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
fc33::/16
First address
fc33::
Last address
fc33: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
fc33:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
3.3.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)

fc33::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc33::/24fc33:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc33:100::/24fc33:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc33:200::/24fc33:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc33:300::/24fc33:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc33:400::/24fc33:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc33:500::/24fc33:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc33:600::/24fc33:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc33:700::/24fc33:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc33:800::/24fc33:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc33:900::/24fc33:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc33:a00::/24fc33:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc33:b00::/24fc33:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc33:c00::/24fc33:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc33:d00::/24fc33:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc33:e00::/24fc33:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc33:f00::/24fc33:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc33:1000::/24fc33:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc33:1100::/24fc33:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc33:1200::/24fc33:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc33:1300::/24fc33:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc33:1400::/24fc33:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc33:1500::/24fc33:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc33:1600::/24fc33:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc33:1700::/24fc33:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc33:1800::/24fc33:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc33:1900::/24fc33:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc33:1a00::/24fc33:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc33:1b00::/24fc33:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc33:1c00::/24fc33:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc33:1d00::/24fc33:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc33:1e00::/24fc33:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc33:1f00::/24fc33:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc33:2000::/24fc33:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc33:2100::/24fc33:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc33:2200::/24fc33:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc33:2300::/24fc33:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc33:2400::/24fc33:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc33:2500::/24fc33:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc33:2600::/24fc33:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc33:2700::/24fc33:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc33:2800::/24fc33:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc33:2900::/24fc33:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc33:2a00::/24fc33:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc33:2b00::/24fc33:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc33:2c00::/24fc33:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc33:2d00::/24fc33:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc33:2e00::/24fc33:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc33:2f00::/24fc33:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc33:3000::/24fc33:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc33:3100::/24fc33:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc33:3200::/24fc33:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc33:3300::/24fc33:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc33:3400::/24fc33:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc33:3500::/24fc33:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc33:3600::/24fc33:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc33:3700::/24fc33:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc33:3800::/24fc33:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc33:3900::/24fc33:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc33:3a00::/24fc33:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc33:3b00::/24fc33:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc33:3c00::/24fc33:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc33:3d00::/24fc33:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc33:3e00::/24fc33:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc33:3f00::/24fc33:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc33:4000::/24fc33:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc33:4100::/24fc33:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc33:4200::/24fc33:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc33:4300::/24fc33:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc33:4400::/24fc33:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc33:4500::/24fc33:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc33:4600::/24fc33:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc33:4700::/24fc33:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc33:4800::/24fc33:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc33:4900::/24fc33:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc33:4a00::/24fc33:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc33:4b00::/24fc33:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc33:4c00::/24fc33:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc33:4d00::/24fc33:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc33:4e00::/24fc33:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc33:4f00::/24fc33:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc33:5000::/24fc33:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc33:5100::/24fc33:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc33:5200::/24fc33:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc33:5300::/24fc33:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc33:5400::/24fc33:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc33:5500::/24fc33:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc33:5600::/24fc33:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc33:5700::/24fc33:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc33:5800::/24fc33:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc33:5900::/24fc33:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc33:5a00::/24fc33:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc33:5b00::/24fc33:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc33:5c00::/24fc33:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc33:5d00::/24fc33:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc33:5e00::/24fc33:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc33:5f00::/24fc33:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc33:6000::/24fc33:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc33:6100::/24fc33:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc33:6200::/24fc33:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc33:6300::/24fc33:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc33:6400::/24fc33:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc33:6500::/24fc33:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc33:6600::/24fc33:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc33:6700::/24fc33:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc33:6800::/24fc33:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc33:6900::/24fc33:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc33:6a00::/24fc33:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc33:6b00::/24fc33:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc33:6c00::/24fc33:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc33:6d00::/24fc33:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc33:6e00::/24fc33:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc33:6f00::/24fc33:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc33:7000::/24fc33:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc33:7100::/24fc33:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc33:7200::/24fc33:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc33:7300::/24fc33:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc33:7400::/24fc33:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc33:7500::/24fc33:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc33:7600::/24fc33:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc33:7700::/24fc33:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc33:7800::/24fc33:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc33:7900::/24fc33:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc33:7a00::/24fc33:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc33:7b00::/24fc33:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc33:7c00::/24fc33:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc33:7d00::/24fc33:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc33:7e00::/24fc33:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc33:7f00::/24fc33:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc33:8000::/24fc33:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc33:8100::/24fc33:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc33:8200::/24fc33:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc33:8300::/24fc33:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc33:8400::/24fc33:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc33:8500::/24fc33:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc33:8600::/24fc33:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc33:8700::/24fc33:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc33:8800::/24fc33:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc33:8900::/24fc33:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc33:8a00::/24fc33:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc33:8b00::/24fc33:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc33:8c00::/24fc33:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc33:8d00::/24fc33:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc33:8e00::/24fc33:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc33:8f00::/24fc33:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc33:9000::/24fc33:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc33:9100::/24fc33:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc33:9200::/24fc33:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc33:9300::/24fc33:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc33:9400::/24fc33:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc33:9500::/24fc33:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc33:9600::/24fc33:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc33:9700::/24fc33:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc33:9800::/24fc33:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc33:9900::/24fc33:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc33:9a00::/24fc33:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc33:9b00::/24fc33:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc33:9c00::/24fc33:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc33:9d00::/24fc33:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc33:9e00::/24fc33:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc33:9f00::/24fc33:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc33:a000::/24fc33:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc33:a100::/24fc33:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc33:a200::/24fc33:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc33:a300::/24fc33:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc33:a400::/24fc33:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc33:a500::/24fc33:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc33:a600::/24fc33:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc33:a700::/24fc33:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc33:a800::/24fc33:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc33:a900::/24fc33:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc33:aa00::/24fc33:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc33:ab00::/24fc33:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc33:ac00::/24fc33:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc33:ad00::/24fc33:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc33:ae00::/24fc33:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc33:af00::/24fc33:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc33:b000::/24fc33:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc33:b100::/24fc33:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc33:b200::/24fc33:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc33:b300::/24fc33:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc33:b400::/24fc33:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc33:b500::/24fc33:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc33:b600::/24fc33:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc33:b700::/24fc33:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc33:b800::/24fc33:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc33:b900::/24fc33:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc33:ba00::/24fc33:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc33:bb00::/24fc33:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc33:bc00::/24fc33:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc33:bd00::/24fc33:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc33:be00::/24fc33:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc33:bf00::/24fc33:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc33:c000::/24fc33:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc33:c100::/24fc33:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc33:c200::/24fc33:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc33:c300::/24fc33:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc33:c400::/24fc33:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc33:c500::/24fc33:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc33:c600::/24fc33:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc33:c700::/24fc33:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc33:c800::/24fc33:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc33:c900::/24fc33:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc33:ca00::/24fc33:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc33:cb00::/24fc33:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc33:cc00::/24fc33:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc33:cd00::/24fc33:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc33:ce00::/24fc33:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc33:cf00::/24fc33:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc33:d000::/24fc33:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc33:d100::/24fc33:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc33:d200::/24fc33:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc33:d300::/24fc33:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc33:d400::/24fc33:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc33:d500::/24fc33:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc33:d600::/24fc33:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc33:d700::/24fc33:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc33:d800::/24fc33:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc33:d900::/24fc33:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc33:da00::/24fc33:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc33:db00::/24fc33:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc33:dc00::/24fc33:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc33:dd00::/24fc33:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc33:de00::/24fc33:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc33:df00::/24fc33:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc33:e000::/24fc33:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc33:e100::/24fc33:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc33:e200::/24fc33:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc33:e300::/24fc33:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc33:e400::/24fc33:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc33:e500::/24fc33:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc33:e600::/24fc33:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc33:e700::/24fc33:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc33:e800::/24fc33:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc33:e900::/24fc33:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc33:ea00::/24fc33:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc33:eb00::/24fc33:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc33:ec00::/24fc33:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc33:ed00::/24fc33:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc33:ee00::/24fc33:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc33:ef00::/24fc33:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc33:f000::/24fc33:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc33:f100::/24fc33:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc33:f200::/24fc33:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc33:f300::/24fc33:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc33:f400::/24fc33:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc33:f500::/24fc33:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc33:f600::/24fc33:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc33:f700::/24fc33:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc33:f800::/24fc33:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc33:f900::/24fc33:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc33:fa00::/24fc33:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc33:fb00::/24fc33:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc33:fc00::/24fc33:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc33:fd00::/24fc33:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc33:fe00::/24fc33:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc33:ff00::/24fc33: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.