CIDR Subnet Calculator

Q: How many usable hosts are in a /24 subnet?

A /24 subnet has a total of 256 host addresses. Subtracting 2 (one for the network address, and one for the broadcast address) leaves 254 usable host IPs.

Q: What is the subnet mask for /28 CIDR?

A /28 CIDR block corresponds to a subnet mask of 255.255.255.240, allowing for 14 usable hosts.

Calculate IPv4 subnet ranges, network addresses, broadcasts, host limits, and wildcards from CIDR blocks.

Subnet Input

IP Address

CIDR Prefix

Network CIDR Calculator

Calculated boundaries

Subnet Mask255.255.255.0

Network Address192.168.1.0

Broadcast Address192.168.1.255

Wildcard Mask0.0.0.255

Usable Host Range192.168.1.1 - 192.168.1.254

Total Usable Hosts254

Binary Representation

IP Address :11000000.10101000.00000001.00000001

Netmask :11111111.11111111.11111111.00000000

Network :11000000.10101000.00000001.00000000

IP Subnet Parameters

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Learn About This Tool

Understanding IP subnetting and CIDR blocks

CIDR (Classless Inter-Domain Routing) notation represents an IP address paired with a routing prefix (e.g. /24). The prefix number defines how many bits are locked for the network portion, with the remaining bits allocated for host addresses. If you are mapping database systems containing network logs or API inputs, try our JSON Formatter & Validator. Here is a standard `/24` subnet mapping:

# CIDR Notation: 192.168.1.1/24

Netmask Address    : 255.255.255.0
Network Address    : 192.168.1.0
Broadcast Address  : 192.168.1.255
Usable Host Range  : 192.168.1.1 - 192.168.1.254
Total Usable Hosts : 254

Subnet Mask defines which portion of the IP is network vs host
Network Address forms the starting identifier of the subnet
Broadcast Address defines the target for sending data to all hosts
Usable Host Range shows the assignable client IPs inside the subnet

Binary mask representations and wildcard calculations

Network routers and firewalls process IPs in binary (32 bits) and use wildcard masks (inverse netmasks) for routing configurations. Our calculator displays the binary values for the IP address, Netmask, and Network boundaries side-by-side. If you are managing text-based server configurations, parse them using our Duplicate Line Remover.

Wildcard mask is calculated by inverting the netmask (e.g. 0.0.0.255 for /24)
Binary views display bits in 8-bit octet blocks separated by periods
Calculates the total host bounds including unusable addresses (network & broadcast)
Helps parse CIDR ranges when writing firewall and security rules

Secure offline calculations for server protection

Inputting corporate network IP schemas (such as private subnets or server gateways) into web tools can disclose internal network architectures. Our CIDR calculator compiles network parameters 100% inside client-side JavaScript. Your IP configurations are never transmitted.

Secures internal IP addresses by running calculations locally in browser memory
Maintains absolute privacy for system configurations and network structures
Runs instantly without loading delays or server round-trip times
Allows copying results immediately for configs, scripts, or documentation

How to Use CIDR Subnet Calculator

Enter your IPv4 address

Type your base IP address (e.g. 192.168.1.1) in the text input. The validator checks the octet ranges (0-255) dynamically.

Select your CIDR prefix block

Choose the CIDR network prefix (from /0 to /32) using the dropdown selector. This determines the netmask boundaries.

Inspect your network parameters

The calculated parameters (Subnet, Broadcast, Wildcard, Host counts, and Binary octets) display instantly in the output panel.

Common questions

How do I calculate a subnet range from a CIDR block?

Enter your base IP address and choose the CIDR network prefix (e.g. /24) in the dropdown. The tool instantly computes the subnet mask, network start, broadcast end, and usable IP host range.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation specifies an IP address and its associated routing prefix length (e.g. 192.168.1.1/24), indicating that 24 bits are allocated for the network prefix.

What is a subnet mask?

A subnet mask is a 32-bit number that splits an IP address into network and host addresses. For a /24 CIDR prefix, the subnet mask is 255.255.255.0.

How many usable hosts are in a /24 subnet?

A /24 subnet has a total of 256 host addresses. Subtracting 2 (one for the network address, and one for the broadcast address) leaves 254 usable host IPs.

Is this CIDR calculator secure for private networks?

Yes, 100%. All subnet math is calculated locally in your browser using JavaScript. No IP addresses or network details are ever uploaded to any server.

What is a wildcard mask?

A wildcard mask is the bitwise inversion of the subnet mask, commonly used in Cisco OSPF and access control lists (ACLs). For netmask 255.255.255.0, the wildcard mask is 0.0.0.255.

How are the network and broadcast addresses determined?

The network address is calculated using a bitwise AND between the IP and the mask. The broadcast address is calculated by performing a bitwise OR between the IP and the inverted mask.

Does the calculator support IPv6?

Currently, our subnet calculator supports IPv4 address blocks, which are the most common configurations for local networks and routing tables.

Can I copy the calculated network parameters?

Yes. You can copy individual fields like the host range or wildcard mask directly from the output results card.

What is the subnet mask for /28 CIDR?

A /28 CIDR block corresponds to a subnet mask of 255.255.255.240, allowing for 14 usable hosts.

How does the tool show the binary IP breakdown?

It converts each octet of the IP, netmask, and network addresses into 8-bit binary strings, displaying them in aligned sections to visualize the network/host boundary.

Does it validate invalid IP address entries?

Yes. If an entered IP does not follow the standard x.y.z.w format or has octet values outside 0-255, the validator flags a syntax error.

What is the difference between usable hosts and total hosts?

Total hosts include all combinations of the host bits. Usable hosts exclude the first address (Network ID) and the last address (Broadcast ID) which are reserved for routing.

What is /32 CIDR prefix used for?

A /32 prefix designates a single, specific host address (subnet mask 255.255.255.255) with 0 usable client host ranges.

Does this subnet tool work offline?

Yes. Once loaded, all binary conversions and mask calculations work offline since they run completely in local client-side memory.