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/11
Addresses2^117
/64 networks2^53
Network
fc80::/11
First address
fc80::
Last address
fc9f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
166,153,499,473,114,484,112,975,882,535,043,072 (2^117)
/64 networks (LANs)
9,007,199,254,740,992 (2^53)
Full form
fc80:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zones
8.c.f.ip6.arpa
9.c.f.ip6.arpa
/11 is not on a 4-bit boundary, so it takes 2 /12 zones.
Split into smaller subnets/24
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/20 (512)/24 (8,192)

fc80::/11 makes 8,192 subnets of /24; the first 256 are listed.

Subnets
#SubnetLast address
1fc80::/24fc80:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc80:100::/24fc80:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc80:200::/24fc80:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc80:300::/24fc80:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc80:400::/24fc80:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc80:500::/24fc80:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc80:600::/24fc80:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc80:700::/24fc80:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc80:800::/24fc80:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc80:900::/24fc80:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc80:a00::/24fc80:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc80:b00::/24fc80:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc80:c00::/24fc80:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc80:d00::/24fc80:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc80:e00::/24fc80:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc80:f00::/24fc80:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc80:1000::/24fc80:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc80:1100::/24fc80:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc80:1200::/24fc80:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc80:1300::/24fc80:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc80:1400::/24fc80:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc80:1500::/24fc80:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc80:1600::/24fc80:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc80:1700::/24fc80:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc80:1800::/24fc80:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc80:1900::/24fc80:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc80:1a00::/24fc80:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc80:1b00::/24fc80:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc80:1c00::/24fc80:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc80:1d00::/24fc80:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc80:1e00::/24fc80:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc80:1f00::/24fc80:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc80:2000::/24fc80:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc80:2100::/24fc80:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc80:2200::/24fc80:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc80:2300::/24fc80:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc80:2400::/24fc80:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc80:2500::/24fc80:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc80:2600::/24fc80:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc80:2700::/24fc80:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc80:2800::/24fc80:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc80:2900::/24fc80:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc80:2a00::/24fc80:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc80:2b00::/24fc80:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc80:2c00::/24fc80:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc80:2d00::/24fc80:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc80:2e00::/24fc80:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc80:2f00::/24fc80:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc80:3000::/24fc80:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc80:3100::/24fc80:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc80:3200::/24fc80:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc80:3300::/24fc80:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc80:3400::/24fc80:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc80:3500::/24fc80:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc80:3600::/24fc80:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc80:3700::/24fc80:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc80:3800::/24fc80:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc80:3900::/24fc80:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc80:3a00::/24fc80:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc80:3b00::/24fc80:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc80:3c00::/24fc80:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc80:3d00::/24fc80:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc80:3e00::/24fc80:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc80:3f00::/24fc80:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc80:4000::/24fc80:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc80:4100::/24fc80:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc80:4200::/24fc80:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc80:4300::/24fc80:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc80:4400::/24fc80:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc80:4500::/24fc80:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc80:4600::/24fc80:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc80:4700::/24fc80:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc80:4800::/24fc80:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc80:4900::/24fc80:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc80:4a00::/24fc80:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc80:4b00::/24fc80:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc80:4c00::/24fc80:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc80:4d00::/24fc80:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc80:4e00::/24fc80:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc80:4f00::/24fc80:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc80:5000::/24fc80:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc80:5100::/24fc80:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc80:5200::/24fc80:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc80:5300::/24fc80:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc80:5400::/24fc80:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc80:5500::/24fc80:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc80:5600::/24fc80:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc80:5700::/24fc80:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc80:5800::/24fc80:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc80:5900::/24fc80:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc80:5a00::/24fc80:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc80:5b00::/24fc80:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc80:5c00::/24fc80:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc80:5d00::/24fc80:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc80:5e00::/24fc80:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc80:5f00::/24fc80:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc80:6000::/24fc80:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc80:6100::/24fc80:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc80:6200::/24fc80:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc80:6300::/24fc80:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc80:6400::/24fc80:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc80:6500::/24fc80:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc80:6600::/24fc80:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc80:6700::/24fc80:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc80:6800::/24fc80:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc80:6900::/24fc80:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc80:6a00::/24fc80:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc80:6b00::/24fc80:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc80:6c00::/24fc80:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc80:6d00::/24fc80:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc80:6e00::/24fc80:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc80:6f00::/24fc80:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc80:7000::/24fc80:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc80:7100::/24fc80:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc80:7200::/24fc80:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc80:7300::/24fc80:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc80:7400::/24fc80:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc80:7500::/24fc80:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc80:7600::/24fc80:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc80:7700::/24fc80:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc80:7800::/24fc80:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc80:7900::/24fc80:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc80:7a00::/24fc80:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc80:7b00::/24fc80:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc80:7c00::/24fc80:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc80:7d00::/24fc80:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc80:7e00::/24fc80:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc80:7f00::/24fc80:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc80:8000::/24fc80:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc80:8100::/24fc80:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc80:8200::/24fc80:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc80:8300::/24fc80:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc80:8400::/24fc80:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc80:8500::/24fc80:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc80:8600::/24fc80:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc80:8700::/24fc80:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc80:8800::/24fc80:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc80:8900::/24fc80:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc80:8a00::/24fc80:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc80:8b00::/24fc80:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc80:8c00::/24fc80:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc80:8d00::/24fc80:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc80:8e00::/24fc80:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc80:8f00::/24fc80:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc80:9000::/24fc80:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc80:9100::/24fc80:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc80:9200::/24fc80:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc80:9300::/24fc80:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc80:9400::/24fc80:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc80:9500::/24fc80:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc80:9600::/24fc80:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc80:9700::/24fc80:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc80:9800::/24fc80:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc80:9900::/24fc80:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc80:9a00::/24fc80:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc80:9b00::/24fc80:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc80:9c00::/24fc80:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc80:9d00::/24fc80:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc80:9e00::/24fc80:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc80:9f00::/24fc80:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc80:a000::/24fc80:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc80:a100::/24fc80:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc80:a200::/24fc80:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc80:a300::/24fc80:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc80:a400::/24fc80:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc80:a500::/24fc80:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc80:a600::/24fc80:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc80:a700::/24fc80:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc80:a800::/24fc80:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc80:a900::/24fc80:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc80:aa00::/24fc80:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc80:ab00::/24fc80:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc80:ac00::/24fc80:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc80:ad00::/24fc80:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc80:ae00::/24fc80:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc80:af00::/24fc80:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc80:b000::/24fc80:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc80:b100::/24fc80:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc80:b200::/24fc80:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc80:b300::/24fc80:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc80:b400::/24fc80:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc80:b500::/24fc80:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc80:b600::/24fc80:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc80:b700::/24fc80:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc80:b800::/24fc80:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc80:b900::/24fc80:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc80:ba00::/24fc80:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc80:bb00::/24fc80:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc80:bc00::/24fc80:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc80:bd00::/24fc80:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc80:be00::/24fc80:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc80:bf00::/24fc80:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc80:c000::/24fc80:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc80:c100::/24fc80:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc80:c200::/24fc80:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc80:c300::/24fc80:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc80:c400::/24fc80:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc80:c500::/24fc80:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc80:c600::/24fc80:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc80:c700::/24fc80:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc80:c800::/24fc80:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc80:c900::/24fc80:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc80:ca00::/24fc80:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc80:cb00::/24fc80:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc80:cc00::/24fc80:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc80:cd00::/24fc80:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc80:ce00::/24fc80:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc80:cf00::/24fc80:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc80:d000::/24fc80:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc80:d100::/24fc80:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc80:d200::/24fc80:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc80:d300::/24fc80:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc80:d400::/24fc80:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc80:d500::/24fc80:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc80:d600::/24fc80:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc80:d700::/24fc80:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc80:d800::/24fc80:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc80:d900::/24fc80:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc80:da00::/24fc80:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc80:db00::/24fc80:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc80:dc00::/24fc80:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc80:dd00::/24fc80:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc80:de00::/24fc80:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc80:df00::/24fc80:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc80:e000::/24fc80:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc80:e100::/24fc80:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc80:e200::/24fc80:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc80:e300::/24fc80:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc80:e400::/24fc80:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc80:e500::/24fc80:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc80:e600::/24fc80:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc80:e700::/24fc80:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc80:e800::/24fc80:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc80:e900::/24fc80:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc80:ea00::/24fc80:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc80:eb00::/24fc80:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc80:ec00::/24fc80:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc80:ed00::/24fc80:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc80:ee00::/24fc80:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc80:ef00::/24fc80:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc80:f000::/24fc80:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc80:f100::/24fc80:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc80:f200::/24fc80:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc80:f300::/24fc80:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc80:f400::/24fc80:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc80:f500::/24fc80:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc80:f600::/24fc80:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc80:f700::/24fc80:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc80:f800::/24fc80:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc80:f900::/24fc80:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc80:fa00::/24fc80:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc80:fb00::/24fc80:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc80:fc00::/24fc80:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc80:fd00::/24fc80:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc80:fe00::/24fc80:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc80:ff00::/24fc80: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.