Subnet Lookup Online

Use this Subnet Calculator to determine the properties of a network subnet. The query can be in a number of forms including network CIDR addresses and IP with network mask.

What is this Subnet Lookup?

When working with networks it is often required to quickly calculate the network boundaries of a subnet from a CIDR address or subnet with network mask. CIDR notation format is a way to express IP addresses and their associated routing prefix. It appends a slash character to the address and the decimal number of leading bits of the routing prefix, e.g., for IPv4, and 2001:db8::/32 for IPv6.

Format of the Subnet to Lookup

Enter the subnet to lookup using one of the following formats.

IPv6 Subnet Lookup

Lookup IPv6 subnets using the same format. Simply enter the IPv6 address and include a CIDR notation.

Here are some examples:

API for the Subnet Calculator

In addition to the web form on this page there is another way to quickly lookup a subnet details. Output is simple and of content type text.

The API is designed to be used in an ad-hoc fashion not for bulk queries and is like all our IP Tools is limited to 50 (total) requests from a single IP Address per day.

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