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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.

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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
fc9b::/16
First address
fc9b::
Last address
fc9b: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
fc9b:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
b.9.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)

fc9b::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc9b::/24fc9b:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc9b:100::/24fc9b:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc9b:200::/24fc9b:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc9b:300::/24fc9b:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc9b:400::/24fc9b:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc9b:500::/24fc9b:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc9b:600::/24fc9b:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc9b:700::/24fc9b:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc9b:800::/24fc9b:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc9b:900::/24fc9b:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc9b:a00::/24fc9b:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc9b:b00::/24fc9b:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc9b:c00::/24fc9b:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc9b:d00::/24fc9b:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc9b:e00::/24fc9b:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc9b:f00::/24fc9b:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc9b:1000::/24fc9b:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc9b:1100::/24fc9b:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc9b:1200::/24fc9b:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc9b:1300::/24fc9b:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc9b:1400::/24fc9b:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc9b:1500::/24fc9b:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc9b:1600::/24fc9b:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc9b:1700::/24fc9b:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc9b:1800::/24fc9b:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc9b:1900::/24fc9b:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc9b:1a00::/24fc9b:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc9b:1b00::/24fc9b:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc9b:1c00::/24fc9b:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc9b:1d00::/24fc9b:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc9b:1e00::/24fc9b:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc9b:1f00::/24fc9b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc9b:2000::/24fc9b:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc9b:2100::/24fc9b:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc9b:2200::/24fc9b:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc9b:2300::/24fc9b:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc9b:2400::/24fc9b:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc9b:2500::/24fc9b:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc9b:2600::/24fc9b:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc9b:2700::/24fc9b:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc9b:2800::/24fc9b:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc9b:2900::/24fc9b:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc9b:2a00::/24fc9b:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc9b:2b00::/24fc9b:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc9b:2c00::/24fc9b:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc9b:2d00::/24fc9b:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc9b:2e00::/24fc9b:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc9b:2f00::/24fc9b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc9b:3000::/24fc9b:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc9b:3100::/24fc9b:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc9b:3200::/24fc9b:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc9b:3300::/24fc9b:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc9b:3400::/24fc9b:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc9b:3500::/24fc9b:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc9b:3600::/24fc9b:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc9b:3700::/24fc9b:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc9b:3800::/24fc9b:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc9b:3900::/24fc9b:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc9b:3a00::/24fc9b:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc9b:3b00::/24fc9b:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc9b:3c00::/24fc9b:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc9b:3d00::/24fc9b:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc9b:3e00::/24fc9b:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc9b:3f00::/24fc9b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc9b:4000::/24fc9b:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc9b:4100::/24fc9b:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc9b:4200::/24fc9b:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc9b:4300::/24fc9b:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc9b:4400::/24fc9b:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc9b:4500::/24fc9b:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc9b:4600::/24fc9b:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc9b:4700::/24fc9b:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc9b:4800::/24fc9b:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc9b:4900::/24fc9b:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc9b:4a00::/24fc9b:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc9b:4b00::/24fc9b:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc9b:4c00::/24fc9b:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc9b:4d00::/24fc9b:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc9b:4e00::/24fc9b:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc9b:4f00::/24fc9b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc9b:5000::/24fc9b:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc9b:5100::/24fc9b:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc9b:5200::/24fc9b:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc9b:5300::/24fc9b:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc9b:5400::/24fc9b:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc9b:5500::/24fc9b:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc9b:5600::/24fc9b:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc9b:5700::/24fc9b:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc9b:5800::/24fc9b:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc9b:5900::/24fc9b:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc9b:5a00::/24fc9b:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc9b:5b00::/24fc9b:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc9b:5c00::/24fc9b:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc9b:5d00::/24fc9b:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc9b:5e00::/24fc9b:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc9b:5f00::/24fc9b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc9b:6000::/24fc9b:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc9b:6100::/24fc9b:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc9b:6200::/24fc9b:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc9b:6300::/24fc9b:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc9b:6400::/24fc9b:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc9b:6500::/24fc9b:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc9b:6600::/24fc9b:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc9b:6700::/24fc9b:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc9b:6800::/24fc9b:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc9b:6900::/24fc9b:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc9b:6a00::/24fc9b:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc9b:6b00::/24fc9b:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc9b:6c00::/24fc9b:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc9b:6d00::/24fc9b:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc9b:6e00::/24fc9b:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc9b:6f00::/24fc9b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc9b:7000::/24fc9b:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc9b:7100::/24fc9b:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc9b:7200::/24fc9b:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc9b:7300::/24fc9b:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc9b:7400::/24fc9b:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc9b:7500::/24fc9b:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc9b:7600::/24fc9b:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc9b:7700::/24fc9b:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc9b:7800::/24fc9b:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc9b:7900::/24fc9b:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc9b:7a00::/24fc9b:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc9b:7b00::/24fc9b:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc9b:7c00::/24fc9b:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc9b:7d00::/24fc9b:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc9b:7e00::/24fc9b:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc9b:7f00::/24fc9b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc9b:8000::/24fc9b:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc9b:8100::/24fc9b:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc9b:8200::/24fc9b:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc9b:8300::/24fc9b:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc9b:8400::/24fc9b:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc9b:8500::/24fc9b:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc9b:8600::/24fc9b:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc9b:8700::/24fc9b:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc9b:8800::/24fc9b:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc9b:8900::/24fc9b:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc9b:8a00::/24fc9b:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc9b:8b00::/24fc9b:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc9b:8c00::/24fc9b:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc9b:8d00::/24fc9b:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc9b:8e00::/24fc9b:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc9b:8f00::/24fc9b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc9b:9000::/24fc9b:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc9b:9100::/24fc9b:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc9b:9200::/24fc9b:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc9b:9300::/24fc9b:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc9b:9400::/24fc9b:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc9b:9500::/24fc9b:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc9b:9600::/24fc9b:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc9b:9700::/24fc9b:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc9b:9800::/24fc9b:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc9b:9900::/24fc9b:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc9b:9a00::/24fc9b:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc9b:9b00::/24fc9b:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc9b:9c00::/24fc9b:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc9b:9d00::/24fc9b:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc9b:9e00::/24fc9b:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc9b:9f00::/24fc9b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc9b:a000::/24fc9b:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc9b:a100::/24fc9b:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc9b:a200::/24fc9b:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc9b:a300::/24fc9b:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc9b:a400::/24fc9b:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc9b:a500::/24fc9b:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc9b:a600::/24fc9b:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc9b:a700::/24fc9b:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc9b:a800::/24fc9b:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc9b:a900::/24fc9b:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc9b:aa00::/24fc9b:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc9b:ab00::/24fc9b:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc9b:ac00::/24fc9b:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc9b:ad00::/24fc9b:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc9b:ae00::/24fc9b:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc9b:af00::/24fc9b:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc9b:b000::/24fc9b:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc9b:b100::/24fc9b:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc9b:b200::/24fc9b:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc9b:b300::/24fc9b:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc9b:b400::/24fc9b:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc9b:b500::/24fc9b:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc9b:b600::/24fc9b:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc9b:b700::/24fc9b:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc9b:b800::/24fc9b:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc9b:b900::/24fc9b:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc9b:ba00::/24fc9b:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc9b:bb00::/24fc9b:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc9b:bc00::/24fc9b:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc9b:bd00::/24fc9b:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc9b:be00::/24fc9b:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc9b:bf00::/24fc9b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc9b:c000::/24fc9b:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc9b:c100::/24fc9b:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc9b:c200::/24fc9b:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc9b:c300::/24fc9b:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc9b:c400::/24fc9b:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc9b:c500::/24fc9b:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc9b:c600::/24fc9b:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc9b:c700::/24fc9b:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc9b:c800::/24fc9b:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc9b:c900::/24fc9b:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc9b:ca00::/24fc9b:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc9b:cb00::/24fc9b:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc9b:cc00::/24fc9b:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc9b:cd00::/24fc9b:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc9b:ce00::/24fc9b:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc9b:cf00::/24fc9b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc9b:d000::/24fc9b:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc9b:d100::/24fc9b:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc9b:d200::/24fc9b:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc9b:d300::/24fc9b:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc9b:d400::/24fc9b:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc9b:d500::/24fc9b:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc9b:d600::/24fc9b:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc9b:d700::/24fc9b:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc9b:d800::/24fc9b:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc9b:d900::/24fc9b:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc9b:da00::/24fc9b:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc9b:db00::/24fc9b:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc9b:dc00::/24fc9b:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc9b:dd00::/24fc9b:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc9b:de00::/24fc9b:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc9b:df00::/24fc9b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc9b:e000::/24fc9b:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc9b:e100::/24fc9b:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc9b:e200::/24fc9b:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc9b:e300::/24fc9b:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc9b:e400::/24fc9b:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc9b:e500::/24fc9b:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc9b:e600::/24fc9b:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc9b:e700::/24fc9b:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc9b:e800::/24fc9b:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc9b:e900::/24fc9b:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc9b:ea00::/24fc9b:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc9b:eb00::/24fc9b:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc9b:ec00::/24fc9b:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc9b:ed00::/24fc9b:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc9b:ee00::/24fc9b:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc9b:ef00::/24fc9b:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc9b:f000::/24fc9b:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc9b:f100::/24fc9b:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc9b:f200::/24fc9b:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc9b:f300::/24fc9b:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc9b:f400::/24fc9b:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc9b:f500::/24fc9b:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc9b:f600::/24fc9b:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc9b:f700::/24fc9b:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc9b:f800::/24fc9b:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc9b:f900::/24fc9b:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc9b:fa00::/24fc9b:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc9b:fb00::/24fc9b:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc9b:fc00::/24fc9b:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc9b:fd00::/24fc9b:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc9b:fe00::/24fc9b:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc9b:ff00::/24fc9b: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.