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.

Prefix/16
Addresses2^112
/64 networks2^48
Network
fc2c::/16
First address
fc2c::
Last address
fc2c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
fc2c:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
c.2.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fc2c::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc2c::/24fc2c:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc2c:100::/24fc2c:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc2c:200::/24fc2c:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc2c:300::/24fc2c:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc2c:400::/24fc2c:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc2c:500::/24fc2c:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc2c:600::/24fc2c:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc2c:700::/24fc2c:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc2c:800::/24fc2c:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc2c:900::/24fc2c:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc2c:a00::/24fc2c:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc2c:b00::/24fc2c:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc2c:c00::/24fc2c:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc2c:d00::/24fc2c:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc2c:e00::/24fc2c:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc2c:f00::/24fc2c:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc2c:1000::/24fc2c:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc2c:1100::/24fc2c:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc2c:1200::/24fc2c:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc2c:1300::/24fc2c:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc2c:1400::/24fc2c:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc2c:1500::/24fc2c:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc2c:1600::/24fc2c:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc2c:1700::/24fc2c:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc2c:1800::/24fc2c:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc2c:1900::/24fc2c:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc2c:1a00::/24fc2c:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc2c:1b00::/24fc2c:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc2c:1c00::/24fc2c:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc2c:1d00::/24fc2c:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc2c:1e00::/24fc2c:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc2c:1f00::/24fc2c:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc2c:2000::/24fc2c:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc2c:2100::/24fc2c:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc2c:2200::/24fc2c:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc2c:2300::/24fc2c:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc2c:2400::/24fc2c:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc2c:2500::/24fc2c:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc2c:2600::/24fc2c:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc2c:2700::/24fc2c:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc2c:2800::/24fc2c:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc2c:2900::/24fc2c:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc2c:2a00::/24fc2c:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc2c:2b00::/24fc2c:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc2c:2c00::/24fc2c:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc2c:2d00::/24fc2c:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc2c:2e00::/24fc2c:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc2c:2f00::/24fc2c:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc2c:3000::/24fc2c:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc2c:3100::/24fc2c:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc2c:3200::/24fc2c:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc2c:3300::/24fc2c:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc2c:3400::/24fc2c:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc2c:3500::/24fc2c:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc2c:3600::/24fc2c:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc2c:3700::/24fc2c:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc2c:3800::/24fc2c:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc2c:3900::/24fc2c:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc2c:3a00::/24fc2c:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc2c:3b00::/24fc2c:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc2c:3c00::/24fc2c:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc2c:3d00::/24fc2c:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc2c:3e00::/24fc2c:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc2c:3f00::/24fc2c:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc2c:4000::/24fc2c:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc2c:4100::/24fc2c:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc2c:4200::/24fc2c:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc2c:4300::/24fc2c:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc2c:4400::/24fc2c:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc2c:4500::/24fc2c:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc2c:4600::/24fc2c:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc2c:4700::/24fc2c:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc2c:4800::/24fc2c:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc2c:4900::/24fc2c:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc2c:4a00::/24fc2c:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc2c:4b00::/24fc2c:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc2c:4c00::/24fc2c:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc2c:4d00::/24fc2c:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc2c:4e00::/24fc2c:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc2c:4f00::/24fc2c:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc2c:5000::/24fc2c:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc2c:5100::/24fc2c:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc2c:5200::/24fc2c:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc2c:5300::/24fc2c:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc2c:5400::/24fc2c:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc2c:5500::/24fc2c:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc2c:5600::/24fc2c:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc2c:5700::/24fc2c:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc2c:5800::/24fc2c:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc2c:5900::/24fc2c:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc2c:5a00::/24fc2c:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc2c:5b00::/24fc2c:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc2c:5c00::/24fc2c:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc2c:5d00::/24fc2c:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc2c:5e00::/24fc2c:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc2c:5f00::/24fc2c:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc2c:6000::/24fc2c:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc2c:6100::/24fc2c:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc2c:6200::/24fc2c:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc2c:6300::/24fc2c:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc2c:6400::/24fc2c:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc2c:6500::/24fc2c:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc2c:6600::/24fc2c:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc2c:6700::/24fc2c:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc2c:6800::/24fc2c:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc2c:6900::/24fc2c:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc2c:6a00::/24fc2c:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc2c:6b00::/24fc2c:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc2c:6c00::/24fc2c:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc2c:6d00::/24fc2c:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc2c:6e00::/24fc2c:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc2c:6f00::/24fc2c:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc2c:7000::/24fc2c:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc2c:7100::/24fc2c:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc2c:7200::/24fc2c:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc2c:7300::/24fc2c:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc2c:7400::/24fc2c:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc2c:7500::/24fc2c:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc2c:7600::/24fc2c:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc2c:7700::/24fc2c:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc2c:7800::/24fc2c:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc2c:7900::/24fc2c:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc2c:7a00::/24fc2c:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc2c:7b00::/24fc2c:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc2c:7c00::/24fc2c:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc2c:7d00::/24fc2c:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc2c:7e00::/24fc2c:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc2c:7f00::/24fc2c:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc2c:8000::/24fc2c:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc2c:8100::/24fc2c:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc2c:8200::/24fc2c:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc2c:8300::/24fc2c:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc2c:8400::/24fc2c:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc2c:8500::/24fc2c:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc2c:8600::/24fc2c:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc2c:8700::/24fc2c:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc2c:8800::/24fc2c:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc2c:8900::/24fc2c:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc2c:8a00::/24fc2c:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc2c:8b00::/24fc2c:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc2c:8c00::/24fc2c:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc2c:8d00::/24fc2c:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc2c:8e00::/24fc2c:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc2c:8f00::/24fc2c:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc2c:9000::/24fc2c:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc2c:9100::/24fc2c:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc2c:9200::/24fc2c:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc2c:9300::/24fc2c:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc2c:9400::/24fc2c:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc2c:9500::/24fc2c:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc2c:9600::/24fc2c:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc2c:9700::/24fc2c:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc2c:9800::/24fc2c:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc2c:9900::/24fc2c:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc2c:9a00::/24fc2c:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc2c:9b00::/24fc2c:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc2c:9c00::/24fc2c:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc2c:9d00::/24fc2c:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc2c:9e00::/24fc2c:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc2c:9f00::/24fc2c:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc2c:a000::/24fc2c:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc2c:a100::/24fc2c:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc2c:a200::/24fc2c:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc2c:a300::/24fc2c:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc2c:a400::/24fc2c:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc2c:a500::/24fc2c:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc2c:a600::/24fc2c:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc2c:a700::/24fc2c:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc2c:a800::/24fc2c:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc2c:a900::/24fc2c:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc2c:aa00::/24fc2c:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc2c:ab00::/24fc2c:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc2c:ac00::/24fc2c:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc2c:ad00::/24fc2c:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc2c:ae00::/24fc2c:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc2c:af00::/24fc2c:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc2c:b000::/24fc2c:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc2c:b100::/24fc2c:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc2c:b200::/24fc2c:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc2c:b300::/24fc2c:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc2c:b400::/24fc2c:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc2c:b500::/24fc2c:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc2c:b600::/24fc2c:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc2c:b700::/24fc2c:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc2c:b800::/24fc2c:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc2c:b900::/24fc2c:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc2c:ba00::/24fc2c:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc2c:bb00::/24fc2c:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc2c:bc00::/24fc2c:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc2c:bd00::/24fc2c:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc2c:be00::/24fc2c:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc2c:bf00::/24fc2c:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc2c:c000::/24fc2c:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc2c:c100::/24fc2c:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc2c:c200::/24fc2c:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc2c:c300::/24fc2c:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc2c:c400::/24fc2c:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc2c:c500::/24fc2c:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc2c:c600::/24fc2c:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc2c:c700::/24fc2c:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc2c:c800::/24fc2c:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc2c:c900::/24fc2c:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc2c:ca00::/24fc2c:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc2c:cb00::/24fc2c:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc2c:cc00::/24fc2c:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc2c:cd00::/24fc2c:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc2c:ce00::/24fc2c:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc2c:cf00::/24fc2c:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc2c:d000::/24fc2c:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc2c:d100::/24fc2c:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc2c:d200::/24fc2c:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc2c:d300::/24fc2c:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc2c:d400::/24fc2c:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc2c:d500::/24fc2c:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc2c:d600::/24fc2c:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc2c:d700::/24fc2c:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc2c:d800::/24fc2c:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc2c:d900::/24fc2c:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc2c:da00::/24fc2c:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc2c:db00::/24fc2c:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc2c:dc00::/24fc2c:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc2c:dd00::/24fc2c:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc2c:de00::/24fc2c:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc2c:df00::/24fc2c:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc2c:e000::/24fc2c:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc2c:e100::/24fc2c:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc2c:e200::/24fc2c:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc2c:e300::/24fc2c:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc2c:e400::/24fc2c:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc2c:e500::/24fc2c:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc2c:e600::/24fc2c:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc2c:e700::/24fc2c:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc2c:e800::/24fc2c:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc2c:e900::/24fc2c:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc2c:ea00::/24fc2c:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc2c:eb00::/24fc2c:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc2c:ec00::/24fc2c:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc2c:ed00::/24fc2c:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc2c:ee00::/24fc2c:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc2c:ef00::/24fc2c:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc2c:f000::/24fc2c:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc2c:f100::/24fc2c:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc2c:f200::/24fc2c:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc2c:f300::/24fc2c:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc2c:f400::/24fc2c:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc2c:f500::/24fc2c:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc2c:f600::/24fc2c:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc2c:f700::/24fc2c:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc2c:f800::/24fc2c:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc2c:f900::/24fc2c:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc2c:fa00::/24fc2c:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc2c:fb00::/24fc2c:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc2c:fc00::/24fc2c:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc2c:fd00::/24fc2c:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc2c:fe00::/24fc2c:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc2c:ff00::/24fc2c:ffff:ffff:ffff:ffff:ffff:ffff:ffff

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.