VLSM Calculator allows you to calculate in one click the number of IPv4 addresses and subnets needed for your business without wasting IPv4 addresses.

To split a network into several subnets, you just need to know the number of subnets and a given network address.

Then fill in the forms below with the required information step by step and click on calculate. By default, the calculator gives you four subnets, but you can increase or decrease in Step 2.

Step 1 :
What is the starting network that you would like to divide into smaller subnets?
For example :

Step 2:
How many subnets do you need?
Enter a value then click on ‘Change’
Step 3:
In the left column, enter a name for each subnet (Example: GRH Department)
In the right column, enter the number of hosts that will be in each subnet

Subnet names: Hosts numbers:

This VLSM Calculator is used by network administrators or engineers to quickly calculate subnets! On the other hand, if you are studying for the CCNA exam or other network certifications, it is best for you to master the calculation methods by yourself. Read here the methods to calculate the subnets.

It is also for the exercises on VLSM calculations (Corrected exercise).

Subnetwork calculator