.171.254224.129.171.2551,022
108224.129.172.0/22224.129.172.1 to 224.129.175.254224.129.175.2551,022
109224.129.176.0/22224.129.176.1 to 224.129.179.254224.129.179.2551,022
110224.129.180.0/22224.129.180.1 to 224.129.183.254224.129.183.2551,022
111224.129.184.0/22224.129.184.1 to 224.129.187.254224.129.187.2551,022
112224.129.188.0/22224.129.188.1 to 224.129.191.254224.129.191.2551,022
113224.129.192.0/22224.129.192.1 to 224.129.195.254224.129.195.2551,022
114224.129.196.0/22224.129.196.1 to 224.129.199.254224.129.199.2551,022
115224.129.200.0/22224.129.200.1 to 224.129.203.254224.129.203.2551,022
116224.129.204.0/22224.129.204.1 to 224.129.207.254224.129.207.2551,022
117224.129.208.0/22224.129.208.1 to 224.129.211.254224.129.211.2551,022
118224.129.212.0/22224.129.212.1 to 224.129.215.254224.129.215.2551,022
119224.129.216.0/22224.129.216.1 to 224.129.219.254224.129.219.2551,022
120224.129.220.0/22224.129.220.1 to 224.129.223.254224.129.223.2551,022
121224.129.224.0/22224.129.224.1 to 224.129.227.254224.129.227.2551,022
122224.129.228.0/22224.129.228.1 to 224.129.231.254224.129.231.2551,022
123224.129.232.0/22224.129.232.1 to 224.129.235.254224.129.235.2551,022
124224.129.236.0/22224.129.236.1 to 224.129.239.254224.129.239.2551,022
125224.129.240.0/22224.129.240.1 to 224.129.243.254224.129.243.2551,022
126224.129.244.0/22224.129.244.1 to 224.129.247.254224.129.247.2551,022
127224.129.248.0/22224.129.248.1 to 224.129.251.254224.129.251.2551,022
128224.129.252.0/22224.129.252.1 to 224.129.255.254224.129.255.2551,022
129224.130.0.0/22224.130.0.1 to 224.130.3.254224.130.3.2551,022
130224.130.4.0/22224.130.4.1 to 224.130.7.254224.130.7.2551,022
131224.130.8.0/22224.130.8.1 to 224.130.11.254224.130.11.2551,022
132224.130.12.0/22224.130.12.1 to 224.130.15.254224.130.15.2551,022
133224.130.16.0/22224.130.16.1 to 224.130.19.254224.130.19.2551,022
134224.130.20.0/22224.130.20.1 to 224.130.23.254224.130.23.2551,022
135224.130.24.0/22224.130.24.1 to 224.130.27.254224.130.27.2551,022
136224.130.28.0/22224.130.28.1 to 224.130.31.254224.130.31.2551,022
137224.130.32.0/22224.130.32.1 to 224.130.35.254224.130.35.2551,022
138224.130.36.0/22224.130.36.1 to 224.130.39.254224.130.39.2551,022
139224.130.40.0/22224.130.40.1 to 224.130.43.254224.130.43.2551,022
140224.130.44.0/22224.130.44.1 to 224.130.47.254224.130.47.2551,022
141224.130.48.0/22224.130.48.1 to 224.130.51.254224.130.51.2551,022
142224.130.52.0/22224.130.52.1 to 224.130.55.254224.130.55.2551,022
143224.130.56.0/22224.130.56.1 to 224.130.59.254224.130.59.2551,022
144224.130.60.0/22224.130.60.1 to 224.130.63.254224.130.63.2551,022
145224.130.64.0/22224.130.64.1 to 224.130.67.254224.130.67.2551,022
146224.130.68.0/22224.130.68.1 to 224.130.71.254224.130.71.2551,022
147224.130.72.0/22224.130.72.1 to 224.130.75.254224.130.75.2551,022
148224.130.76.0/22224.130.76.1 to 224.130.79.254224.130.79.2551,022
149224.130.80.0/22224.130.80.1 to 224.130.83.254224.130.83.2551,022
150224.130.84.0/22224.130.84.1 to 224.130.87.254224.130.87.2551,022
151224.130.88.0/22224.130.88.1 to 224.130.91.254224.130.91.2551,022
152224.130.92.0/22224.130.92.1 to 224.130.95.254224.130.95.2551,022
153224.130.96.0/22224.130.96.1 to 224.130.99.254224.130.99.2551,022
154224.130.100.0/22224.130.100.1 to 224.130.103.254224.130.103.2551,022
155224.130.104.0/22224.130.104.1 to 224.130.107.254224.130.107.2551,022
156224.130.108.0/22224.130.108.1 to 224.130.111.254224.130.111.2551,022
157224.130.112.0/22224.130.112.1 to 224.130.115.254224.130.115.2551,022
158224.130.116.0/22224.130.116.1 to 224.130.119.254224.130.119.2551,022
159224.130.120.0/22224.130.120.1 to 224.130.123.254224.130.123.2551,022
160224.130.124.0/22224.130.124.1 to 224.130.127.254224.130.127.2551,022
161224.130.128.0/22224.130.128.1 to 224.130.131.254224.130.131.2551,022
162224.130.132.0/22224.130.132.1 to 224.130.135.254224.130.135.2551,022
163224.130.136.0/22224.130.136.1 to 224.130.139.254224.130.139.2551,022
164224.130.140.0/22224.130.140.1 to 224.130.143.254224.130.143.2551,022
165224.130.144.0/22224.130.144.1 to 224.130.147.254224.130.147.2551,022
166224.130.148.0/22224.130.148.1 to 224.130.151.254224.130.151.2551,022
167224.130.152.0/22224.130.152.1 to 224.130.155.254224.130.155.2551,022
168224.130.156.0/22224.130.156.1 to 224.130.159.254224.130.159.2551,022
169224.130.160.0/22224.130.160.1 to 224.130.163.254224.130.163.2551,022
170224.130.164.0/22224.130.164.1 to 224.130.167.254224.130.167.2551,022
171224.130.168.0/22224.130.168.1 to 224.130.171.254224.130.171.2551,022
172224.130.172.0/22224.130.172.1 to 224.130.175.254224.130.175.2551,022
173224.130.176.0/22224.130.176.1 to 224.130.179.254224.130.179.2551,022
174224.130.180.0/22224.130.180.1 to 224.130.183.254224.130.183.2551,022
175224.130.184.0/22224.130.184.1 to 224.130.187.254224.130.187.2551,022
176224.130.188.0/22224.130.188.1 to 224.130.191.254224.130.191.2551,022
177224.130.192.0/22224.130.192.1 to 224.130.195.254224.130.195.2551,022
178224.130.196.0/22224.130.196.1 to 224.130.199.254224.130.199.2551,022
179224.130.200.0/22224.130.200.1 to 224.130.203.254224.130.203.2551,022
180224.130.204.0/22224.130.204.1 to 224.130.207.254224.130.207.2551,022
181224.130.208.0/22224.130.208.1 to 224.130.211.254224.130.211.2551,022
182224.130.212.0/22224.130.212.1 to 224.130.215.254224.130.215.2551,022
183224.130.216.0/22224.130.216.1 to 224.130.219.254224.130.219.2551,022
184224.130.220.0/22224.130.220.1 to 224.130.223.254224.130.223.2551,022
185224.130.224.0/22224.130.224.1 to 224.130.227.254224.130.227.2551,022
186224.130.228.0/22224.130.228.1 to 224.130.231.254224.130.231.2551,022
187224.130.232.0/22224.130.232.1 to 224.130.235.254224.130.235.2551,022
188224.130.236.0/22224.130.236.1 to 224.130.239.254224.130.239.2551,022
189224.130.240.0/22224.130.240.1 to 224.130.243.254224.130.243.2551,022
190224.130.244.0/22224.130.244.1 to 224.130.247.254224.130.247.2551,022
191224.130.248.0/22224.130.248.1 to 224.130.251.254224.130.251.2551,022
192224.130.252.0/22224.130.252.1 to 224.130.255.254224.130.255.2551,022
193224.131.0.0/22224.131.0.1 to 224.131.3.254224.131.3.2551,022
194224.131.4.0/22224.131.4.1 to 224.131.7.254224.131.7.2551,022
195224.131.8.0/22224.131.8.1 to 224.131.11.254224.131.11.2551,022
196224.131.12.0/22224.131.12.1 to 224.131.15.254224.131.15.2551,022
197224.131.16.0/22224.131.16.1 to 224.131.19.254224.131.19.2551,022
198224.131.20.0/22224.131.20.1 to 224.131.23.254224.131.23.2551,022
199224.131.24.0/22224.131.24.1 to 224.131.27.254224.131.27.2551,022
200224.131.28.0/22224.131.28.1 to 224.131.31.254224.131.31.2551,022
201224.131.32.0/22224.131.32.1 to 224.131.35.254224.131.35.2551,022
202224.131.36.0/22224.131.36.1 to 224.131.39.254224.131.39.2551,022
203224.131.40.0/22224.131.40.1 to 224.131.43.254224.131.43.2551,022
204224.131.44.0/22224.131.44.1 to 224.131.47.254224.131.47.2551,022
205224.131.48.0/22224.131.48.1 to 224.131.51.254224.131.51.2551,022
206224.131.52.0/22224.131.52.1 to 224.131.55.254224.131.55.2551,022
207224.131.56.0/22224.131.56.1 to 224.131.59.254224.131.59.2551,022
208224.131.60.0/22224.131.60.1 to 224.131.63.254224.131.63.2551,022
209224.131.64.0/22224.131.64.1 to 224.131.67.254224.131.67.2551,022
210224.131.68.0/22224.131.68.1 to 224.131.71.254224.131.71.2551,022
211224.131.72.0/22224.131.72.1 to 224.131.75.254224.131.75.2551,022
212224.131.76.0/22224.131.76.1 to 224.131.79.254224.131.79.2551,022
213224.131.80.0/22224.131.80.1 to 224.131.83.254224.131.83.2551,022
214224.131.84.0/22224.131.84.1 to 224.131.87.254224.131.87.2551,022
215224.131.88.0/22224.131.88.1 to 224.131.91.254224.131.91.2551,022
216224.131.92.0/22224.131.92.1 to 224.131.95.254224.131.95.2551,022
217224.131.96.0/22224.131.96.1 to 224.131.99.254224.131.99.2551,022
218224.131.100.0/22224.131.100.1 to 224.131.103.254224.131.103.2551,022
219224.131.104.0/22224.131.104.1 to 224.131.107.254224.131.107.2551,022
220224.131.108.0/22224.131.108.1 to 224.131.111.254224.131.111.2551,022
221224.131.112.0/22224.131.112.1 to 224.131.115.254224.131.115.2551,022
222224.131.116.0/22224.131.116.1 to 224.131.119.254224.131.119.2551,022
223224.131.120.0/22224.131.120.1 to 224.131.123.254224.131.123.2551,022
224224.131.124.0/22224.131.124.1 to 224.131.127.254224.131.127.2551,022
225224.131.128.0/22224.131.128.1 to 224.131.131.254224.131.131.2551,022
226224.131.132.0/22224.131.132.1 to 224.131.135.254224.131.135.2551,022
227224.131.136.0/22224.131.136.1 to 224.131.139.254224.131.139.2551,022
228224.131.140.0/22224.131.140.1 to 224.131.143.254224.131.143.2551,022
229224.131.144.0/22224.131.144.1 to 224.131.147.254224.131.147.2551,022
230224.131.148.0/22224.131.148.1 to 224.131.151.254224.131.151.2551,022
231224.131.152.0/22224.131.152.1 to 224.131.155.254224.131.155.2551,022
232224.131.156.0/22224.131.156.1 to 224.131.159.254224.131.159.2551,022
233224.131.160.0/22224.131.160.1 to 224.131.163.254224.131.163.2551,022
234224.131.164.0/22224.131.164.1 to 224.131.167.254224.131.167.2551,022
235224.131.168.0/22224.131.168.1 to 224.131.171.254224.131.171.2551,022
236224.131.172.0/22224.131.172.1 to 224.131.175.254224.131.175.2551,022
237224.131.176.0/22224.131.176.1 to 224.131.179.254224.131.179.2551,022
238224.131.180.0/22224.131.180.1 to 224.131.183.254224.131.183.2551,022
239224.131.184.0/22224.131.184.1 to 224.131.187.254224.131.187.2551,022
240224.131.188.0/22224.131.188.1 to 224.131.191.254224.131.191.2551,022
241224.131.192.0/22224.131.192.1 to 224.131.195.254224.131.195.2551,022
242224.131.196.0/22224.131.196.1 to 224.131.199.254224.131.199.2551,022
243224.131.200.0/22224.131.200.1 to 224.131.203.254224.131.203.2551,022
244224.131.204.0/22224.131.204.1 to 224.131.207.254224.131.207.2551,022
245224.131.208.0/22224.131.208.1 to 224.131.211.254224.131.211.2551,022
246224.131.212.0/22224.131.212.1 to 224.131.215.254224.131.215.2551,022
247224.131.216.0/22224.131.216.1 to 224.131.219.254224.131.219.2551,022
248224.131.220.0/22224.131.220.1 to 224.131.223.254224.131.223.2551,022
249224.131.224.0/22224.131.224.1 to 224.131.227.254224.131.227.2551,022
250224.131.228.0/22224.131.228.1 to 224.131.231.254224.131.231.2551,022
251224.131.232.0/22224.131.232.1 to 224.131.235.254224.131.235.2551,022
252224.131.236.0/22224.131.236.1 to 224.131.239.254224.131.239.2551,022
253224.131.240.0/22224.131.240.1 to 224.131.243.254224.131.243.2551,022
254224.131.244.0/22224.131.244.1 to 224.131.247.254224.131.247.2551,022
255224.131.248.0/22224.131.248.1 to 224.131.251.254224.131.251.2551,022
256224.131.252.0/22224.131.252.1 to 224.131.255.254224.131.255.2551,022

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.