IP
VLSM Subnet Calculator
Give each segment a name and a host count; the full range for each subnet is calculated for you.
1
Which network do you want to split?
Write the network prefix in slash notation — e.g. 192.168.1.0/24
2
How many subnets do you need?
Enter a number and click "Apply" to set how many rows step 3 has.
3
Name and host count for each subnet
In the right-hand column, enter the segment name (e.g. "Sales"), and in the next column, the number of hosts that segment needs.
Subnet name
Host count
| # | Subnet name | Hosts needed | Network address | CIDR | Subnet mask | First host | Last host | Broadcast | Usable capacity | Wasted |
|---|
Prefix
or mask
Allocation uses the standard VLSM method: the largest subnets are placed first so the least space is wasted. Every subnet sets aside two addresses for the network ID and broadcast, so a segment with 50 hosts needs a
/26 block. To inspect a single CIDR block, use CIDR Calculator.