IP Subnet Calculator
Calculate the network address, broadcast address, subnet mask and usable host range from an IPv4 address and CIDR prefix length.
Small LAN
A /24 network provides 254 usable host addresses — that puts it in the "Small LAN" range of subnet sizes.
- Broadcast Address192.168.1.255
- Subnet Mask255.255.255.0
- Usable Host Range192.168.1.1 – 192.168.1.254
- Usable Hosts254
About the IP Subnet Calculator
Given an IP address and a CIDR prefix like /24, the practical questions that follow are always the same: what's the network address, what's the broadcast address, and how many actual devices can I put on this network? Those aren't things you read off the IP address directly — they come from applying the subnet mask, which is exactly what this calculator works out.
It's aimed at the people who need this regularly: network engineers and sysadmins planning IP address ranges, students working through CCNA or Network+ material where subnetting is a core skill, and anyone setting up a home lab, VLAN, or router configuration who needs to know whether a given block of addresses is big enough for the devices going on it.
Enter any IPv4 address and a prefix from /0 to /32, and it returns the network address, broadcast address, dotted-decimal subnet mask, and the usable host range in one pass — the numbers you'd otherwise work out by converting to binary and masking by hand.
How it’s calculated
The CIDR prefix determines how many leading bits of the 32-bit address are the "network" portion versus the "host" portion — a /24 fixes the first 24 bits as network, leaving 8 bits (256 addresses) for hosts. The subnet mask is just that split expressed in dotted-decimal form: /24 is 255.255.255.0.
The network address is found by applying a bitwise AND between the IP address and the subnet mask, which zeroes out the host bits. The broadcast address flips the host bits to all 1s instead, giving the highest address in the range. Two addresses in every subnet are reserved this way — the network address and the broadcast address — so the usable host count is the total address space minus 2 (except for /31 and /32, which use special conventions with no reserved addresses).
Frequently asked questions
What's the difference between the network address and broadcast address?
The network address is the lowest address in the subnet (all host bits set to 0) and identifies the subnet itself rather than any device on it. The broadcast address is the highest address (all host bits set to 1) and is used to send a packet to every device on that subnet at once. Neither is assignable to an individual device.
How many usable hosts does a /24 network provide?
A /24 has 256 total addresses, minus 2 reserved for the network and broadcast addresses, leaving 254 usable host addresses — the classic setup behind a typical 192.168.1.0/24 home or small-office network.
What does the CIDR notation /24 actually mean?
It means the first 24 bits of the 32-bit IPv4 address are fixed as the network portion, leaving the remaining 8 bits available for host addresses — equivalent to a 255.255.255.0 subnet mask.
Why are 2 addresses always subtracted from the total for usable hosts?
Every subnet reserves its lowest address as the network address and its highest as the broadcast address — neither can be assigned to a device — so usable hosts is always the total address count minus those two, except at /31 and /32 where special rules apply for point-to-point links and single hosts.
What's a subnet mask, and how does it relate to CIDR notation?
A subnet mask is the dotted-decimal form of the same information a CIDR prefix conveys — both mark where the network portion of an address ends and the host portion begins; /24 and 255.255.255.0 describe the identical subnet.
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