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)10.4.240.0/21
network10.4.240.0/21
broadcast10.4.247.255
first host10.4.240.1
last host10.4.247.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.4.240.0/21
address00001010.00000100.11110000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000100.11110000.00000000
broadcast00001010.00000100.11110111.11111111
green = network part, grey = host part
hex0x0a04f000
decimal168095744
reverse dns0.240.4.10.in-addr.arpa
ipv4-mapped::ffff:a04:f000
/21 split into /28 · 128 subnets
close ×| # | network | host range | broadcast |
|---|---|---|---|
| 1 | 10.4.240.0/28 | 10.4.240.1 – 10.4.240.14 | 10.4.240.15 |
| 2 | 10.4.240.16/28 | 10.4.240.17 – 10.4.240.30 | 10.4.240.31 |
| 3 | 10.4.240.32/28 | 10.4.240.33 – 10.4.240.46 | 10.4.240.47 |
| 4 | 10.4.240.48/28 | 10.4.240.49 – 10.4.240.62 | 10.4.240.63 |
| 5 | 10.4.240.64/28 | 10.4.240.65 – 10.4.240.78 | 10.4.240.79 |
| 6 | 10.4.240.80/28 | 10.4.240.81 – 10.4.240.94 | 10.4.240.95 |
| 7 | 10.4.240.96/28 | 10.4.240.97 – 10.4.240.110 | 10.4.240.111 |
| 8 | 10.4.240.112/28 | 10.4.240.113 – 10.4.240.126 | 10.4.240.127 |
| 9 | 10.4.240.128/28 | 10.4.240.129 – 10.4.240.142 | 10.4.240.143 |
| 10 | 10.4.240.144/28 | 10.4.240.145 – 10.4.240.158 | 10.4.240.159 |
| 11 | 10.4.240.160/28 | 10.4.240.161 – 10.4.240.174 | 10.4.240.175 |
| 12 | 10.4.240.176/28 | 10.4.240.177 – 10.4.240.190 | 10.4.240.191 |
| 13 | 10.4.240.192/28 | 10.4.240.193 – 10.4.240.206 | 10.4.240.207 |
| 14 | 10.4.240.208/28 | 10.4.240.209 – 10.4.240.222 | 10.4.240.223 |
| 15 | 10.4.240.224/28 | 10.4.240.225 – 10.4.240.238 | 10.4.240.239 |
| 16 | 10.4.240.240/28 | 10.4.240.241 – 10.4.240.254 | 10.4.240.255 |
| 17 | 10.4.241.0/28 | 10.4.241.1 – 10.4.241.14 | 10.4.241.15 |
| 18 | 10.4.241.16/28 | 10.4.241.17 – 10.4.241.30 | 10.4.241.31 |
| 19 | 10.4.241.32/28 | 10.4.241.33 – 10.4.241.46 | 10.4.241.47 |
| 20 | 10.4.241.48/28 | 10.4.241.49 – 10.4.241.62 | 10.4.241.63 |
| 21 | 10.4.241.64/28 | 10.4.241.65 – 10.4.241.78 | 10.4.241.79 |
| 22 | 10.4.241.80/28 | 10.4.241.81 – 10.4.241.94 | 10.4.241.95 |
| 23 | 10.4.241.96/28 | 10.4.241.97 – 10.4.241.110 | 10.4.241.111 |
| 24 | 10.4.241.112/28 | 10.4.241.113 – 10.4.241.126 | 10.4.241.127 |
| 25 | 10.4.241.128/28 | 10.4.241.129 – 10.4.241.142 | 10.4.241.143 |
| 26 | 10.4.241.144/28 | 10.4.241.145 – 10.4.241.158 | 10.4.241.159 |
| 27 | 10.4.241.160/28 | 10.4.241.161 – 10.4.241.174 | 10.4.241.175 |
| 28 | 10.4.241.176/28 | 10.4.241.177 – 10.4.241.190 | 10.4.241.191 |
| 29 | 10.4.241.192/28 | 10.4.241.193 – 10.4.241.206 | 10.4.241.207 |
| 30 | 10.4.241.208/28 | 10.4.241.209 – 10.4.241.222 | 10.4.241.223 |
| 31 | 10.4.241.224/28 | 10.4.241.225 – 10.4.241.238 | 10.4.241.239 |
| 32 | 10.4.241.240/28 | 10.4.241.241 – 10.4.241.254 | 10.4.241.255 |
| 33 | 10.4.242.0/28 | 10.4.242.1 – 10.4.242.14 | 10.4.242.15 |
| 34 | 10.4.242.16/28 | 10.4.242.17 – 10.4.242.30 | 10.4.242.31 |
| 35 | 10.4.242.32/28 | 10.4.242.33 – 10.4.242.46 | 10.4.242.47 |
| 36 | 10.4.242.48/28 | 10.4.242.49 – 10.4.242.62 | 10.4.242.63 |
| 37 | 10.4.242.64/28 | 10.4.242.65 – 10.4.242.78 | 10.4.242.79 |
| 38 | 10.4.242.80/28 | 10.4.242.81 – 10.4.242.94 | 10.4.242.95 |
| 39 | 10.4.242.96/28 | 10.4.242.97 – 10.4.242.110 | 10.4.242.111 |
| 40 | 10.4.242.112/28 | 10.4.242.113 – 10.4.242.126 | 10.4.242.127 |
| 41 | 10.4.242.128/28 | 10.4.242.129 – 10.4.242.142 | 10.4.242.143 |
| 42 | 10.4.242.144/28 | 10.4.242.145 – 10.4.242.158 | 10.4.242.159 |
| 43 | 10.4.242.160/28 | 10.4.242.161 – 10.4.242.174 | 10.4.242.175 |
| 44 | 10.4.242.176/28 | 10.4.242.177 – 10.4.242.190 | 10.4.242.191 |
| 45 | 10.4.242.192/28 | 10.4.242.193 – 10.4.242.206 | 10.4.242.207 |
| 46 | 10.4.242.208/28 | 10.4.242.209 – 10.4.242.222 | 10.4.242.223 |
| 47 | 10.4.242.224/28 | 10.4.242.225 – 10.4.242.238 | 10.4.242.239 |
| 48 | 10.4.242.240/28 | 10.4.242.241 – 10.4.242.254 | 10.4.242.255 |
| 49 | 10.4.243.0/28 | 10.4.243.1 – 10.4.243.14 | 10.4.243.15 |
| 50 | 10.4.243.16/28 | 10.4.243.17 – 10.4.243.30 | 10.4.243.31 |
| 51 | 10.4.243.32/28 | 10.4.243.33 – 10.4.243.46 | 10.4.243.47 |
| 52 | 10.4.243.48/28 | 10.4.243.49 – 10.4.243.62 | 10.4.243.63 |
| 53 | 10.4.243.64/28 | 10.4.243.65 – 10.4.243.78 | 10.4.243.79 |
| 54 | 10.4.243.80/28 | 10.4.243.81 – 10.4.243.94 | 10.4.243.95 |
| 55 | 10.4.243.96/28 | 10.4.243.97 – 10.4.243.110 | 10.4.243.111 |
| 56 | 10.4.243.112/28 | 10.4.243.113 – 10.4.243.126 | 10.4.243.127 |
| 57 | 10.4.243.128/28 | 10.4.243.129 – 10.4.243.142 | 10.4.243.143 |
| 58 | 10.4.243.144/28 | 10.4.243.145 – 10.4.243.158 | 10.4.243.159 |
| 59 | 10.4.243.160/28 | 10.4.243.161 – 10.4.243.174 | 10.4.243.175 |
| 60 | 10.4.243.176/28 | 10.4.243.177 – 10.4.243.190 | 10.4.243.191 |
| 61 | 10.4.243.192/28 | 10.4.243.193 – 10.4.243.206 | 10.4.243.207 |
| 62 | 10.4.243.208/28 | 10.4.243.209 – 10.4.243.222 | 10.4.243.223 |
| 63 | 10.4.243.224/28 | 10.4.243.225 – 10.4.243.238 | 10.4.243.239 |
| 64 | 10.4.243.240/28 | 10.4.243.241 – 10.4.243.254 | 10.4.243.255 |
| 65 | 10.4.244.0/28 | 10.4.244.1 – 10.4.244.14 | 10.4.244.15 |
| 66 | 10.4.244.16/28 | 10.4.244.17 – 10.4.244.30 | 10.4.244.31 |
| 67 | 10.4.244.32/28 | 10.4.244.33 – 10.4.244.46 | 10.4.244.47 |
| 68 | 10.4.244.48/28 | 10.4.244.49 – 10.4.244.62 | 10.4.244.63 |
| 69 | 10.4.244.64/28 | 10.4.244.65 – 10.4.244.78 | 10.4.244.79 |
| 70 | 10.4.244.80/28 | 10.4.244.81 – 10.4.244.94 | 10.4.244.95 |
| 71 | 10.4.244.96/28 | 10.4.244.97 – 10.4.244.110 | 10.4.244.111 |
| 72 | 10.4.244.112/28 | 10.4.244.113 – 10.4.244.126 | 10.4.244.127 |
| 73 | 10.4.244.128/28 | 10.4.244.129 – 10.4.244.142 | 10.4.244.143 |
| 74 | 10.4.244.144/28 | 10.4.244.145 – 10.4.244.158 | 10.4.244.159 |
| 75 | 10.4.244.160/28 | 10.4.244.161 – 10.4.244.174 | 10.4.244.175 |
| 76 | 10.4.244.176/28 | 10.4.244.177 – 10.4.244.190 | 10.4.244.191 |
| 77 | 10.4.244.192/28 | 10.4.244.193 – 10.4.244.206 | 10.4.244.207 |
| 78 | 10.4.244.208/28 | 10.4.244.209 – 10.4.244.222 | 10.4.244.223 |
| 79 | 10.4.244.224/28 | 10.4.244.225 – 10.4.244.238 | 10.4.244.239 |
| 80 | 10.4.244.240/28 | 10.4.244.241 – 10.4.244.254 | 10.4.244.255 |
| 81 | 10.4.245.0/28 | 10.4.245.1 – 10.4.245.14 | 10.4.245.15 |
| 82 | 10.4.245.16/28 | 10.4.245.17 – 10.4.245.30 | 10.4.245.31 |
| 83 | 10.4.245.32/28 | 10.4.245.33 – 10.4.245.46 | 10.4.245.47 |
| 84 | 10.4.245.48/28 | 10.4.245.49 – 10.4.245.62 | 10.4.245.63 |
| 85 | 10.4.245.64/28 | 10.4.245.65 – 10.4.245.78 | 10.4.245.79 |
| 86 | 10.4.245.80/28 | 10.4.245.81 – 10.4.245.94 | 10.4.245.95 |
| 87 | 10.4.245.96/28 | 10.4.245.97 – 10.4.245.110 | 10.4.245.111 |
| 88 | 10.4.245.112/28 | 10.4.245.113 – 10.4.245.126 | 10.4.245.127 |
| 89 | 10.4.245.128/28 | 10.4.245.129 – 10.4.245.142 | 10.4.245.143 |
| 90 | 10.4.245.144/28 | 10.4.245.145 – 10.4.245.158 | 10.4.245.159 |
| 91 | 10.4.245.160/28 | 10.4.245.161 – 10.4.245.174 | 10.4.245.175 |
| 92 | 10.4.245.176/28 | 10.4.245.177 – 10.4.245.190 | 10.4.245.191 |
| 93 | 10.4.245.192/28 | 10.4.245.193 – 10.4.245.206 | 10.4.245.207 |
| 94 | 10.4.245.208/28 | 10.4.245.209 – 10.4.245.222 | 10.4.245.223 |
| 95 | 10.4.245.224/28 | 10.4.245.225 – 10.4.245.238 | 10.4.245.239 |
| 96 | 10.4.245.240/28 | 10.4.245.241 – 10.4.245.254 | 10.4.245.255 |
| 97 | 10.4.246.0/28 | 10.4.246.1 – 10.4.246.14 | 10.4.246.15 |
| 98 | 10.4.246.16/28 | 10.4.246.17 – 10.4.246.30 | 10.4.246.31 |
| 99 | 10.4.246.32/28 | 10.4.246.33 – 10.4.246.46 | 10.4.246.47 |
| 100 | 10.4.246.48/28 | 10.4.246.49 – 10.4.246.62 | 10.4.246.63 |
| 101 | 10.4.246.64/28 | 10.4.246.65 – 10.4.246.78 | 10.4.246.79 |
| 102 | 10.4.246.80/28 | 10.4.246.81 – 10.4.246.94 | 10.4.246.95 |
| 103 | 10.4.246.96/28 | 10.4.246.97 – 10.4.246.110 | 10.4.246.111 |
| 104 | 10.4.246.112/28 | 10.4.246.113 – 10.4.246.126 | 10.4.246.127 |
| 105 | 10.4.246.128/28 | 10.4.246.129 – 10.4.246.142 | 10.4.246.143 |
| 106 | 10.4.246.144/28 | 10.4.246.145 – 10.4.246.158 | 10.4.246.159 |
| 107 | 10.4.246.160/28 | 10.4.246.161 – 10.4.246.174 | 10.4.246.175 |
| 108 | 10.4.246.176/28 | 10.4.246.177 – 10.4.246.190 | 10.4.246.191 |
| 109 | 10.4.246.192/28 | 10.4.246.193 – 10.4.246.206 | 10.4.246.207 |
| 110 | 10.4.246.208/28 | 10.4.246.209 – 10.4.246.222 | 10.4.246.223 |
| 111 | 10.4.246.224/28 | 10.4.246.225 – 10.4.246.238 | 10.4.246.239 |
| 112 | 10.4.246.240/28 | 10.4.246.241 – 10.4.246.254 | 10.4.246.255 |
| 113 | 10.4.247.0/28 | 10.4.247.1 – 10.4.247.14 | 10.4.247.15 |
| 114 | 10.4.247.16/28 | 10.4.247.17 – 10.4.247.30 | 10.4.247.31 |
| 115 | 10.4.247.32/28 | 10.4.247.33 – 10.4.247.46 | 10.4.247.47 |
| 116 | 10.4.247.48/28 | 10.4.247.49 – 10.4.247.62 | 10.4.247.63 |
| 117 | 10.4.247.64/28 | 10.4.247.65 – 10.4.247.78 | 10.4.247.79 |
| 118 | 10.4.247.80/28 | 10.4.247.81 – 10.4.247.94 | 10.4.247.95 |
| 119 | 10.4.247.96/28 | 10.4.247.97 – 10.4.247.110 | 10.4.247.111 |
| 120 | 10.4.247.112/28 | 10.4.247.113 – 10.4.247.126 | 10.4.247.127 |
| 121 | 10.4.247.128/28 | 10.4.247.129 – 10.4.247.142 | 10.4.247.143 |
| 122 | 10.4.247.144/28 | 10.4.247.145 – 10.4.247.158 | 10.4.247.159 |
| 123 | 10.4.247.160/28 | 10.4.247.161 – 10.4.247.174 | 10.4.247.175 |
| 124 | 10.4.247.176/28 | 10.4.247.177 – 10.4.247.190 | 10.4.247.191 |
| 125 | 10.4.247.192/28 | 10.4.247.193 – 10.4.247.206 | 10.4.247.207 |
| 126 | 10.4.247.208/28 | 10.4.247.209 – 10.4.247.222 | 10.4.247.223 |
| 127 | 10.4.247.224/28 | 10.4.247.225 – 10.4.247.238 | 10.4.247.239 |
| 128 | 10.4.247.240/28 | 10.4.247.241 – 10.4.247.254 | 10.4.247.255 |
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 /21 |
|---|---|---|---|---|
| /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 | - |
| /19 | 255.255.224.0 | 8,192 | 8,190 | - |
| /20 | 255.255.240.0 | 4,096 | 4,094 | - |
| /21 | 255.255.248.0 | 2,048 | 2,046 | 1 |
| /22 | 255.255.252.0 | 1,024 | 1,022 | 2 split → |
| /23 | 255.255.254.0 | 512 | 510 | 4 split → |
| /24 | 255.255.255.0 | 256 | 254 | 8 split → |
| /25 | 255.255.255.128 | 128 | 126 | 16 split → |
| /26 | 255.255.255.192 | 64 | 62 | 32 split → |
| /27 | 255.255.255.224 | 32 | 30 | 64 split → |
| /28 | 255.255.255.240 | 16 | 14 | 128 split → |
| /29 | 255.255.255.248 | 8 | 6 | 256 split → |
| /30 | 255.255.255.252 | 4 | 2 | 512 split → |
| /31 | 255.255.255.254 | 2 | 2 | 1,024 split → |
| /32 | 255.255.255.255 | 1 | 1 | 2,048 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.