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/48
Addresses2^80
/64 networks65,536
Network
fc39:ec00:dde4::/48
First address
fc39:ec00:dde4::
Last address
fc39:ec00:dde4:ffff:ffff:ffff:ffff:ffff
Addresses
1,208,925,819,614,629,174,706,176 (2^80)
/64 networks (LANs)
65,536
Full form
fc39:ec00:dde4:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
4.e.d.d.0.0.c.e.9.3.c.f.ip6.arpa
Split into smaller subnets/56
/49 (2)/50 (4)/51 (8)/52 (16)/56 (256)/60 (4,096)/64 (65,536)

fc39:ec00:dde4::/48 makes 256 subnets of /56.

Subnets
#SubnetLast address
1fc39:ec00:dde4::/56fc39:ec00:dde4:ff:ffff:ffff:ffff:ffff
2fc39:ec00:dde4:100::/56fc39:ec00:dde4:1ff:ffff:ffff:ffff:ffff
3fc39:ec00:dde4:200::/56fc39:ec00:dde4:2ff:ffff:ffff:ffff:ffff
4fc39:ec00:dde4:300::/56fc39:ec00:dde4:3ff:ffff:ffff:ffff:ffff
5fc39:ec00:dde4:400::/56fc39:ec00:dde4:4ff:ffff:ffff:ffff:ffff
6fc39:ec00:dde4:500::/56fc39:ec00:dde4:5ff:ffff:ffff:ffff:ffff
7fc39:ec00:dde4:600::/56fc39:ec00:dde4:6ff:ffff:ffff:ffff:ffff
8fc39:ec00:dde4:700::/56fc39:ec00:dde4:7ff:ffff:ffff:ffff:ffff
9fc39:ec00:dde4:800::/56fc39:ec00:dde4:8ff:ffff:ffff:ffff:ffff
10fc39:ec00:dde4:900::/56fc39:ec00:dde4:9ff:ffff:ffff:ffff:ffff
11fc39:ec00:dde4:a00::/56fc39:ec00:dde4:aff:ffff:ffff:ffff:ffff
12fc39:ec00:dde4:b00::/56fc39:ec00:dde4:bff:ffff:ffff:ffff:ffff
13fc39:ec00:dde4:c00::/56fc39:ec00:dde4:cff:ffff:ffff:ffff:ffff
14fc39:ec00:dde4:d00::/56fc39:ec00:dde4:dff:ffff:ffff:ffff:ffff
15fc39:ec00:dde4:e00::/56fc39:ec00:dde4:eff:ffff:ffff:ffff:ffff
16fc39:ec00:dde4:f00::/56fc39:ec00:dde4:fff:ffff:ffff:ffff:ffff
17fc39:ec00:dde4:1000::/56fc39:ec00:dde4:10ff:ffff:ffff:ffff:ffff
18fc39:ec00:dde4:1100::/56fc39:ec00:dde4:11ff:ffff:ffff:ffff:ffff
19fc39:ec00:dde4:1200::/56fc39:ec00:dde4:12ff:ffff:ffff:ffff:ffff
20fc39:ec00:dde4:1300::/56fc39:ec00:dde4:13ff:ffff:ffff:ffff:ffff
21fc39:ec00:dde4:1400::/56fc39:ec00:dde4:14ff:ffff:ffff:ffff:ffff
22fc39:ec00:dde4:1500::/56fc39:ec00:dde4:15ff:ffff:ffff:ffff:ffff
23fc39:ec00:dde4:1600::/56fc39:ec00:dde4:16ff:ffff:ffff:ffff:ffff
24fc39:ec00:dde4:1700::/56fc39:ec00:dde4:17ff:ffff:ffff:ffff:ffff
25fc39:ec00:dde4:1800::/56fc39:ec00:dde4:18ff:ffff:ffff:ffff:ffff
26fc39:ec00:dde4:1900::/56fc39:ec00:dde4:19ff:ffff:ffff:ffff:ffff
27fc39:ec00:dde4:1a00::/56fc39:ec00:dde4:1aff:ffff:ffff:ffff:ffff
28fc39:ec00:dde4:1b00::/56fc39:ec00:dde4:1bff:ffff:ffff:ffff:ffff
29fc39:ec00:dde4:1c00::/56fc39:ec00:dde4:1cff:ffff:ffff:ffff:ffff
30fc39:ec00:dde4:1d00::/56fc39:ec00:dde4:1dff:ffff:ffff:ffff:ffff
31fc39:ec00:dde4:1e00::/56fc39:ec00:dde4:1eff:ffff:ffff:ffff:ffff
32fc39:ec00:dde4:1f00::/56fc39:ec00:dde4:1fff:ffff:ffff:ffff:ffff
33fc39:ec00:dde4:2000::/56fc39:ec00:dde4:20ff:ffff:ffff:ffff:ffff
34fc39:ec00:dde4:2100::/56fc39:ec00:dde4:21ff:ffff:ffff:ffff:ffff
35fc39:ec00:dde4:2200::/56fc39:ec00:dde4:22ff:ffff:ffff:ffff:ffff
36fc39:ec00:dde4:2300::/56fc39:ec00:dde4:23ff:ffff:ffff:ffff:ffff
37fc39:ec00:dde4:2400::/56fc39:ec00:dde4:24ff:ffff:ffff:ffff:ffff
38fc39:ec00:dde4:2500::/56fc39:ec00:dde4:25ff:ffff:ffff:ffff:ffff
39fc39:ec00:dde4:2600::/56fc39:ec00:dde4:26ff:ffff:ffff:ffff:ffff
40fc39:ec00:dde4:2700::/56fc39:ec00:dde4:27ff:ffff:ffff:ffff:ffff
41fc39:ec00:dde4:2800::/56fc39:ec00:dde4:28ff:ffff:ffff:ffff:ffff
42fc39:ec00:dde4:2900::/56fc39:ec00:dde4:29ff:ffff:ffff:ffff:ffff
43fc39:ec00:dde4:2a00::/56fc39:ec00:dde4:2aff:ffff:ffff:ffff:ffff
44fc39:ec00:dde4:2b00::/56fc39:ec00:dde4:2bff:ffff:ffff:ffff:ffff
45fc39:ec00:dde4:2c00::/56fc39:ec00:dde4:2cff:ffff:ffff:ffff:ffff
46fc39:ec00:dde4:2d00::/56fc39:ec00:dde4:2dff:ffff:ffff:ffff:ffff
47fc39:ec00:dde4:2e00::/56fc39:ec00:dde4:2eff:ffff:ffff:ffff:ffff
48fc39:ec00:dde4:2f00::/56fc39:ec00:dde4:2fff:ffff:ffff:ffff:ffff
49fc39:ec00:dde4:3000::/56fc39:ec00:dde4:30ff:ffff:ffff:ffff:ffff
50fc39:ec00:dde4:3100::/56fc39:ec00:dde4:31ff:ffff:ffff:ffff:ffff
51fc39:ec00:dde4:3200::/56fc39:ec00:dde4:32ff:ffff:ffff:ffff:ffff
52fc39:ec00:dde4:3300::/56fc39:ec00:dde4:33ff:ffff:ffff:ffff:ffff
53fc39:ec00:dde4:3400::/56fc39:ec00:dde4:34ff:ffff:ffff:ffff:ffff
54fc39:ec00:dde4:3500::/56fc39:ec00:dde4:35ff:ffff:ffff:ffff:ffff
55fc39:ec00:dde4:3600::/56fc39:ec00:dde4:36ff:ffff:ffff:ffff:ffff
56fc39:ec00:dde4:3700::/56fc39:ec00:dde4:37ff:ffff:ffff:ffff:ffff
57fc39:ec00:dde4:3800::/56fc39:ec00:dde4:38ff:ffff:ffff:ffff:ffff
58fc39:ec00:dde4:3900::/56fc39:ec00:dde4:39ff:ffff:ffff:ffff:ffff
59fc39:ec00:dde4:3a00::/56fc39:ec00:dde4:3aff:ffff:ffff:ffff:ffff
60fc39:ec00:dde4:3b00::/56fc39:ec00:dde4:3bff:ffff:ffff:ffff:ffff
61fc39:ec00:dde4:3c00::/56fc39:ec00:dde4:3cff:ffff:ffff:ffff:ffff
62fc39:ec00:dde4:3d00::/56fc39:ec00:dde4:3dff:ffff:ffff:ffff:ffff
63fc39:ec00:dde4:3e00::/56fc39:ec00:dde4:3eff:ffff:ffff:ffff:ffff
64fc39:ec00:dde4:3f00::/56fc39:ec00:dde4:3fff:ffff:ffff:ffff:ffff
65fc39:ec00:dde4:4000::/56fc39:ec00:dde4:40ff:ffff:ffff:ffff:ffff
66fc39:ec00:dde4:4100::/56fc39:ec00:dde4:41ff:ffff:ffff:ffff:ffff
67fc39:ec00:dde4:4200::/56fc39:ec00:dde4:42ff:ffff:ffff:ffff:ffff
68fc39:ec00:dde4:4300::/56fc39:ec00:dde4:43ff:ffff:ffff:ffff:ffff
69fc39:ec00:dde4:4400::/56fc39:ec00:dde4:44ff:ffff:ffff:ffff:ffff
70fc39:ec00:dde4:4500::/56fc39:ec00:dde4:45ff:ffff:ffff:ffff:ffff
71fc39:ec00:dde4:4600::/56fc39:ec00:dde4:46ff:ffff:ffff:ffff:ffff
72fc39:ec00:dde4:4700::/56fc39:ec00:dde4:47ff:ffff:ffff:ffff:ffff
73fc39:ec00:dde4:4800::/56fc39:ec00:dde4:48ff:ffff:ffff:ffff:ffff
74fc39:ec00:dde4:4900::/56fc39:ec00:dde4:49ff:ffff:ffff:ffff:ffff
75fc39:ec00:dde4:4a00::/56fc39:ec00:dde4:4aff:ffff:ffff:ffff:ffff
76fc39:ec00:dde4:4b00::/56fc39:ec00:dde4:4bff:ffff:ffff:ffff:ffff
77fc39:ec00:dde4:4c00::/56fc39:ec00:dde4:4cff:ffff:ffff:ffff:ffff
78fc39:ec00:dde4:4d00::/56fc39:ec00:dde4:4dff:ffff:ffff:ffff:ffff
79fc39:ec00:dde4:4e00::/56fc39:ec00:dde4:4eff:ffff:ffff:ffff:ffff
80fc39:ec00:dde4:4f00::/56fc39:ec00:dde4:4fff:ffff:ffff:ffff:ffff
81fc39:ec00:dde4:5000::/56fc39:ec00:dde4:50ff:ffff:ffff:ffff:ffff
82fc39:ec00:dde4:5100::/56fc39:ec00:dde4:51ff:ffff:ffff:ffff:ffff
83fc39:ec00:dde4:5200::/56fc39:ec00:dde4:52ff:ffff:ffff:ffff:ffff
84fc39:ec00:dde4:5300::/56fc39:ec00:dde4:53ff:ffff:ffff:ffff:ffff
85fc39:ec00:dde4:5400::/56fc39:ec00:dde4:54ff:ffff:ffff:ffff:ffff
86fc39:ec00:dde4:5500::/56fc39:ec00:dde4:55ff:ffff:ffff:ffff:ffff
87fc39:ec00:dde4:5600::/56fc39:ec00:dde4:56ff:ffff:ffff:ffff:ffff
88fc39:ec00:dde4:5700::/56fc39:ec00:dde4:57ff:ffff:ffff:ffff:ffff
89fc39:ec00:dde4:5800::/56fc39:ec00:dde4:58ff:ffff:ffff:ffff:ffff
90fc39:ec00:dde4:5900::/56fc39:ec00:dde4:59ff:ffff:ffff:ffff:ffff
91fc39:ec00:dde4:5a00::/56fc39:ec00:dde4:5aff:ffff:ffff:ffff:ffff
92fc39:ec00:dde4:5b00::/56fc39:ec00:dde4:5bff:ffff:ffff:ffff:ffff
93fc39:ec00:dde4:5c00::/56fc39:ec00:dde4:5cff:ffff:ffff:ffff:ffff
94fc39:ec00:dde4:5d00::/56fc39:ec00:dde4:5dff:ffff:ffff:ffff:ffff
95fc39:ec00:dde4:5e00::/56fc39:ec00:dde4:5eff:ffff:ffff:ffff:ffff
96fc39:ec00:dde4:5f00::/56fc39:ec00:dde4:5fff:ffff:ffff:ffff:ffff
97fc39:ec00:dde4:6000::/56fc39:ec00:dde4:60ff:ffff:ffff:ffff:ffff
98fc39:ec00:dde4:6100::/56fc39:ec00:dde4:61ff:ffff:ffff:ffff:ffff
99fc39:ec00:dde4:6200::/56fc39:ec00:dde4:62ff:ffff:ffff:ffff:ffff
100fc39:ec00:dde4:6300::/56fc39:ec00:dde4:63ff:ffff:ffff:ffff:ffff
101fc39:ec00:dde4:6400::/56fc39:ec00:dde4:64ff:ffff:ffff:ffff:ffff
102fc39:ec00:dde4:6500::/56fc39:ec00:dde4:65ff:ffff:ffff:ffff:ffff
103fc39:ec00:dde4:6600::/56fc39:ec00:dde4:66ff:ffff:ffff:ffff:ffff
104fc39:ec00:dde4:6700::/56fc39:ec00:dde4:67ff:ffff:ffff:ffff:ffff
105fc39:ec00:dde4:6800::/56fc39:ec00:dde4:68ff:ffff:ffff:ffff:ffff
106fc39:ec00:dde4:6900::/56fc39:ec00:dde4:69ff:ffff:ffff:ffff:ffff
107fc39:ec00:dde4:6a00::/56fc39:ec00:dde4:6aff:ffff:ffff:ffff:ffff
108fc39:ec00:dde4:6b00::/56fc39:ec00:dde4:6bff:ffff:ffff:ffff:ffff
109fc39:ec00:dde4:6c00::/56fc39:ec00:dde4:6cff:ffff:ffff:ffff:ffff
110fc39:ec00:dde4:6d00::/56fc39:ec00:dde4:6dff:ffff:ffff:ffff:ffff
111fc39:ec00:dde4:6e00::/56fc39:ec00:dde4:6eff:ffff:ffff:ffff:ffff
112fc39:ec00:dde4:6f00::/56fc39:ec00:dde4:6fff:ffff:ffff:ffff:ffff
113fc39:ec00:dde4:7000::/56fc39:ec00:dde4:70ff:ffff:ffff:ffff:ffff
114fc39:ec00:dde4:7100::/56fc39:ec00:dde4:71ff:ffff:ffff:ffff:ffff
115fc39:ec00:dde4:7200::/56fc39:ec00:dde4:72ff:ffff:ffff:ffff:ffff
116fc39:ec00:dde4:7300::/56fc39:ec00:dde4:73ff:ffff:ffff:ffff:ffff
117fc39:ec00:dde4:7400::/56fc39:ec00:dde4:74ff:ffff:ffff:ffff:ffff
118fc39:ec00:dde4:7500::/56fc39:ec00:dde4:75ff:ffff:ffff:ffff:ffff
119fc39:ec00:dde4:7600::/56fc39:ec00:dde4:76ff:ffff:ffff:ffff:ffff
120fc39:ec00:dde4:7700::/56fc39:ec00:dde4:77ff:ffff:ffff:ffff:ffff
121fc39:ec00:dde4:7800::/56fc39:ec00:dde4:78ff:ffff:ffff:ffff:ffff
122fc39:ec00:dde4:7900::/56fc39:ec00:dde4:79ff:ffff:ffff:ffff:ffff
123fc39:ec00:dde4:7a00::/56fc39:ec00:dde4:7aff:ffff:ffff:ffff:ffff
124fc39:ec00:dde4:7b00::/56fc39:ec00:dde4:7bff:ffff:ffff:ffff:ffff
125fc39:ec00:dde4:7c00::/56fc39:ec00:dde4:7cff:ffff:ffff:ffff:ffff
126fc39:ec00:dde4:7d00::/56fc39:ec00:dde4:7dff:ffff:ffff:ffff:ffff
127fc39:ec00:dde4:7e00::/56fc39:ec00:dde4:7eff:ffff:ffff:ffff:ffff
128fc39:ec00:dde4:7f00::/56fc39:ec00:dde4:7fff:ffff:ffff:ffff:ffff
129fc39:ec00:dde4:8000::/56fc39:ec00:dde4:80ff:ffff:ffff:ffff:ffff
130fc39:ec00:dde4:8100::/56fc39:ec00:dde4:81ff:ffff:ffff:ffff:ffff
131fc39:ec00:dde4:8200::/56fc39:ec00:dde4:82ff:ffff:ffff:ffff:ffff
132fc39:ec00:dde4:8300::/56fc39:ec00:dde4:83ff:ffff:ffff:ffff:ffff
133fc39:ec00:dde4:8400::/56fc39:ec00:dde4:84ff:ffff:ffff:ffff:ffff
134fc39:ec00:dde4:8500::/56fc39:ec00:dde4:85ff:ffff:ffff:ffff:ffff
135fc39:ec00:dde4:8600::/56fc39:ec00:dde4:86ff:ffff:ffff:ffff:ffff
136fc39:ec00:dde4:8700::/56fc39:ec00:dde4:87ff:ffff:ffff:ffff:ffff
137fc39:ec00:dde4:8800::/56fc39:ec00:dde4:88ff:ffff:ffff:ffff:ffff
138fc39:ec00:dde4:8900::/56fc39:ec00:dde4:89ff:ffff:ffff:ffff:ffff
139fc39:ec00:dde4:8a00::/56fc39:ec00:dde4:8aff:ffff:ffff:ffff:ffff
140fc39:ec00:dde4:8b00::/56fc39:ec00:dde4:8bff:ffff:ffff:ffff:ffff
141fc39:ec00:dde4:8c00::/56fc39:ec00:dde4:8cff:ffff:ffff:ffff:ffff
142fc39:ec00:dde4:8d00::/56fc39:ec00:dde4:8dff:ffff:ffff:ffff:ffff
143fc39:ec00:dde4:8e00::/56fc39:ec00:dde4:8eff:ffff:ffff:ffff:ffff
144fc39:ec00:dde4:8f00::/56fc39:ec00:dde4:8fff:ffff:ffff:ffff:ffff
145fc39:ec00:dde4:9000::/56fc39:ec00:dde4:90ff:ffff:ffff:ffff:ffff
146fc39:ec00:dde4:9100::/56fc39:ec00:dde4:91ff:ffff:ffff:ffff:ffff
147fc39:ec00:dde4:9200::/56fc39:ec00:dde4:92ff:ffff:ffff:ffff:ffff
148fc39:ec00:dde4:9300::/56fc39:ec00:dde4:93ff:ffff:ffff:ffff:ffff
149fc39:ec00:dde4:9400::/56fc39:ec00:dde4:94ff:ffff:ffff:ffff:ffff
150fc39:ec00:dde4:9500::/56fc39:ec00:dde4:95ff:ffff:ffff:ffff:ffff
151fc39:ec00:dde4:9600::/56fc39:ec00:dde4:96ff:ffff:ffff:ffff:ffff
152fc39:ec00:dde4:9700::/56fc39:ec00:dde4:97ff:ffff:ffff:ffff:ffff
153fc39:ec00:dde4:9800::/56fc39:ec00:dde4:98ff:ffff:ffff:ffff:ffff
154fc39:ec00:dde4:9900::/56fc39:ec00:dde4:99ff:ffff:ffff:ffff:ffff
155fc39:ec00:dde4:9a00::/56fc39:ec00:dde4:9aff:ffff:ffff:ffff:ffff
156fc39:ec00:dde4:9b00::/56fc39:ec00:dde4:9bff:ffff:ffff:ffff:ffff
157fc39:ec00:dde4:9c00::/56fc39:ec00:dde4:9cff:ffff:ffff:ffff:ffff
158fc39:ec00:dde4:9d00::/56fc39:ec00:dde4:9dff:ffff:ffff:ffff:ffff
159fc39:ec00:dde4:9e00::/56fc39:ec00:dde4:9eff:ffff:ffff:ffff:ffff
160fc39:ec00:dde4:9f00::/56fc39:ec00:dde4:9fff:ffff:ffff:ffff:ffff
161fc39:ec00:dde4:a000::/56fc39:ec00:dde4:a0ff:ffff:ffff:ffff:ffff
162fc39:ec00:dde4:a100::/56fc39:ec00:dde4:a1ff:ffff:ffff:ffff:ffff
163fc39:ec00:dde4:a200::/56fc39:ec00:dde4:a2ff:ffff:ffff:ffff:ffff
164fc39:ec00:dde4:a300::/56fc39:ec00:dde4:a3ff:ffff:ffff:ffff:ffff
165fc39:ec00:dde4:a400::/56fc39:ec00:dde4:a4ff:ffff:ffff:ffff:ffff
166fc39:ec00:dde4:a500::/56fc39:ec00:dde4:a5ff:ffff:ffff:ffff:ffff
167fc39:ec00:dde4:a600::/56fc39:ec00:dde4:a6ff:ffff:ffff:ffff:ffff
168fc39:ec00:dde4:a700::/56fc39:ec00:dde4:a7ff:ffff:ffff:ffff:ffff
169fc39:ec00:dde4:a800::/56fc39:ec00:dde4:a8ff:ffff:ffff:ffff:ffff
170fc39:ec00:dde4:a900::/56fc39:ec00:dde4:a9ff:ffff:ffff:ffff:ffff
171fc39:ec00:dde4:aa00::/56fc39:ec00:dde4:aaff:ffff:ffff:ffff:ffff
172fc39:ec00:dde4:ab00::/56fc39:ec00:dde4:abff:ffff:ffff:ffff:ffff
173fc39:ec00:dde4:ac00::/56fc39:ec00:dde4:acff:ffff:ffff:ffff:ffff
174fc39:ec00:dde4:ad00::/56fc39:ec00:dde4:adff:ffff:ffff:ffff:ffff
175fc39:ec00:dde4:ae00::/56fc39:ec00:dde4:aeff:ffff:ffff:ffff:ffff
176fc39:ec00:dde4:af00::/56fc39:ec00:dde4:afff:ffff:ffff:ffff:ffff
177fc39:ec00:dde4:b000::/56fc39:ec00:dde4:b0ff:ffff:ffff:ffff:ffff
178fc39:ec00:dde4:b100::/56fc39:ec00:dde4:b1ff:ffff:ffff:ffff:ffff
179fc39:ec00:dde4:b200::/56fc39:ec00:dde4:b2ff:ffff:ffff:ffff:ffff
180fc39:ec00:dde4:b300::/56fc39:ec00:dde4:b3ff:ffff:ffff:ffff:ffff
181fc39:ec00:dde4:b400::/56fc39:ec00:dde4:b4ff:ffff:ffff:ffff:ffff
182fc39:ec00:dde4:b500::/56fc39:ec00:dde4:b5ff:ffff:ffff:ffff:ffff
183fc39:ec00:dde4:b600::/56fc39:ec00:dde4:b6ff:ffff:ffff:ffff:ffff
184fc39:ec00:dde4:b700::/56fc39:ec00:dde4:b7ff:ffff:ffff:ffff:ffff
185fc39:ec00:dde4:b800::/56fc39:ec00:dde4:b8ff:ffff:ffff:ffff:ffff
186fc39:ec00:dde4:b900::/56fc39:ec00:dde4:b9ff:ffff:ffff:ffff:ffff
187fc39:ec00:dde4:ba00::/56fc39:ec00:dde4:baff:ffff:ffff:ffff:ffff
188fc39:ec00:dde4:bb00::/56fc39:ec00:dde4:bbff:ffff:ffff:ffff:ffff
189fc39:ec00:dde4:bc00::/56fc39:ec00:dde4:bcff:ffff:ffff:ffff:ffff
190fc39:ec00:dde4:bd00::/56fc39:ec00:dde4:bdff:ffff:ffff:ffff:ffff
191fc39:ec00:dde4:be00::/56fc39:ec00:dde4:beff:ffff:ffff:ffff:ffff
192fc39:ec00:dde4:bf00::/56fc39:ec00:dde4:bfff:ffff:ffff:ffff:ffff
193fc39:ec00:dde4:c000::/56fc39:ec00:dde4:c0ff:ffff:ffff:ffff:ffff
194fc39:ec00:dde4:c100::/56fc39:ec00:dde4:c1ff:ffff:ffff:ffff:ffff
195fc39:ec00:dde4:c200::/56fc39:ec00:dde4:c2ff:ffff:ffff:ffff:ffff
196fc39:ec00:dde4:c300::/56fc39:ec00:dde4:c3ff:ffff:ffff:ffff:ffff
197fc39:ec00:dde4:c400::/56fc39:ec00:dde4:c4ff:ffff:ffff:ffff:ffff
198fc39:ec00:dde4:c500::/56fc39:ec00:dde4:c5ff:ffff:ffff:ffff:ffff
199fc39:ec00:dde4:c600::/56fc39:ec00:dde4:c6ff:ffff:ffff:ffff:ffff
200fc39:ec00:dde4:c700::/56fc39:ec00:dde4:c7ff:ffff:ffff:ffff:ffff
201fc39:ec00:dde4:c800::/56fc39:ec00:dde4:c8ff:ffff:ffff:ffff:ffff
202fc39:ec00:dde4:c900::/56fc39:ec00:dde4:c9ff:ffff:ffff:ffff:ffff
203fc39:ec00:dde4:ca00::/56fc39:ec00:dde4:caff:ffff:ffff:ffff:ffff
204fc39:ec00:dde4:cb00::/56fc39:ec00:dde4:cbff:ffff:ffff:ffff:ffff
205fc39:ec00:dde4:cc00::/56fc39:ec00:dde4:ccff:ffff:ffff:ffff:ffff
206fc39:ec00:dde4:cd00::/56fc39:ec00:dde4:cdff:ffff:ffff:ffff:ffff
207fc39:ec00:dde4:ce00::/56fc39:ec00:dde4:ceff:ffff:ffff:ffff:ffff
208fc39:ec00:dde4:cf00::/56fc39:ec00:dde4:cfff:ffff:ffff:ffff:ffff
209fc39:ec00:dde4:d000::/56fc39:ec00:dde4:d0ff:ffff:ffff:ffff:ffff
210fc39:ec00:dde4:d100::/56fc39:ec00:dde4:d1ff:ffff:ffff:ffff:ffff
211fc39:ec00:dde4:d200::/56fc39:ec00:dde4:d2ff:ffff:ffff:ffff:ffff
212fc39:ec00:dde4:d300::/56fc39:ec00:dde4:d3ff:ffff:ffff:ffff:ffff
213fc39:ec00:dde4:d400::/56fc39:ec00:dde4:d4ff:ffff:ffff:ffff:ffff
214fc39:ec00:dde4:d500::/56fc39:ec00:dde4:d5ff:ffff:ffff:ffff:ffff
215fc39:ec00:dde4:d600::/56fc39:ec00:dde4:d6ff:ffff:ffff:ffff:ffff
216fc39:ec00:dde4:d700::/56fc39:ec00:dde4:d7ff:ffff:ffff:ffff:ffff
217fc39:ec00:dde4:d800::/56fc39:ec00:dde4:d8ff:ffff:ffff:ffff:ffff
218fc39:ec00:dde4:d900::/56fc39:ec00:dde4:d9ff:ffff:ffff:ffff:ffff
219fc39:ec00:dde4:da00::/56fc39:ec00:dde4:daff:ffff:ffff:ffff:ffff
220fc39:ec00:dde4:db00::/56fc39:ec00:dde4:dbff:ffff:ffff:ffff:ffff
221fc39:ec00:dde4:dc00::/56fc39:ec00:dde4:dcff:ffff:ffff:ffff:ffff
222fc39:ec00:dde4:dd00::/56fc39:ec00:dde4:ddff:ffff:ffff:ffff:ffff
223fc39:ec00:dde4:de00::/56fc39:ec00:dde4:deff:ffff:ffff:ffff:ffff
224fc39:ec00:dde4:df00::/56fc39:ec00:dde4:dfff:ffff:ffff:ffff:ffff
225fc39:ec00:dde4:e000::/56fc39:ec00:dde4:e0ff:ffff:ffff:ffff:ffff
226fc39:ec00:dde4:e100::/56fc39:ec00:dde4:e1ff:ffff:ffff:ffff:ffff
227fc39:ec00:dde4:e200::/56fc39:ec00:dde4:e2ff:ffff:ffff:ffff:ffff
228fc39:ec00:dde4:e300::/56fc39:ec00:dde4:e3ff:ffff:ffff:ffff:ffff
229fc39:ec00:dde4:e400::/56fc39:ec00:dde4:e4ff:ffff:ffff:ffff:ffff
230fc39:ec00:dde4:e500::/56fc39:ec00:dde4:e5ff:ffff:ffff:ffff:ffff
231fc39:ec00:dde4:e600::/56fc39:ec00:dde4:e6ff:ffff:ffff:ffff:ffff
232fc39:ec00:dde4:e700::/56fc39:ec00:dde4:e7ff:ffff:ffff:ffff:ffff
233fc39:ec00:dde4:e800::/56fc39:ec00:dde4:e8ff:ffff:ffff:ffff:ffff
234fc39:ec00:dde4:e900::/56fc39:ec00:dde4:e9ff:ffff:ffff:ffff:ffff
235fc39:ec00:dde4:ea00::/56fc39:ec00:dde4:eaff:ffff:ffff:ffff:ffff
236fc39:ec00:dde4:eb00::/56fc39:ec00:dde4:ebff:ffff:ffff:ffff:ffff
237fc39:ec00:dde4:ec00::/56fc39:ec00:dde4:ecff:ffff:ffff:ffff:ffff
238fc39:ec00:dde4:ed00::/56fc39:ec00:dde4:edff:ffff:ffff:ffff:ffff
239fc39:ec00:dde4:ee00::/56fc39:ec00:dde4:eeff:ffff:ffff:ffff:ffff
240fc39:ec00:dde4:ef00::/56fc39:ec00:dde4:efff:ffff:ffff:ffff:ffff
241fc39:ec00:dde4:f000::/56fc39:ec00:dde4:f0ff:ffff:ffff:ffff:ffff
242fc39:ec00:dde4:f100::/56fc39:ec00:dde4:f1ff:ffff:ffff:ffff:ffff
243fc39:ec00:dde4:f200::/56fc39:ec00:dde4:f2ff:ffff:ffff:ffff:ffff
244fc39:ec00:dde4:f300::/56fc39:ec00:dde4:f3ff:ffff:ffff:ffff:ffff
245fc39:ec00:dde4:f400::/56fc39:ec00:dde4:f4ff:ffff:ffff:ffff:ffff
246fc39:ec00:dde4:f500::/56fc39:ec00:dde4:f5ff:ffff:ffff:ffff:ffff
247fc39:ec00:dde4:f600::/56fc39:ec00:dde4:f6ff:ffff:ffff:ffff:ffff
248fc39:ec00:dde4:f700::/56fc39:ec00:dde4:f7ff:ffff:ffff:ffff:ffff
249fc39:ec00:dde4:f800::/56fc39:ec00:dde4:f8ff:ffff:ffff:ffff:ffff
250fc39:ec00:dde4:f900::/56fc39:ec00:dde4:f9ff:ffff:ffff:ffff:ffff
251fc39:ec00:dde4:fa00::/56fc39:ec00:dde4:faff:ffff:ffff:ffff:ffff
252fc39:ec00:dde4:fb00::/56fc39:ec00:dde4:fbff:ffff:ffff:ffff:ffff
253fc39:ec00:dde4:fc00::/56fc39:ec00:dde4:fcff:ffff:ffff:ffff:ffff
254fc39:ec00:dde4:fd00::/56fc39:ec00:dde4:fdff:ffff:ffff:ffff:ffff
255fc39:ec00:dde4:fe00::/56fc39:ec00:dde4:feff:ffff:ffff:ffff:ffff
256fc39:ec00:dde4:ff00::/56fc39:ec00:dde4: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.