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/20
Addresses2^108
/64 networks2^44
Network
fc86::/20
First address
fc86::
Last address
fc86:fff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
324,518,553,658,426,726,783,156,020,576,256 (2^108)
/64 networks (LANs)
17,592,186,044,416 (2^44)
Full form
fc86:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
0.6.8.c.f.ip6.arpa
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fc86::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1fc86::/28fc86:f:ffff:ffff:ffff:ffff:ffff:ffff
2fc86:10::/28fc86:1f:ffff:ffff:ffff:ffff:ffff:ffff
3fc86:20::/28fc86:2f:ffff:ffff:ffff:ffff:ffff:ffff
4fc86:30::/28fc86:3f:ffff:ffff:ffff:ffff:ffff:ffff
5fc86:40::/28fc86:4f:ffff:ffff:ffff:ffff:ffff:ffff
6fc86:50::/28fc86:5f:ffff:ffff:ffff:ffff:ffff:ffff
7fc86:60::/28fc86:6f:ffff:ffff:ffff:ffff:ffff:ffff
8fc86:70::/28fc86:7f:ffff:ffff:ffff:ffff:ffff:ffff
9fc86:80::/28fc86:8f:ffff:ffff:ffff:ffff:ffff:ffff
10fc86:90::/28fc86:9f:ffff:ffff:ffff:ffff:ffff:ffff
11fc86:a0::/28fc86:af:ffff:ffff:ffff:ffff:ffff:ffff
12fc86:b0::/28fc86:bf:ffff:ffff:ffff:ffff:ffff:ffff
13fc86:c0::/28fc86:cf:ffff:ffff:ffff:ffff:ffff:ffff
14fc86:d0::/28fc86:df:ffff:ffff:ffff:ffff:ffff:ffff
15fc86:e0::/28fc86:ef:ffff:ffff:ffff:ffff:ffff:ffff
16fc86:f0::/28fc86:ff:ffff:ffff:ffff:ffff:ffff:ffff
17fc86:100::/28fc86:10f:ffff:ffff:ffff:ffff:ffff:ffff
18fc86:110::/28fc86:11f:ffff:ffff:ffff:ffff:ffff:ffff
19fc86:120::/28fc86:12f:ffff:ffff:ffff:ffff:ffff:ffff
20fc86:130::/28fc86:13f:ffff:ffff:ffff:ffff:ffff:ffff
21fc86:140::/28fc86:14f:ffff:ffff:ffff:ffff:ffff:ffff
22fc86:150::/28fc86:15f:ffff:ffff:ffff:ffff:ffff:ffff
23fc86:160::/28fc86:16f:ffff:ffff:ffff:ffff:ffff:ffff
24fc86:170::/28fc86:17f:ffff:ffff:ffff:ffff:ffff:ffff
25fc86:180::/28fc86:18f:ffff:ffff:ffff:ffff:ffff:ffff
26fc86:190::/28fc86:19f:ffff:ffff:ffff:ffff:ffff:ffff
27fc86:1a0::/28fc86:1af:ffff:ffff:ffff:ffff:ffff:ffff
28fc86:1b0::/28fc86:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29fc86:1c0::/28fc86:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30fc86:1d0::/28fc86:1df:ffff:ffff:ffff:ffff:ffff:ffff
31fc86:1e0::/28fc86:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32fc86:1f0::/28fc86:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33fc86:200::/28fc86:20f:ffff:ffff:ffff:ffff:ffff:ffff
34fc86:210::/28fc86:21f:ffff:ffff:ffff:ffff:ffff:ffff
35fc86:220::/28fc86:22f:ffff:ffff:ffff:ffff:ffff:ffff
36fc86:230::/28fc86:23f:ffff:ffff:ffff:ffff:ffff:ffff
37fc86:240::/28fc86:24f:ffff:ffff:ffff:ffff:ffff:ffff
38fc86:250::/28fc86:25f:ffff:ffff:ffff:ffff:ffff:ffff
39fc86:260::/28fc86:26f:ffff:ffff:ffff:ffff:ffff:ffff
40fc86:270::/28fc86:27f:ffff:ffff:ffff:ffff:ffff:ffff
41fc86:280::/28fc86:28f:ffff:ffff:ffff:ffff:ffff:ffff
42fc86:290::/28fc86:29f:ffff:ffff:ffff:ffff:ffff:ffff
43fc86:2a0::/28fc86:2af:ffff:ffff:ffff:ffff:ffff:ffff
44fc86:2b0::/28fc86:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45fc86:2c0::/28fc86:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46fc86:2d0::/28fc86:2df:ffff:ffff:ffff:ffff:ffff:ffff
47fc86:2e0::/28fc86:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48fc86:2f0::/28fc86:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49fc86:300::/28fc86:30f:ffff:ffff:ffff:ffff:ffff:ffff
50fc86:310::/28fc86:31f:ffff:ffff:ffff:ffff:ffff:ffff
51fc86:320::/28fc86:32f:ffff:ffff:ffff:ffff:ffff:ffff
52fc86:330::/28fc86:33f:ffff:ffff:ffff:ffff:ffff:ffff
53fc86:340::/28fc86:34f:ffff:ffff:ffff:ffff:ffff:ffff
54fc86:350::/28fc86:35f:ffff:ffff:ffff:ffff:ffff:ffff
55fc86:360::/28fc86:36f:ffff:ffff:ffff:ffff:ffff:ffff
56fc86:370::/28fc86:37f:ffff:ffff:ffff:ffff:ffff:ffff
57fc86:380::/28fc86:38f:ffff:ffff:ffff:ffff:ffff:ffff
58fc86:390::/28fc86:39f:ffff:ffff:ffff:ffff:ffff:ffff
59fc86:3a0::/28fc86:3af:ffff:ffff:ffff:ffff:ffff:ffff
60fc86:3b0::/28fc86:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61fc86:3c0::/28fc86:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62fc86:3d0::/28fc86:3df:ffff:ffff:ffff:ffff:ffff:ffff
63fc86:3e0::/28fc86:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64fc86:3f0::/28fc86:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65fc86:400::/28fc86:40f:ffff:ffff:ffff:ffff:ffff:ffff
66fc86:410::/28fc86:41f:ffff:ffff:ffff:ffff:ffff:ffff
67fc86:420::/28fc86:42f:ffff:ffff:ffff:ffff:ffff:ffff
68fc86:430::/28fc86:43f:ffff:ffff:ffff:ffff:ffff:ffff
69fc86:440::/28fc86:44f:ffff:ffff:ffff:ffff:ffff:ffff
70fc86:450::/28fc86:45f:ffff:ffff:ffff:ffff:ffff:ffff
71fc86:460::/28fc86:46f:ffff:ffff:ffff:ffff:ffff:ffff
72fc86:470::/28fc86:47f:ffff:ffff:ffff:ffff:ffff:ffff
73fc86:480::/28fc86:48f:ffff:ffff:ffff:ffff:ffff:ffff
74fc86:490::/28fc86:49f:ffff:ffff:ffff:ffff:ffff:ffff
75fc86:4a0::/28fc86:4af:ffff:ffff:ffff:ffff:ffff:ffff
76fc86:4b0::/28fc86:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77fc86:4c0::/28fc86:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78fc86:4d0::/28fc86:4df:ffff:ffff:ffff:ffff:ffff:ffff
79fc86:4e0::/28fc86:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80fc86:4f0::/28fc86:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81fc86:500::/28fc86:50f:ffff:ffff:ffff:ffff:ffff:ffff
82fc86:510::/28fc86:51f:ffff:ffff:ffff:ffff:ffff:ffff
83fc86:520::/28fc86:52f:ffff:ffff:ffff:ffff:ffff:ffff
84fc86:530::/28fc86:53f:ffff:ffff:ffff:ffff:ffff:ffff
85fc86:540::/28fc86:54f:ffff:ffff:ffff:ffff:ffff:ffff
86fc86:550::/28fc86:55f:ffff:ffff:ffff:ffff:ffff:ffff
87fc86:560::/28fc86:56f:ffff:ffff:ffff:ffff:ffff:ffff
88fc86:570::/28fc86:57f:ffff:ffff:ffff:ffff:ffff:ffff
89fc86:580::/28fc86:58f:ffff:ffff:ffff:ffff:ffff:ffff
90fc86:590::/28fc86:59f:ffff:ffff:ffff:ffff:ffff:ffff
91fc86:5a0::/28fc86:5af:ffff:ffff:ffff:ffff:ffff:ffff
92fc86:5b0::/28fc86:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93fc86:5c0::/28fc86:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94fc86:5d0::/28fc86:5df:ffff:ffff:ffff:ffff:ffff:ffff
95fc86:5e0::/28fc86:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96fc86:5f0::/28fc86:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97fc86:600::/28fc86:60f:ffff:ffff:ffff:ffff:ffff:ffff
98fc86:610::/28fc86:61f:ffff:ffff:ffff:ffff:ffff:ffff
99fc86:620::/28fc86:62f:ffff:ffff:ffff:ffff:ffff:ffff
100fc86:630::/28fc86:63f:ffff:ffff:ffff:ffff:ffff:ffff
101fc86:640::/28fc86:64f:ffff:ffff:ffff:ffff:ffff:ffff
102fc86:650::/28fc86:65f:ffff:ffff:ffff:ffff:ffff:ffff
103fc86:660::/28fc86:66f:ffff:ffff:ffff:ffff:ffff:ffff
104fc86:670::/28fc86:67f:ffff:ffff:ffff:ffff:ffff:ffff
105fc86:680::/28fc86:68f:ffff:ffff:ffff:ffff:ffff:ffff
106fc86:690::/28fc86:69f:ffff:ffff:ffff:ffff:ffff:ffff
107fc86:6a0::/28fc86:6af:ffff:ffff:ffff:ffff:ffff:ffff
108fc86:6b0::/28fc86:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109fc86:6c0::/28fc86:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110fc86:6d0::/28fc86:6df:ffff:ffff:ffff:ffff:ffff:ffff
111fc86:6e0::/28fc86:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112fc86:6f0::/28fc86:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113fc86:700::/28fc86:70f:ffff:ffff:ffff:ffff:ffff:ffff
114fc86:710::/28fc86:71f:ffff:ffff:ffff:ffff:ffff:ffff
115fc86:720::/28fc86:72f:ffff:ffff:ffff:ffff:ffff:ffff
116fc86:730::/28fc86:73f:ffff:ffff:ffff:ffff:ffff:ffff
117fc86:740::/28fc86:74f:ffff:ffff:ffff:ffff:ffff:ffff
118fc86:750::/28fc86:75f:ffff:ffff:ffff:ffff:ffff:ffff
119fc86:760::/28fc86:76f:ffff:ffff:ffff:ffff:ffff:ffff
120fc86:770::/28fc86:77f:ffff:ffff:ffff:ffff:ffff:ffff
121fc86:780::/28fc86:78f:ffff:ffff:ffff:ffff:ffff:ffff
122fc86:790::/28fc86:79f:ffff:ffff:ffff:ffff:ffff:ffff
123fc86:7a0::/28fc86:7af:ffff:ffff:ffff:ffff:ffff:ffff
124fc86:7b0::/28fc86:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125fc86:7c0::/28fc86:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126fc86:7d0::/28fc86:7df:ffff:ffff:ffff:ffff:ffff:ffff
127fc86:7e0::/28fc86:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128fc86:7f0::/28fc86:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129fc86:800::/28fc86:80f:ffff:ffff:ffff:ffff:ffff:ffff
130fc86:810::/28fc86:81f:ffff:ffff:ffff:ffff:ffff:ffff
131fc86:820::/28fc86:82f:ffff:ffff:ffff:ffff:ffff:ffff
132fc86:830::/28fc86:83f:ffff:ffff:ffff:ffff:ffff:ffff
133fc86:840::/28fc86:84f:ffff:ffff:ffff:ffff:ffff:ffff
134fc86:850::/28fc86:85f:ffff:ffff:ffff:ffff:ffff:ffff
135fc86:860::/28fc86:86f:ffff:ffff:ffff:ffff:ffff:ffff
136fc86:870::/28fc86:87f:ffff:ffff:ffff:ffff:ffff:ffff
137fc86:880::/28fc86:88f:ffff:ffff:ffff:ffff:ffff:ffff
138fc86:890::/28fc86:89f:ffff:ffff:ffff:ffff:ffff:ffff
139fc86:8a0::/28fc86:8af:ffff:ffff:ffff:ffff:ffff:ffff
140fc86:8b0::/28fc86:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141fc86:8c0::/28fc86:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142fc86:8d0::/28fc86:8df:ffff:ffff:ffff:ffff:ffff:ffff
143fc86:8e0::/28fc86:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144fc86:8f0::/28fc86:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145fc86:900::/28fc86:90f:ffff:ffff:ffff:ffff:ffff:ffff
146fc86:910::/28fc86:91f:ffff:ffff:ffff:ffff:ffff:ffff
147fc86:920::/28fc86:92f:ffff:ffff:ffff:ffff:ffff:ffff
148fc86:930::/28fc86:93f:ffff:ffff:ffff:ffff:ffff:ffff
149fc86:940::/28fc86:94f:ffff:ffff:ffff:ffff:ffff:ffff
150fc86:950::/28fc86:95f:ffff:ffff:ffff:ffff:ffff:ffff
151fc86:960::/28fc86:96f:ffff:ffff:ffff:ffff:ffff:ffff
152fc86:970::/28fc86:97f:ffff:ffff:ffff:ffff:ffff:ffff
153fc86:980::/28fc86:98f:ffff:ffff:ffff:ffff:ffff:ffff
154fc86:990::/28fc86:99f:ffff:ffff:ffff:ffff:ffff:ffff
155fc86:9a0::/28fc86:9af:ffff:ffff:ffff:ffff:ffff:ffff
156fc86:9b0::/28fc86:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157fc86:9c0::/28fc86:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158fc86:9d0::/28fc86:9df:ffff:ffff:ffff:ffff:ffff:ffff
159fc86:9e0::/28fc86:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160fc86:9f0::/28fc86:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161fc86:a00::/28fc86:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162fc86:a10::/28fc86:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163fc86:a20::/28fc86:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164fc86:a30::/28fc86:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165fc86:a40::/28fc86:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166fc86:a50::/28fc86:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167fc86:a60::/28fc86:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168fc86:a70::/28fc86:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169fc86:a80::/28fc86:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170fc86:a90::/28fc86:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171fc86:aa0::/28fc86:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172fc86:ab0::/28fc86:abf:ffff:ffff:ffff:ffff:ffff:ffff
173fc86:ac0::/28fc86:acf:ffff:ffff:ffff:ffff:ffff:ffff
174fc86:ad0::/28fc86:adf:ffff:ffff:ffff:ffff:ffff:ffff
175fc86:ae0::/28fc86:aef:ffff:ffff:ffff:ffff:ffff:ffff
176fc86:af0::/28fc86:aff:ffff:ffff:ffff:ffff:ffff:ffff
177fc86:b00::/28fc86:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178fc86:b10::/28fc86:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179fc86:b20::/28fc86:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180fc86:b30::/28fc86:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181fc86:b40::/28fc86:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182fc86:b50::/28fc86:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183fc86:b60::/28fc86:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184fc86:b70::/28fc86:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185fc86:b80::/28fc86:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186fc86:b90::/28fc86:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187fc86:ba0::/28fc86:baf:ffff:ffff:ffff:ffff:ffff:ffff
188fc86:bb0::/28fc86:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189fc86:bc0::/28fc86:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190fc86:bd0::/28fc86:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191fc86:be0::/28fc86:bef:ffff:ffff:ffff:ffff:ffff:ffff
192fc86:bf0::/28fc86:bff:ffff:ffff:ffff:ffff:ffff:ffff
193fc86:c00::/28fc86:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194fc86:c10::/28fc86:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195fc86:c20::/28fc86:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196fc86:c30::/28fc86:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197fc86:c40::/28fc86:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198fc86:c50::/28fc86:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199fc86:c60::/28fc86:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200fc86:c70::/28fc86:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201fc86:c80::/28fc86:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202fc86:c90::/28fc86:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203fc86:ca0::/28fc86:caf:ffff:ffff:ffff:ffff:ffff:ffff
204fc86:cb0::/28fc86:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205fc86:cc0::/28fc86:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206fc86:cd0::/28fc86:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207fc86:ce0::/28fc86:cef:ffff:ffff:ffff:ffff:ffff:ffff
208fc86:cf0::/28fc86:cff:ffff:ffff:ffff:ffff:ffff:ffff
209fc86:d00::/28fc86:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210fc86:d10::/28fc86:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211fc86:d20::/28fc86:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212fc86:d30::/28fc86:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213fc86:d40::/28fc86:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214fc86:d50::/28fc86:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215fc86:d60::/28fc86:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216fc86:d70::/28fc86:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217fc86:d80::/28fc86:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218fc86:d90::/28fc86:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219fc86:da0::/28fc86:daf:ffff:ffff:ffff:ffff:ffff:ffff
220fc86:db0::/28fc86:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221fc86:dc0::/28fc86:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222fc86:dd0::/28fc86:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223fc86:de0::/28fc86:def:ffff:ffff:ffff:ffff:ffff:ffff
224fc86:df0::/28fc86:dff:ffff:ffff:ffff:ffff:ffff:ffff
225fc86:e00::/28fc86:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226fc86:e10::/28fc86:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227fc86:e20::/28fc86:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228fc86:e30::/28fc86:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229fc86:e40::/28fc86:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230fc86:e50::/28fc86:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231fc86:e60::/28fc86:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232fc86:e70::/28fc86:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233fc86:e80::/28fc86:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234fc86:e90::/28fc86:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235fc86:ea0::/28fc86:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236fc86:eb0::/28fc86:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237fc86:ec0::/28fc86:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238fc86:ed0::/28fc86:edf:ffff:ffff:ffff:ffff:ffff:ffff
239fc86:ee0::/28fc86:eef:ffff:ffff:ffff:ffff:ffff:ffff
240fc86:ef0::/28fc86:eff:ffff:ffff:ffff:ffff:ffff:ffff
241fc86:f00::/28fc86:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242fc86:f10::/28fc86:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243fc86:f20::/28fc86:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244fc86:f30::/28fc86:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245fc86:f40::/28fc86:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246fc86:f50::/28fc86:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247fc86:f60::/28fc86:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248fc86:f70::/28fc86:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249fc86:f80::/28fc86:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250fc86:f90::/28fc86:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251fc86:fa0::/28fc86:faf:ffff:ffff:ffff:ffff:ffff:ffff
252fc86:fb0::/28fc86:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253fc86:fc0::/28fc86:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254fc86:fd0::/28fc86:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255fc86:fe0::/28fc86:fef:ffff:ffff:ffff:ffff:ffff:ffff
256fc86:ff0::/28fc86: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.