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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.

Network17.65.44.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
17.65.44.0
Broadcast address
17.65.45.255
First usable
17.65.44.1
Last usable
17.65.45.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Public public
Old class
A (default /8)
As numbers
Hex 11412C00 · Integer 289483776 to 289484287
Reverse DNS zones
44.65.17.in-addr.arpa
45.65.17.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001.01000001.00101100.0000000017.65.44.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network00010001.01000001.00101100.0000000017.65.44.0
Broadcast00010001.01000001.00101101.1111111117.65.45.255
Split into smaller subnets/32
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

17.65.44.0/23 makes 512 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.65.44.0/3217.65.44.0 to 17.65.44.0—1
217.65.44.1/3217.65.44.1 to 17.65.44.1—1
317.65.44.2/3217.65.44.2 to 17.65.44.2—1
417.65.44.3/3217.65.44.3 to 17.65.44.3—1
517.65.44.4/3217.65.44.4 to 17.65.44.4—1
617.65.44.5/3217.65.44.5 to 17.65.44.5—1
717.65.44.6/3217.65.44.6 to 17.65.44.6—1
817.65.44.7/3217.65.44.7 to 17.65.44.7—1
917.65.44.8/3217.65.44.8 to 17.65.44.8—1
1017.65.44.9/3217.65.44.9 to 17.65.44.9—1
1117.65.44.10/3217.65.44.10 to 17.65.44.10—1
1217.65.44.11/3217.65.44.11 to 17.65.44.11—1
1317.65.44.12/3217.65.44.12 to 17.65.44.12—1
1417.65.44.13/3217.65.44.13 to 17.65.44.13—1
1517.65.44.14/3217.65.44.14 to 17.65.44.14—1
1617.65.44.15/3217.65.44.15 to 17.65.44.15—1
1717.65.44.16/3217.65.44.16 to 17.65.44.16—1
1817.65.44.17/3217.65.44.17 to 17.65.44.17—1
1917.65.44.18/3217.65.44.18 to 17.65.44.18—1
2017.65.44.19/3217.65.44.19 to 17.65.44.19—1
2117.65.44.20/3217.65.44.20 to 17.65.44.20—1
2217.65.44.21/3217.65.44.21 to 17.65.44.21—1
2317.65.44.22/3217.65.44.22 to 17.65.44.22—1
2417.65.44.23/3217.65.44.23 to 17.65.44.23—1
2517.65.44.24/3217.65.44.24 to 17.65.44.24—1
2617.65.44.25/3217.65.44.25 to 17.65.44.25—1
2717.65.44.26/3217.65.44.26 to 17.65.44.26—1
2817.65.44.27/3217.65.44.27 to 17.65.44.27—1
2917.65.44.28/3217.65.44.28 to 17.65.44.28—1
3017.65.44.29/3217.65.44.29 to 17.65.44.29—1
3117.65.44.30/3217.65.44.30 to 17.65.44.30—1
3217.65.44.31/3217.65.44.31 to 17.65.44.31—1
3317.65.44.32/3217.65.44.32 to 17.65.44.32—1
3417.65.44.33/3217.65.44.33 to 17.65.44.33—1
3517.65.44.34/3217.65.44.34 to 17.65.44.34—1
3617.65.44.35/3217.65.44.35 to 17.65.44.35—1
3717.65.44.36/3217.65.44.36 to 17.65.44.36—1
3817.65.44.37/3217.65.44.37 to 17.65.44.37—1
3917.65.44.38/3217.65.44.38 to 17.65.44.38—1
4017.65.44.39/3217.65.44.39 to 17.65.44.39—1
4117.65.44.40/3217.65.44.40 to 17.65.44.40—1
4217.65.44.41/3217.65.44.41 to 17.65.44.41—1
4317.65.44.42/3217.65.44.42 to 17.65.44.42—1
4417.65.44.43/3217.65.44.43 to 17.65.44.43—1
4517.65.44.44/3217.65.44.44 to 17.65.44.44—1
4617.65.44.45/3217.65.44.45 to 17.65.44.45—1
4717.65.44.46/3217.65.44.46 to 17.65.44.46—1
4817.65.44.47/3217.65.44.47 to 17.65.44.47—1
4917.65.44.48/3217.65.44.48 to 17.65.44.48—1
5017.65.44.49/3217.65.44.49 to 17.65.44.49—1
5117.65.44.50/3217.65.44.50 to 17.65.44.50—1
5217.65.44.51/3217.65.44.51 to 17.65.44.51—1
5317.65.44.52/3217.65.44.52 to 17.65.44.52—1
5417.65.44.53/3217.65.44.53 to 17.65.44.53—1
5517.65.44.54/3217.65.44.54 to 17.65.44.54—1
5617.65.44.55/3217.65.44.55 to 17.65.44.55—1
5717.65.44.56/3217.65.44.56 to 17.65.44.56—1
5817.65.44.57/3217.65.44.57 to 17.65.44.57—1
5917.65.44.58/3217.65.44.58 to 17.65.44.58—1
6017.65.44.59/3217.65.44.59 to 17.65.44.59—1
6117.65.44.60/3217.65.44.60 to 17.65.44.60—1
6217.65.44.61/3217.65.44.61 to 17.65.44.61—1
6317.65.44.62/3217.65.44.62 to 17.65.44.62—1
6417.65.44.63/3217.65.44.63 to 17.65.44.63—1
6517.65.44.64/3217.65.44.64 to 17.65.44.64—1
6617.65.44.65/3217.65.44.65 to 17.65.44.65—1
6717.65.44.66/3217.65.44.66 to 17.65.44.66—1
6817.65.44.67/3217.65.44.67 to 17.65.44.67—1
6917.65.44.68/3217.65.44.68 to 17.65.44.68—1
7017.65.44.69/3217.65.44.69 to 17.65.44.69—1
7117.65.44.70/3217.65.44.70 to 17.65.44.70—1
7217.65.44.71/3217.65.44.71 to 17.65.44.71—1
7317.65.44.72/3217.65.44.72 to 17.65.44.72—1
7417.65.44.73/3217.65.44.73 to 17.65.44.73—1
7517.65.44.74/3217.65.44.74 to 17.65.44.74—1
7617.65.44.75/3217.65.44.75 to 17.65.44.75—1
7717.65.44.76/3217.65.44.76 to 17.65.44.76—1
7817.65.44.77/3217.65.44.77 to 17.65.44.77—1
7917.65.44.78/3217.65.44.78 to 17.65.44.78—1
8017.65.44.79/3217.65.44.79 to 17.65.44.79—1
8117.65.44.80/3217.65.44.80 to 17.65.44.80—1
8217.65.44.81/3217.65.44.81 to 17.65.44.81—1
8317.65.44.82/3217.65.44.82 to 17.65.44.82—1
8417.65.44.83/3217.65.44.83 to 17.65.44.83—1
8517.65.44.84/3217.65.44.84 to 17.65.44.84—1
8617.65.44.85/3217.65.44.85 to 17.65.44.85—1
8717.65.44.86/3217.65.44.86 to 17.65.44.86—1
8817.65.44.87/3217.65.44.87 to 17.65.44.87—1
8917.65.44.88/3217.65.44.88 to 17.65.44.88—1
9017.65.44.89/3217.65.44.89 to 17.65.44.89—1
9117.65.44.90/3217.65.44.90 to 17.65.44.90—1
9217.65.44.91/3217.65.44.91 to 17.65.44.91—1
9317.65.44.92/3217.65.44.92 to 17.65.44.92—1
9417.65.44.93/3217.65.44.93 to 17.65.44.93—1
9517.65.44.94/3217.65.44.94 to 17.65.44.94—1
9617.65.44.95/3217.65.44.95 to 17.65.44.95—1
9717.65.44.96/3217.65.44.96 to 17.65.44.96—1
9817.65.44.97/3217.65.44.97 to 17.65.44.97—1
9917.65.44.98/3217.65.44.98 to 17.65.44.98—1
10017.65.44.99/3217.65.44.99 to 17.65.44.99—1
10117.65.44.100/3217.65.44.100 to 17.65.44.100—1
10217.65.44.101/3217.65.44.101 to 17.65.44.101—1
10317.65.44.102/3217.65.44.102 to 17.65.44.102—1
10417.65.44.103/3217.65.44.103 to 17.65.44.103—1
10517.65.44.104/3217.65.44.104 to 17.65.44.104—1
10617.65.44.105/3217.65.44.105 to 17.65.44.105—1
10717.65.44.106/3217.65.44.106 to 17.65.44.106—1
10817.65.44.107/3217.65.44.107 to 17.65.44.107—1
10917.65.44.108/3217.65.44.108 to 17.65.44.108—1
11017.65.44.109/3217.65.44.109 to 17.65.44.109—1
11117.65.44.110/3217.65.44.110 to 17.65.44.110—1
11217.65.44.111/3217.65.44.111 to 17.65.44.111—1
11317.65.44.112/3217.65.44.112 to 17.65.44.112—1
11417.65.44.113/3217.65.44.113 to 17.65.44.113—1
11517.65.44.114/3217.65.44.114 to 17.65.44.114—1
11617.65.44.115/3217.65.44.115 to 17.65.44.115—1
11717.65.44.116/3217.65.44.116 to 17.65.44.116—1
11817.65.44.117/3217.65.44.117 to 17.65.44.117—1
11917.65.44.118/3217.65.44.118 to 17.65.44.118—1
12017.65.44.119/3217.65.44.119 to 17.65.44.119—1
12117.65.44.120/3217.65.44.120 to 17.65.44.120—1
12217.65.44.121/3217.65.44.121 to 17.65.44.121—1
12317.65.44.122/3217.65.44.122 to 17.65.44.122—1
12417.65.44.123/3217.65.44.123 to 17.65.44.123—1
12517.65.44.124/3217.65.44.124 to 17.65.44.124—1
12617.65.44.125/3217.65.44.125 to 17.65.44.125—1
12717.65.44.126/3217.65.44.126 to 17.65.44.126—1
12817.65.44.127/3217.65.44.127 to 17.65.44.127—1
12917.65.44.128/3217.65.44.128 to 17.65.44.128—1
13017.65.44.129/3217.65.44.129 to 17.65.44.129—1
13117.65.44.130/3217.65.44.130 to 17.65.44.130—1
13217.65.44.131/3217.65.44.131 to 17.65.44.131—1
13317.65.44.132/3217.65.44.132 to 17.65.44.132—1
13417.65.44.133/3217.65.44.133 to 17.65.44.133—1
13517.65.44.134/3217.65.44.134 to 17.65.44.134—1
13617.65.44.135/3217.65.44.135 to 17.65.44.135—1
13717.65.44.136/3217.65.44.136 to 17.65.44.136—1
13817.65.44.137/3217.65.44.137 to 17.65.44.137—1
13917.65.44.138/3217.65.44.138 to 17.65.44.138—1
14017.65.44.139/3217.65.44.139 to 17.65.44.139—1
14117.65.44.140/3217.65.44.140 to 17.65.44.140—1
14217.65.44.141/3217.65.44.141 to 17.65.44.141—1
14317.65.44.142/3217.65.44.142 to 17.65.44.142—1
14417.65.44.143/3217.65.44.143 to 17.65.44.143—1
14517.65.44.144/3217.65.44.144 to 17.65.44.144—1
14617.65.44.145/3217.65.44.145 to 17.65.44.145—1
14717.65.44.146/3217.65.44.146 to 17.65.44.146—1
14817.65.44.147/3217.65.44.147 to 17.65.44.147—1
14917.65.44.148/3217.65.44.148 to 17.65.44.148—1
15017.65.44.149/3217.65.44.149 to 17.65.44.149—1
15117.65.44.150/3217.65.44.150 to 17.65.44.150—1
15217.65.44.151/3217.65.44.151 to 17.65.44.151—1
15317.65.44.152/3217.65.44.152 to 17.65.44.152—1
15417.65.44.153/3217.65.44.153 to 17.65.44.153—1
15517.65.44.154/3217.65.44.154 to 17.65.44.154—1
15617.65.44.155/3217.65.44.155 to 17.65.44.155—1
15717.65.44.156/3217.65.44.156 to 17.65.44.156—1
15817.65.44.157/3217.65.44.157 to 17.65.44.157—1
15917.65.44.158/3217.65.44.158 to 17.65.44.158—1
16017.65.44.159/3217.65.44.159 to 17.65.44.159—1
16117.65.44.160/3217.65.44.160 to 17.65.44.160—1
16217.65.44.161/3217.65.44.161 to 17.65.44.161—1
16317.65.44.162/3217.65.44.162 to 17.65.44.162—1
16417.65.44.163/3217.65.44.163 to 17.65.44.163—1
16517.65.44.164/3217.65.44.164 to 17.65.44.164—1
16617.65.44.165/3217.65.44.165 to 17.65.44.165—1
16717.65.44.166/3217.65.44.166 to 17.65.44.166—1
16817.65.44.167/3217.65.44.167 to 17.65.44.167—1
16917.65.44.168/3217.65.44.168 to 17.65.44.168—1
17017.65.44.169/3217.65.44.169 to 17.65.44.169—1
17117.65.44.170/3217.65.44.170 to 17.65.44.170—1
17217.65.44.171/3217.65.44.171 to 17.65.44.171—1
17317.65.44.172/3217.65.44.172 to 17.65.44.172—1
17417.65.44.173/3217.65.44.173 to 17.65.44.173—1
17517.65.44.174/3217.65.44.174 to 17.65.44.174—1
17617.65.44.175/3217.65.44.175 to 17.65.44.175—1
17717.65.44.176/3217.65.44.176 to 17.65.44.176—1
17817.65.44.177/3217.65.44.177 to 17.65.44.177—1
17917.65.44.178/3217.65.44.178 to 17.65.44.178—1
18017.65.44.179/3217.65.44.179 to 17.65.44.179—1
18117.65.44.180/3217.65.44.180 to 17.65.44.180—1
18217.65.44.181/3217.65.44.181 to 17.65.44.181—1
18317.65.44.182/3217.65.44.182 to 17.65.44.182—1
18417.65.44.183/3217.65.44.183 to 17.65.44.183—1
18517.65.44.184/3217.65.44.184 to 17.65.44.184—1
18617.65.44.185/3217.65.44.185 to 17.65.44.185—1
18717.65.44.186/3217.65.44.186 to 17.65.44.186—1
18817.65.44.187/3217.65.44.187 to 17.65.44.187—1
18917.65.44.188/3217.65.44.188 to 17.65.44.188—1
19017.65.44.189/3217.65.44.189 to 17.65.44.189—1
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22017.65.44.219/3217.65.44.219 to 17.65.44.219—1
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25217.65.44.251/3217.65.44.251 to 17.65.44.251—1
25317.65.44.252/3217.65.44.252 to 17.65.44.252—1
25417.65.44.253/3217.65.44.253 to 17.65.44.253—1
25517.65.44.254/3217.65.44.254 to 17.65.44.254—1
25617.65.44.255/3217.65.44.255 to 17.65.44.255—1

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.