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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
fc20::/16
First address
fc20::
Last address
fc20: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
fc20:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
0.2.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)

fc20::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc20::/24fc20:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc20:100::/24fc20:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc20:200::/24fc20:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc20:300::/24fc20:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc20:400::/24fc20:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc20:500::/24fc20:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc20:600::/24fc20:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc20:700::/24fc20:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc20:800::/24fc20:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc20:900::/24fc20:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc20:a00::/24fc20:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc20:b00::/24fc20:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc20:c00::/24fc20:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc20:d00::/24fc20:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc20:e00::/24fc20:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc20:f00::/24fc20:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc20:1000::/24fc20:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc20:1100::/24fc20:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc20:1200::/24fc20:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc20:1300::/24fc20:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc20:1400::/24fc20:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc20:1500::/24fc20:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc20:1600::/24fc20:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc20:1700::/24fc20:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc20:1800::/24fc20:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc20:1900::/24fc20:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc20:1a00::/24fc20:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc20:1b00::/24fc20:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc20:1c00::/24fc20:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc20:1d00::/24fc20:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc20:1e00::/24fc20:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc20:1f00::/24fc20:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc20:2000::/24fc20:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc20:2100::/24fc20:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc20:2200::/24fc20:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc20:2300::/24fc20:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc20:2400::/24fc20:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc20:2500::/24fc20:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc20:2600::/24fc20:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc20:2700::/24fc20:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc20:2800::/24fc20:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc20:2900::/24fc20:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc20:2a00::/24fc20:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc20:2b00::/24fc20:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc20:2c00::/24fc20:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc20:2d00::/24fc20:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc20:2e00::/24fc20:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc20:2f00::/24fc20:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc20:3000::/24fc20:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc20:3100::/24fc20:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc20:3200::/24fc20:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc20:3300::/24fc20:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc20:3400::/24fc20:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc20:3500::/24fc20:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc20:3600::/24fc20:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc20:3700::/24fc20:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc20:3800::/24fc20:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc20:3900::/24fc20:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc20:3a00::/24fc20:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc20:3b00::/24fc20:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc20:3c00::/24fc20:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc20:3d00::/24fc20:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc20:3e00::/24fc20:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc20:3f00::/24fc20:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc20:4000::/24fc20:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc20:4100::/24fc20:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc20:4200::/24fc20:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc20:4300::/24fc20:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc20:4400::/24fc20:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc20:4500::/24fc20:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc20:4600::/24fc20:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc20:4700::/24fc20:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc20:4800::/24fc20:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc20:4900::/24fc20:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc20:4a00::/24fc20:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc20:4b00::/24fc20:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc20:4c00::/24fc20:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc20:4d00::/24fc20:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc20:4e00::/24fc20:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc20:4f00::/24fc20:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc20:5000::/24fc20:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc20:5100::/24fc20:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc20:5200::/24fc20:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc20:5300::/24fc20:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc20:5400::/24fc20:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc20:5500::/24fc20:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc20:5600::/24fc20:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc20:5700::/24fc20:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc20:5800::/24fc20:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc20:5900::/24fc20:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc20:5a00::/24fc20:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc20:5b00::/24fc20:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc20:5c00::/24fc20:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc20:5d00::/24fc20:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc20:5e00::/24fc20:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc20:5f00::/24fc20:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc20:6000::/24fc20:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc20:6100::/24fc20:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc20:6200::/24fc20:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc20:6300::/24fc20:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc20:6400::/24fc20:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc20:6500::/24fc20:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc20:6600::/24fc20:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc20:6700::/24fc20:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc20:6800::/24fc20:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc20:6900::/24fc20:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc20:6a00::/24fc20:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc20:6b00::/24fc20:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc20:6c00::/24fc20:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc20:6d00::/24fc20:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc20:6e00::/24fc20:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc20:6f00::/24fc20:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc20:7000::/24fc20:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc20:7100::/24fc20:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc20:7200::/24fc20:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc20:7300::/24fc20:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc20:7400::/24fc20:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc20:7500::/24fc20:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc20:7600::/24fc20:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc20:7700::/24fc20:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc20:7800::/24fc20:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc20:7900::/24fc20:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc20:7a00::/24fc20:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc20:7b00::/24fc20:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc20:7c00::/24fc20:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc20:7d00::/24fc20:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc20:7e00::/24fc20:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc20:7f00::/24fc20:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc20:8000::/24fc20:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc20:8100::/24fc20:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc20:8200::/24fc20:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc20:8300::/24fc20:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc20:8400::/24fc20:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc20:8500::/24fc20:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc20:8600::/24fc20:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc20:8700::/24fc20:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc20:8800::/24fc20:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc20:8900::/24fc20:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc20:8a00::/24fc20:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc20:8b00::/24fc20:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc20:8c00::/24fc20:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc20:8d00::/24fc20:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc20:8e00::/24fc20:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc20:8f00::/24fc20:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc20:9000::/24fc20:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc20:9100::/24fc20:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc20:9200::/24fc20:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc20:9300::/24fc20:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc20:9400::/24fc20:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc20:9500::/24fc20:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc20:9600::/24fc20:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc20:9700::/24fc20:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc20:9800::/24fc20:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc20:9900::/24fc20:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc20:9a00::/24fc20:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc20:9b00::/24fc20:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc20:9c00::/24fc20:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc20:9d00::/24fc20:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc20:9e00::/24fc20:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc20:9f00::/24fc20:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc20:a000::/24fc20:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc20:a100::/24fc20:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc20:a200::/24fc20:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc20:a300::/24fc20:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc20:a400::/24fc20:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc20:a500::/24fc20:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc20:a600::/24fc20:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc20:a700::/24fc20:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc20:a800::/24fc20:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc20:a900::/24fc20:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc20:aa00::/24fc20:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc20:ab00::/24fc20:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc20:ac00::/24fc20:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc20:ad00::/24fc20:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc20:ae00::/24fc20:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc20:af00::/24fc20:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc20:b000::/24fc20:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc20:b100::/24fc20:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc20:b200::/24fc20:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc20:b300::/24fc20:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc20:b400::/24fc20:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc20:b500::/24fc20:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc20:b600::/24fc20:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc20:b700::/24fc20:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc20:b800::/24fc20:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc20:b900::/24fc20:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc20:ba00::/24fc20:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc20:bb00::/24fc20:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc20:bc00::/24fc20:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc20:bd00::/24fc20:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc20:be00::/24fc20:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc20:bf00::/24fc20:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc20:c000::/24fc20:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc20:c100::/24fc20:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc20:c200::/24fc20:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc20:c300::/24fc20:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc20:c400::/24fc20:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc20:c500::/24fc20:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc20:c600::/24fc20:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc20:c700::/24fc20:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc20:c800::/24fc20:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc20:c900::/24fc20:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc20:ca00::/24fc20:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc20:cb00::/24fc20:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc20:cc00::/24fc20:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc20:cd00::/24fc20:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc20:ce00::/24fc20:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc20:cf00::/24fc20:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc20:d000::/24fc20:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc20:d100::/24fc20:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc20:d200::/24fc20:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc20:d300::/24fc20:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc20:d400::/24fc20:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc20:d500::/24fc20:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc20:d600::/24fc20:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc20:d700::/24fc20:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc20:d800::/24fc20:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc20:d900::/24fc20:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc20:da00::/24fc20:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc20:db00::/24fc20:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc20:dc00::/24fc20:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc20:dd00::/24fc20:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc20:de00::/24fc20:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc20:df00::/24fc20:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc20:e000::/24fc20:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc20:e100::/24fc20:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc20:e200::/24fc20:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc20:e300::/24fc20:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc20:e400::/24fc20:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc20:e500::/24fc20:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc20:e600::/24fc20:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc20:e700::/24fc20:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc20:e800::/24fc20:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc20:e900::/24fc20:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc20:ea00::/24fc20:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc20:eb00::/24fc20:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc20:ec00::/24fc20:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc20:ed00::/24fc20:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc20:ee00::/24fc20:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc20:ef00::/24fc20:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc20:f000::/24fc20:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc20:f100::/24fc20:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc20:f200::/24fc20:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc20:f300::/24fc20:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc20:f400::/24fc20:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc20:f500::/24fc20:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc20:f600::/24fc20:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc20:f700::/24fc20:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc20:f800::/24fc20:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc20:f900::/24fc20:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc20:fa00::/24fc20:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc20:fb00::/24fc20:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc20:fc00::/24fc20:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc20:fd00::/24fc20:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc20:fe00::/24fc20:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc20:ff00::/24fc20: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.