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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)10.0.240.0/21
network10.0.240.0/21
broadcast10.0.247.255
first host10.0.240.1
last host10.0.247.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.0.240.0/21
address00001010.00000000.11110000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000000.11110000.00000000
broadcast00001010.00000000.11110111.11111111
green = network part, grey = host part
hex0x0a00f000
decimal167833600
reverse dns0.240.0.10.in-addr.arpa
ipv4-mapped::ffff:a00:f000

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.0.240.0/2710.0.240.1 – 10.0.240.3010.0.240.31
210.0.240.32/2710.0.240.33 – 10.0.240.6210.0.240.63
310.0.240.64/2710.0.240.65 – 10.0.240.9410.0.240.95
410.0.240.96/2710.0.240.97 – 10.0.240.12610.0.240.127
510.0.240.128/2710.0.240.129 – 10.0.240.15810.0.240.159
610.0.240.160/2710.0.240.161 – 10.0.240.19010.0.240.191
710.0.240.192/2710.0.240.193 – 10.0.240.22210.0.240.223
810.0.240.224/2710.0.240.225 – 10.0.240.25410.0.240.255
910.0.241.0/2710.0.241.1 – 10.0.241.3010.0.241.31
1010.0.241.32/2710.0.241.33 – 10.0.241.6210.0.241.63
1110.0.241.64/2710.0.241.65 – 10.0.241.9410.0.241.95
1210.0.241.96/2710.0.241.97 – 10.0.241.12610.0.241.127
1310.0.241.128/2710.0.241.129 – 10.0.241.15810.0.241.159
1410.0.241.160/2710.0.241.161 – 10.0.241.19010.0.241.191
1510.0.241.192/2710.0.241.193 – 10.0.241.22210.0.241.223
1610.0.241.224/2710.0.241.225 – 10.0.241.25410.0.241.255
1710.0.242.0/2710.0.242.1 – 10.0.242.3010.0.242.31
1810.0.242.32/2710.0.242.33 – 10.0.242.6210.0.242.63
1910.0.242.64/2710.0.242.65 – 10.0.242.9410.0.242.95
2010.0.242.96/2710.0.242.97 – 10.0.242.12610.0.242.127
2110.0.242.128/2710.0.242.129 – 10.0.242.15810.0.242.159
2210.0.242.160/2710.0.242.161 – 10.0.242.19010.0.242.191
2310.0.242.192/2710.0.242.193 – 10.0.242.22210.0.242.223
2410.0.242.224/2710.0.242.225 – 10.0.242.25410.0.242.255
2510.0.243.0/2710.0.243.1 – 10.0.243.3010.0.243.31
2610.0.243.32/2710.0.243.33 – 10.0.243.6210.0.243.63
2710.0.243.64/2710.0.243.65 – 10.0.243.9410.0.243.95
2810.0.243.96/2710.0.243.97 – 10.0.243.12610.0.243.127
2910.0.243.128/2710.0.243.129 – 10.0.243.15810.0.243.159
3010.0.243.160/2710.0.243.161 – 10.0.243.19010.0.243.191
3110.0.243.192/2710.0.243.193 – 10.0.243.22210.0.243.223
3210.0.243.224/2710.0.243.225 – 10.0.243.25410.0.243.255
3310.0.244.0/2710.0.244.1 – 10.0.244.3010.0.244.31
3410.0.244.32/2710.0.244.33 – 10.0.244.6210.0.244.63
3510.0.244.64/2710.0.244.65 – 10.0.244.9410.0.244.95
3610.0.244.96/2710.0.244.97 – 10.0.244.12610.0.244.127
3710.0.244.128/2710.0.244.129 – 10.0.244.15810.0.244.159
3810.0.244.160/2710.0.244.161 – 10.0.244.19010.0.244.191
3910.0.244.192/2710.0.244.193 – 10.0.244.22210.0.244.223
4010.0.244.224/2710.0.244.225 – 10.0.244.25410.0.244.255
4110.0.245.0/2710.0.245.1 – 10.0.245.3010.0.245.31
4210.0.245.32/2710.0.245.33 – 10.0.245.6210.0.245.63
4310.0.245.64/2710.0.245.65 – 10.0.245.9410.0.245.95
4410.0.245.96/2710.0.245.97 – 10.0.245.12610.0.245.127
4510.0.245.128/2710.0.245.129 – 10.0.245.15810.0.245.159
4610.0.245.160/2710.0.245.161 – 10.0.245.19010.0.245.191
4710.0.245.192/2710.0.245.193 – 10.0.245.22210.0.245.223
4810.0.245.224/2710.0.245.225 – 10.0.245.25410.0.245.255
4910.0.246.0/2710.0.246.1 – 10.0.246.3010.0.246.31
5010.0.246.32/2710.0.246.33 – 10.0.246.6210.0.246.63
5110.0.246.64/2710.0.246.65 – 10.0.246.9410.0.246.95
5210.0.246.96/2710.0.246.97 – 10.0.246.12610.0.246.127
5310.0.246.128/2710.0.246.129 – 10.0.246.15810.0.246.159
5410.0.246.160/2710.0.246.161 – 10.0.246.19010.0.246.191
5510.0.246.192/2710.0.246.193 – 10.0.246.22210.0.246.223
5610.0.246.224/2710.0.246.225 – 10.0.246.25410.0.246.255
5710.0.247.0/2710.0.247.1 – 10.0.247.3010.0.247.31
5810.0.247.32/2710.0.247.33 – 10.0.247.6210.0.247.63
5910.0.247.64/2710.0.247.65 – 10.0.247.9410.0.247.95
6010.0.247.96/2710.0.247.97 – 10.0.247.12610.0.247.127
6110.0.247.128/2710.0.247.129 – 10.0.247.15810.0.247.159
6210.0.247.160/2710.0.247.161 – 10.0.247.19010.0.247.191
6310.0.247.192/2710.0.247.193 – 10.0.247.22210.0.247.223
6410.0.247.224/2710.0.247.225 – 10.0.247.25410.0.247.255
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 →