IPCalc

We definitely cannot live without IP Addresses in the Networking world. But when it comes to calculations on IP Addresses; It is a headache. Finding subnet masks, wildcard mask, network address, subnetting; It is a total disaster.​ Don't you worry. IPCalc will do the job for you. Whether your problem is class-full IP or a classless IP or--

ARE YOU LAZY TO CREATE SUBNETS FROM A IP BLOCK?
Yeah no worries IPCalc will do it for you.

Key Features:
Class-full -
You can find relevant IP class, subnet mask, wildcard mask, network address, broadcast address and no of hosts for a given class-full IP address.

CIDR -
You can find subnet mask, wildcard mask, network address, broadcast address and no of hosts for a given classless IP address.

Subnetting -
You can find new subnet mask, new wildcard mask, no of host/subnet bits and required subnets for a given IP block to break-down.