What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation represents an IP address and its associated network prefix. For example, 192.168.1.0/24 means the first 24 bits are the network portion and the remaining 8 bits are for hosts, giving 254 usable addresses.

How many hosts does a /24 subnet have?

A /24 subnet has 256 total addresses (2^8), but 2 are reserved — the network address and the broadcast address — leaving 254 usable host addresses.

What is the difference between subnet mask and wildcard mask?

The subnet mask uses 1s for the network bits and 0s for the host bits (e.g., 255.255.255.0 for /24). The wildcard mask is the inverse — it uses 0s for network bits and 1s for host bits (e.g., 0.0.0.255). Wildcard masks are commonly used in Cisco ACLs and OSPF configurations.

What is the network address?

The network address is the first address in the subnet, with all host bits set to 0. It identifies the network itself and cannot be assigned to a host.

What is the broadcast address?

The broadcast address is the last address in the subnet, with all host bits set to 1. Packets sent to this address are delivered to all hosts on the subnet. It also cannot be assigned to a host.

Does this tool work offline?

Yes. All calculations are performed client-side in JavaScript — no server calls are made. Once the page is loaded, the calculator works completely offline.

Free Subnet Calculator

IP Subnetting,
Calculated Instantly

Enter any IPv4 CIDR block (e.g., 192.168.1.0/24) and instantly see the network address, broadcast address, subnet mask, wildcard mask, host range, and full binary breakdown.

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Instant Results

All subnet calculations happen client-side in real time as you type — no server round trips, no delays.

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Complete Breakdown

Network address, broadcast, first/last host, subnet mask, wildcard mask, binary view — everything in one place.

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Your IP addresses never leave your browser. Fully client-side with no data collection.

IPv4 CIDR Block

Examples:

/24Class CPrivate (RFC 1918)254 usable hosts

Network Details

Network Address192.168.1.0

Broadcast Address192.168.1.255

First Usable Host192.168.1.1

Last Usable Host192.168.1.254

Subnet Mask255.255.255.0

Wildcard Mask0.0.0.255

Total Addresses256

Usable Hosts254

CIDR Notation192.168.1.0/24

Binary Breakdown

Network Address11000000.10101000.00000001.00000000

Subnet Mask11111111.11111111.11111111.00000000

Broadcast Address11000000.10101000.00000001.11111111

Frequently Asked Questions

Everything you need to know about IP Subnet Calculator.

IP Subnetting,Calculated Instantly