How many usable hosts are in a /24 subnet?

A /24 subnet has 256 total addresses (2^8 = 256), but two are reserved: the network address (first address, all host bits set to 0) and the broadcast address (last address, all host bits set to 1). This leaves 254 usable host addresses. The calculator shows both the total count and the usable range so you do not need to remember to subtract 2.

What is a broadcast address?

The broadcast address is the last address in a subnet, with all host bits set to 1. A packet sent to the broadcast address is delivered to all hosts in the subnet simultaneously. For example, in the 192.168.1.0/24 network, the broadcast address is 192.168.1.255. Routers do not forward broadcasts between subnets, which is why segmenting networks into smaller subnets reduces unnecessary traffic.

What is the difference between a subnet mask and a CIDR prefix?

They represent the same information in two different formats. A CIDR prefix like /24 indicates that the first 24 bits are the network portion. The equivalent subnet mask, 255.255.255.0, expresses this as a 32-bit number where the first 24 bits are 1 and the remaining 8 are 0. The calculator converts between both formats so you can work with whichever your equipment or documentation expects.

How do I split a large subnet into smaller subnets?

To subnet a network, increase the prefix length — each additional bit doubles the number of subnets and halves the host count per subnet. For example, splitting a /24 into /25 subnets gives you two subnets of 126 usable hosts each. Use the calculator iteratively: enter each resulting network with its new prefix length to verify the address ranges, then continue subdividing as needed. This process is called VLSM (Variable-Length Subnet Masking).

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IP / Subnet Calculator

Calculate network address, broadcast, subnet mask, and host range for any IP/CIDR.

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IP Address

CIDR /

e.g. 192.168.1.0 / 24 — or enter as 192.168.1.1/24

How to Use

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Enter IP address and subnet

Type an IP address with CIDR notation (e.g., 192.168.1.0/24) or with a subnet mask. The calculator auto-detects the input format.

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View subnet details

See network address, broadcast address, usable host range, total hosts, subnet mask, and wildcard mask — all calculated instantly.

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Copy any value

Click any field to copy it. Essential for network engineers, sysadmins, DevOps, and anyone configuring firewalls, routing, or VLANs.

What is IP / Subnet Calculator?

The IP subnet calculator computes the subnet mask, network address, broadcast address, and full usable IP range from any CIDR notation input such as 192.168.1.0/24. It supports all prefix lengths from /0 to /32 and instantly shows how many host addresses are available in the subnet. This tool is essential for network administrators, DevOps engineers, and anyone studying for networking certifications like CompTIA Network+ or CCNA.

Why use IP / Subnet Calculator?

Manually calculating subnet ranges from CIDR notation requires binary arithmetic that is easy to get wrong under pressure — this IP calculator eliminates errors and gives instant results. Network engineers planning IP address allocation across multiple subnets can quickly test different prefix lengths to find the right block size. Students studying for networking certifications use it to check their manual CIDR calculations and learn the relationships between prefix length and host count.

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How it works

System administrators use this tool when segmenting office networks to ensure subnets do not overlap. Cloud engineers use it to plan VPC CIDR blocks in AWS or Azure before provisioning resources. Security professionals use it during network audits to verify that firewall rules apply to the correct address ranges.

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Pro Tip

For VLSM (variable-length subnet masking) planning, start with the largest required subnet first — use the calculator to confirm the host count, then work down to smaller subnets, ensuring each fits within the remaining address space without overlap.

Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) notation represents an IP address and its subnet mask together using a slash followed by a prefix length, such as 192.168.1.0/24. The prefix length specifies how many leading bits of the address are the network portion — /24 means 24 bits are the network, leaving 8 bits for host addresses. CIDR replaced the older class-based system (Class A/B/C) to allow more flexible subnet sizing.

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