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.

Network199.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
199.0.0.0
Broadcast address
199.63.255.255
First usable
199.0.0.1
Last usable
199.63.255.254
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
Public public
Old class
C (default /24)
As numbers
Hex C7000000 · Integer 3338665984 to 3342860287
Reverse DNS zones
0.199.in-addr.arpa
1.199.in-addr.arpa
2.199.in-addr.arpa
3.199.in-addr.arpa
4.199.in-addr.arpa
5.199.in-addr.arpa
6.199.in-addr.arpa
7.199.in-addr.arpa
8.199.in-addr.arpa
9.199.in-addr.arpa
10.199.in-addr.arpa
11.199.in-addr.arpa
12.199.in-addr.arpa
13.199.in-addr.arpa
14.199.in-addr.arpa
15.199.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
Address11000111.00000000.00000000.00000000199.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11000111.00000000.00000000.00000000199.0.0.0
Broadcast11000111.00111111.11111111.11111111199.63.255.255
Split into smaller subnets/18
/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)

199.0.0.0/10 makes 256 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1199.0.0.0/18199.0.0.1 to 199.0.63.254199.0.63.25516,382
2199.0.64.0/18199.0.64.1 to 199.0.127.254199.0.127.25516,382
3199.0.128.0/18199.0.128.1 to 199.0.191.254199.0.191.25516,382
4199.0.192.0/18199.0.192.1 to 199.0.255.254199.0.255.25516,382
5199.1.0.0/18199.1.0.1 to 199.1.63.254199.1.63.25516,382
6199.1.64.0/18199.1.64.1 to 199.1.127.254199.1.127.25516,382
7199.1.128.0/18199.1.128.1 to 199.1.191.254199.1.191.25516,382
8199.1.192.0/18199.1.192.1 to 199.1.255.254199.1.255.25516,382
9199.2.0.0/18199.2.0.1 to 199.2.63.254199.2.63.25516,382
10199.2.64.0/18199.2.64.1 to 199.2.127.254199.2.127.25516,382
11199.2.128.0/18199.2.128.1 to 199.2.191.254199.2.191.25516,382
12199.2.192.0/18199.2.192.1 to 199.2.255.254199.2.255.25516,382
13199.3.0.0/18199.3.0.1 to 199.3.63.254199.3.63.25516,382
14199.3.64.0/18199.3.64.1 to 199.3.127.254199.3.127.25516,382
15199.3.128.0/18199.3.128.1 to 199.3.191.254199.3.191.25516,382
16199.3.192.0/18199.3.192.1 to 199.3.255.254199.3.255.25516,382
17199.4.0.0/18199.4.0.1 to 199.4.63.254199.4.63.25516,382
18199.4.64.0/18199.4.64.1 to 199.4.127.254199.4.127.25516,382
19199.4.128.0/18199.4.128.1 to 199.4.191.254199.4.191.25516,382
20199.4.192.0/18199.4.192.1 to 199.4.255.254199.4.255.25516,382
21199.5.0.0/18199.5.0.1 to 199.5.63.254199.5.63.25516,382
22199.5.64.0/18199.5.64.1 to 199.5.127.254199.5.127.25516,382
23199.5.128.0/18199.5.128.1 to 199.5.191.254199.5.191.25516,382
24199.5.192.0/18199.5.192.1 to 199.5.255.254199.5.255.25516,382
25199.6.0.0/18199.6.0.1 to 199.6.63.254199.6.63.25516,382
26199.6.64.0/18199.6.64.1 to 199.6.127.254199.6.127.25516,382
27199.6.128.0/18199.6.128.1 to 199.6.191.254199.6.191.25516,382
28199.6.192.0/18199.6.192.1 to 199.6.255.254199.6.255.25516,382
29199.7.0.0/18199.7.0.1 to 199.7.63.254199.7.63.25516,382
30199.7.64.0/18199.7.64.1 to 199.7.127.254199.7.127.25516,382
31199.7.128.0/18199.7.128.1 to 199.7.191.254199.7.191.25516,382
32199.7.192.0/18199.7.192.1 to 199.7.255.254199.7.255.25516,382
33199.8.0.0/18199.8.0.1 to 199.8.63.254199.8.63.25516,382
34199.8.64.0/18199.8.64.1 to 199.8.127.254199.8.127.25516,382
35199.8.128.0/18199.8.128.1 to 199.8.191.254199.8.191.25516,382
36199.8.192.0/18199.8.192.1 to 199.8.255.254199.8.255.25516,382
37199.9.0.0/18199.9.0.1 to 199.9.63.254199.9.63.25516,382
38199.9.64.0/18199.9.64.1 to 199.9.127.254199.9.127.25516,382
39199.9.128.0/18199.9.128.1 to 199.9.191.254199.9.191.25516,382
40199.9.192.0/18199.9.192.1 to 199.9.255.254199.9.255.25516,382
41199.10.0.0/18199.10.0.1 to 199.10.63.254199.10.63.25516,382
42199.10.64.0/18199.10.64.1 to 199.10.127.254199.10.127.25516,382
43199.10.128.0/18199.10.128.1 to 199.10.191.254199.10.191.25516,382
44199.10.192.0/18199.10.192.1 to 199.10.255.254199.10.255.25516,382
45199.11.0.0/18199.11.0.1 to 199.11.63.254199.11.63.25516,382
46199.11.64.0/18199.11.64.1 to 199.11.127.254199.11.127.25516,382
47199.11.128.0/18199.11.128.1 to 199.11.191.254199.11.191.25516,382
48199.11.192.0/18199.11.192.1 to 199.11.255.254199.11.255.25516,382
49199.12.0.0/18199.12.0.1 to 199.12.63.254199.12.63.25516,382
50199.12.64.0/18199.12.64.1 to 199.12.127.254199.12.127.25516,382
51199.12.128.0/18199.12.128.1 to 199.12.191.254199.12.191.25516,382
52199.12.192.0/18199.12.192.1 to 199.12.255.254199.12.255.25516,382
53199.13.0.0/18199.13.0.1 to 199.13.63.254199.13.63.25516,382
54199.13.64.0/18199.13.64.1 to 199.13.127.254199.13.127.25516,382
55199.13.128.0/18199.13.128.1 to 199.13.191.254199.13.191.25516,382
56199.13.192.0/18199.13.192.1 to 199.13.255.254199.13.255.25516,382
57199.14.0.0/18199.14.0.1 to 199.14.63.254199.14.63.25516,382
58199.14.64.0/18199.14.64.1 to 199.14.127.254199.14.127.25516,382
59199.14.128.0/18199.14.128.1 to 199.14.191.254199.14.191.25516,382
60199.14.192.0/18199.14.192.1 to 199.14.255.254199.14.255.25516,382
61199.15.0.0/18199.15.0.1 to 199.15.63.254199.15.63.25516,382
62199.15.64.0/18199.15.64.1 to 199.15.127.254199.15.127.25516,382
63199.15.128.0/18199.15.128.1 to 199.15.191.254199.15.191.25516,382
64199.15.192.0/18199.15.192.1 to 199.15.255.254199.15.255.25516,382
65199.16.0.0/18199.16.0.1 to 199.16.63.254199.16.63.25516,382
66199.16.64.0/18199.16.64.1 to 199.16.127.254199.16.127.25516,382
67199.16.128.0/18199.16.128.1 to 199.16.191.254199.16.191.25516,382
68199.16.192.0/18199.16.192.1 to 199.16.255.254199.16.255.25516,382
69199.17.0.0/18199.17.0.1 to 199.17.63.254199.17.63.25516,382
70199.17.64.0/18199.17.64.1 to 199.17.127.254199.17.127.25516,382
71199.17.128.0/18199.17.128.1 to 199.17.191.254199.17.191.25516,382
72199.17.192.0/18199.17.192.1 to 199.17.255.254199.17.255.25516,382
73199.18.0.0/18199.18.0.1 to 199.18.63.254199.18.63.25516,382
74199.18.64.0/18199.18.64.1 to 199.18.127.254199.18.127.25516,382
75199.18.128.0/18199.18.128.1 to 199.18.191.254199.18.191.25516,382
76199.18.192.0/18199.18.192.1 to 199.18.255.254199.18.255.25516,382
77199.19.0.0/18199.19.0.1 to 199.19.63.254199.19.63.25516,382
78199.19.64.0/18199.19.64.1 to 199.19.127.254199.19.127.25516,382
79199.19.128.0/18199.19.128.1 to 199.19.191.254199.19.191.25516,382
80199.19.192.0/18199.19.192.1 to 199.19.255.254199.19.255.25516,382
81199.20.0.0/18199.20.0.1 to 199.20.63.254199.20.63.25516,382
82199.20.64.0/18199.20.64.1 to 199.20.127.254199.20.127.25516,382
83199.20.128.0/18199.20.128.1 to 199.20.191.254199.20.191.25516,382
84199.20.192.0/18199.20.192.1 to 199.20.255.254199.20.255.25516,382
85199.21.0.0/18199.21.0.1 to 199.21.63.254199.21.63.25516,382
86199.21.64.0/18199.21.64.1 to 199.21.127.254199.21.127.25516,382
87199.21.128.0/18199.21.128.1 to 199.21.191.254199.21.191.25516,382
88199.21.192.0/18199.21.192.1 to 199.21.255.254199.21.255.25516,382
89199.22.0.0/18199.22.0.1 to 199.22.63.254199.22.63.25516,382
90199.22.64.0/18199.22.64.1 to 199.22.127.254199.22.127.25516,382
91199.22.128.0/18199.22.128.1 to 199.22.191.254199.22.191.25516,382
92199.22.192.0/18199.22.192.1 to 199.22.255.254199.22.255.25516,382
93199.23.0.0/18199.23.0.1 to 199.23.63.254199.23.63.25516,382
94199.23.64.0/18199.23.64.1 to 199.23.127.254199.23.127.25516,382
95199.23.128.0/18199.23.128.1 to 199.23.191.254199.23.191.25516,382
96199.23.192.0/18199.23.192.1 to 199.23.255.254199.23.255.25516,382
97199.24.0.0/18199.24.0.1 to 199.24.63.254199.24.63.25516,382
98199.24.64.0/18199.24.64.1 to 199.24.127.254199.24.127.25516,382
99199.24.128.0/18199.24.128.1 to 199.24.191.254199.24.191.25516,382
100199.24.192.0/18199.24.192.1 to 199.24.255.254199.24.255.25516,382
101199.25.0.0/18199.25.0.1 to 199.25.63.254199.25.63.25516,382
102199.25.64.0/18199.25.64.1 to 199.25.127.254199.25.127.25516,382
103199.25.128.0/18199.25.128.1 to 199.25.191.254199.25.191.25516,382
104199.25.192.0/18199.25.192.1 to 199.25.255.254199.25.255.25516,382
105199.26.0.0/18199.26.0.1 to 199.26.63.254199.26.63.25516,382
106199.26.64.0/18199.26.64.1 to 199.26.127.254199.26.127.25516,382
107199.26.128.0/18199.26.128.1 to 199.26.191.254199.26.191.25516,382
108199.26.192.0/18199.26.192.1 to 199.26.255.254199.26.255.25516,382
109199.27.0.0/18199.27.0.1 to 199.27.63.254199.27.63.25516,382
110199.27.64.0/18199.27.64.1 to 199.27.127.254199.27.127.25516,382
111199.27.128.0/18199.27.128.1 to 199.27.191.254199.27.191.25516,382
112199.27.192.0/18199.27.192.1 to 199.27.255.254199.27.255.25516,382
113199.28.0.0/18199.28.0.1 to 199.28.63.254199.28.63.25516,382
114199.28.64.0/18199.28.64.1 to 199.28.127.254199.28.127.25516,382
115199.28.128.0/18199.28.128.1 to 199.28.191.254199.28.191.25516,382
116199.28.192.0/18199.28.192.1 to 199.28.255.254199.28.255.25516,382
117199.29.0.0/18199.29.0.1 to 199.29.63.254199.29.63.25516,382
118199.29.64.0/18199.29.64.1 to 199.29.127.254199.29.127.25516,382
119199.29.128.0/18199.29.128.1 to 199.29.191.254199.29.191.25516,382
120199.29.192.0/18199.29.192.1 to 199.29.255.254199.29.255.25516,382
121199.30.0.0/18199.30.0.1 to 199.30.63.254199.30.63.25516,382
122199.30.64.0/18199.30.64.1 to 199.30.127.254199.30.127.25516,382
123199.30.128.0/18199.30.128.1 to 199.30.191.254199.30.191.25516,382
124199.30.192.0/18199.30.192.1 to 199.30.255.254199.30.255.25516,382
125199.31.0.0/18199.31.0.1 to 199.31.63.254199.31.63.25516,382
126199.31.64.0/18199.31.64.1 to 199.31.127.254199.31.127.25516,382
127199.31.128.0/18199.31.128.1 to 199.31.191.254199.31.191.25516,382
128199.31.192.0/18199.31.192.1 to 199.31.255.254199.31.255.25516,382
129199.32.0.0/18199.32.0.1 to 199.32.63.254199.32.63.25516,382
130199.32.64.0/18199.32.64.1 to 199.32.127.254199.32.127.25516,382
131199.32.128.0/18199.32.128.1 to 199.32.191.254199.32.191.25516,382
132199.32.192.0/18199.32.192.1 to 199.32.255.254199.32.255.25516,382
133199.33.0.0/18199.33.0.1 to 199.33.63.254199.33.63.25516,382
134199.33.64.0/18199.33.64.1 to 199.33.127.254199.33.127.25516,382
135199.33.128.0/18199.33.128.1 to 199.33.191.254199.33.191.25516,382
136199.33.192.0/18199.33.192.1 to 199.33.255.254199.33.255.25516,382
137199.34.0.0/18199.34.0.1 to 199.34.63.254199.34.63.25516,382
138199.34.64.0/18199.34.64.1 to 199.34.127.254199.34.127.25516,382
139199.34.128.0/18199.34.128.1 to 199.34.191.254199.34.191.25516,382
140199.34.192.0/18199.34.192.1 to 199.34.255.254199.34.255.25516,382
141199.35.0.0/18199.35.0.1 to 199.35.63.254199.35.63.25516,382
142199.35.64.0/18199.35.64.1 to 199.35.127.254199.35.127.25516,382
143199.35.128.0/18199.35.128.1 to 199.35.191.254199.35.191.25516,382
144199.35.192.0/18199.35.192.1 to 199.35.255.254199.35.255.25516,382
145199.36.0.0/18199.36.0.1 to 199.36.63.254199.36.63.25516,382
146199.36.64.0/18199.36.64.1 to 199.36.127.254199.36.127.25516,382
147199.36.128.0/18199.36.128.1 to 199.36.191.254199.36.191.25516,382
148199.36.192.0/18199.36.192.1 to 199.36.255.254199.36.255.25516,382
149199.37.0.0/18199.37.0.1 to 199.37.63.254199.37.63.25516,382
150199.37.64.0/18199.37.64.1 to 199.37.127.254199.37.127.25516,382
151199.37.128.0/18199.37.128.1 to 199.37.191.254199.37.191.25516,382
152199.37.192.0/18199.37.192.1 to 199.37.255.254199.37.255.25516,382
153199.38.0.0/18199.38.0.1 to 199.38.63.254199.38.63.25516,382
154199.38.64.0/18199.38.64.1 to 199.38.127.254199.38.127.25516,382
155199.38.128.0/18199.38.128.1 to 199.38.191.254199.38.191.25516,382
156199.38.192.0/18199.38.192.1 to 199.38.255.254199.38.255.25516,382
157199.39.0.0/18199.39.0.1 to 199.39.63.254199.39.63.25516,382
158199.39.64.0/18199.39.64.1 to 199.39.127.254199.39.127.25516,382
159199.39.128.0/18199.39.128.1 to 199.39.191.254199.39.191.25516,382
160199.39.192.0/18199.39.192.1 to 199.39.255.254199.39.255.25516,382
161199.40.0.0/18199.40.0.1 to 199.40.63.254199.40.63.25516,382
162199.40.64.0/18199.40.64.1 to 199.40.127.254199.40.127.25516,382
163199.40.128.0/18199.40.128.1 to 199.40.191.254199.40.191.25516,382
164199.40.192.0/18199.40.192.1 to 199.40.255.254199.40.255.25516,382
165199.41.0.0/18199.41.0.1 to 199.41.63.254199.41.63.25516,382
166199.41.64.0/18199.41.64.1 to 199.41.127.254199.41.127.25516,382
167199.41.128.0/18199.41.128.1 to 199.41.191.254199.41.191.25516,382
168199.41.192.0/18199.41.192.1 to 199.41.255.254199.41.255.25516,382
169199.42.0.0/18199.42.0.1 to 199.42.63.254199.42.63.25516,382
170199.42.64.0/18199.42.64.1 to 199.42.127.254199.42.127.25516,382
171199.42.128.0/18199.42.128.1 to 199.42.191.254199.42.191.25516,382
172199.42.192.0/18199.42.192.1 to 199.42.255.254199.42.255.25516,382
173199.43.0.0/18199.43.0.1 to 199.43.63.254199.43.63.25516,382
174199.43.64.0/18199.43.64.1 to 199.43.127.254199.43.127.25516,382
175199.43.128.0/18199.43.128.1 to 199.43.191.254199.43.191.25516,382
176199.43.192.0/18199.43.192.1 to 199.43.255.254199.43.255.25516,382
177199.44.0.0/18199.44.0.1 to 199.44.63.254199.44.63.25516,382
178199.44.64.0/18199.44.64.1 to 199.44.127.254199.44.127.25516,382
179199.44.128.0/18199.44.128.1 to 199.44.191.254199.44.191.25516,382
180199.44.192.0/18199.44.192.1 to 199.44.255.254199.44.255.25516,382
181199.45.0.0/18199.45.0.1 to 199.45.63.254199.45.63.25516,382
182199.45.64.0/18199.45.64.1 to 199.45.127.254199.45.127.25516,382
183199.45.128.0/18199.45.128.1 to 199.45.191.254199.45.191.25516,382
184199.45.192.0/18199.45.192.1 to 199.45.255.254199.45.255.25516,382
185199.46.0.0/18199.46.0.1 to 199.46.63.254199.46.63.25516,382
186199.46.64.0/18199.46.64.1 to 199.46.127.254199.46.127.25516,382
187199.46.128.0/18199.46.128.1 to 199.46.191.254199.46.191.25516,382
188199.46.192.0/18199.46.192.1 to 199.46.255.254199.46.255.25516,382
189199.47.0.0/18199.47.0.1 to 199.47.63.254199.47.63.25516,382
190199.47.64.0/18199.47.64.1 to 199.47.127.254199.47.127.25516,382
191199.47.128.0/18199.47.128.1 to 199.47.191.254199.47.191.25516,382
192199.47.192.0/18199.47.192.1 to 199.47.255.254199.47.255.25516,382
193199.48.0.0/18199.48.0.1 to 199.48.63.254199.48.63.25516,382
194199.48.64.0/18199.48.64.1 to 199.48.127.254199.48.127.25516,382
195199.48.128.0/18199.48.128.1 to 199.48.191.254199.48.191.25516,382
196199.48.192.0/18199.48.192.1 to 199.48.255.254199.48.255.25516,382
197199.49.0.0/18199.49.0.1 to 199.49.63.254199.49.63.25516,382
198199.49.64.0/18199.49.64.1 to 199.49.127.254199.49.127.25516,382
199199.49.128.0/18199.49.128.1 to 199.49.191.254199.49.191.25516,382
200199.49.192.0/18199.49.192.1 to 199.49.255.254199.49.255.25516,382
201199.50.0.0/18199.50.0.1 to 199.50.63.254199.50.63.25516,382
202199.50.64.0/18199.50.64.1 to 199.50.127.254199.50.127.25516,382
203199.50.128.0/18199.50.128.1 to 199.50.191.254199.50.191.25516,382
204199.50.192.0/18199.50.192.1 to 199.50.255.254199.50.255.25516,382
205199.51.0.0/18199.51.0.1 to 199.51.63.254199.51.63.25516,382
206199.51.64.0/18199.51.64.1 to 199.51.127.254199.51.127.25516,382
207199.51.128.0/18199.51.128.1 to 199.51.191.254199.51.191.25516,382
208199.51.192.0/18199.51.192.1 to 199.51.255.254199.51.255.25516,382
209199.52.0.0/18199.52.0.1 to 199.52.63.254199.52.63.25516,382
210199.52.64.0/18199.52.64.1 to 199.52.127.254199.52.127.25516,382
211199.52.128.0/18199.52.128.1 to 199.52.191.254199.52.191.25516,382
212199.52.192.0/18199.52.192.1 to 199.52.255.254199.52.255.25516,382
213199.53.0.0/18199.53.0.1 to 199.53.63.254199.53.63.25516,382
214199.53.64.0/18199.53.64.1 to 199.53.127.254199.53.127.25516,382
215199.53.128.0/18199.53.128.1 to 199.53.191.254199.53.191.25516,382
216199.53.192.0/18199.53.192.1 to 199.53.255.254199.53.255.25516,382
217199.54.0.0/18199.54.0.1 to 199.54.63.254199.54.63.25516,382
218199.54.64.0/18199.54.64.1 to 199.54.127.254199.54.127.25516,382
219199.54.128.0/18199.54.128.1 to 199.54.191.254199.54.191.25516,382
220199.54.192.0/18199.54.192.1 to 199.54.255.254199.54.255.25516,382
221199.55.0.0/18199.55.0.1 to 199.55.63.254199.55.63.25516,382
222199.55.64.0/18199.55.64.1 to 199.55.127.254199.55.127.25516,382
223199.55.128.0/18199.55.128.1 to 199.55.191.254199.55.191.25516,382
224199.55.192.0/18199.55.192.1 to 199.55.255.254199.55.255.25516,382
225199.56.0.0/18199.56.0.1 to 199.56.63.254199.56.63.25516,382
226199.56.64.0/18199.56.64.1 to 199.56.127.254199.56.127.25516,382
227199.56.128.0/18199.56.128.1 to 199.56.191.254199.56.191.25516,382
228199.56.192.0/18199.56.192.1 to 199.56.255.254199.56.255.25516,382
229199.57.0.0/18199.57.0.1 to 199.57.63.254199.57.63.25516,382
230199.57.64.0/18199.57.64.1 to 199.57.127.254199.57.127.25516,382
231199.57.128.0/18199.57.128.1 to 199.57.191.254199.57.191.25516,382
232199.57.192.0/18199.57.192.1 to 199.57.255.254199.57.255.25516,382
233199.58.0.0/18199.58.0.1 to 199.58.63.254199.58.63.25516,382
234199.58.64.0/18199.58.64.1 to 199.58.127.254199.58.127.25516,382
235199.58.128.0/18199.58.128.1 to 199.58.191.254199.58.191.25516,382
236199.58.192.0/18199.58.192.1 to 199.58.255.254199.58.255.25516,382
237199.59.0.0/18199.59.0.1 to 199.59.63.254199.59.63.25516,382
238199.59.64.0/18199.59.64.1 to 199.59.127.254199.59.127.25516,382
239199.59.128.0/18199.59.128.1 to 199.59.191.254199.59.191.25516,382
240199.59.192.0/18199.59.192.1 to 199.59.255.254199.59.255.25516,382
241199.60.0.0/18199.60.0.1 to 199.60.63.254199.60.63.25516,382
242199.60.64.0/18199.60.64.1 to 199.60.127.254199.60.127.25516,382
243199.60.128.0/18199.60.128.1 to 199.60.191.254199.60.191.25516,382
244199.60.192.0/18199.60.192.1 to 199.60.255.254199.60.255.25516,382
245199.61.0.0/18199.61.0.1 to 199.61.63.254199.61.63.25516,382
246199.61.64.0/18199.61.64.1 to 199.61.127.254199.61.127.25516,382
247199.61.128.0/18199.61.128.1 to 199.61.191.254199.61.191.25516,382
248199.61.192.0/18199.61.192.1 to 199.61.255.254199.61.255.25516,382
249199.62.0.0/18199.62.0.1 to 199.62.63.254199.62.63.25516,382
250199.62.64.0/18199.62.64.1 to 199.62.127.254199.62.127.25516,382
251199.62.128.0/18199.62.128.1 to 199.62.191.254199.62.191.25516,382
252199.62.192.0/18199.62.192.1 to 199.62.255.254199.62.255.25516,382
253199.63.0.0/18199.63.0.1 to 199.63.63.254199.63.63.25516,382
254199.63.64.0/18199.63.64.1 to 199.63.127.254199.63.127.25516,382
255199.63.128.0/18199.63.128.1 to 199.63.191.254199.63.191.25516,382
256199.63.192.0/18199.63.192.1 to 199.63.255.254199.63.255.25516,382

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.