IPv4 Subnet Calculator
Enter an IP with a CIDR prefix or a subnet mask to see its network, broadcast, host range, and host count. You can also split the network into smaller subnets.
private IP (RFC 1918)10.121.128.0/17
network10.121.128.0/17
broadcast10.121.255.255
first host10.121.128.1
last host10.121.255.254
subnet mask255.255.128.0
wildcard0.0.127.255
addresses32,768
usable hosts32,766
classA
ipcalc 10.121.128.0/17
address00001010.01111001.10000000.00000000
subnet mask11111111.11111111.10000000.00000000
network00001010.01111001.10000000.00000000
broadcast00001010.01111001.11111111.11111111
green = network part, grey = host part
hex0x0a798000
decimal175734784
reverse dns0.128.121.10.in-addr.arpa
ipv4-mapped::ffff:a79:8000
/17 split into /24 · 128 subnets
close ×| # | network | host range | broadcast |
|---|---|---|---|
| 1 | 10.121.128.0/24 | 10.121.128.1 – 10.121.128.254 | 10.121.128.255 |
| 2 | 10.121.129.0/24 | 10.121.129.1 – 10.121.129.254 | 10.121.129.255 |
| 3 | 10.121.130.0/24 | 10.121.130.1 – 10.121.130.254 | 10.121.130.255 |
| 4 | 10.121.131.0/24 | 10.121.131.1 – 10.121.131.254 | 10.121.131.255 |
| 5 | 10.121.132.0/24 | 10.121.132.1 – 10.121.132.254 | 10.121.132.255 |
| 6 | 10.121.133.0/24 | 10.121.133.1 – 10.121.133.254 | 10.121.133.255 |
| 7 | 10.121.134.0/24 | 10.121.134.1 – 10.121.134.254 | 10.121.134.255 |
| 8 | 10.121.135.0/24 | 10.121.135.1 – 10.121.135.254 | 10.121.135.255 |
| 9 | 10.121.136.0/24 | 10.121.136.1 – 10.121.136.254 | 10.121.136.255 |
| 10 | 10.121.137.0/24 | 10.121.137.1 – 10.121.137.254 | 10.121.137.255 |
| 11 | 10.121.138.0/24 | 10.121.138.1 – 10.121.138.254 | 10.121.138.255 |
| 12 | 10.121.139.0/24 | 10.121.139.1 – 10.121.139.254 | 10.121.139.255 |
| 13 | 10.121.140.0/24 | 10.121.140.1 – 10.121.140.254 | 10.121.140.255 |
| 14 | 10.121.141.0/24 | 10.121.141.1 – 10.121.141.254 | 10.121.141.255 |
| 15 | 10.121.142.0/24 | 10.121.142.1 – 10.121.142.254 | 10.121.142.255 |
| 16 | 10.121.143.0/24 | 10.121.143.1 – 10.121.143.254 | 10.121.143.255 |
| 17 | 10.121.144.0/24 | 10.121.144.1 – 10.121.144.254 | 10.121.144.255 |
| 18 | 10.121.145.0/24 | 10.121.145.1 – 10.121.145.254 | 10.121.145.255 |
| 19 | 10.121.146.0/24 | 10.121.146.1 – 10.121.146.254 | 10.121.146.255 |
| 20 | 10.121.147.0/24 | 10.121.147.1 – 10.121.147.254 | 10.121.147.255 |
| 21 | 10.121.148.0/24 | 10.121.148.1 – 10.121.148.254 | 10.121.148.255 |
| 22 | 10.121.149.0/24 | 10.121.149.1 – 10.121.149.254 | 10.121.149.255 |
| 23 | 10.121.150.0/24 | 10.121.150.1 – 10.121.150.254 | 10.121.150.255 |
| 24 | 10.121.151.0/24 | 10.121.151.1 – 10.121.151.254 | 10.121.151.255 |
| 25 | 10.121.152.0/24 | 10.121.152.1 – 10.121.152.254 | 10.121.152.255 |
| 26 | 10.121.153.0/24 | 10.121.153.1 – 10.121.153.254 | 10.121.153.255 |
| 27 | 10.121.154.0/24 | 10.121.154.1 – 10.121.154.254 | 10.121.154.255 |
| 28 | 10.121.155.0/24 | 10.121.155.1 – 10.121.155.254 | 10.121.155.255 |
| 29 | 10.121.156.0/24 | 10.121.156.1 – 10.121.156.254 | 10.121.156.255 |
| 30 | 10.121.157.0/24 | 10.121.157.1 – 10.121.157.254 | 10.121.157.255 |
| 31 | 10.121.158.0/24 | 10.121.158.1 – 10.121.158.254 | 10.121.158.255 |
| 32 | 10.121.159.0/24 | 10.121.159.1 – 10.121.159.254 | 10.121.159.255 |
| 33 | 10.121.160.0/24 | 10.121.160.1 – 10.121.160.254 | 10.121.160.255 |
| 34 | 10.121.161.0/24 | 10.121.161.1 – 10.121.161.254 | 10.121.161.255 |
| 35 | 10.121.162.0/24 | 10.121.162.1 – 10.121.162.254 | 10.121.162.255 |
| 36 | 10.121.163.0/24 | 10.121.163.1 – 10.121.163.254 | 10.121.163.255 |
| 37 | 10.121.164.0/24 | 10.121.164.1 – 10.121.164.254 | 10.121.164.255 |
| 38 | 10.121.165.0/24 | 10.121.165.1 – 10.121.165.254 | 10.121.165.255 |
| 39 | 10.121.166.0/24 | 10.121.166.1 – 10.121.166.254 | 10.121.166.255 |
| 40 | 10.121.167.0/24 | 10.121.167.1 – 10.121.167.254 | 10.121.167.255 |
| 41 | 10.121.168.0/24 | 10.121.168.1 – 10.121.168.254 | 10.121.168.255 |
| 42 | 10.121.169.0/24 | 10.121.169.1 – 10.121.169.254 | 10.121.169.255 |
| 43 | 10.121.170.0/24 | 10.121.170.1 – 10.121.170.254 | 10.121.170.255 |
| 44 | 10.121.171.0/24 | 10.121.171.1 – 10.121.171.254 | 10.121.171.255 |
| 45 | 10.121.172.0/24 | 10.121.172.1 – 10.121.172.254 | 10.121.172.255 |
| 46 | 10.121.173.0/24 | 10.121.173.1 – 10.121.173.254 | 10.121.173.255 |
| 47 | 10.121.174.0/24 | 10.121.174.1 – 10.121.174.254 | 10.121.174.255 |
| 48 | 10.121.175.0/24 | 10.121.175.1 – 10.121.175.254 | 10.121.175.255 |
| 49 | 10.121.176.0/24 | 10.121.176.1 – 10.121.176.254 | 10.121.176.255 |
| 50 | 10.121.177.0/24 | 10.121.177.1 – 10.121.177.254 | 10.121.177.255 |
| 51 | 10.121.178.0/24 | 10.121.178.1 – 10.121.178.254 | 10.121.178.255 |
| 52 | 10.121.179.0/24 | 10.121.179.1 – 10.121.179.254 | 10.121.179.255 |
| 53 | 10.121.180.0/24 | 10.121.180.1 – 10.121.180.254 | 10.121.180.255 |
| 54 | 10.121.181.0/24 | 10.121.181.1 – 10.121.181.254 | 10.121.181.255 |
| 55 | 10.121.182.0/24 | 10.121.182.1 – 10.121.182.254 | 10.121.182.255 |
| 56 | 10.121.183.0/24 | 10.121.183.1 – 10.121.183.254 | 10.121.183.255 |
| 57 | 10.121.184.0/24 | 10.121.184.1 – 10.121.184.254 | 10.121.184.255 |
| 58 | 10.121.185.0/24 | 10.121.185.1 – 10.121.185.254 | 10.121.185.255 |
| 59 | 10.121.186.0/24 | 10.121.186.1 – 10.121.186.254 | 10.121.186.255 |
| 60 | 10.121.187.0/24 | 10.121.187.1 – 10.121.187.254 | 10.121.187.255 |
| 61 | 10.121.188.0/24 | 10.121.188.1 – 10.121.188.254 | 10.121.188.255 |
| 62 | 10.121.189.0/24 | 10.121.189.1 – 10.121.189.254 | 10.121.189.255 |
| 63 | 10.121.190.0/24 | 10.121.190.1 – 10.121.190.254 | 10.121.190.255 |
| 64 | 10.121.191.0/24 | 10.121.191.1 – 10.121.191.254 | 10.121.191.255 |
| 65 | 10.121.192.0/24 | 10.121.192.1 – 10.121.192.254 | 10.121.192.255 |
| 66 | 10.121.193.0/24 | 10.121.193.1 – 10.121.193.254 | 10.121.193.255 |
| 67 | 10.121.194.0/24 | 10.121.194.1 – 10.121.194.254 | 10.121.194.255 |
| 68 | 10.121.195.0/24 | 10.121.195.1 – 10.121.195.254 | 10.121.195.255 |
| 69 | 10.121.196.0/24 | 10.121.196.1 – 10.121.196.254 | 10.121.196.255 |
| 70 | 10.121.197.0/24 | 10.121.197.1 – 10.121.197.254 | 10.121.197.255 |
| 71 | 10.121.198.0/24 | 10.121.198.1 – 10.121.198.254 | 10.121.198.255 |
| 72 | 10.121.199.0/24 | 10.121.199.1 – 10.121.199.254 | 10.121.199.255 |
| 73 | 10.121.200.0/24 | 10.121.200.1 – 10.121.200.254 | 10.121.200.255 |
| 74 | 10.121.201.0/24 | 10.121.201.1 – 10.121.201.254 | 10.121.201.255 |
| 75 | 10.121.202.0/24 | 10.121.202.1 – 10.121.202.254 | 10.121.202.255 |
| 76 | 10.121.203.0/24 | 10.121.203.1 – 10.121.203.254 | 10.121.203.255 |
| 77 | 10.121.204.0/24 | 10.121.204.1 – 10.121.204.254 | 10.121.204.255 |
| 78 | 10.121.205.0/24 | 10.121.205.1 – 10.121.205.254 | 10.121.205.255 |
| 79 | 10.121.206.0/24 | 10.121.206.1 – 10.121.206.254 | 10.121.206.255 |
| 80 | 10.121.207.0/24 | 10.121.207.1 – 10.121.207.254 | 10.121.207.255 |
| 81 | 10.121.208.0/24 | 10.121.208.1 – 10.121.208.254 | 10.121.208.255 |
| 82 | 10.121.209.0/24 | 10.121.209.1 – 10.121.209.254 | 10.121.209.255 |
| 83 | 10.121.210.0/24 | 10.121.210.1 – 10.121.210.254 | 10.121.210.255 |
| 84 | 10.121.211.0/24 | 10.121.211.1 – 10.121.211.254 | 10.121.211.255 |
| 85 | 10.121.212.0/24 | 10.121.212.1 – 10.121.212.254 | 10.121.212.255 |
| 86 | 10.121.213.0/24 | 10.121.213.1 – 10.121.213.254 | 10.121.213.255 |
| 87 | 10.121.214.0/24 | 10.121.214.1 – 10.121.214.254 | 10.121.214.255 |
| 88 | 10.121.215.0/24 | 10.121.215.1 – 10.121.215.254 | 10.121.215.255 |
| 89 | 10.121.216.0/24 | 10.121.216.1 – 10.121.216.254 | 10.121.216.255 |
| 90 | 10.121.217.0/24 | 10.121.217.1 – 10.121.217.254 | 10.121.217.255 |
| 91 | 10.121.218.0/24 | 10.121.218.1 – 10.121.218.254 | 10.121.218.255 |
| 92 | 10.121.219.0/24 | 10.121.219.1 – 10.121.219.254 | 10.121.219.255 |
| 93 | 10.121.220.0/24 | 10.121.220.1 – 10.121.220.254 | 10.121.220.255 |
| 94 | 10.121.221.0/24 | 10.121.221.1 – 10.121.221.254 | 10.121.221.255 |
| 95 | 10.121.222.0/24 | 10.121.222.1 – 10.121.222.254 | 10.121.222.255 |
| 96 | 10.121.223.0/24 | 10.121.223.1 – 10.121.223.254 | 10.121.223.255 |
| 97 | 10.121.224.0/24 | 10.121.224.1 – 10.121.224.254 | 10.121.224.255 |
| 98 | 10.121.225.0/24 | 10.121.225.1 – 10.121.225.254 | 10.121.225.255 |
| 99 | 10.121.226.0/24 | 10.121.226.1 – 10.121.226.254 | 10.121.226.255 |
| 100 | 10.121.227.0/24 | 10.121.227.1 – 10.121.227.254 | 10.121.227.255 |
| 101 | 10.121.228.0/24 | 10.121.228.1 – 10.121.228.254 | 10.121.228.255 |
| 102 | 10.121.229.0/24 | 10.121.229.1 – 10.121.229.254 | 10.121.229.255 |
| 103 | 10.121.230.0/24 | 10.121.230.1 – 10.121.230.254 | 10.121.230.255 |
| 104 | 10.121.231.0/24 | 10.121.231.1 – 10.121.231.254 | 10.121.231.255 |
| 105 | 10.121.232.0/24 | 10.121.232.1 – 10.121.232.254 | 10.121.232.255 |
| 106 | 10.121.233.0/24 | 10.121.233.1 – 10.121.233.254 | 10.121.233.255 |
| 107 | 10.121.234.0/24 | 10.121.234.1 – 10.121.234.254 | 10.121.234.255 |
| 108 | 10.121.235.0/24 | 10.121.235.1 – 10.121.235.254 | 10.121.235.255 |
| 109 | 10.121.236.0/24 | 10.121.236.1 – 10.121.236.254 | 10.121.236.255 |
| 110 | 10.121.237.0/24 | 10.121.237.1 – 10.121.237.254 | 10.121.237.255 |
| 111 | 10.121.238.0/24 | 10.121.238.1 – 10.121.238.254 | 10.121.238.255 |
| 112 | 10.121.239.0/24 | 10.121.239.1 – 10.121.239.254 | 10.121.239.255 |
| 113 | 10.121.240.0/24 | 10.121.240.1 – 10.121.240.254 | 10.121.240.255 |
| 114 | 10.121.241.0/24 | 10.121.241.1 – 10.121.241.254 | 10.121.241.255 |
| 115 | 10.121.242.0/24 | 10.121.242.1 – 10.121.242.254 | 10.121.242.255 |
| 116 | 10.121.243.0/24 | 10.121.243.1 – 10.121.243.254 | 10.121.243.255 |
| 117 | 10.121.244.0/24 | 10.121.244.1 – 10.121.244.254 | 10.121.244.255 |
| 118 | 10.121.245.0/24 | 10.121.245.1 – 10.121.245.254 | 10.121.245.255 |
| 119 | 10.121.246.0/24 | 10.121.246.1 – 10.121.246.254 | 10.121.246.255 |
| 120 | 10.121.247.0/24 | 10.121.247.1 – 10.121.247.254 | 10.121.247.255 |
| 121 | 10.121.248.0/24 | 10.121.248.1 – 10.121.248.254 | 10.121.248.255 |
| 122 | 10.121.249.0/24 | 10.121.249.1 – 10.121.249.254 | 10.121.249.255 |
| 123 | 10.121.250.0/24 | 10.121.250.1 – 10.121.250.254 | 10.121.250.255 |
| 124 | 10.121.251.0/24 | 10.121.251.1 – 10.121.251.254 | 10.121.251.255 |
| 125 | 10.121.252.0/24 | 10.121.252.1 – 10.121.252.254 | 10.121.252.255 |
| 126 | 10.121.253.0/24 | 10.121.253.1 – 10.121.253.254 | 10.121.253.255 |
| 127 | 10.121.254.0/24 | 10.121.254.1 – 10.121.254.254 | 10.121.254.255 |
| 128 | 10.121.255.0/24 | 10.121.255.1 – 10.121.255.254 | 10.121.255.255 |
01 / table
IPv4 CIDR prefix table.
Click a prefix longer than your network to split it into subnets.
| prefix | subnet mask | addresses | hosts | in your /17 |
|---|---|---|---|---|
| /0 | 0.0.0.0 | 4,294,967,296 | 4,294,967,294 | - |
| /1 | 128.0.0.0 | 2,147,483,648 | 2,147,483,646 | - |
| /2 | 192.0.0.0 | 1,073,741,824 | 1,073,741,822 | - |
| /3 | 224.0.0.0 | 536,870,912 | 536,870,910 | - |
| /4 | 240.0.0.0 | 268,435,456 | 268,435,454 | - |
| /5 | 248.0.0.0 | 134,217,728 | 134,217,726 | - |
| /6 | 252.0.0.0 | 67,108,864 | 67,108,862 | - |
| /7 | 254.0.0.0 | 33,554,432 | 33,554,430 | - |
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 | - |
| /9 | 255.128.0.0 | 8,388,608 | 8,388,606 | - |
| /10 | 255.192.0.0 | 4,194,304 | 4,194,302 | - |
| /11 | 255.224.0.0 | 2,097,152 | 2,097,150 | - |
| /12 | 255.240.0.0 | 1,048,576 | 1,048,574 | - |
| /13 | 255.248.0.0 | 524,288 | 524,286 | - |
| /14 | 255.252.0.0 | 262,144 | 262,142 | - |
| /15 | 255.254.0.0 | 131,072 | 131,070 | - |
| /16 | 255.255.0.0 | 65,536 | 65,534 | - |
| /17 | 255.255.128.0 | 32,768 | 32,766 | 1 |
| /18 | 255.255.192.0 | 16,384 | 16,382 | 2 split → |
| /19 | 255.255.224.0 | 8,192 | 8,190 | 4 split → |
| /20 | 255.255.240.0 | 4,096 | 4,094 | 8 split → |
| /21 | 255.255.248.0 | 2,048 | 2,046 | 16 split → |
| /22 | 255.255.252.0 | 1,024 | 1,022 | 32 split → |
| /23 | 255.255.254.0 | 512 | 510 | 64 split → |
| /24 | 255.255.255.0 | 256 | 254 | 128 split → |
| /25 | 255.255.255.128 | 128 | 126 | 256 split → |
| /26 | 255.255.255.192 | 64 | 62 | 512 split → |
| /27 | 255.255.255.224 | 32 | 30 | 1,024 split → |
| /28 | 255.255.255.240 | 16 | 14 | 2,048 split → |
| /29 | 255.255.255.248 | 8 | 6 | 4,096 split → |
| /30 | 255.255.255.252 | 4 | 2 | 8,192 split → |
| /31 | 255.255.255.254 | 2 | 2 | 16,384 split → |
| /32 | 255.255.255.255 | 1 | 1 | 32,768 split → |
02 / faq
About this calculator.
How do I use this subnet calculator?
▼
Type an IP address followed by a prefix, like 192.168.1.10/24, or by a subnet mask, like 192.168.1.10 255.255.255.0. Without a prefix it uses /24. Click a row in the table to split the network into smaller subnets.
Why are usable hosts always 2 fewer?
▼
The first address in a subnet is the network address and the last is the broadcast address, so neither can go to a device. The exceptions are /31 (point-to-point links, RFC 3021) and /32 (a single address), which use every address.
Can I use it from a terminal?
▼
Yes. curl 'ipku.in/en/tools/ipv4-subnet-calculator?q=192.168.1.10/24' returns the result as plain text.