OmniCalcsAdvertisement
Subnet Calculator (IPv4)
Get the network address, broadcast address, usable host range and CIDR notation for any IPv4 subnet.
Advertisement
How to Use This Calculator
Enter an IP and its prefix length, then calculate. Useful for network planning, DHCP scopes and firewall rules.
- /24 is the classic home-network subnet — 254 usable addresses.
- Two addresses are always reserved: network and broadcast.
Frequently Asked Questions
What is CIDR?
Classless Inter-Domain Routing — the slash notation (e.g. /24) that defines how many bits of the IP identify the network.
Why is usable hosts always minus 2?
The first address in a subnet is the network address and the last is the broadcast address — neither can be assigned to a device.
What is a /24 subnet?
One where 24 bits are the network and 8 bits are hosts: 2⁸ − 2 = 254 usable addresses. Its mask is 255.255.255.0.
Can I calculate IPv6 subnets here?
Not yet. This tool covers IPv4 only. IPv6 uses 128-bit addresses and a similar but separate scheme.
Practical Example
Calculate 192.168.1.35/24:
- Network address:
192.168.1.0 - Broadcast address:
192.168.1.255 - Usable host range:
192.168.1.1to192.168.1.254 - Usable hosts: 2^(32-24) - 2 = 2^8 - 2 = 254, with subnet mask
255.255.255.0
What Your Results Mean
- Network address — the first address in the subnet; it identifies the network and cannot be assigned to a device.
- Broadcast address — the last address, used to reach every host in the subnet at once; also not assignable.
- Usable hosts — total addresses minus the two reserved ones; this is the pool of IPs you can actually hand out.
- CIDR notation —
IP/prefix, where the prefix counts the leading network bits (0-32 for IPv4).
Trusted Sources
Advertisement