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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)10.1.24.0/21
network10.1.24.0/21
broadcast10.1.31.255
first host10.1.24.1
last host10.1.31.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.1.24.0/21
address00001010.00000001.00011000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000001.00011000.00000000
broadcast00001010.00000001.00011111.11111111
green = network part, grey = host part
hex0x0a011800
decimal167843840
reverse dns0.24.1.10.in-addr.arpa
ipv4-mapped::ffff:a01:1800

/21 split into /27 · 64 subnets

close ×
#networkhost rangebroadcast
110.1.24.0/2710.1.24.1 – 10.1.24.3010.1.24.31
210.1.24.32/2710.1.24.33 – 10.1.24.6210.1.24.63
310.1.24.64/2710.1.24.65 – 10.1.24.9410.1.24.95
410.1.24.96/2710.1.24.97 – 10.1.24.12610.1.24.127
510.1.24.128/2710.1.24.129 – 10.1.24.15810.1.24.159
610.1.24.160/2710.1.24.161 – 10.1.24.19010.1.24.191
710.1.24.192/2710.1.24.193 – 10.1.24.22210.1.24.223
810.1.24.224/2710.1.24.225 – 10.1.24.25410.1.24.255
910.1.25.0/2710.1.25.1 – 10.1.25.3010.1.25.31
1010.1.25.32/2710.1.25.33 – 10.1.25.6210.1.25.63
1110.1.25.64/2710.1.25.65 – 10.1.25.9410.1.25.95
1210.1.25.96/2710.1.25.97 – 10.1.25.12610.1.25.127
1310.1.25.128/2710.1.25.129 – 10.1.25.15810.1.25.159
1410.1.25.160/2710.1.25.161 – 10.1.25.19010.1.25.191
1510.1.25.192/2710.1.25.193 – 10.1.25.22210.1.25.223
1610.1.25.224/2710.1.25.225 – 10.1.25.25410.1.25.255
1710.1.26.0/2710.1.26.1 – 10.1.26.3010.1.26.31
1810.1.26.32/2710.1.26.33 – 10.1.26.6210.1.26.63
1910.1.26.64/2710.1.26.65 – 10.1.26.9410.1.26.95
2010.1.26.96/2710.1.26.97 – 10.1.26.12610.1.26.127
2110.1.26.128/2710.1.26.129 – 10.1.26.15810.1.26.159
2210.1.26.160/2710.1.26.161 – 10.1.26.19010.1.26.191
2310.1.26.192/2710.1.26.193 – 10.1.26.22210.1.26.223
2410.1.26.224/2710.1.26.225 – 10.1.26.25410.1.26.255
2510.1.27.0/2710.1.27.1 – 10.1.27.3010.1.27.31
2610.1.27.32/2710.1.27.33 – 10.1.27.6210.1.27.63
2710.1.27.64/2710.1.27.65 – 10.1.27.9410.1.27.95
2810.1.27.96/2710.1.27.97 – 10.1.27.12610.1.27.127
2910.1.27.128/2710.1.27.129 – 10.1.27.15810.1.27.159
3010.1.27.160/2710.1.27.161 – 10.1.27.19010.1.27.191
3110.1.27.192/2710.1.27.193 – 10.1.27.22210.1.27.223
3210.1.27.224/2710.1.27.225 – 10.1.27.25410.1.27.255
3310.1.28.0/2710.1.28.1 – 10.1.28.3010.1.28.31
3410.1.28.32/2710.1.28.33 – 10.1.28.6210.1.28.63
3510.1.28.64/2710.1.28.65 – 10.1.28.9410.1.28.95
3610.1.28.96/2710.1.28.97 – 10.1.28.12610.1.28.127
3710.1.28.128/2710.1.28.129 – 10.1.28.15810.1.28.159
3810.1.28.160/2710.1.28.161 – 10.1.28.19010.1.28.191
3910.1.28.192/2710.1.28.193 – 10.1.28.22210.1.28.223
4010.1.28.224/2710.1.28.225 – 10.1.28.25410.1.28.255
4110.1.29.0/2710.1.29.1 – 10.1.29.3010.1.29.31
4210.1.29.32/2710.1.29.33 – 10.1.29.6210.1.29.63
4310.1.29.64/2710.1.29.65 – 10.1.29.9410.1.29.95
4410.1.29.96/2710.1.29.97 – 10.1.29.12610.1.29.127
4510.1.29.128/2710.1.29.129 – 10.1.29.15810.1.29.159
4610.1.29.160/2710.1.29.161 – 10.1.29.19010.1.29.191
4710.1.29.192/2710.1.29.193 – 10.1.29.22210.1.29.223
4810.1.29.224/2710.1.29.225 – 10.1.29.25410.1.29.255
4910.1.30.0/2710.1.30.1 – 10.1.30.3010.1.30.31
5010.1.30.32/2710.1.30.33 – 10.1.30.6210.1.30.63
5110.1.30.64/2710.1.30.65 – 10.1.30.9410.1.30.95
5210.1.30.96/2710.1.30.97 – 10.1.30.12610.1.30.127
5310.1.30.128/2710.1.30.129 – 10.1.30.15810.1.30.159
5410.1.30.160/2710.1.30.161 – 10.1.30.19010.1.30.191
5510.1.30.192/2710.1.30.193 – 10.1.30.22210.1.30.223
5610.1.30.224/2710.1.30.225 – 10.1.30.25410.1.30.255
5710.1.31.0/2710.1.31.1 – 10.1.31.3010.1.31.31
5810.1.31.32/2710.1.31.33 – 10.1.31.6210.1.31.63
5910.1.31.64/2710.1.31.65 – 10.1.31.9410.1.31.95
6010.1.31.96/2710.1.31.97 – 10.1.31.12610.1.31.127
6110.1.31.128/2710.1.31.129 – 10.1.31.15810.1.31.159
6210.1.31.160/2710.1.31.161 – 10.1.31.19010.1.31.191
6310.1.31.192/2710.1.31.193 – 10.1.31.22210.1.31.223
6410.1.31.224/2710.1.31.225 – 10.1.31.25410.1.31.255
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 →