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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)10.6.56.0/21
network10.6.56.0/21
broadcast10.6.63.255
first host10.6.56.1
last host10.6.63.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.6.56.0/21
address00001010.00000110.00111000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000110.00111000.00000000
broadcast00001010.00000110.00111111.11111111
green = network part, grey = host part
hex0x0a063800
decimal168179712
reverse dns0.56.6.10.in-addr.arpa
ipv4-mapped::ffff:a06:3800

/21 split into /26 · 32 subnets

close ×
#networkhost rangebroadcast
110.6.56.0/2610.6.56.1 – 10.6.56.6210.6.56.63
210.6.56.64/2610.6.56.65 – 10.6.56.12610.6.56.127
310.6.56.128/2610.6.56.129 – 10.6.56.19010.6.56.191
410.6.56.192/2610.6.56.193 – 10.6.56.25410.6.56.255
510.6.57.0/2610.6.57.1 – 10.6.57.6210.6.57.63
610.6.57.64/2610.6.57.65 – 10.6.57.12610.6.57.127
710.6.57.128/2610.6.57.129 – 10.6.57.19010.6.57.191
810.6.57.192/2610.6.57.193 – 10.6.57.25410.6.57.255
910.6.58.0/2610.6.58.1 – 10.6.58.6210.6.58.63
1010.6.58.64/2610.6.58.65 – 10.6.58.12610.6.58.127
1110.6.58.128/2610.6.58.129 – 10.6.58.19010.6.58.191
1210.6.58.192/2610.6.58.193 – 10.6.58.25410.6.58.255
1310.6.59.0/2610.6.59.1 – 10.6.59.6210.6.59.63
1410.6.59.64/2610.6.59.65 – 10.6.59.12610.6.59.127
1510.6.59.128/2610.6.59.129 – 10.6.59.19010.6.59.191
1610.6.59.192/2610.6.59.193 – 10.6.59.25410.6.59.255
1710.6.60.0/2610.6.60.1 – 10.6.60.6210.6.60.63
1810.6.60.64/2610.6.60.65 – 10.6.60.12610.6.60.127
1910.6.60.128/2610.6.60.129 – 10.6.60.19010.6.60.191
2010.6.60.192/2610.6.60.193 – 10.6.60.25410.6.60.255
2110.6.61.0/2610.6.61.1 – 10.6.61.6210.6.61.63
2210.6.61.64/2610.6.61.65 – 10.6.61.12610.6.61.127
2310.6.61.128/2610.6.61.129 – 10.6.61.19010.6.61.191
2410.6.61.192/2610.6.61.193 – 10.6.61.25410.6.61.255
2510.6.62.0/2610.6.62.1 – 10.6.62.6210.6.62.63
2610.6.62.64/2610.6.62.65 – 10.6.62.12610.6.62.127
2710.6.62.128/2610.6.62.129 – 10.6.62.19010.6.62.191
2810.6.62.192/2610.6.62.193 – 10.6.62.25410.6.62.255
2910.6.63.0/2610.6.63.1 – 10.6.63.6210.6.63.63
3010.6.63.64/2610.6.63.65 – 10.6.63.12610.6.63.127
3110.6.63.128/2610.6.63.129 – 10.6.63.19010.6.63.191
3210.6.63.192/2610.6.63.193 – 10.6.63.25410.6.63.255
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 →