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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)10.4.208.0/21
network10.4.208.0/21
broadcast10.4.215.255
first host10.4.208.1
last host10.4.215.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.4.208.0/21
address00001010.00000100.11010000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000100.11010000.00000000
broadcast00001010.00000100.11010111.11111111
green = network part, grey = host part
hex0x0a04d000
decimal168087552
reverse dns0.208.4.10.in-addr.arpa
ipv4-mapped::ffff:a04:d000

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.4.208.0/2710.4.208.1 – 10.4.208.3010.4.208.31
210.4.208.32/2710.4.208.33 – 10.4.208.6210.4.208.63
310.4.208.64/2710.4.208.65 – 10.4.208.9410.4.208.95
410.4.208.96/2710.4.208.97 – 10.4.208.12610.4.208.127
510.4.208.128/2710.4.208.129 – 10.4.208.15810.4.208.159
610.4.208.160/2710.4.208.161 – 10.4.208.19010.4.208.191
710.4.208.192/2710.4.208.193 – 10.4.208.22210.4.208.223
810.4.208.224/2710.4.208.225 – 10.4.208.25410.4.208.255
910.4.209.0/2710.4.209.1 – 10.4.209.3010.4.209.31
1010.4.209.32/2710.4.209.33 – 10.4.209.6210.4.209.63
1110.4.209.64/2710.4.209.65 – 10.4.209.9410.4.209.95
1210.4.209.96/2710.4.209.97 – 10.4.209.12610.4.209.127
1310.4.209.128/2710.4.209.129 – 10.4.209.15810.4.209.159
1410.4.209.160/2710.4.209.161 – 10.4.209.19010.4.209.191
1510.4.209.192/2710.4.209.193 – 10.4.209.22210.4.209.223
1610.4.209.224/2710.4.209.225 – 10.4.209.25410.4.209.255
1710.4.210.0/2710.4.210.1 – 10.4.210.3010.4.210.31
1810.4.210.32/2710.4.210.33 – 10.4.210.6210.4.210.63
1910.4.210.64/2710.4.210.65 – 10.4.210.9410.4.210.95
2010.4.210.96/2710.4.210.97 – 10.4.210.12610.4.210.127
2110.4.210.128/2710.4.210.129 – 10.4.210.15810.4.210.159
2210.4.210.160/2710.4.210.161 – 10.4.210.19010.4.210.191
2310.4.210.192/2710.4.210.193 – 10.4.210.22210.4.210.223
2410.4.210.224/2710.4.210.225 – 10.4.210.25410.4.210.255
2510.4.211.0/2710.4.211.1 – 10.4.211.3010.4.211.31
2610.4.211.32/2710.4.211.33 – 10.4.211.6210.4.211.63
2710.4.211.64/2710.4.211.65 – 10.4.211.9410.4.211.95
2810.4.211.96/2710.4.211.97 – 10.4.211.12610.4.211.127
2910.4.211.128/2710.4.211.129 – 10.4.211.15810.4.211.159
3010.4.211.160/2710.4.211.161 – 10.4.211.19010.4.211.191
3110.4.211.192/2710.4.211.193 – 10.4.211.22210.4.211.223
3210.4.211.224/2710.4.211.225 – 10.4.211.25410.4.211.255
3310.4.212.0/2710.4.212.1 – 10.4.212.3010.4.212.31
3410.4.212.32/2710.4.212.33 – 10.4.212.6210.4.212.63
3510.4.212.64/2710.4.212.65 – 10.4.212.9410.4.212.95
3610.4.212.96/2710.4.212.97 – 10.4.212.12610.4.212.127
3710.4.212.128/2710.4.212.129 – 10.4.212.15810.4.212.159
3810.4.212.160/2710.4.212.161 – 10.4.212.19010.4.212.191
3910.4.212.192/2710.4.212.193 – 10.4.212.22210.4.212.223
4010.4.212.224/2710.4.212.225 – 10.4.212.25410.4.212.255
4110.4.213.0/2710.4.213.1 – 10.4.213.3010.4.213.31
4210.4.213.32/2710.4.213.33 – 10.4.213.6210.4.213.63
4310.4.213.64/2710.4.213.65 – 10.4.213.9410.4.213.95
4410.4.213.96/2710.4.213.97 – 10.4.213.12610.4.213.127
4510.4.213.128/2710.4.213.129 – 10.4.213.15810.4.213.159
4610.4.213.160/2710.4.213.161 – 10.4.213.19010.4.213.191
4710.4.213.192/2710.4.213.193 – 10.4.213.22210.4.213.223
4810.4.213.224/2710.4.213.225 – 10.4.213.25410.4.213.255
4910.4.214.0/2710.4.214.1 – 10.4.214.3010.4.214.31
5010.4.214.32/2710.4.214.33 – 10.4.214.6210.4.214.63
5110.4.214.64/2710.4.214.65 – 10.4.214.9410.4.214.95
5210.4.214.96/2710.4.214.97 – 10.4.214.12610.4.214.127
5310.4.214.128/2710.4.214.129 – 10.4.214.15810.4.214.159
5410.4.214.160/2710.4.214.161 – 10.4.214.19010.4.214.191
5510.4.214.192/2710.4.214.193 – 10.4.214.22210.4.214.223
5610.4.214.224/2710.4.214.225 – 10.4.214.25410.4.214.255
5710.4.215.0/2710.4.215.1 – 10.4.215.3010.4.215.31
5810.4.215.32/2710.4.215.33 – 10.4.215.6210.4.215.63
5910.4.215.64/2710.4.215.65 – 10.4.215.9410.4.215.95
6010.4.215.96/2710.4.215.97 – 10.4.215.12610.4.215.127
6110.4.215.128/2710.4.215.129 – 10.4.215.15810.4.215.159
6210.4.215.160/2710.4.215.161 – 10.4.215.19010.4.215.191
6310.4.215.192/2710.4.215.193 – 10.4.215.22210.4.215.223
6410.4.215.224/2710.4.215.225 – 10.4.215.25410.4.215.255
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 →