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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)10.4.168.0/21
network10.4.168.0/21
broadcast10.4.175.255
first host10.4.168.1
last host10.4.175.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.4.168.0/21
address00001010.00000100.10101000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000100.10101000.00000000
broadcast00001010.00000100.10101111.11111111
green = network part, grey = host part
hex0x0a04a800
decimal168077312
reverse dns0.168.4.10.in-addr.arpa
ipv4-mapped::ffff:a04:a800

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.4.168.0/2710.4.168.1 – 10.4.168.3010.4.168.31
210.4.168.32/2710.4.168.33 – 10.4.168.6210.4.168.63
310.4.168.64/2710.4.168.65 – 10.4.168.9410.4.168.95
410.4.168.96/2710.4.168.97 – 10.4.168.12610.4.168.127
510.4.168.128/2710.4.168.129 – 10.4.168.15810.4.168.159
610.4.168.160/2710.4.168.161 – 10.4.168.19010.4.168.191
710.4.168.192/2710.4.168.193 – 10.4.168.22210.4.168.223
810.4.168.224/2710.4.168.225 – 10.4.168.25410.4.168.255
910.4.169.0/2710.4.169.1 – 10.4.169.3010.4.169.31
1010.4.169.32/2710.4.169.33 – 10.4.169.6210.4.169.63
1110.4.169.64/2710.4.169.65 – 10.4.169.9410.4.169.95
1210.4.169.96/2710.4.169.97 – 10.4.169.12610.4.169.127
1310.4.169.128/2710.4.169.129 – 10.4.169.15810.4.169.159
1410.4.169.160/2710.4.169.161 – 10.4.169.19010.4.169.191
1510.4.169.192/2710.4.169.193 – 10.4.169.22210.4.169.223
1610.4.169.224/2710.4.169.225 – 10.4.169.25410.4.169.255
1710.4.170.0/2710.4.170.1 – 10.4.170.3010.4.170.31
1810.4.170.32/2710.4.170.33 – 10.4.170.6210.4.170.63
1910.4.170.64/2710.4.170.65 – 10.4.170.9410.4.170.95
2010.4.170.96/2710.4.170.97 – 10.4.170.12610.4.170.127
2110.4.170.128/2710.4.170.129 – 10.4.170.15810.4.170.159
2210.4.170.160/2710.4.170.161 – 10.4.170.19010.4.170.191
2310.4.170.192/2710.4.170.193 – 10.4.170.22210.4.170.223
2410.4.170.224/2710.4.170.225 – 10.4.170.25410.4.170.255
2510.4.171.0/2710.4.171.1 – 10.4.171.3010.4.171.31
2610.4.171.32/2710.4.171.33 – 10.4.171.6210.4.171.63
2710.4.171.64/2710.4.171.65 – 10.4.171.9410.4.171.95
2810.4.171.96/2710.4.171.97 – 10.4.171.12610.4.171.127
2910.4.171.128/2710.4.171.129 – 10.4.171.15810.4.171.159
3010.4.171.160/2710.4.171.161 – 10.4.171.19010.4.171.191
3110.4.171.192/2710.4.171.193 – 10.4.171.22210.4.171.223
3210.4.171.224/2710.4.171.225 – 10.4.171.25410.4.171.255
3310.4.172.0/2710.4.172.1 – 10.4.172.3010.4.172.31
3410.4.172.32/2710.4.172.33 – 10.4.172.6210.4.172.63
3510.4.172.64/2710.4.172.65 – 10.4.172.9410.4.172.95
3610.4.172.96/2710.4.172.97 – 10.4.172.12610.4.172.127
3710.4.172.128/2710.4.172.129 – 10.4.172.15810.4.172.159
3810.4.172.160/2710.4.172.161 – 10.4.172.19010.4.172.191
3910.4.172.192/2710.4.172.193 – 10.4.172.22210.4.172.223
4010.4.172.224/2710.4.172.225 – 10.4.172.25410.4.172.255
4110.4.173.0/2710.4.173.1 – 10.4.173.3010.4.173.31
4210.4.173.32/2710.4.173.33 – 10.4.173.6210.4.173.63
4310.4.173.64/2710.4.173.65 – 10.4.173.9410.4.173.95
4410.4.173.96/2710.4.173.97 – 10.4.173.12610.4.173.127
4510.4.173.128/2710.4.173.129 – 10.4.173.15810.4.173.159
4610.4.173.160/2710.4.173.161 – 10.4.173.19010.4.173.191
4710.4.173.192/2710.4.173.193 – 10.4.173.22210.4.173.223
4810.4.173.224/2710.4.173.225 – 10.4.173.25410.4.173.255
4910.4.174.0/2710.4.174.1 – 10.4.174.3010.4.174.31
5010.4.174.32/2710.4.174.33 – 10.4.174.6210.4.174.63
5110.4.174.64/2710.4.174.65 – 10.4.174.9410.4.174.95
5210.4.174.96/2710.4.174.97 – 10.4.174.12610.4.174.127
5310.4.174.128/2710.4.174.129 – 10.4.174.15810.4.174.159
5410.4.174.160/2710.4.174.161 – 10.4.174.19010.4.174.191
5510.4.174.192/2710.4.174.193 – 10.4.174.22210.4.174.223
5610.4.174.224/2710.4.174.225 – 10.4.174.25410.4.174.255
5710.4.175.0/2710.4.175.1 – 10.4.175.3010.4.175.31
5810.4.175.32/2710.4.175.33 – 10.4.175.6210.4.175.63
5910.4.175.64/2710.4.175.65 – 10.4.175.9410.4.175.95
6010.4.175.96/2710.4.175.97 – 10.4.175.12610.4.175.127
6110.4.175.128/2710.4.175.129 – 10.4.175.15810.4.175.159
6210.4.175.160/2710.4.175.161 – 10.4.175.19010.4.175.191
6310.4.175.192/2710.4.175.193 – 10.4.175.22210.4.175.223
6410.4.175.224/2710.4.175.225 – 10.4.175.25410.4.175.255
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 →