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)10.21.64.0/18
network10.21.64.0/18
broadcast10.21.127.255
first host10.21.64.1
last host10.21.127.254
subnet mask255.255.192.0
wildcard0.0.63.255
addresses16,384
usable hosts16,382
classA
ipcalc 10.21.64.0/18
address00001010.00010101.01000000.00000000
subnet mask11111111.11111111.11000000.00000000
network00001010.00010101.01000000.00000000
broadcast00001010.00010101.01111111.11111111
green = network part, grey = host part
hex0x0a154000
decimal169164800
reverse dns0.64.21.10.in-addr.arpa
ipv4-mapped::ffff:a15:4000
/18 split into /25 · 128 subnets
close ×| # | network | host range | broadcast |
|---|---|---|---|
| 1 | 10.21.64.0/25 | 10.21.64.1 – 10.21.64.126 | 10.21.64.127 |
| 2 | 10.21.64.128/25 | 10.21.64.129 – 10.21.64.254 | 10.21.64.255 |
| 3 | 10.21.65.0/25 | 10.21.65.1 – 10.21.65.126 | 10.21.65.127 |
| 4 | 10.21.65.128/25 | 10.21.65.129 – 10.21.65.254 | 10.21.65.255 |
| 5 | 10.21.66.0/25 | 10.21.66.1 – 10.21.66.126 | 10.21.66.127 |
| 6 | 10.21.66.128/25 | 10.21.66.129 – 10.21.66.254 | 10.21.66.255 |
| 7 | 10.21.67.0/25 | 10.21.67.1 – 10.21.67.126 | 10.21.67.127 |
| 8 | 10.21.67.128/25 | 10.21.67.129 – 10.21.67.254 | 10.21.67.255 |
| 9 | 10.21.68.0/25 | 10.21.68.1 – 10.21.68.126 | 10.21.68.127 |
| 10 | 10.21.68.128/25 | 10.21.68.129 – 10.21.68.254 | 10.21.68.255 |
| 11 | 10.21.69.0/25 | 10.21.69.1 – 10.21.69.126 | 10.21.69.127 |
| 12 | 10.21.69.128/25 | 10.21.69.129 – 10.21.69.254 | 10.21.69.255 |
| 13 | 10.21.70.0/25 | 10.21.70.1 – 10.21.70.126 | 10.21.70.127 |
| 14 | 10.21.70.128/25 | 10.21.70.129 – 10.21.70.254 | 10.21.70.255 |
| 15 | 10.21.71.0/25 | 10.21.71.1 – 10.21.71.126 | 10.21.71.127 |
| 16 | 10.21.71.128/25 | 10.21.71.129 – 10.21.71.254 | 10.21.71.255 |
| 17 | 10.21.72.0/25 | 10.21.72.1 – 10.21.72.126 | 10.21.72.127 |
| 18 | 10.21.72.128/25 | 10.21.72.129 – 10.21.72.254 | 10.21.72.255 |
| 19 | 10.21.73.0/25 | 10.21.73.1 – 10.21.73.126 | 10.21.73.127 |
| 20 | 10.21.73.128/25 | 10.21.73.129 – 10.21.73.254 | 10.21.73.255 |
| 21 | 10.21.74.0/25 | 10.21.74.1 – 10.21.74.126 | 10.21.74.127 |
| 22 | 10.21.74.128/25 | 10.21.74.129 – 10.21.74.254 | 10.21.74.255 |
| 23 | 10.21.75.0/25 | 10.21.75.1 – 10.21.75.126 | 10.21.75.127 |
| 24 | 10.21.75.128/25 | 10.21.75.129 – 10.21.75.254 | 10.21.75.255 |
| 25 | 10.21.76.0/25 | 10.21.76.1 – 10.21.76.126 | 10.21.76.127 |
| 26 | 10.21.76.128/25 | 10.21.76.129 – 10.21.76.254 | 10.21.76.255 |
| 27 | 10.21.77.0/25 | 10.21.77.1 – 10.21.77.126 | 10.21.77.127 |
| 28 | 10.21.77.128/25 | 10.21.77.129 – 10.21.77.254 | 10.21.77.255 |
| 29 | 10.21.78.0/25 | 10.21.78.1 – 10.21.78.126 | 10.21.78.127 |
| 30 | 10.21.78.128/25 | 10.21.78.129 – 10.21.78.254 | 10.21.78.255 |
| 31 | 10.21.79.0/25 | 10.21.79.1 – 10.21.79.126 | 10.21.79.127 |
| 32 | 10.21.79.128/25 | 10.21.79.129 – 10.21.79.254 | 10.21.79.255 |
| 33 | 10.21.80.0/25 | 10.21.80.1 – 10.21.80.126 | 10.21.80.127 |
| 34 | 10.21.80.128/25 | 10.21.80.129 – 10.21.80.254 | 10.21.80.255 |
| 35 | 10.21.81.0/25 | 10.21.81.1 – 10.21.81.126 | 10.21.81.127 |
| 36 | 10.21.81.128/25 | 10.21.81.129 – 10.21.81.254 | 10.21.81.255 |
| 37 | 10.21.82.0/25 | 10.21.82.1 – 10.21.82.126 | 10.21.82.127 |
| 38 | 10.21.82.128/25 | 10.21.82.129 – 10.21.82.254 | 10.21.82.255 |
| 39 | 10.21.83.0/25 | 10.21.83.1 – 10.21.83.126 | 10.21.83.127 |
| 40 | 10.21.83.128/25 | 10.21.83.129 – 10.21.83.254 | 10.21.83.255 |
| 41 | 10.21.84.0/25 | 10.21.84.1 – 10.21.84.126 | 10.21.84.127 |
| 42 | 10.21.84.128/25 | 10.21.84.129 – 10.21.84.254 | 10.21.84.255 |
| 43 | 10.21.85.0/25 | 10.21.85.1 – 10.21.85.126 | 10.21.85.127 |
| 44 | 10.21.85.128/25 | 10.21.85.129 – 10.21.85.254 | 10.21.85.255 |
| 45 | 10.21.86.0/25 | 10.21.86.1 – 10.21.86.126 | 10.21.86.127 |
| 46 | 10.21.86.128/25 | 10.21.86.129 – 10.21.86.254 | 10.21.86.255 |
| 47 | 10.21.87.0/25 | 10.21.87.1 – 10.21.87.126 | 10.21.87.127 |
| 48 | 10.21.87.128/25 | 10.21.87.129 – 10.21.87.254 | 10.21.87.255 |
| 49 | 10.21.88.0/25 | 10.21.88.1 – 10.21.88.126 | 10.21.88.127 |
| 50 | 10.21.88.128/25 | 10.21.88.129 – 10.21.88.254 | 10.21.88.255 |
| 51 | 10.21.89.0/25 | 10.21.89.1 – 10.21.89.126 | 10.21.89.127 |
| 52 | 10.21.89.128/25 | 10.21.89.129 – 10.21.89.254 | 10.21.89.255 |
| 53 | 10.21.90.0/25 | 10.21.90.1 – 10.21.90.126 | 10.21.90.127 |
| 54 | 10.21.90.128/25 | 10.21.90.129 – 10.21.90.254 | 10.21.90.255 |
| 55 | 10.21.91.0/25 | 10.21.91.1 – 10.21.91.126 | 10.21.91.127 |
| 56 | 10.21.91.128/25 | 10.21.91.129 – 10.21.91.254 | 10.21.91.255 |
| 57 | 10.21.92.0/25 | 10.21.92.1 – 10.21.92.126 | 10.21.92.127 |
| 58 | 10.21.92.128/25 | 10.21.92.129 – 10.21.92.254 | 10.21.92.255 |
| 59 | 10.21.93.0/25 | 10.21.93.1 – 10.21.93.126 | 10.21.93.127 |
| 60 | 10.21.93.128/25 | 10.21.93.129 – 10.21.93.254 | 10.21.93.255 |
| 61 | 10.21.94.0/25 | 10.21.94.1 – 10.21.94.126 | 10.21.94.127 |
| 62 | 10.21.94.128/25 | 10.21.94.129 – 10.21.94.254 | 10.21.94.255 |
| 63 | 10.21.95.0/25 | 10.21.95.1 – 10.21.95.126 | 10.21.95.127 |
| 64 | 10.21.95.128/25 | 10.21.95.129 – 10.21.95.254 | 10.21.95.255 |
| 65 | 10.21.96.0/25 | 10.21.96.1 – 10.21.96.126 | 10.21.96.127 |
| 66 | 10.21.96.128/25 | 10.21.96.129 – 10.21.96.254 | 10.21.96.255 |
| 67 | 10.21.97.0/25 | 10.21.97.1 – 10.21.97.126 | 10.21.97.127 |
| 68 | 10.21.97.128/25 | 10.21.97.129 – 10.21.97.254 | 10.21.97.255 |
| 69 | 10.21.98.0/25 | 10.21.98.1 – 10.21.98.126 | 10.21.98.127 |
| 70 | 10.21.98.128/25 | 10.21.98.129 – 10.21.98.254 | 10.21.98.255 |
| 71 | 10.21.99.0/25 | 10.21.99.1 – 10.21.99.126 | 10.21.99.127 |
| 72 | 10.21.99.128/25 | 10.21.99.129 – 10.21.99.254 | 10.21.99.255 |
| 73 | 10.21.100.0/25 | 10.21.100.1 – 10.21.100.126 | 10.21.100.127 |
| 74 | 10.21.100.128/25 | 10.21.100.129 – 10.21.100.254 | 10.21.100.255 |
| 75 | 10.21.101.0/25 | 10.21.101.1 – 10.21.101.126 | 10.21.101.127 |
| 76 | 10.21.101.128/25 | 10.21.101.129 – 10.21.101.254 | 10.21.101.255 |
| 77 | 10.21.102.0/25 | 10.21.102.1 – 10.21.102.126 | 10.21.102.127 |
| 78 | 10.21.102.128/25 | 10.21.102.129 – 10.21.102.254 | 10.21.102.255 |
| 79 | 10.21.103.0/25 | 10.21.103.1 – 10.21.103.126 | 10.21.103.127 |
| 80 | 10.21.103.128/25 | 10.21.103.129 – 10.21.103.254 | 10.21.103.255 |
| 81 | 10.21.104.0/25 | 10.21.104.1 – 10.21.104.126 | 10.21.104.127 |
| 82 | 10.21.104.128/25 | 10.21.104.129 – 10.21.104.254 | 10.21.104.255 |
| 83 | 10.21.105.0/25 | 10.21.105.1 – 10.21.105.126 | 10.21.105.127 |
| 84 | 10.21.105.128/25 | 10.21.105.129 – 10.21.105.254 | 10.21.105.255 |
| 85 | 10.21.106.0/25 | 10.21.106.1 – 10.21.106.126 | 10.21.106.127 |
| 86 | 10.21.106.128/25 | 10.21.106.129 – 10.21.106.254 | 10.21.106.255 |
| 87 | 10.21.107.0/25 | 10.21.107.1 – 10.21.107.126 | 10.21.107.127 |
| 88 | 10.21.107.128/25 | 10.21.107.129 – 10.21.107.254 | 10.21.107.255 |
| 89 | 10.21.108.0/25 | 10.21.108.1 – 10.21.108.126 | 10.21.108.127 |
| 90 | 10.21.108.128/25 | 10.21.108.129 – 10.21.108.254 | 10.21.108.255 |
| 91 | 10.21.109.0/25 | 10.21.109.1 – 10.21.109.126 | 10.21.109.127 |
| 92 | 10.21.109.128/25 | 10.21.109.129 – 10.21.109.254 | 10.21.109.255 |
| 93 | 10.21.110.0/25 | 10.21.110.1 – 10.21.110.126 | 10.21.110.127 |
| 94 | 10.21.110.128/25 | 10.21.110.129 – 10.21.110.254 | 10.21.110.255 |
| 95 | 10.21.111.0/25 | 10.21.111.1 – 10.21.111.126 | 10.21.111.127 |
| 96 | 10.21.111.128/25 | 10.21.111.129 – 10.21.111.254 | 10.21.111.255 |
| 97 | 10.21.112.0/25 | 10.21.112.1 – 10.21.112.126 | 10.21.112.127 |
| 98 | 10.21.112.128/25 | 10.21.112.129 – 10.21.112.254 | 10.21.112.255 |
| 99 | 10.21.113.0/25 | 10.21.113.1 – 10.21.113.126 | 10.21.113.127 |
| 100 | 10.21.113.128/25 | 10.21.113.129 – 10.21.113.254 | 10.21.113.255 |
| 101 | 10.21.114.0/25 | 10.21.114.1 – 10.21.114.126 | 10.21.114.127 |
| 102 | 10.21.114.128/25 | 10.21.114.129 – 10.21.114.254 | 10.21.114.255 |
| 103 | 10.21.115.0/25 | 10.21.115.1 – 10.21.115.126 | 10.21.115.127 |
| 104 | 10.21.115.128/25 | 10.21.115.129 – 10.21.115.254 | 10.21.115.255 |
| 105 | 10.21.116.0/25 | 10.21.116.1 – 10.21.116.126 | 10.21.116.127 |
| 106 | 10.21.116.128/25 | 10.21.116.129 – 10.21.116.254 | 10.21.116.255 |
| 107 | 10.21.117.0/25 | 10.21.117.1 – 10.21.117.126 | 10.21.117.127 |
| 108 | 10.21.117.128/25 | 10.21.117.129 – 10.21.117.254 | 10.21.117.255 |
| 109 | 10.21.118.0/25 | 10.21.118.1 – 10.21.118.126 | 10.21.118.127 |
| 110 | 10.21.118.128/25 | 10.21.118.129 – 10.21.118.254 | 10.21.118.255 |
| 111 | 10.21.119.0/25 | 10.21.119.1 – 10.21.119.126 | 10.21.119.127 |
| 112 | 10.21.119.128/25 | 10.21.119.129 – 10.21.119.254 | 10.21.119.255 |
| 113 | 10.21.120.0/25 | 10.21.120.1 – 10.21.120.126 | 10.21.120.127 |
| 114 | 10.21.120.128/25 | 10.21.120.129 – 10.21.120.254 | 10.21.120.255 |
| 115 | 10.21.121.0/25 | 10.21.121.1 – 10.21.121.126 | 10.21.121.127 |
| 116 | 10.21.121.128/25 | 10.21.121.129 – 10.21.121.254 | 10.21.121.255 |
| 117 | 10.21.122.0/25 | 10.21.122.1 – 10.21.122.126 | 10.21.122.127 |
| 118 | 10.21.122.128/25 | 10.21.122.129 – 10.21.122.254 | 10.21.122.255 |
| 119 | 10.21.123.0/25 | 10.21.123.1 – 10.21.123.126 | 10.21.123.127 |
| 120 | 10.21.123.128/25 | 10.21.123.129 – 10.21.123.254 | 10.21.123.255 |
| 121 | 10.21.124.0/25 | 10.21.124.1 – 10.21.124.126 | 10.21.124.127 |
| 122 | 10.21.124.128/25 | 10.21.124.129 – 10.21.124.254 | 10.21.124.255 |
| 123 | 10.21.125.0/25 | 10.21.125.1 – 10.21.125.126 | 10.21.125.127 |
| 124 | 10.21.125.128/25 | 10.21.125.129 – 10.21.125.254 | 10.21.125.255 |
| 125 | 10.21.126.0/25 | 10.21.126.1 – 10.21.126.126 | 10.21.126.127 |
| 126 | 10.21.126.128/25 | 10.21.126.129 – 10.21.126.254 | 10.21.126.255 |
| 127 | 10.21.127.0/25 | 10.21.127.1 – 10.21.127.126 | 10.21.127.127 |
| 128 | 10.21.127.128/25 | 10.21.127.129 – 10.21.127.254 | 10.21.127.255 |
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 /18 |
|---|---|---|---|---|
| /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 | - |
| /18 | 255.255.192.0 | 16,384 | 16,382 | 1 |
| /19 | 255.255.224.0 | 8,192 | 8,190 | 2 split → |
| /20 | 255.255.240.0 | 4,096 | 4,094 | 4 split → |
| /21 | 255.255.248.0 | 2,048 | 2,046 | 8 split → |
| /22 | 255.255.252.0 | 1,024 | 1,022 | 16 split → |
| /23 | 255.255.254.0 | 512 | 510 | 32 split → |
| /24 | 255.255.255.0 | 256 | 254 | 64 split → |
| /25 | 255.255.255.128 | 128 | 126 | 128 split → |
| /26 | 255.255.255.192 | 64 | 62 | 256 split → |
| /27 | 255.255.255.224 | 32 | 30 | 512 split → |
| /28 | 255.255.255.240 | 16 | 14 | 1,024 split → |
| /29 | 255.255.255.248 | 8 | 6 | 2,048 split → |
| /30 | 255.255.255.252 | 4 | 2 | 4,096 split → |
| /31 | 255.255.255.254 | 2 | 2 | 8,192 split → |
| /32 | 255.255.255.255 | 1 | 1 | 16,384 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.