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
fc30::/16
First address
fc30::
Last address
fc30: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
fc30:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
0.3.c.f.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fc30::/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
1fc30::/28fc30:f:ffff:ffff:ffff:ffff:ffff:ffff
2fc30:10::/28fc30:1f:ffff:ffff:ffff:ffff:ffff:ffff
3fc30:20::/28fc30:2f:ffff:ffff:ffff:ffff:ffff:ffff
4fc30:30::/28fc30:3f:ffff:ffff:ffff:ffff:ffff:ffff
5fc30:40::/28fc30:4f:ffff:ffff:ffff:ffff:ffff:ffff
6fc30:50::/28fc30:5f:ffff:ffff:ffff:ffff:ffff:ffff
7fc30:60::/28fc30:6f:ffff:ffff:ffff:ffff:ffff:ffff
8fc30:70::/28fc30:7f:ffff:ffff:ffff:ffff:ffff:ffff
9fc30:80::/28fc30:8f:ffff:ffff:ffff:ffff:ffff:ffff
10fc30:90::/28fc30:9f:ffff:ffff:ffff:ffff:ffff:ffff
11fc30:a0::/28fc30:af:ffff:ffff:ffff:ffff:ffff:ffff
12fc30:b0::/28fc30:bf:ffff:ffff:ffff:ffff:ffff:ffff
13fc30:c0::/28fc30:cf:ffff:ffff:ffff:ffff:ffff:ffff
14fc30:d0::/28fc30:df:ffff:ffff:ffff:ffff:ffff:ffff
15fc30:e0::/28fc30:ef:ffff:ffff:ffff:ffff:ffff:ffff
16fc30:f0::/28fc30:ff:ffff:ffff:ffff:ffff:ffff:ffff
17fc30:100::/28fc30:10f:ffff:ffff:ffff:ffff:ffff:ffff
18fc30:110::/28fc30:11f:ffff:ffff:ffff:ffff:ffff:ffff
19fc30:120::/28fc30:12f:ffff:ffff:ffff:ffff:ffff:ffff
20fc30:130::/28fc30:13f:ffff:ffff:ffff:ffff:ffff:ffff
21fc30:140::/28fc30:14f:ffff:ffff:ffff:ffff:ffff:ffff
22fc30:150::/28fc30:15f:ffff:ffff:ffff:ffff:ffff:ffff
23fc30:160::/28fc30:16f:ffff:ffff:ffff:ffff:ffff:ffff
24fc30:170::/28fc30:17f:ffff:ffff:ffff:ffff:ffff:ffff
25fc30:180::/28fc30:18f:ffff:ffff:ffff:ffff:ffff:ffff
26fc30:190::/28fc30:19f:ffff:ffff:ffff:ffff:ffff:ffff
27fc30:1a0::/28fc30:1af:ffff:ffff:ffff:ffff:ffff:ffff
28fc30:1b0::/28fc30:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29fc30:1c0::/28fc30:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30fc30:1d0::/28fc30:1df:ffff:ffff:ffff:ffff:ffff:ffff
31fc30:1e0::/28fc30:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32fc30:1f0::/28fc30:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33fc30:200::/28fc30:20f:ffff:ffff:ffff:ffff:ffff:ffff
34fc30:210::/28fc30:21f:ffff:ffff:ffff:ffff:ffff:ffff
35fc30:220::/28fc30:22f:ffff:ffff:ffff:ffff:ffff:ffff
36fc30:230::/28fc30:23f:ffff:ffff:ffff:ffff:ffff:ffff
37fc30:240::/28fc30:24f:ffff:ffff:ffff:ffff:ffff:ffff
38fc30:250::/28fc30:25f:ffff:ffff:ffff:ffff:ffff:ffff
39fc30:260::/28fc30:26f:ffff:ffff:ffff:ffff:ffff:ffff
40fc30:270::/28fc30:27f:ffff:ffff:ffff:ffff:ffff:ffff
41fc30:280::/28fc30:28f:ffff:ffff:ffff:ffff:ffff:ffff
42fc30:290::/28fc30:29f:ffff:ffff:ffff:ffff:ffff:ffff
43fc30:2a0::/28fc30:2af:ffff:ffff:ffff:ffff:ffff:ffff
44fc30:2b0::/28fc30:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45fc30:2c0::/28fc30:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46fc30:2d0::/28fc30:2df:ffff:ffff:ffff:ffff:ffff:ffff
47fc30:2e0::/28fc30:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48fc30:2f0::/28fc30:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49fc30:300::/28fc30:30f:ffff:ffff:ffff:ffff:ffff:ffff
50fc30:310::/28fc30:31f:ffff:ffff:ffff:ffff:ffff:ffff
51fc30:320::/28fc30:32f:ffff:ffff:ffff:ffff:ffff:ffff
52fc30:330::/28fc30:33f:ffff:ffff:ffff:ffff:ffff:ffff
53fc30:340::/28fc30:34f:ffff:ffff:ffff:ffff:ffff:ffff
54fc30:350::/28fc30:35f:ffff:ffff:ffff:ffff:ffff:ffff
55fc30:360::/28fc30:36f:ffff:ffff:ffff:ffff:ffff:ffff
56fc30:370::/28fc30:37f:ffff:ffff:ffff:ffff:ffff:ffff
57fc30:380::/28fc30:38f:ffff:ffff:ffff:ffff:ffff:ffff
58fc30:390::/28fc30:39f:ffff:ffff:ffff:ffff:ffff:ffff
59fc30:3a0::/28fc30:3af:ffff:ffff:ffff:ffff:ffff:ffff
60fc30:3b0::/28fc30:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61fc30:3c0::/28fc30:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62fc30:3d0::/28fc30:3df:ffff:ffff:ffff:ffff:ffff:ffff
63fc30:3e0::/28fc30:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64fc30:3f0::/28fc30:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65fc30:400::/28fc30:40f:ffff:ffff:ffff:ffff:ffff:ffff
66fc30:410::/28fc30:41f:ffff:ffff:ffff:ffff:ffff:ffff
67fc30:420::/28fc30:42f:ffff:ffff:ffff:ffff:ffff:ffff
68fc30:430::/28fc30:43f:ffff:ffff:ffff:ffff:ffff:ffff
69fc30:440::/28fc30:44f:ffff:ffff:ffff:ffff:ffff:ffff
70fc30:450::/28fc30:45f:ffff:ffff:ffff:ffff:ffff:ffff
71fc30:460::/28fc30:46f:ffff:ffff:ffff:ffff:ffff:ffff
72fc30:470::/28fc30:47f:ffff:ffff:ffff:ffff:ffff:ffff
73fc30:480::/28fc30:48f:ffff:ffff:ffff:ffff:ffff:ffff
74fc30:490::/28fc30:49f:ffff:ffff:ffff:ffff:ffff:ffff
75fc30:4a0::/28fc30:4af:ffff:ffff:ffff:ffff:ffff:ffff
76fc30:4b0::/28fc30:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77fc30:4c0::/28fc30:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78fc30:4d0::/28fc30:4df:ffff:ffff:ffff:ffff:ffff:ffff
79fc30:4e0::/28fc30:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80fc30:4f0::/28fc30:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81fc30:500::/28fc30:50f:ffff:ffff:ffff:ffff:ffff:ffff
82fc30:510::/28fc30:51f:ffff:ffff:ffff:ffff:ffff:ffff
83fc30:520::/28fc30:52f:ffff:ffff:ffff:ffff:ffff:ffff
84fc30:530::/28fc30:53f:ffff:ffff:ffff:ffff:ffff:ffff
85fc30:540::/28fc30:54f:ffff:ffff:ffff:ffff:ffff:ffff
86fc30:550::/28fc30:55f:ffff:ffff:ffff:ffff:ffff:ffff
87fc30:560::/28fc30:56f:ffff:ffff:ffff:ffff:ffff:ffff
88fc30:570::/28fc30:57f:ffff:ffff:ffff:ffff:ffff:ffff
89fc30:580::/28fc30:58f:ffff:ffff:ffff:ffff:ffff:ffff
90fc30:590::/28fc30:59f:ffff:ffff:ffff:ffff:ffff:ffff
91fc30:5a0::/28fc30:5af:ffff:ffff:ffff:ffff:ffff:ffff
92fc30:5b0::/28fc30:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93fc30:5c0::/28fc30:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94fc30:5d0::/28fc30:5df:ffff:ffff:ffff:ffff:ffff:ffff
95fc30:5e0::/28fc30:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96fc30:5f0::/28fc30:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97fc30:600::/28fc30:60f:ffff:ffff:ffff:ffff:ffff:ffff
98fc30:610::/28fc30:61f:ffff:ffff:ffff:ffff:ffff:ffff
99fc30:620::/28fc30:62f:ffff:ffff:ffff:ffff:ffff:ffff
100fc30:630::/28fc30:63f:ffff:ffff:ffff:ffff:ffff:ffff
101fc30:640::/28fc30:64f:ffff:ffff:ffff:ffff:ffff:ffff
102fc30:650::/28fc30:65f:ffff:ffff:ffff:ffff:ffff:ffff
103fc30:660::/28fc30:66f:ffff:ffff:ffff:ffff:ffff:ffff
104fc30:670::/28fc30:67f:ffff:ffff:ffff:ffff:ffff:ffff
105fc30:680::/28fc30:68f:ffff:ffff:ffff:ffff:ffff:ffff
106fc30:690::/28fc30:69f:ffff:ffff:ffff:ffff:ffff:ffff
107fc30:6a0::/28fc30:6af:ffff:ffff:ffff:ffff:ffff:ffff
108fc30:6b0::/28fc30:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109fc30:6c0::/28fc30:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110fc30:6d0::/28fc30:6df:ffff:ffff:ffff:ffff:ffff:ffff
111fc30:6e0::/28fc30:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112fc30:6f0::/28fc30:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113fc30:700::/28fc30:70f:ffff:ffff:ffff:ffff:ffff:ffff
114fc30:710::/28fc30:71f:ffff:ffff:ffff:ffff:ffff:ffff
115fc30:720::/28fc30:72f:ffff:ffff:ffff:ffff:ffff:ffff
116fc30:730::/28fc30:73f:ffff:ffff:ffff:ffff:ffff:ffff
117fc30:740::/28fc30:74f:ffff:ffff:ffff:ffff:ffff:ffff
118fc30:750::/28fc30:75f:ffff:ffff:ffff:ffff:ffff:ffff
119fc30:760::/28fc30:76f:ffff:ffff:ffff:ffff:ffff:ffff
120fc30:770::/28fc30:77f:ffff:ffff:ffff:ffff:ffff:ffff
121fc30:780::/28fc30:78f:ffff:ffff:ffff:ffff:ffff:ffff
122fc30:790::/28fc30:79f:ffff:ffff:ffff:ffff:ffff:ffff
123fc30:7a0::/28fc30:7af:ffff:ffff:ffff:ffff:ffff:ffff
124fc30:7b0::/28fc30:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125fc30:7c0::/28fc30:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126fc30:7d0::/28fc30:7df:ffff:ffff:ffff:ffff:ffff:ffff
127fc30:7e0::/28fc30:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128fc30:7f0::/28fc30:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129fc30:800::/28fc30:80f:ffff:ffff:ffff:ffff:ffff:ffff
130fc30:810::/28fc30:81f:ffff:ffff:ffff:ffff:ffff:ffff
131fc30:820::/28fc30:82f:ffff:ffff:ffff:ffff:ffff:ffff
132fc30:830::/28fc30:83f:ffff:ffff:ffff:ffff:ffff:ffff
133fc30:840::/28fc30:84f:ffff:ffff:ffff:ffff:ffff:ffff
134fc30:850::/28fc30:85f:ffff:ffff:ffff:ffff:ffff:ffff
135fc30:860::/28fc30:86f:ffff:ffff:ffff:ffff:ffff:ffff
136fc30:870::/28fc30:87f:ffff:ffff:ffff:ffff:ffff:ffff
137fc30:880::/28fc30:88f:ffff:ffff:ffff:ffff:ffff:ffff
138fc30:890::/28fc30:89f:ffff:ffff:ffff:ffff:ffff:ffff
139fc30:8a0::/28fc30:8af:ffff:ffff:ffff:ffff:ffff:ffff
140fc30:8b0::/28fc30:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141fc30:8c0::/28fc30:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142fc30:8d0::/28fc30:8df:ffff:ffff:ffff:ffff:ffff:ffff
143fc30:8e0::/28fc30:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144fc30:8f0::/28fc30:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145fc30:900::/28fc30:90f:ffff:ffff:ffff:ffff:ffff:ffff
146fc30:910::/28fc30:91f:ffff:ffff:ffff:ffff:ffff:ffff
147fc30:920::/28fc30:92f:ffff:ffff:ffff:ffff:ffff:ffff
148fc30:930::/28fc30:93f:ffff:ffff:ffff:ffff:ffff:ffff
149fc30:940::/28fc30:94f:ffff:ffff:ffff:ffff:ffff:ffff
150fc30:950::/28fc30:95f:ffff:ffff:ffff:ffff:ffff:ffff
151fc30:960::/28fc30:96f:ffff:ffff:ffff:ffff:ffff:ffff
152fc30:970::/28fc30:97f:ffff:ffff:ffff:ffff:ffff:ffff
153fc30:980::/28fc30:98f:ffff:ffff:ffff:ffff:ffff:ffff
154fc30:990::/28fc30:99f:ffff:ffff:ffff:ffff:ffff:ffff
155fc30:9a0::/28fc30:9af:ffff:ffff:ffff:ffff:ffff:ffff
156fc30:9b0::/28fc30:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157fc30:9c0::/28fc30:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158fc30:9d0::/28fc30:9df:ffff:ffff:ffff:ffff:ffff:ffff
159fc30:9e0::/28fc30:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160fc30:9f0::/28fc30:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161fc30:a00::/28fc30:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162fc30:a10::/28fc30:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163fc30:a20::/28fc30:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164fc30:a30::/28fc30:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165fc30:a40::/28fc30:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166fc30:a50::/28fc30:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167fc30:a60::/28fc30:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168fc30:a70::/28fc30:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169fc30:a80::/28fc30:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170fc30:a90::/28fc30:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171fc30:aa0::/28fc30:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172fc30:ab0::/28fc30:abf:ffff:ffff:ffff:ffff:ffff:ffff
173fc30:ac0::/28fc30:acf:ffff:ffff:ffff:ffff:ffff:ffff
174fc30:ad0::/28fc30:adf:ffff:ffff:ffff:ffff:ffff:ffff
175fc30:ae0::/28fc30:aef:ffff:ffff:ffff:ffff:ffff:ffff
176fc30:af0::/28fc30:aff:ffff:ffff:ffff:ffff:ffff:ffff
177fc30:b00::/28fc30:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178fc30:b10::/28fc30:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179fc30:b20::/28fc30:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180fc30:b30::/28fc30:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181fc30:b40::/28fc30:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182fc30:b50::/28fc30:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183fc30:b60::/28fc30:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184fc30:b70::/28fc30:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185fc30:b80::/28fc30:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186fc30:b90::/28fc30:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187fc30:ba0::/28fc30:baf:ffff:ffff:ffff:ffff:ffff:ffff
188fc30:bb0::/28fc30:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189fc30:bc0::/28fc30:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190fc30:bd0::/28fc30:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191fc30:be0::/28fc30:bef:ffff:ffff:ffff:ffff:ffff:ffff
192fc30:bf0::/28fc30:bff:ffff:ffff:ffff:ffff:ffff:ffff
193fc30:c00::/28fc30:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194fc30:c10::/28fc30:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195fc30:c20::/28fc30:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196fc30:c30::/28fc30:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197fc30:c40::/28fc30:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198fc30:c50::/28fc30:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199fc30:c60::/28fc30:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200fc30:c70::/28fc30:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201fc30:c80::/28fc30:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202fc30:c90::/28fc30:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203fc30:ca0::/28fc30:caf:ffff:ffff:ffff:ffff:ffff:ffff
204fc30:cb0::/28fc30:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205fc30:cc0::/28fc30:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206fc30:cd0::/28fc30:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207fc30:ce0::/28fc30:cef:ffff:ffff:ffff:ffff:ffff:ffff
208fc30:cf0::/28fc30:cff:ffff:ffff:ffff:ffff:ffff:ffff
209fc30:d00::/28fc30:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210fc30:d10::/28fc30:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211fc30:d20::/28fc30:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212fc30:d30::/28fc30:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213fc30:d40::/28fc30:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214fc30:d50::/28fc30:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215fc30:d60::/28fc30:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216fc30:d70::/28fc30:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217fc30:d80::/28fc30:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218fc30:d90::/28fc30:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219fc30:da0::/28fc30:daf:ffff:ffff:ffff:ffff:ffff:ffff
220fc30:db0::/28fc30:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221fc30:dc0::/28fc30:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222fc30:dd0::/28fc30:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223fc30:de0::/28fc30:def:ffff:ffff:ffff:ffff:ffff:ffff
224fc30:df0::/28fc30:dff:ffff:ffff:ffff:ffff:ffff:ffff
225fc30:e00::/28fc30:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226fc30:e10::/28fc30:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227fc30:e20::/28fc30:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228fc30:e30::/28fc30:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229fc30:e40::/28fc30:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230fc30:e50::/28fc30:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231fc30:e60::/28fc30:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232fc30:e70::/28fc30:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233fc30:e80::/28fc30:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234fc30:e90::/28fc30:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235fc30:ea0::/28fc30:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236fc30:eb0::/28fc30:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237fc30:ec0::/28fc30:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238fc30:ed0::/28fc30:edf:ffff:ffff:ffff:ffff:ffff:ffff
239fc30:ee0::/28fc30:eef:ffff:ffff:ffff:ffff:ffff:ffff
240fc30:ef0::/28fc30:eff:ffff:ffff:ffff:ffff:ffff:ffff
241fc30:f00::/28fc30:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242fc30:f10::/28fc30:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243fc30:f20::/28fc30:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244fc30:f30::/28fc30:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245fc30:f40::/28fc30:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246fc30:f50::/28fc30:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247fc30:f60::/28fc30:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248fc30:f70::/28fc30:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249fc30:f80::/28fc30:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250fc30:f90::/28fc30:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251fc30:fa0::/28fc30:faf:ffff:ffff:ffff:ffff:ffff:ffff
252fc30:fb0::/28fc30:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253fc30:fc0::/28fc30:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254fc30:fd0::/28fc30:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255fc30:fe0::/28fc30:fef:ffff:ffff:ffff:ffff:ffff:ffff
256fc30:ff0::/28fc30:fff: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.