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: 12.0.3.128/31
Addresses: 2 (2¹)
First IP: 12.0.3.128 (128.3.0.12.in-addr.arpa)
Last IP: 12.0.3.129 (129.3.0.12.in-addr.arpa)

/8 Operated By: AT&T Bell Laboratories

Related Networks

12.0.0.0/8
11.0.0.0/8
13.0.0.0/8
12.0.3.128/30
12.0.3.128/32
12.0.3.129/32

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