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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)10.0.64.0/21
network10.0.64.0/21
broadcast10.0.71.255
first host10.0.64.1
last host10.0.71.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.0.64.0/21
address00001010.00000000.01000000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000000.01000000.00000000
broadcast00001010.00000000.01000111.11111111
green = network part, grey = host part
hex0x0a004000
decimal167788544
reverse dns0.64.0.10.in-addr.arpa
ipv4-mapped::ffff:a00:4000

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.0.64.0/2710.0.64.1 – 10.0.64.3010.0.64.31
210.0.64.32/2710.0.64.33 – 10.0.64.6210.0.64.63
310.0.64.64/2710.0.64.65 – 10.0.64.9410.0.64.95
410.0.64.96/2710.0.64.97 – 10.0.64.12610.0.64.127
510.0.64.128/2710.0.64.129 – 10.0.64.15810.0.64.159
610.0.64.160/2710.0.64.161 – 10.0.64.19010.0.64.191
710.0.64.192/2710.0.64.193 – 10.0.64.22210.0.64.223
810.0.64.224/2710.0.64.225 – 10.0.64.25410.0.64.255
910.0.65.0/2710.0.65.1 – 10.0.65.3010.0.65.31
1010.0.65.32/2710.0.65.33 – 10.0.65.6210.0.65.63
1110.0.65.64/2710.0.65.65 – 10.0.65.9410.0.65.95
1210.0.65.96/2710.0.65.97 – 10.0.65.12610.0.65.127
1310.0.65.128/2710.0.65.129 – 10.0.65.15810.0.65.159
1410.0.65.160/2710.0.65.161 – 10.0.65.19010.0.65.191
1510.0.65.192/2710.0.65.193 – 10.0.65.22210.0.65.223
1610.0.65.224/2710.0.65.225 – 10.0.65.25410.0.65.255
1710.0.66.0/2710.0.66.1 – 10.0.66.3010.0.66.31
1810.0.66.32/2710.0.66.33 – 10.0.66.6210.0.66.63
1910.0.66.64/2710.0.66.65 – 10.0.66.9410.0.66.95
2010.0.66.96/2710.0.66.97 – 10.0.66.12610.0.66.127
2110.0.66.128/2710.0.66.129 – 10.0.66.15810.0.66.159
2210.0.66.160/2710.0.66.161 – 10.0.66.19010.0.66.191
2310.0.66.192/2710.0.66.193 – 10.0.66.22210.0.66.223
2410.0.66.224/2710.0.66.225 – 10.0.66.25410.0.66.255
2510.0.67.0/2710.0.67.1 – 10.0.67.3010.0.67.31
2610.0.67.32/2710.0.67.33 – 10.0.67.6210.0.67.63
2710.0.67.64/2710.0.67.65 – 10.0.67.9410.0.67.95
2810.0.67.96/2710.0.67.97 – 10.0.67.12610.0.67.127
2910.0.67.128/2710.0.67.129 – 10.0.67.15810.0.67.159
3010.0.67.160/2710.0.67.161 – 10.0.67.19010.0.67.191
3110.0.67.192/2710.0.67.193 – 10.0.67.22210.0.67.223
3210.0.67.224/2710.0.67.225 – 10.0.67.25410.0.67.255
3310.0.68.0/2710.0.68.1 – 10.0.68.3010.0.68.31
3410.0.68.32/2710.0.68.33 – 10.0.68.6210.0.68.63
3510.0.68.64/2710.0.68.65 – 10.0.68.9410.0.68.95
3610.0.68.96/2710.0.68.97 – 10.0.68.12610.0.68.127
3710.0.68.128/2710.0.68.129 – 10.0.68.15810.0.68.159
3810.0.68.160/2710.0.68.161 – 10.0.68.19010.0.68.191
3910.0.68.192/2710.0.68.193 – 10.0.68.22210.0.68.223
4010.0.68.224/2710.0.68.225 – 10.0.68.25410.0.68.255
4110.0.69.0/2710.0.69.1 – 10.0.69.3010.0.69.31
4210.0.69.32/2710.0.69.33 – 10.0.69.6210.0.69.63
4310.0.69.64/2710.0.69.65 – 10.0.69.9410.0.69.95
4410.0.69.96/2710.0.69.97 – 10.0.69.12610.0.69.127
4510.0.69.128/2710.0.69.129 – 10.0.69.15810.0.69.159
4610.0.69.160/2710.0.69.161 – 10.0.69.19010.0.69.191
4710.0.69.192/2710.0.69.193 – 10.0.69.22210.0.69.223
4810.0.69.224/2710.0.69.225 – 10.0.69.25410.0.69.255
4910.0.70.0/2710.0.70.1 – 10.0.70.3010.0.70.31
5010.0.70.32/2710.0.70.33 – 10.0.70.6210.0.70.63
5110.0.70.64/2710.0.70.65 – 10.0.70.9410.0.70.95
5210.0.70.96/2710.0.70.97 – 10.0.70.12610.0.70.127
5310.0.70.128/2710.0.70.129 – 10.0.70.15810.0.70.159
5410.0.70.160/2710.0.70.161 – 10.0.70.19010.0.70.191
5510.0.70.192/2710.0.70.193 – 10.0.70.22210.0.70.223
5610.0.70.224/2710.0.70.225 – 10.0.70.25410.0.70.255
5710.0.71.0/2710.0.71.1 – 10.0.71.3010.0.71.31
5810.0.71.32/2710.0.71.33 – 10.0.71.6210.0.71.63
5910.0.71.64/2710.0.71.65 – 10.0.71.9410.0.71.95
6010.0.71.96/2710.0.71.97 – 10.0.71.12610.0.71.127
6110.0.71.128/2710.0.71.129 – 10.0.71.15810.0.71.159
6210.0.71.160/2710.0.71.161 – 10.0.71.19010.0.71.191
6310.0.71.192/2710.0.71.193 – 10.0.71.22210.0.71.223
6410.0.71.224/2710.0.71.225 – 10.0.71.25410.0.71.255
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 →