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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)10.3.72.0/21
network10.3.72.0/21
broadcast10.3.79.255
first host10.3.72.1
last host10.3.79.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.3.72.0/21
address00001010.00000011.01001000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000011.01001000.00000000
broadcast00001010.00000011.01001111.11111111
green = network part, grey = host part
hex0x0a034800
decimal167987200
reverse dns0.72.3.10.in-addr.arpa
ipv4-mapped::ffff:a03:4800

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.3.72.0/2710.3.72.1 – 10.3.72.3010.3.72.31
210.3.72.32/2710.3.72.33 – 10.3.72.6210.3.72.63
310.3.72.64/2710.3.72.65 – 10.3.72.9410.3.72.95
410.3.72.96/2710.3.72.97 – 10.3.72.12610.3.72.127
510.3.72.128/2710.3.72.129 – 10.3.72.15810.3.72.159
610.3.72.160/2710.3.72.161 – 10.3.72.19010.3.72.191
710.3.72.192/2710.3.72.193 – 10.3.72.22210.3.72.223
810.3.72.224/2710.3.72.225 – 10.3.72.25410.3.72.255
910.3.73.0/2710.3.73.1 – 10.3.73.3010.3.73.31
1010.3.73.32/2710.3.73.33 – 10.3.73.6210.3.73.63
1110.3.73.64/2710.3.73.65 – 10.3.73.9410.3.73.95
1210.3.73.96/2710.3.73.97 – 10.3.73.12610.3.73.127
1310.3.73.128/2710.3.73.129 – 10.3.73.15810.3.73.159
1410.3.73.160/2710.3.73.161 – 10.3.73.19010.3.73.191
1510.3.73.192/2710.3.73.193 – 10.3.73.22210.3.73.223
1610.3.73.224/2710.3.73.225 – 10.3.73.25410.3.73.255
1710.3.74.0/2710.3.74.1 – 10.3.74.3010.3.74.31
1810.3.74.32/2710.3.74.33 – 10.3.74.6210.3.74.63
1910.3.74.64/2710.3.74.65 – 10.3.74.9410.3.74.95
2010.3.74.96/2710.3.74.97 – 10.3.74.12610.3.74.127
2110.3.74.128/2710.3.74.129 – 10.3.74.15810.3.74.159
2210.3.74.160/2710.3.74.161 – 10.3.74.19010.3.74.191
2310.3.74.192/2710.3.74.193 – 10.3.74.22210.3.74.223
2410.3.74.224/2710.3.74.225 – 10.3.74.25410.3.74.255
2510.3.75.0/2710.3.75.1 – 10.3.75.3010.3.75.31
2610.3.75.32/2710.3.75.33 – 10.3.75.6210.3.75.63
2710.3.75.64/2710.3.75.65 – 10.3.75.9410.3.75.95
2810.3.75.96/2710.3.75.97 – 10.3.75.12610.3.75.127
2910.3.75.128/2710.3.75.129 – 10.3.75.15810.3.75.159
3010.3.75.160/2710.3.75.161 – 10.3.75.19010.3.75.191
3110.3.75.192/2710.3.75.193 – 10.3.75.22210.3.75.223
3210.3.75.224/2710.3.75.225 – 10.3.75.25410.3.75.255
3310.3.76.0/2710.3.76.1 – 10.3.76.3010.3.76.31
3410.3.76.32/2710.3.76.33 – 10.3.76.6210.3.76.63
3510.3.76.64/2710.3.76.65 – 10.3.76.9410.3.76.95
3610.3.76.96/2710.3.76.97 – 10.3.76.12610.3.76.127
3710.3.76.128/2710.3.76.129 – 10.3.76.15810.3.76.159
3810.3.76.160/2710.3.76.161 – 10.3.76.19010.3.76.191
3910.3.76.192/2710.3.76.193 – 10.3.76.22210.3.76.223
4010.3.76.224/2710.3.76.225 – 10.3.76.25410.3.76.255
4110.3.77.0/2710.3.77.1 – 10.3.77.3010.3.77.31
4210.3.77.32/2710.3.77.33 – 10.3.77.6210.3.77.63
4310.3.77.64/2710.3.77.65 – 10.3.77.9410.3.77.95
4410.3.77.96/2710.3.77.97 – 10.3.77.12610.3.77.127
4510.3.77.128/2710.3.77.129 – 10.3.77.15810.3.77.159
4610.3.77.160/2710.3.77.161 – 10.3.77.19010.3.77.191
4710.3.77.192/2710.3.77.193 – 10.3.77.22210.3.77.223
4810.3.77.224/2710.3.77.225 – 10.3.77.25410.3.77.255
4910.3.78.0/2710.3.78.1 – 10.3.78.3010.3.78.31
5010.3.78.32/2710.3.78.33 – 10.3.78.6210.3.78.63
5110.3.78.64/2710.3.78.65 – 10.3.78.9410.3.78.95
5210.3.78.96/2710.3.78.97 – 10.3.78.12610.3.78.127
5310.3.78.128/2710.3.78.129 – 10.3.78.15810.3.78.159
5410.3.78.160/2710.3.78.161 – 10.3.78.19010.3.78.191
5510.3.78.192/2710.3.78.193 – 10.3.78.22210.3.78.223
5610.3.78.224/2710.3.78.225 – 10.3.78.25410.3.78.255
5710.3.79.0/2710.3.79.1 – 10.3.79.3010.3.79.31
5810.3.79.32/2710.3.79.33 – 10.3.79.6210.3.79.63
5910.3.79.64/2710.3.79.65 – 10.3.79.9410.3.79.95
6010.3.79.96/2710.3.79.97 – 10.3.79.12610.3.79.127
6110.3.79.128/2710.3.79.129 – 10.3.79.15810.3.79.159
6210.3.79.160/2710.3.79.161 – 10.3.79.19010.3.79.191
6310.3.79.192/2710.3.79.193 – 10.3.79.22210.3.79.223
6410.3.79.224/2710.3.79.225 – 10.3.79.25410.3.79.255
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 →