IP Subnet Calculator
Instantly calculate network address, subnet mask, broadcast, CIDR range, and usable hosts for IPv4 and IPv6 networks.
What is an IP Subnet Calculator?
An IP subnet calculator is a tool used by network engineers, system administrators, and IT professionals to divide an IP network into smaller, more manageable sub-networks (subnets). By entering an IP address and a prefix length (CIDR notation), the calculator instantly returns the network address, broadcast address, subnet mask, usable host range, and total number of addresses.
Why is subnetting important?
Subnetting improves network performance by reducing broadcast traffic, enhances security by isolating network segments, and allows efficient use of IP address space. It is a fundamental skill for anyone working with TCP/IP networks, whether on-premise or in cloud environments like AWS, Azure, and GCP.
How to use CIDR notation
CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its network prefix together, for example 192.168.1.0/24. The number after the slash (/24) tells you how many bits are reserved for the network. The remaining bits are available for host addresses.
Frequently Asked Questions
What is a subnet mask?
A subnet mask is a 32-bit number that separates the network portion of an IP address from the host portion. For example, the subnet mask 255.255.255.0 (or /24 in CIDR) means the first 24 bits identify the network and the last 8 bits identify hosts within that network.
What does /24 mean in networking?
A /24 prefix means 24 out of 32 bits are used for the network address. This leaves 8 bits for host addresses, allowing for 256 total IPs — of which 254 are usable (the first is the network address and the last is the broadcast address). The subnet mask for /24 is 255.255.255.0.
What is the difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses and supports approximately 4.3 billion unique addresses. IPv6 uses 128-bit addresses, providing an astronomically larger address space (340 undecillion addresses). IPv6 also eliminates the need for NAT, simplifies routing, and includes built-in security features.
How many usable hosts are in a /24 subnet?
A /24 subnet contains 256 IP addresses total. Of these, 254 are usable for hosts — the network address (first IP) and broadcast address (last IP) are reserved and cannot be assigned to devices.
What is a broadcast address?
The broadcast address is the last IP address in a subnet. Packets sent to this address are received by all hosts in the subnet. It is always reserved and cannot be assigned to a device. For a /24 network like 192.168.1.0, the broadcast address is 192.168.1.255.