IPv4 Subnet Calculator

This calculator and tool allows you to type an IP address in and get information on a particular subnet. Enter an IP or range in CIDR notation.

Network: 243.128.0.0/21
Addresses: 2048 (2¹¹)
First IP: 243.128.0.0 (0.0.128.243.in-addr.arpa)
Last IP: 243.128.7.255 (255.7.128.243.in-addr.arpa)

Owned By: IANA (Reserved (Future Use))
/8 Operated By: IANA (Reserved (Future Use))

Related Networks

243.0.0.0/8
242.0.0.0/8
244.0.0.0/8
243.128.0.0/20
243.128.0.0/32
243.128.7.255/32

You can also use some of the other examples such as:

0.0.0.0/0
1.0.0.0/8
127.0.0.1
30.0.0.0/8
192.168.0.0/16