How many hosts are in a /24 subnet?

A /24 subnet has 256 total addresses (2^8) but only 254 usable host addresses. The first address is reserved as the network address and the last as the broadcast address.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation appends a prefix length to an IP address (e.g., 192.168.1.0/24). The prefix length indicates how many bits are used for the network portion, with the remaining bits for host addresses.

How do I calculate a subnet mask from a CIDR prefix?

Set the first N bits to 1 and the remaining (32-N) bits to 0, then convert each octet to decimal. For example, /24 = 11111111.11111111.11111111.00000000 = 255.255.255.0.

What is a wildcard mask?

A wildcard mask is the bitwise inverse of the subnet mask. For a /24 subnet (255.255.255.0), the wildcard mask is 0.0.0.255. Wildcard masks are used in Cisco ACLs and OSPF area configurations.

What is the difference between a network address and a broadcast address?

The network address is the first address in a subnet (all host bits set to 0) and identifies the subnet itself. The broadcast address is the last address (all host bits set to 1) and is used to send packets to all hosts in the subnet. Neither can be assigned to a device.

What is VLSM and why is it important?

VLSM (Variable Length Subnet Masking) allows different subnets within the same network to use different prefix lengths. This avoids wasting addresses — for example, a point-to-point link only needs a /30 (2 hosts), while a LAN might need a /24 (254 hosts).

Subnet Calculator

Subnetting divides a larger network into smaller, more efficient sub-networks. This calculator takes an IPv4 address with a CIDR prefix length (e.g., 192.168.1.0/24) or a separate subnet mask and computes every detail you need: network address, broadcast address, first and last usable hosts, total and usable host counts, wildcard mask, IP class, and binary representations. A built-in CIDR cheat sheet from /8 to /32 gives quick reference for common subnet sizes, making it an essential tool for network engineers, system administrators, and students studying for CCNA or CompTIA Network+ certifications.

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lan IP Address / CIDR Notation

Enter IP with CIDR prefix (e.g., 192.168.1.0/24) or just an IP below

tune Or enter IP and subnet mask separately

IP Address

Subnet Mask

hub Network Address

192.168.1.0

cell_tower Broadcast Address

192.168.1.255

shield Subnet Mask

255.255.255.0

flip_to_back Wildcard Mask

0.0.0.255

first_page First Usable Host

192.168.1.1

last_page Last Usable Host

192.168.1.254

groups Total Addresses

256

devices Usable Hosts

254

IP Class C

CIDR Notation /24

Type Private

data_object Binary Representations

IP Address

11000000.10101000.00000001.00000000

Subnet Mask

11111111.11111111.11111111.00000000

Network Address

11000000.10101000.00000001.00000000

table_chart CIDR Cheat Sheet (/8 through /32)

CIDR	Subnet Mask	Total IPs	Usable Hosts

tips_and_updates Tips

• A /24 subnet has 254 usable hosts and is the most common subnet for small networks
• The wildcard mask is the inverse of the subnet mask and is used in ACLs and OSPF configurations
• A /32 subnet represents a single host address, commonly used for loopback interfaces
• Private IP ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 (RFC 1918)
• Each additional prefix bit halves the number of available hosts in the subnet
• VLSM (Variable Length Subnet Masking) lets you use different prefix lengths within the same network
• Always reserve the first address (network) and last address (broadcast) — they cannot be assigned to hosts
• For point-to-point links, a /30 subnet provides exactly 2 usable addresses

How to Use This Calculator

Enter an IP address

Type an IPv4 address with CIDR notation (e.g., 192.168.1.0/24) or enter the IP and subnet mask separately.

View subnet details

See the network address, broadcast address, host range, usable hosts, subnet mask, wildcard mask, and IP class.

Reference the cheat sheet

Use the built-in CIDR cheat sheet to quickly look up subnet sizes from /8 through /32.

The Formula

The number of usable host addresses in a subnet is 2 raised to the power of the host bits (32 minus the prefix length), minus 2 for the network and broadcast addresses. For a /24 subnet, that is 2^8 - 2 = 254 usable hosts.

Usable Hosts = 2^(32 - prefix) - 2

lightbulb Variables Explained

prefix The CIDR prefix length (0-32)
32 Total bits in an IPv4 address
2 Subtracted for network and broadcast addresses

tips_and_updates Pro Tips

A /24 subnet has 254 usable hosts and is the most common subnet for small networks

The wildcard mask is the inverse of the subnet mask and is used in ACLs and OSPF configurations

A /32 subnet represents a single host address, commonly used for loopback interfaces

Private IP ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 (RFC 1918)

Each additional prefix bit halves the number of available hosts in the subnet

VLSM (Variable Length Subnet Masking) lets you use different prefix lengths within the same network

Always reserve the first address (network) and last address (broadcast) — they cannot be assigned to hosts

For point-to-point links, a /30 subnet provides exactly 2 usable addresses

Subnet Calculator - IPv4 CIDR, Subnet Mask & Host Range

Calculate network address, broadcast address, subnet mask, wildcard mask, host range, and usable hosts for any IPv4 CIDR notation. Essential tool for network engineers, sysadmins, and networking students preparing for CCNA or CompTIA Network+ exams.

IPv4 Subnetting Explained

Subnetting divides a network into smaller segments, improving security, performance, and address allocation. Each subnet is defined by a network address and a prefix length that determines how many bits identify the network vs. the hosts.

CIDR Notation and Subnet Masks

CIDR notation (e.g., /24) replaced classful addressing to allow flexible allocation. A /24 corresponds to subnet mask 255.255.255.0, providing 254 usable hosts. Longer prefixes create smaller subnets with fewer hosts.

Wildcard Masks and Network Configuration

Wildcard masks are the inverse of subnet masks and are used in Cisco ACLs and OSPF configurations. For example, a subnet mask of 255.255.255.0 has a wildcard mask of 0.0.0.255, matching any address in that /24 block.

Frequently Asked Questions

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