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Subnet Calculator

Calculate network address, broadcast address, subnet mask, and usable hosts for any IP/CIDR.

Common CIDR Reference

CIDRSubnet MaskAddressesUsable HostsClass
/8255.0.0.016,777,21616,777,214A
/16255.255.0.065,53665,534B
/24255.255.255.0256254C
/25255.255.255.128128126-
/26255.255.255.1926462-
/28255.255.255.2401614-
/30255.255.255.25242-
/32255.255.255.25511-

How to Use This Subnet Calculator

Step 1 — Enter an IP Address with CIDR: Type any IPv4 address followed by a slash and the prefix length, for example 192.168.1.0/24. If you omit the CIDR notation, the calculator defaults to /24. You can also click the quick CIDR buttons (/8, /16, /24, etc.) for common subnet sizes.

Step 2 — Click Calculate: The tool instantly computes the network address, broadcast address, subnet mask, wildcard mask, total addresses, usable hosts, first and last host addresses, and the IP class. A binary breakdown shows which bits belong to the network portion versus the host portion.

Step 3 — Review Results: The results grid displays all computed values at a glance. Accent-colored values highlight the most important results. The IP Range section shows the full network range and usable host range. Use the Common CIDR Reference table below for quick lookups of frequently used subnet sizes.

Tips: When designing networks, plan for growth by choosing a CIDR that provides more hosts than you currently need. A /24 (254 hosts) is standard for small office networks, while /16 (65,534 hosts) suits large enterprise environments. Remember that /31 and /32 are special cases — /31 gives 2 addresses for point-to-point links, and /32 represents a single host.

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What is subnetting?
Subnetting is the process of dividing a large network into smaller, more efficient sub-networks. It helps organize networks, improve performance, and enhance security.
What is CIDR notation?
CIDR notation expresses a subnet using an IP followed by a slash and the number of network bits, e.g. 192.168.1.0/24.
What is a subnet mask?
A subnet mask is a 32-bit number that separates the IP address into network and host portions. For /24, the mask is 255.255.255.0.
How many usable hosts in a /24 subnet?
A /24 subnet has 256 total addresses and 254 usable hosts (minus network and broadcast addresses).
What is the broadcast address?
The broadcast address is the last address in a subnet, used to send messages to all devices. For 192.168.1.0/24 it is 192.168.1.255.
What is the network address?
The network address is the first address in a subnet, identifying the network itself.
What is the difference between public and private IPs?
Private IPs (10.x.x.x, 172.16-31.x.x, 192.168.x.x) are for local networks. Public IPs are routable on the internet.
Can I subnet IPv6 addresses?
Yes, IPv6 uses the same CIDR concept with 128-bit addresses. Standard IPv6 subnets are /64.