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.

Network227.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
227.136.0.0
Broadcast address
227.143.255.255
First usable
227.136.0.1
Last usable
227.143.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E3880000 · Integer 3817340928 to 3817865215
Reverse DNS zones
136.227.in-addr.arpa
137.227.in-addr.arpa
138.227.in-addr.arpa
139.227.in-addr.arpa
140.227.in-addr.arpa
141.227.in-addr.arpa
142.227.in-addr.arpa
143.227.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100011.10001000.00000000.00000000227.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11100011.10001000.00000000.00000000227.136.0.0
Broadcast11100011.10001111.11111111.11111111227.143.255.255
Split into smaller subnets/25
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

227.136.0.0/13 makes 4,096 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1227.136.0.0/25227.136.0.1 to 227.136.0.126227.136.0.127126
2227.136.0.128/25227.136.0.129 to 227.136.0.254227.136.0.255126
3227.136.1.0/25227.136.1.1 to 227.136.1.126227.136.1.127126
4227.136.1.128/25227.136.1.129 to 227.136.1.254227.136.1.255126
5227.136.2.0/25227.136.2.1 to 227.136.2.126227.136.2.127126
6227.136.2.128/25227.136.2.129 to 227.136.2.254227.136.2.255126
7227.136.3.0/25227.136.3.1 to 227.136.3.126227.136.3.127126
8227.136.3.128/25227.136.3.129 to 227.136.3.254227.136.3.255126
9227.136.4.0/25227.136.4.1 to 227.136.4.126227.136.4.127126
10227.136.4.128/25227.136.4.129 to 227.136.4.254227.136.4.255126
11227.136.5.0/25227.136.5.1 to 227.136.5.126227.136.5.127126
12227.136.5.128/25227.136.5.129 to 227.136.5.254227.136.5.255126
13227.136.6.0/25227.136.6.1 to 227.136.6.126227.136.6.127126
14227.136.6.128/25227.136.6.129 to 227.136.6.254227.136.6.255126
15227.136.7.0/25227.136.7.1 to 227.136.7.126227.136.7.127126
16227.136.7.128/25227.136.7.129 to 227.136.7.254227.136.7.255126
17227.136.8.0/25227.136.8.1 to 227.136.8.126227.136.8.127126
18227.136.8.128/25227.136.8.129 to 227.136.8.254227.136.8.255126
19227.136.9.0/25227.136.9.1 to 227.136.9.126227.136.9.127126
20227.136.9.128/25227.136.9.129 to 227.136.9.254227.136.9.255126
21227.136.10.0/25227.136.10.1 to 227.136.10.126227.136.10.127126
22227.136.10.128/25227.136.10.129 to 227.136.10.254227.136.10.255126
23227.136.11.0/25227.136.11.1 to 227.136.11.126227.136.11.127126
24227.136.11.128/25227.136.11.129 to 227.136.11.254227.136.11.255126
25227.136.12.0/25227.136.12.1 to 227.136.12.126227.136.12.127126
26227.136.12.128/25227.136.12.129 to 227.136.12.254227.136.12.255126
27227.136.13.0/25227.136.13.1 to 227.136.13.126227.136.13.127126
28227.136.13.128/25227.136.13.129 to 227.136.13.254227.136.13.255126
29227.136.14.0/25227.136.14.1 to 227.136.14.126227.136.14.127126
30227.136.14.128/25227.136.14.129 to 227.136.14.254227.136.14.255126
31227.136.15.0/25227.136.15.1 to 227.136.15.126227.136.15.127126
32227.136.15.128/25227.136.15.129 to 227.136.15.254227.136.15.255126
33227.136.16.0/25227.136.16.1 to 227.136.16.126227.136.16.127126
34227.136.16.128/25227.136.16.129 to 227.136.16.254227.136.16.255126
35227.136.17.0/25227.136.17.1 to 227.136.17.126227.136.17.127126
36227.136.17.128/25227.136.17.129 to 227.136.17.254227.136.17.255126
37227.136.18.0/25227.136.18.1 to 227.136.18.126227.136.18.127126
38227.136.18.128/25227.136.18.129 to 227.136.18.254227.136.18.255126
39227.136.19.0/25227.136.19.1 to 227.136.19.126227.136.19.127126
40227.136.19.128/25227.136.19.129 to 227.136.19.254227.136.19.255126
41227.136.20.0/25227.136.20.1 to 227.136.20.126227.136.20.127126
42227.136.20.128/25227.136.20.129 to 227.136.20.254227.136.20.255126
43227.136.21.0/25227.136.21.1 to 227.136.21.126227.136.21.127126
44227.136.21.128/25227.136.21.129 to 227.136.21.254227.136.21.255126
45227.136.22.0/25227.136.22.1 to 227.136.22.126227.136.22.127126
46227.136.22.128/25227.136.22.129 to 227.136.22.254227.136.22.255126
47227.136.23.0/25227.136.23.1 to 227.136.23.126227.136.23.127126
48227.136.23.128/25227.136.23.129 to 227.136.23.254227.136.23.255126
49227.136.24.0/25227.136.24.1 to 227.136.24.126227.136.24.127126
50227.136.24.128/25227.136.24.129 to 227.136.24.254227.136.24.255126
51227.136.25.0/25227.136.25.1 to 227.136.25.126227.136.25.127126
52227.136.25.128/25227.136.25.129 to 227.136.25.254227.136.25.255126
53227.136.26.0/25227.136.26.1 to 227.136.26.126227.136.26.127126
54227.136.26.128/25227.136.26.129 to 227.136.26.254227.136.26.255126
55227.136.27.0/25227.136.27.1 to 227.136.27.126227.136.27.127126
56227.136.27.128/25227.136.27.129 to 227.136.27.254227.136.27.255126
57227.136.28.0/25227.136.28.1 to 227.136.28.126227.136.28.127126
58227.136.28.128/25227.136.28.129 to 227.136.28.254227.136.28.255126
59227.136.29.0/25227.136.29.1 to 227.136.29.126227.136.29.127126
60227.136.29.128/25227.136.29.129 to 227.136.29.254227.136.29.255126
61227.136.30.0/25227.136.30.1 to 227.136.30.126227.136.30.127126
62227.136.30.128/25227.136.30.129 to 227.136.30.254227.136.30.255126
63227.136.31.0/25227.136.31.1 to 227.136.31.126227.136.31.127126
64227.136.31.128/25227.136.31.129 to 227.136.31.254227.136.31.255126
65227.136.32.0/25227.136.32.1 to 227.136.32.126227.136.32.127126
66227.136.32.128/25227.136.32.129 to 227.136.32.254227.136.32.255126
67227.136.33.0/25227.136.33.1 to 227.136.33.126227.136.33.127126
68227.136.33.128/25227.136.33.129 to 227.136.33.254227.136.33.255126
69227.136.34.0/25227.136.34.1 to 227.136.34.126227.136.34.127126
70227.136.34.128/25227.136.34.129 to 227.136.34.254227.136.34.255126
71227.136.35.0/25227.136.35.1 to 227.136.35.126227.136.35.127126
72227.136.35.128/25227.136.35.129 to 227.136.35.254227.136.35.255126
73227.136.36.0/25227.136.36.1 to 227.136.36.126227.136.36.127126
74227.136.36.128/25227.136.36.129 to 227.136.36.254227.136.36.255126
75227.136.37.0/25227.136.37.1 to 227.136.37.126227.136.37.127126
76227.136.37.128/25227.136.37.129 to 227.136.37.254227.136.37.255126
77227.136.38.0/25227.136.38.1 to 227.136.38.126227.136.38.127126
78227.136.38.128/25227.136.38.129 to 227.136.38.254227.136.38.255126
79227.136.39.0/25227.136.39.1 to 227.136.39.126227.136.39.127126
80227.136.39.128/25227.136.39.129 to 227.136.39.254227.136.39.255126
81227.136.40.0/25227.136.40.1 to 227.136.40.126227.136.40.127126
82227.136.40.128/25227.136.40.129 to 227.136.40.254227.136.40.255126
83227.136.41.0/25227.136.41.1 to 227.136.41.126227.136.41.127126
84227.136.41.128/25227.136.41.129 to 227.136.41.254227.136.41.255126
85227.136.42.0/25227.136.42.1 to 227.136.42.126227.136.42.127126
86227.136.42.128/25227.136.42.129 to 227.136.42.254227.136.42.255126
87227.136.43.0/25227.136.43.1 to 227.136.43.126227.136.43.127126
88227.136.43.128/25227.136.43.129 to 227.136.43.254227.136.43.255126
89227.136.44.0/25227.136.44.1 to 227.136.44.126227.136.44.127126
90227.136.44.128/25227.136.44.129 to 227.136.44.254227.136.44.255126
91227.136.45.0/25227.136.45.1 to 227.136.45.126227.136.45.127126
92227.136.45.128/25227.136.45.129 to 227.136.45.254227.136.45.255126
93227.136.46.0/25227.136.46.1 to 227.136.46.126227.136.46.127126
94227.136.46.128/25227.136.46.129 to 227.136.46.254227.136.46.255126
95227.136.47.0/25227.136.47.1 to 227.136.47.126227.136.47.127126
96227.136.47.128/25227.136.47.129 to 227.136.47.254227.136.47.255126
97227.136.48.0/25227.136.48.1 to 227.136.48.126227.136.48.127126
98227.136.48.128/25227.136.48.129 to 227.136.48.254227.136.48.255126
99227.136.49.0/25227.136.49.1 to 227.136.49.126227.136.49.127126
100227.136.49.128/25227.136.49.129 to 227.136.49.254227.136.49.255126
101227.136.50.0/25227.136.50.1 to 227.136.50.126227.136.50.127126
102227.136.50.128/25227.136.50.129 to 227.136.50.254227.136.50.255126
103227.136.51.0/25227.136.51.1 to 227.136.51.126227.136.51.127126
104227.136.51.128/25227.136.51.129 to 227.136.51.254227.136.51.255126
105227.136.52.0/25227.136.52.1 to 227.136.52.126227.136.52.127126
106227.136.52.128/25227.136.52.129 to 227.136.52.254227.136.52.255126
107227.136.53.0/25227.136.53.1 to 227.136.53.126227.136.53.127126
108227.136.53.128/25227.136.53.129 to 227.136.53.254227.136.53.255126
109227.136.54.0/25227.136.54.1 to 227.136.54.126227.136.54.127126
110227.136.54.128/25227.136.54.129 to 227.136.54.254227.136.54.255126
111227.136.55.0/25227.136.55.1 to 227.136.55.126227.136.55.127126
112227.136.55.128/25227.136.55.129 to 227.136.55.254227.136.55.255126
113227.136.56.0/25227.136.56.1 to 227.136.56.126227.136.56.127126
114227.136.56.128/25227.136.56.129 to 227.136.56.254227.136.56.255126
115227.136.57.0/25227.136.57.1 to 227.136.57.126227.136.57.127126
116227.136.57.128/25227.136.57.129 to 227.136.57.254227.136.57.255126
117227.136.58.0/25227.136.58.1 to 227.136.58.126227.136.58.127126
118227.136.58.128/25227.136.58.129 to 227.136.58.254227.136.58.255126
119227.136.59.0/25227.136.59.1 to 227.136.59.126227.136.59.127126
120227.136.59.128/25227.136.59.129 to 227.136.59.254227.136.59.255126
121227.136.60.0/25227.136.60.1 to 227.136.60.126227.136.60.127126
122227.136.60.128/25227.136.60.129 to 227.136.60.254227.136.60.255126
123227.136.61.0/25227.136.61.1 to 227.136.61.126227.136.61.127126
124227.136.61.128/25227.136.61.129 to 227.136.61.254227.136.61.255126
125227.136.62.0/25227.136.62.1 to 227.136.62.126227.136.62.127126
126227.136.62.128/25227.136.62.129 to 227.136.62.254227.136.62.255126
127227.136.63.0/25227.136.63.1 to 227.136.63.126227.136.63.127126
128227.136.63.128/25227.136.63.129 to 227.136.63.254227.136.63.255126
129227.136.64.0/25227.136.64.1 to 227.136.64.126227.136.64.127126
130227.136.64.128/25227.136.64.129 to 227.136.64.254227.136.64.255126
131227.136.65.0/25227.136.65.1 to 227.136.65.126227.136.65.127126
132227.136.65.128/25227.136.65.129 to 227.136.65.254227.136.65.255126
133227.136.66.0/25227.136.66.1 to 227.136.66.126227.136.66.127126
134227.136.66.128/25227.136.66.129 to 227.136.66.254227.136.66.255126
135227.136.67.0/25227.136.67.1 to 227.136.67.126227.136.67.127126
136227.136.67.128/25227.136.67.129 to 227.136.67.254227.136.67.255126
137227.136.68.0/25227.136.68.1 to 227.136.68.126227.136.68.127126
138227.136.68.128/25227.136.68.129 to 227.136.68.254227.136.68.255126
139227.136.69.0/25227.136.69.1 to 227.136.69.126227.136.69.127126
140227.136.69.128/25227.136.69.129 to 227.136.69.254227.136.69.255126
141227.136.70.0/25227.136.70.1 to 227.136.70.126227.136.70.127126
142227.136.70.128/25227.136.70.129 to 227.136.70.254227.136.70.255126
143227.136.71.0/25227.136.71.1 to 227.136.71.126227.136.71.127126
144227.136.71.128/25227.136.71.129 to 227.136.71.254227.136.71.255126
145227.136.72.0/25227.136.72.1 to 227.136.72.126227.136.72.127126
146227.136.72.128/25227.136.72.129 to 227.136.72.254227.136.72.255126
147227.136.73.0/25227.136.73.1 to 227.136.73.126227.136.73.127126
148227.136.73.128/25227.136.73.129 to 227.136.73.254227.136.73.255126
149227.136.74.0/25227.136.74.1 to 227.136.74.126227.136.74.127126
150227.136.74.128/25227.136.74.129 to 227.136.74.254227.136.74.255126
151227.136.75.0/25227.136.75.1 to 227.136.75.126227.136.75.127126
152227.136.75.128/25227.136.75.129 to 227.136.75.254227.136.75.255126
153227.136.76.0/25227.136.76.1 to 227.136.76.126227.136.76.127126
154227.136.76.128/25227.136.76.129 to 227.136.76.254227.136.76.255126
155227.136.77.0/25227.136.77.1 to 227.136.77.126227.136.77.127126
156227.136.77.128/25227.136.77.129 to 227.136.77.254227.136.77.255126
157227.136.78.0/25227.136.78.1 to 227.136.78.126227.136.78.127126
158227.136.78.128/25227.136.78.129 to 227.136.78.254227.136.78.255126
159227.136.79.0/25227.136.79.1 to 227.136.79.126227.136.79.127126
160227.136.79.128/25227.136.79.129 to 227.136.79.254227.136.79.255126
161227.136.80.0/25227.136.80.1 to 227.136.80.126227.136.80.127126
162227.136.80.128/25227.136.80.129 to 227.136.80.254227.136.80.255126
163227.136.81.0/25227.136.81.1 to 227.136.81.126227.136.81.127126
164227.136.81.128/25227.136.81.129 to 227.136.81.254227.136.81.255126
165227.136.82.0/25227.136.82.1 to 227.136.82.126227.136.82.127126
166227.136.82.128/25227.136.82.129 to 227.136.82.254227.136.82.255126
167227.136.83.0/25227.136.83.1 to 227.136.83.126227.136.83.127126
168227.136.83.128/25227.136.83.129 to 227.136.83.254227.136.83.255126
169227.136.84.0/25227.136.84.1 to 227.136.84.126227.136.84.127126
170227.136.84.128/25227.136.84.129 to 227.136.84.254227.136.84.255126
171227.136.85.0/25227.136.85.1 to 227.136.85.126227.136.85.127126
172227.136.85.128/25227.136.85.129 to 227.136.85.254227.136.85.255126
173227.136.86.0/25227.136.86.1 to 227.136.86.126227.136.86.127126
174227.136.86.128/25227.136.86.129 to 227.136.86.254227.136.86.255126
175227.136.87.0/25227.136.87.1 to 227.136.87.126227.136.87.127126
176227.136.87.128/25227.136.87.129 to 227.136.87.254227.136.87.255126
177227.136.88.0/25227.136.88.1 to 227.136.88.126227.136.88.127126
178227.136.88.128/25227.136.88.129 to 227.136.88.254227.136.88.255126
179227.136.89.0/25227.136.89.1 to 227.136.89.126227.136.89.127126
180227.136.89.128/25227.136.89.129 to 227.136.89.254227.136.89.255126
181227.136.90.0/25227.136.90.1 to 227.136.90.126227.136.90.127126
182227.136.90.128/25227.136.90.129 to 227.136.90.254227.136.90.255126
183227.136.91.0/25227.136.91.1 to 227.136.91.126227.136.91.127126
184227.136.91.128/25227.136.91.129 to 227.136.91.254227.136.91.255126
185227.136.92.0/25227.136.92.1 to 227.136.92.126227.136.92.127126
186227.136.92.128/25227.136.92.129 to 227.136.92.254227.136.92.255126
187227.136.93.0/25227.136.93.1 to 227.136.93.126227.136.93.127126
188227.136.93.128/25227.136.93.129 to 227.136.93.254227.136.93.255126
189227.136.94.0/25227.136.94.1 to 227.136.94.126227.136.94.127126
190227.136.94.128/25227.136.94.129 to 227.136.94.254227.136.94.255126
191227.136.95.0/25227.136.95.1 to 227.136.95.126227.136.95.127126
192227.136.95.128/25227.136.95.129 to 227.136.95.254227.136.95.255126
193227.136.96.0/25227.136.96.1 to 227.136.96.126227.136.96.127126
194227.136.96.128/25227.136.96.129 to 227.136.96.254227.136.96.255126
195227.136.97.0/25227.136.97.1 to 227.136.97.126227.136.97.127126
196227.136.97.128/25227.136.97.129 to 227.136.97.254227.136.97.255126
197227.136.98.0/25227.136.98.1 to 227.136.98.126227.136.98.127126
198227.136.98.128/25227.136.98.129 to 227.136.98.254227.136.98.255126
199227.136.99.0/25227.136.99.1 to 227.136.99.126227.136.99.127126
200227.136.99.128/25227.136.99.129 to 227.136.99.254227.136.99.255126
201227.136.100.0/25227.136.100.1 to 227.136.100.126227.136.100.127126
202227.136.100.128/25227.136.100.129 to 227.136.100.254227.136.100.255126
203227.136.101.0/25227.136.101.1 to 227.136.101.126227.136.101.127126
204227.136.101.128/25227.136.101.129 to 227.136.101.254227.136.101.255126
205227.136.102.0/25227.136.102.1 to 227.136.102.126227.136.102.127126
206227.136.102.128/25227.136.102.129 to 227.136.102.254227.136.102.255126
207227.136.103.0/25227.136.103.1 to 227.136.103.126227.136.103.127126
208227.136.103.128/25227.136.103.129 to 227.136.103.254227.136.103.255126
209227.136.104.0/25227.136.104.1 to 227.136.104.126227.136.104.127126
210227.136.104.128/25227.136.104.129 to 227.136.104.254227.136.104.255126
211227.136.105.0/25227.136.105.1 to 227.136.105.126227.136.105.127126
212227.136.105.128/25227.136.105.129 to 227.136.105.254227.136.105.255126
213227.136.106.0/25227.136.106.1 to 227.136.106.126227.136.106.127126
214227.136.106.128/25227.136.106.129 to 227.136.106.254227.136.106.255126
215227.136.107.0/25227.136.107.1 to 227.136.107.126227.136.107.127126
216227.136.107.128/25227.136.107.129 to 227.136.107.254227.136.107.255126
217227.136.108.0/25227.136.108.1 to 227.136.108.126227.136.108.127126
218227.136.108.128/25227.136.108.129 to 227.136.108.254227.136.108.255126
219227.136.109.0/25227.136.109.1 to 227.136.109.126227.136.109.127126
220227.136.109.128/25227.136.109.129 to 227.136.109.254227.136.109.255126
221227.136.110.0/25227.136.110.1 to 227.136.110.126227.136.110.127126
222227.136.110.128/25227.136.110.129 to 227.136.110.254227.136.110.255126
223227.136.111.0/25227.136.111.1 to 227.136.111.126227.136.111.127126
224227.136.111.128/25227.136.111.129 to 227.136.111.254227.136.111.255126
225227.136.112.0/25227.136.112.1 to 227.136.112.126227.136.112.127126
226227.136.112.128/25227.136.112.129 to 227.136.112.254227.136.112.255126
227227.136.113.0/25227.136.113.1 to 227.136.113.126227.136.113.127126
228227.136.113.128/25227.136.113.129 to 227.136.113.254227.136.113.255126
229227.136.114.0/25227.136.114.1 to 227.136.114.126227.136.114.127126
230227.136.114.128/25227.136.114.129 to 227.136.114.254227.136.114.255126
231227.136.115.0/25227.136.115.1 to 227.136.115.126227.136.115.127126
232227.136.115.128/25227.136.115.129 to 227.136.115.254227.136.115.255126
233227.136.116.0/25227.136.116.1 to 227.136.116.126227.136.116.127126
234227.136.116.128/25227.136.116.129 to 227.136.116.254227.136.116.255126
235227.136.117.0/25227.136.117.1 to 227.136.117.126227.136.117.127126
236227.136.117.128/25227.136.117.129 to 227.136.117.254227.136.117.255126
237227.136.118.0/25227.136.118.1 to 227.136.118.126227.136.118.127126
238227.136.118.128/25227.136.118.129 to 227.136.118.254227.136.118.255126
239227.136.119.0/25227.136.119.1 to 227.136.119.126227.136.119.127126
240227.136.119.128/25227.136.119.129 to 227.136.119.254227.136.119.255126
241227.136.120.0/25227.136.120.1 to 227.136.120.126227.136.120.127126
242227.136.120.128/25227.136.120.129 to 227.136.120.254227.136.120.255126
243227.136.121.0/25227.136.121.1 to 227.136.121.126227.136.121.127126
244227.136.121.128/25227.136.121.129 to 227.136.121.254227.136.121.255126
245227.136.122.0/25227.136.122.1 to 227.136.122.126227.136.122.127126
246227.136.122.128/25227.136.122.129 to 227.136.122.254227.136.122.255126
247227.136.123.0/25227.136.123.1 to 227.136.123.126227.136.123.127126
248227.136.123.128/25227.136.123.129 to 227.136.123.254227.136.123.255126
249227.136.124.0/25227.136.124.1 to 227.136.124.126227.136.124.127126
250227.136.124.128/25227.136.124.129 to 227.136.124.254227.136.124.255126
251227.136.125.0/25227.136.125.1 to 227.136.125.126227.136.125.127126
252227.136.125.128/25227.136.125.129 to 227.136.125.254227.136.125.255126
253227.136.126.0/25227.136.126.1 to 227.136.126.126227.136.126.127126
254227.136.126.128/25227.136.126.129 to 227.136.126.254227.136.126.255126
255227.136.127.0/25227.136.127.1 to 227.136.127.126227.136.127.127126
256227.136.127.128/25227.136.127.129 to 227.136.127.254227.136.127.255126

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.