Last Host Calculator
Find the last usable host address in an IP subnet.
Inputs
Last Usable Host
192.168.10.254
Broadcast Address
192.168.10.255
Prefix
/24
Step by step
Compute broadcast
192.168.10.0 OR NOT(mask)
= 192.168.10.255
Subtract 1 for last host
192.168.10.255 - 1
= 192.168.10.254
How it works
The last usable host address is the broadcast address minus one. The broadcast address (all host bits set to 1) is reserved for subnet-wide communication, so the address just before it is the last one assignable to a host device.
Formula
Last host
last_host = broadcast_address - 1
- broadcast_address
- Network address OR inverse mask
Frequently Asked Questions
Why is the broadcast address not usable?
Packets sent to the broadcast address are delivered to every host on the subnet — assigning it to a specific device would break this fundamental networking mechanism and cause unpredictable behavior.
Is the last host commonly used for anything specific?
Some administrators assign the last usable host to the default gateway by convention (while others use the first). Either is valid — choose one convention and apply it consistently.