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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.

Network27.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
27.128.0.0
Broadcast address
27.255.255.255
First usable
27.128.0.1
Last usable
27.255.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 1B800000 · Integer 461373440 to 469762047
Reverse DNS zones
128.27.in-addr.arpa
129.27.in-addr.arpa
130.27.in-addr.arpa
131.27.in-addr.arpa
132.27.in-addr.arpa
133.27.in-addr.arpa
134.27.in-addr.arpa
135.27.in-addr.arpa
136.27.in-addr.arpa
137.27.in-addr.arpa
138.27.in-addr.arpa
139.27.in-addr.arpa
140.27.in-addr.arpa
141.27.in-addr.arpa
142.27.in-addr.arpa
143.27.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011011.10000000.00000000.0000000027.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00011011.10000000.00000000.0000000027.128.0.0
Broadcast00011011.11111111.11111111.1111111127.255.255.255
Split into smaller subnets/17
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

27.128.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
127.128.0.0/1727.128.0.1 to 27.128.127.25427.128.127.25532,766
227.128.128.0/1727.128.128.1 to 27.128.255.25427.128.255.25532,766
327.129.0.0/1727.129.0.1 to 27.129.127.25427.129.127.25532,766
427.129.128.0/1727.129.128.1 to 27.129.255.25427.129.255.25532,766
527.130.0.0/1727.130.0.1 to 27.130.127.25427.130.127.25532,766
627.130.128.0/1727.130.128.1 to 27.130.255.25427.130.255.25532,766
727.131.0.0/1727.131.0.1 to 27.131.127.25427.131.127.25532,766
827.131.128.0/1727.131.128.1 to 27.131.255.25427.131.255.25532,766
927.132.0.0/1727.132.0.1 to 27.132.127.25427.132.127.25532,766
1027.132.128.0/1727.132.128.1 to 27.132.255.25427.132.255.25532,766
1127.133.0.0/1727.133.0.1 to 27.133.127.25427.133.127.25532,766
1227.133.128.0/1727.133.128.1 to 27.133.255.25427.133.255.25532,766
1327.134.0.0/1727.134.0.1 to 27.134.127.25427.134.127.25532,766
1427.134.128.0/1727.134.128.1 to 27.134.255.25427.134.255.25532,766
1527.135.0.0/1727.135.0.1 to 27.135.127.25427.135.127.25532,766
1627.135.128.0/1727.135.128.1 to 27.135.255.25427.135.255.25532,766
1727.136.0.0/1727.136.0.1 to 27.136.127.25427.136.127.25532,766
1827.136.128.0/1727.136.128.1 to 27.136.255.25427.136.255.25532,766
1927.137.0.0/1727.137.0.1 to 27.137.127.25427.137.127.25532,766
2027.137.128.0/1727.137.128.1 to 27.137.255.25427.137.255.25532,766
2127.138.0.0/1727.138.0.1 to 27.138.127.25427.138.127.25532,766
2227.138.128.0/1727.138.128.1 to 27.138.255.25427.138.255.25532,766
2327.139.0.0/1727.139.0.1 to 27.139.127.25427.139.127.25532,766
2427.139.128.0/1727.139.128.1 to 27.139.255.25427.139.255.25532,766
2527.140.0.0/1727.140.0.1 to 27.140.127.25427.140.127.25532,766
2627.140.128.0/1727.140.128.1 to 27.140.255.25427.140.255.25532,766
2727.141.0.0/1727.141.0.1 to 27.141.127.25427.141.127.25532,766
2827.141.128.0/1727.141.128.1 to 27.141.255.25427.141.255.25532,766
2927.142.0.0/1727.142.0.1 to 27.142.127.25427.142.127.25532,766
3027.142.128.0/1727.142.128.1 to 27.142.255.25427.142.255.25532,766
3127.143.0.0/1727.143.0.1 to 27.143.127.25427.143.127.25532,766
3227.143.128.0/1727.143.128.1 to 27.143.255.25427.143.255.25532,766
3327.144.0.0/1727.144.0.1 to 27.144.127.25427.144.127.25532,766
3427.144.128.0/1727.144.128.1 to 27.144.255.25427.144.255.25532,766
3527.145.0.0/1727.145.0.1 to 27.145.127.25427.145.127.25532,766
3627.145.128.0/1727.145.128.1 to 27.145.255.25427.145.255.25532,766
3727.146.0.0/1727.146.0.1 to 27.146.127.25427.146.127.25532,766
3827.146.128.0/1727.146.128.1 to 27.146.255.25427.146.255.25532,766
3927.147.0.0/1727.147.0.1 to 27.147.127.25427.147.127.25532,766
4027.147.128.0/1727.147.128.1 to 27.147.255.25427.147.255.25532,766
4127.148.0.0/1727.148.0.1 to 27.148.127.25427.148.127.25532,766
4227.148.128.0/1727.148.128.1 to 27.148.255.25427.148.255.25532,766
4327.149.0.0/1727.149.0.1 to 27.149.127.25427.149.127.25532,766
4427.149.128.0/1727.149.128.1 to 27.149.255.25427.149.255.25532,766
4527.150.0.0/1727.150.0.1 to 27.150.127.25427.150.127.25532,766
4627.150.128.0/1727.150.128.1 to 27.150.255.25427.150.255.25532,766
4727.151.0.0/1727.151.0.1 to 27.151.127.25427.151.127.25532,766
4827.151.128.0/1727.151.128.1 to 27.151.255.25427.151.255.25532,766
4927.152.0.0/1727.152.0.1 to 27.152.127.25427.152.127.25532,766
5027.152.128.0/1727.152.128.1 to 27.152.255.25427.152.255.25532,766
5127.153.0.0/1727.153.0.1 to 27.153.127.25427.153.127.25532,766
5227.153.128.0/1727.153.128.1 to 27.153.255.25427.153.255.25532,766
5327.154.0.0/1727.154.0.1 to 27.154.127.25427.154.127.25532,766
5427.154.128.0/1727.154.128.1 to 27.154.255.25427.154.255.25532,766
5527.155.0.0/1727.155.0.1 to 27.155.127.25427.155.127.25532,766
5627.155.128.0/1727.155.128.1 to 27.155.255.25427.155.255.25532,766
5727.156.0.0/1727.156.0.1 to 27.156.127.25427.156.127.25532,766
5827.156.128.0/1727.156.128.1 to 27.156.255.25427.156.255.25532,766
5927.157.0.0/1727.157.0.1 to 27.157.127.25427.157.127.25532,766
6027.157.128.0/1727.157.128.1 to 27.157.255.25427.157.255.25532,766
6127.158.0.0/1727.158.0.1 to 27.158.127.25427.158.127.25532,766
6227.158.128.0/1727.158.128.1 to 27.158.255.25427.158.255.25532,766
6327.159.0.0/1727.159.0.1 to 27.159.127.25427.159.127.25532,766
6427.159.128.0/1727.159.128.1 to 27.159.255.25427.159.255.25532,766
6527.160.0.0/1727.160.0.1 to 27.160.127.25427.160.127.25532,766
6627.160.128.0/1727.160.128.1 to 27.160.255.25427.160.255.25532,766
6727.161.0.0/1727.161.0.1 to 27.161.127.25427.161.127.25532,766
6827.161.128.0/1727.161.128.1 to 27.161.255.25427.161.255.25532,766
6927.162.0.0/1727.162.0.1 to 27.162.127.25427.162.127.25532,766
7027.162.128.0/1727.162.128.1 to 27.162.255.25427.162.255.25532,766
7127.163.0.0/1727.163.0.1 to 27.163.127.25427.163.127.25532,766
7227.163.128.0/1727.163.128.1 to 27.163.255.25427.163.255.25532,766
7327.164.0.0/1727.164.0.1 to 27.164.127.25427.164.127.25532,766
7427.164.128.0/1727.164.128.1 to 27.164.255.25427.164.255.25532,766
7527.165.0.0/1727.165.0.1 to 27.165.127.25427.165.127.25532,766
7627.165.128.0/1727.165.128.1 to 27.165.255.25427.165.255.25532,766
7727.166.0.0/1727.166.0.1 to 27.166.127.25427.166.127.25532,766
7827.166.128.0/1727.166.128.1 to 27.166.255.25427.166.255.25532,766
7927.167.0.0/1727.167.0.1 to 27.167.127.25427.167.127.25532,766
8027.167.128.0/1727.167.128.1 to 27.167.255.25427.167.255.25532,766
8127.168.0.0/1727.168.0.1 to 27.168.127.25427.168.127.25532,766
8227.168.128.0/1727.168.128.1 to 27.168.255.25427.168.255.25532,766
8327.169.0.0/1727.169.0.1 to 27.169.127.25427.169.127.25532,766
8427.169.128.0/1727.169.128.1 to 27.169.255.25427.169.255.25532,766
8527.170.0.0/1727.170.0.1 to 27.170.127.25427.170.127.25532,766
8627.170.128.0/1727.170.128.1 to 27.170.255.25427.170.255.25532,766
8727.171.0.0/1727.171.0.1 to 27.171.127.25427.171.127.25532,766
8827.171.128.0/1727.171.128.1 to 27.171.255.25427.171.255.25532,766
8927.172.0.0/1727.172.0.1 to 27.172.127.25427.172.127.25532,766
9027.172.128.0/1727.172.128.1 to 27.172.255.25427.172.255.25532,766
9127.173.0.0/1727.173.0.1 to 27.173.127.25427.173.127.25532,766
9227.173.128.0/1727.173.128.1 to 27.173.255.25427.173.255.25532,766
9327.174.0.0/1727.174.0.1 to 27.174.127.25427.174.127.25532,766
9427.174.128.0/1727.174.128.1 to 27.174.255.25427.174.255.25532,766
9527.175.0.0/1727.175.0.1 to 27.175.127.25427.175.127.25532,766
9627.175.128.0/1727.175.128.1 to 27.175.255.25427.175.255.25532,766
9727.176.0.0/1727.176.0.1 to 27.176.127.25427.176.127.25532,766
9827.176.128.0/1727.176.128.1 to 27.176.255.25427.176.255.25532,766
9927.177.0.0/1727.177.0.1 to 27.177.127.25427.177.127.25532,766
10027.177.128.0/1727.177.128.1 to 27.177.255.25427.177.255.25532,766
10127.178.0.0/1727.178.0.1 to 27.178.127.25427.178.127.25532,766
10227.178.128.0/1727.178.128.1 to 27.178.255.25427.178.255.25532,766
10327.179.0.0/1727.179.0.1 to 27.179.127.25427.179.127.25532,766
10427.179.128.0/1727.179.128.1 to 27.179.255.25427.179.255.25532,766
10527.180.0.0/1727.180.0.1 to 27.180.127.25427.180.127.25532,766
10627.180.128.0/1727.180.128.1 to 27.180.255.25427.180.255.25532,766
10727.181.0.0/1727.181.0.1 to 27.181.127.25427.181.127.25532,766
10827.181.128.0/1727.181.128.1 to 27.181.255.25427.181.255.25532,766
10927.182.0.0/1727.182.0.1 to 27.182.127.25427.182.127.25532,766
11027.182.128.0/1727.182.128.1 to 27.182.255.25427.182.255.25532,766
11127.183.0.0/1727.183.0.1 to 27.183.127.25427.183.127.25532,766
11227.183.128.0/1727.183.128.1 to 27.183.255.25427.183.255.25532,766
11327.184.0.0/1727.184.0.1 to 27.184.127.25427.184.127.25532,766
11427.184.128.0/1727.184.128.1 to 27.184.255.25427.184.255.25532,766
11527.185.0.0/1727.185.0.1 to 27.185.127.25427.185.127.25532,766
11627.185.128.0/1727.185.128.1 to 27.185.255.25427.185.255.25532,766
11727.186.0.0/1727.186.0.1 to 27.186.127.25427.186.127.25532,766
11827.186.128.0/1727.186.128.1 to 27.186.255.25427.186.255.25532,766
11927.187.0.0/1727.187.0.1 to 27.187.127.25427.187.127.25532,766
12027.187.128.0/1727.187.128.1 to 27.187.255.25427.187.255.25532,766
12127.188.0.0/1727.188.0.1 to 27.188.127.25427.188.127.25532,766
12227.188.128.0/1727.188.128.1 to 27.188.255.25427.188.255.25532,766
12327.189.0.0/1727.189.0.1 to 27.189.127.25427.189.127.25532,766
12427.189.128.0/1727.189.128.1 to 27.189.255.25427.189.255.25532,766
12527.190.0.0/1727.190.0.1 to 27.190.127.25427.190.127.25532,766
12627.190.128.0/1727.190.128.1 to 27.190.255.25427.190.255.25532,766
12727.191.0.0/1727.191.0.1 to 27.191.127.25427.191.127.25532,766
12827.191.128.0/1727.191.128.1 to 27.191.255.25427.191.255.25532,766
12927.192.0.0/1727.192.0.1 to 27.192.127.25427.192.127.25532,766
13027.192.128.0/1727.192.128.1 to 27.192.255.25427.192.255.25532,766
13127.193.0.0/1727.193.0.1 to 27.193.127.25427.193.127.25532,766
13227.193.128.0/1727.193.128.1 to 27.193.255.25427.193.255.25532,766
13327.194.0.0/1727.194.0.1 to 27.194.127.25427.194.127.25532,766
13427.194.128.0/1727.194.128.1 to 27.194.255.25427.194.255.25532,766
13527.195.0.0/1727.195.0.1 to 27.195.127.25427.195.127.25532,766
13627.195.128.0/1727.195.128.1 to 27.195.255.25427.195.255.25532,766
13727.196.0.0/1727.196.0.1 to 27.196.127.25427.196.127.25532,766
13827.196.128.0/1727.196.128.1 to 27.196.255.25427.196.255.25532,766
13927.197.0.0/1727.197.0.1 to 27.197.127.25427.197.127.25532,766
14027.197.128.0/1727.197.128.1 to 27.197.255.25427.197.255.25532,766
14127.198.0.0/1727.198.0.1 to 27.198.127.25427.198.127.25532,766
14227.198.128.0/1727.198.128.1 to 27.198.255.25427.198.255.25532,766
14327.199.0.0/1727.199.0.1 to 27.199.127.25427.199.127.25532,766
14427.199.128.0/1727.199.128.1 to 27.199.255.25427.199.255.25532,766
14527.200.0.0/1727.200.0.1 to 27.200.127.25427.200.127.25532,766
14627.200.128.0/1727.200.128.1 to 27.200.255.25427.200.255.25532,766
14727.201.0.0/1727.201.0.1 to 27.201.127.25427.201.127.25532,766
14827.201.128.0/1727.201.128.1 to 27.201.255.25427.201.255.25532,766
14927.202.0.0/1727.202.0.1 to 27.202.127.25427.202.127.25532,766
15027.202.128.0/1727.202.128.1 to 27.202.255.25427.202.255.25532,766
15127.203.0.0/1727.203.0.1 to 27.203.127.25427.203.127.25532,766
15227.203.128.0/1727.203.128.1 to 27.203.255.25427.203.255.25532,766
15327.204.0.0/1727.204.0.1 to 27.204.127.25427.204.127.25532,766
15427.204.128.0/1727.204.128.1 to 27.204.255.25427.204.255.25532,766
15527.205.0.0/1727.205.0.1 to 27.205.127.25427.205.127.25532,766
15627.205.128.0/1727.205.128.1 to 27.205.255.25427.205.255.25532,766
15727.206.0.0/1727.206.0.1 to 27.206.127.25427.206.127.25532,766
15827.206.128.0/1727.206.128.1 to 27.206.255.25427.206.255.25532,766
15927.207.0.0/1727.207.0.1 to 27.207.127.25427.207.127.25532,766
16027.207.128.0/1727.207.128.1 to 27.207.255.25427.207.255.25532,766
16127.208.0.0/1727.208.0.1 to 27.208.127.25427.208.127.25532,766
16227.208.128.0/1727.208.128.1 to 27.208.255.25427.208.255.25532,766
16327.209.0.0/1727.209.0.1 to 27.209.127.25427.209.127.25532,766
16427.209.128.0/1727.209.128.1 to 27.209.255.25427.209.255.25532,766
16527.210.0.0/1727.210.0.1 to 27.210.127.25427.210.127.25532,766
16627.210.128.0/1727.210.128.1 to 27.210.255.25427.210.255.25532,766
16727.211.0.0/1727.211.0.1 to 27.211.127.25427.211.127.25532,766
16827.211.128.0/1727.211.128.1 to 27.211.255.25427.211.255.25532,766
16927.212.0.0/1727.212.0.1 to 27.212.127.25427.212.127.25532,766
17027.212.128.0/1727.212.128.1 to 27.212.255.25427.212.255.25532,766
17127.213.0.0/1727.213.0.1 to 27.213.127.25427.213.127.25532,766
17227.213.128.0/1727.213.128.1 to 27.213.255.25427.213.255.25532,766
17327.214.0.0/1727.214.0.1 to 27.214.127.25427.214.127.25532,766
17427.214.128.0/1727.214.128.1 to 27.214.255.25427.214.255.25532,766
17527.215.0.0/1727.215.0.1 to 27.215.127.25427.215.127.25532,766
17627.215.128.0/1727.215.128.1 to 27.215.255.25427.215.255.25532,766
17727.216.0.0/1727.216.0.1 to 27.216.127.25427.216.127.25532,766
17827.216.128.0/1727.216.128.1 to 27.216.255.25427.216.255.25532,766
17927.217.0.0/1727.217.0.1 to 27.217.127.25427.217.127.25532,766
18027.217.128.0/1727.217.128.1 to 27.217.255.25427.217.255.25532,766
18127.218.0.0/1727.218.0.1 to 27.218.127.25427.218.127.25532,766
18227.218.128.0/1727.218.128.1 to 27.218.255.25427.218.255.25532,766
18327.219.0.0/1727.219.0.1 to 27.219.127.25427.219.127.25532,766
18427.219.128.0/1727.219.128.1 to 27.219.255.25427.219.255.25532,766
18527.220.0.0/1727.220.0.1 to 27.220.127.25427.220.127.25532,766
18627.220.128.0/1727.220.128.1 to 27.220.255.25427.220.255.25532,766
18727.221.0.0/1727.221.0.1 to 27.221.127.25427.221.127.25532,766
18827.221.128.0/1727.221.128.1 to 27.221.255.25427.221.255.25532,766
18927.222.0.0/1727.222.0.1 to 27.222.127.25427.222.127.25532,766
19027.222.128.0/1727.222.128.1 to 27.222.255.25427.222.255.25532,766
19127.223.0.0/1727.223.0.1 to 27.223.127.25427.223.127.25532,766
19227.223.128.0/1727.223.128.1 to 27.223.255.25427.223.255.25532,766
19327.224.0.0/1727.224.0.1 to 27.224.127.25427.224.127.25532,766
19427.224.128.0/1727.224.128.1 to 27.224.255.25427.224.255.25532,766
19527.225.0.0/1727.225.0.1 to 27.225.127.25427.225.127.25532,766
19627.225.128.0/1727.225.128.1 to 27.225.255.25427.225.255.25532,766
19727.226.0.0/1727.226.0.1 to 27.226.127.25427.226.127.25532,766
19827.226.128.0/1727.226.128.1 to 27.226.255.25427.226.255.25532,766
19927.227.0.0/1727.227.0.1 to 27.227.127.25427.227.127.25532,766
20027.227.128.0/1727.227.128.1 to 27.227.255.25427.227.255.25532,766
20127.228.0.0/1727.228.0.1 to 27.228.127.25427.228.127.25532,766
20227.228.128.0/1727.228.128.1 to 27.228.255.25427.228.255.25532,766
20327.229.0.0/1727.229.0.1 to 27.229.127.25427.229.127.25532,766
20427.229.128.0/1727.229.128.1 to 27.229.255.25427.229.255.25532,766
20527.230.0.0/1727.230.0.1 to 27.230.127.25427.230.127.25532,766
20627.230.128.0/1727.230.128.1 to 27.230.255.25427.230.255.25532,766
20727.231.0.0/1727.231.0.1 to 27.231.127.25427.231.127.25532,766
20827.231.128.0/1727.231.128.1 to 27.231.255.25427.231.255.25532,766
20927.232.0.0/1727.232.0.1 to 27.232.127.25427.232.127.25532,766
21027.232.128.0/1727.232.128.1 to 27.232.255.25427.232.255.25532,766
21127.233.0.0/1727.233.0.1 to 27.233.127.25427.233.127.25532,766
21227.233.128.0/1727.233.128.1 to 27.233.255.25427.233.255.25532,766
21327.234.0.0/1727.234.0.1 to 27.234.127.25427.234.127.25532,766
21427.234.128.0/1727.234.128.1 to 27.234.255.25427.234.255.25532,766
21527.235.0.0/1727.235.0.1 to 27.235.127.25427.235.127.25532,766
21627.235.128.0/1727.235.128.1 to 27.235.255.25427.235.255.25532,766
21727.236.0.0/1727.236.0.1 to 27.236.127.25427.236.127.25532,766
21827.236.128.0/1727.236.128.1 to 27.236.255.25427.236.255.25532,766
21927.237.0.0/1727.237.0.1 to 27.237.127.25427.237.127.25532,766
22027.237.128.0/1727.237.128.1 to 27.237.255.25427.237.255.25532,766
22127.238.0.0/1727.238.0.1 to 27.238.127.25427.238.127.25532,766
22227.238.128.0/1727.238.128.1 to 27.238.255.25427.238.255.25532,766
22327.239.0.0/1727.239.0.1 to 27.239.127.25427.239.127.25532,766
22427.239.128.0/1727.239.128.1 to 27.239.255.25427.239.255.25532,766
22527.240.0.0/1727.240.0.1 to 27.240.127.25427.240.127.25532,766
22627.240.128.0/1727.240.128.1 to 27.240.255.25427.240.255.25532,766
22727.241.0.0/1727.241.0.1 to 27.241.127.25427.241.127.25532,766
22827.241.128.0/1727.241.128.1 to 27.241.255.25427.241.255.25532,766
22927.242.0.0/1727.242.0.1 to 27.242.127.25427.242.127.25532,766
23027.242.128.0/1727.242.128.1 to 27.242.255.25427.242.255.25532,766
23127.243.0.0/1727.243.0.1 to 27.243.127.25427.243.127.25532,766
23227.243.128.0/1727.243.128.1 to 27.243.255.25427.243.255.25532,766
23327.244.0.0/1727.244.0.1 to 27.244.127.25427.244.127.25532,766
23427.244.128.0/1727.244.128.1 to 27.244.255.25427.244.255.25532,766
23527.245.0.0/1727.245.0.1 to 27.245.127.25427.245.127.25532,766
23627.245.128.0/1727.245.128.1 to 27.245.255.25427.245.255.25532,766
23727.246.0.0/1727.246.0.1 to 27.246.127.25427.246.127.25532,766
23827.246.128.0/1727.246.128.1 to 27.246.255.25427.246.255.25532,766
23927.247.0.0/1727.247.0.1 to 27.247.127.25427.247.127.25532,766
24027.247.128.0/1727.247.128.1 to 27.247.255.25427.247.255.25532,766
24127.248.0.0/1727.248.0.1 to 27.248.127.25427.248.127.25532,766
24227.248.128.0/1727.248.128.1 to 27.248.255.25427.248.255.25532,766
24327.249.0.0/1727.249.0.1 to 27.249.127.25427.249.127.25532,766
24427.249.128.0/1727.249.128.1 to 27.249.255.25427.249.255.25532,766
24527.250.0.0/1727.250.0.1 to 27.250.127.25427.250.127.25532,766
24627.250.128.0/1727.250.128.1 to 27.250.255.25427.250.255.25532,766
24727.251.0.0/1727.251.0.1 to 27.251.127.25427.251.127.25532,766
24827.251.128.0/1727.251.128.1 to 27.251.255.25427.251.255.25532,766
24927.252.0.0/1727.252.0.1 to 27.252.127.25427.252.127.25532,766
25027.252.128.0/1727.252.128.1 to 27.252.255.25427.252.255.25532,766
25127.253.0.0/1727.253.0.1 to 27.253.127.25427.253.127.25532,766
25227.253.128.0/1727.253.128.1 to 27.253.255.25427.253.255.25532,766
25327.254.0.0/1727.254.0.1 to 27.254.127.25427.254.127.25532,766
25427.254.128.0/1727.254.128.1 to 27.254.255.25427.254.255.25532,766
25527.255.0.0/1727.255.0.1 to 27.255.127.25427.255.127.25532,766
25627.255.128.0/1727.255.128.1 to 27.255.255.25427.255.255.25532,766

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.