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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.

$ ipcalc
Try:192.168.1.10/2410.0.0.0/8172.16.5.4/20203.0.113.9/29
IPv6 calculator →
private IP (RFC 1918)10.4.120.0/21
network10.4.120.0/21
broadcast10.4.127.255
first host10.4.120.1
last host10.4.127.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.4.120.0/21
address00001010.00000100.01111000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000100.01111000.00000000
broadcast00001010.00000100.01111111.11111111
green = network part, grey = host part
hex0x0a047800
decimal168065024
reverse dns0.120.4.10.in-addr.arpa
ipv4-mapped::ffff:a04:7800

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.4.120.0/2710.4.120.1 – 10.4.120.3010.4.120.31
210.4.120.32/2710.4.120.33 – 10.4.120.6210.4.120.63
310.4.120.64/2710.4.120.65 – 10.4.120.9410.4.120.95
410.4.120.96/2710.4.120.97 – 10.4.120.12610.4.120.127
510.4.120.128/2710.4.120.129 – 10.4.120.15810.4.120.159
610.4.120.160/2710.4.120.161 – 10.4.120.19010.4.120.191
710.4.120.192/2710.4.120.193 – 10.4.120.22210.4.120.223
810.4.120.224/2710.4.120.225 – 10.4.120.25410.4.120.255
910.4.121.0/2710.4.121.1 – 10.4.121.3010.4.121.31
1010.4.121.32/2710.4.121.33 – 10.4.121.6210.4.121.63
1110.4.121.64/2710.4.121.65 – 10.4.121.9410.4.121.95
1210.4.121.96/2710.4.121.97 – 10.4.121.12610.4.121.127
1310.4.121.128/2710.4.121.129 – 10.4.121.15810.4.121.159
1410.4.121.160/2710.4.121.161 – 10.4.121.19010.4.121.191
1510.4.121.192/2710.4.121.193 – 10.4.121.22210.4.121.223
1610.4.121.224/2710.4.121.225 – 10.4.121.25410.4.121.255
1710.4.122.0/2710.4.122.1 – 10.4.122.3010.4.122.31
1810.4.122.32/2710.4.122.33 – 10.4.122.6210.4.122.63
1910.4.122.64/2710.4.122.65 – 10.4.122.9410.4.122.95
2010.4.122.96/2710.4.122.97 – 10.4.122.12610.4.122.127
2110.4.122.128/2710.4.122.129 – 10.4.122.15810.4.122.159
2210.4.122.160/2710.4.122.161 – 10.4.122.19010.4.122.191
2310.4.122.192/2710.4.122.193 – 10.4.122.22210.4.122.223
2410.4.122.224/2710.4.122.225 – 10.4.122.25410.4.122.255
2510.4.123.0/2710.4.123.1 – 10.4.123.3010.4.123.31
2610.4.123.32/2710.4.123.33 – 10.4.123.6210.4.123.63
2710.4.123.64/2710.4.123.65 – 10.4.123.9410.4.123.95
2810.4.123.96/2710.4.123.97 – 10.4.123.12610.4.123.127
2910.4.123.128/2710.4.123.129 – 10.4.123.15810.4.123.159
3010.4.123.160/2710.4.123.161 – 10.4.123.19010.4.123.191
3110.4.123.192/2710.4.123.193 – 10.4.123.22210.4.123.223
3210.4.123.224/2710.4.123.225 – 10.4.123.25410.4.123.255
3310.4.124.0/2710.4.124.1 – 10.4.124.3010.4.124.31
3410.4.124.32/2710.4.124.33 – 10.4.124.6210.4.124.63
3510.4.124.64/2710.4.124.65 – 10.4.124.9410.4.124.95
3610.4.124.96/2710.4.124.97 – 10.4.124.12610.4.124.127
3710.4.124.128/2710.4.124.129 – 10.4.124.15810.4.124.159
3810.4.124.160/2710.4.124.161 – 10.4.124.19010.4.124.191
3910.4.124.192/2710.4.124.193 – 10.4.124.22210.4.124.223
4010.4.124.224/2710.4.124.225 – 10.4.124.25410.4.124.255
4110.4.125.0/2710.4.125.1 – 10.4.125.3010.4.125.31
4210.4.125.32/2710.4.125.33 – 10.4.125.6210.4.125.63
4310.4.125.64/2710.4.125.65 – 10.4.125.9410.4.125.95
4410.4.125.96/2710.4.125.97 – 10.4.125.12610.4.125.127
4510.4.125.128/2710.4.125.129 – 10.4.125.15810.4.125.159
4610.4.125.160/2710.4.125.161 – 10.4.125.19010.4.125.191
4710.4.125.192/2710.4.125.193 – 10.4.125.22210.4.125.223
4810.4.125.224/2710.4.125.225 – 10.4.125.25410.4.125.255
4910.4.126.0/2710.4.126.1 – 10.4.126.3010.4.126.31
5010.4.126.32/2710.4.126.33 – 10.4.126.6210.4.126.63
5110.4.126.64/2710.4.126.65 – 10.4.126.9410.4.126.95
5210.4.126.96/2710.4.126.97 – 10.4.126.12610.4.126.127
5310.4.126.128/2710.4.126.129 – 10.4.126.15810.4.126.159
5410.4.126.160/2710.4.126.161 – 10.4.126.19010.4.126.191
5510.4.126.192/2710.4.126.193 – 10.4.126.22210.4.126.223
5610.4.126.224/2710.4.126.225 – 10.4.126.25410.4.126.255
5710.4.127.0/2710.4.127.1 – 10.4.127.3010.4.127.31
5810.4.127.32/2710.4.127.33 – 10.4.127.6210.4.127.63
5910.4.127.64/2710.4.127.65 – 10.4.127.9410.4.127.95
6010.4.127.96/2710.4.127.97 – 10.4.127.12610.4.127.127
6110.4.127.128/2710.4.127.129 – 10.4.127.15810.4.127.159
6210.4.127.160/2710.4.127.161 – 10.4.127.19010.4.127.191
6310.4.127.192/2710.4.127.193 – 10.4.127.22210.4.127.223
6410.4.127.224/2710.4.127.225 – 10.4.127.25410.4.127.255
01 / table

IPv4 CIDR prefix table.

Click a prefix longer than your network to split it into subnets.

prefixsubnet maskaddresseshostsin your /21
/00.0.0.04,294,967,2964,294,967,294-
/1128.0.0.02,147,483,6482,147,483,646-
/2192.0.0.01,073,741,8241,073,741,822-
/3224.0.0.0536,870,912536,870,910-
/4240.0.0.0268,435,456268,435,454-
/5248.0.0.0134,217,728134,217,726-
/6252.0.0.067,108,86467,108,862-
/7254.0.0.033,554,43233,554,430-
/8255.0.0.016,777,21616,777,214-
/9255.128.0.08,388,6088,388,606-
/10255.192.0.04,194,3044,194,302-
/11255.224.0.02,097,1522,097,150-
/12255.240.0.01,048,5761,048,574-
/13255.248.0.0524,288524,286-
/14255.252.0.0262,144262,142-
/15255.254.0.0131,072131,070-
/16255.255.0.065,53665,534-
/17255.255.128.032,76832,766-
/18255.255.192.016,38416,382-
/19255.255.224.08,1928,190-
/20255.255.240.04,0964,094-
/21255.255.248.02,0482,0461
/22255.255.252.01,0241,0222 split →
/23255.255.254.05125104 split →
/24255.255.255.02562548 split →
/25255.255.255.12812812616 split →
/26255.255.255.192646232 split →
/27255.255.255.224323064 split →
/28255.255.255.2401614128 split →
/29255.255.255.24886256 split →
/30255.255.255.25242512 split →
/31255.255.255.254221,024 split →
/32255.255.255.255112,048 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.

Learn how to work it out →