Broadcast Address Calculator
Enter an IPv4 address and its mask to get the subnet’s broadcast address, the last address of the network. The working is shown in binary: the network address combined with the wildcard mask using a bitwise OR, which sets every host bit to one. The usable host range and network address are shown alongside.
- Runs in your browser
- No sign-up
- Free to use
How to use Broadcast Address Calculator
- Enter an address in the subnet.
- Enter the mask or prefix length.
- Read the broadcast address.
- Check the binary working and the host range.
Broadcast Address Calculator features
Broadcast address
The last address of the subnet.
Binary working
Network OR wildcard, bit by bit.
Host range
First and last usable host.
Edge cases
/31 and /32 explained correctly.
Any notation
Prefix length or dotted mask.
Private
Runs in your browser.
When to use Broadcast Address Calculator
- Configuring interfaces and DHCP scopes.
- Writing firewall rules that exclude broadcasts.
- Diagnosing broadcast-related network issues.
- Subnetting practice.
Broadcast Address Calculator FAQ
What is a broadcast address?
The last address of an IPv4 subnet, with all host bits set to one. Packets sent there reach every host on the subnet.
How is it calculated?
Take the network address and OR it with the wildcard mask (the inverted subnet mask), which sets all host bits to one.
Can I assign the broadcast address to a device?
No, not in normal subnets. In /31 point-to-point links there is no broadcast address and both addresses are usable.
Does IPv6 have broadcast?
No. IPv6 uses multicast instead; the last address of an IPv6 prefix is an ordinary address.
Is 255.255.255.255 the same?
That is the limited broadcast, which never leaves the local network. The subnet broadcast address is specific to each subnet.
Is anything sent?
No.
The address that reaches everyone
In an IPv4 subnet, the address with every host bit set to one is reserved for broadcast. A packet sent to it is delivered to all devices on the subnet, which is how protocols such as DHCP discovery and some legacy services find each other.
The calculation mirrors the network address. Instead of clearing the host bits with AND, the broadcast address sets them all with OR, using the wildcard mask, the inverse of the subnet mask. In binary the operation is immediate; in decimal it trips people up whenever the prefix does not end on an octet boundary.
Knowing the broadcast address matters when configuring interfaces, defining DHCP ranges that must end before it, and writing access lists. It also explains why each IPv4 subnet has two fewer usable addresses than its size.
Two cases are special. On /31 links, defined for point-to-point connections, both addresses are hosts and there is no broadcast. IPv6 dropped broadcast entirely in favour of multicast, so the concept does not apply there.