CIDR Calculator - Free Subnet Tool
Calculate IP ranges, subnets, and broadcast addresses from CIDR notation.
Data Privacy & Security
100% Local Processing. Your data never leaves your browser. All calculations are securely executed using client-side JavaScript.
How to Use Cidr Calculator
- Enter your IP address and CIDR suffix (e.g., 192.168.1.10/24) into the input box.
- Press Enter or click the calculate button to evaluate the network blocks.
- The system instantly outputs the Network Address, Broadcast Address, Subnet Mask, and Usable Host Range.
Tool Limitations & Specs
- Operates exclusively via DOM-level JavaScript without server validation.
- Inputs exceeding standard format lengths will be securely rejected.
- Does not interact with external DNS or ICMP systems.
- Requires HTML5 Canvas and modern browser capabilities.
Frequently Asked Questions
What does CIDR stand for?
CIDR stands for Classless Inter-Domain Routing. It is a method of IP addressing that replaces older class-based networks (Class A, B, C) with a flexible prefix length.
What does the slash (/) mean in a CIDR address?
The slash notation indicates the number of bits in the subnet mask that are fixed for the network portion. For example, /24 means the first 24 bits are fixed.
How do I calculate the number of usable hosts from a CIDR?
Subtract the prefix length from 32 to get the host bits (N). The formula for usable hosts is 2^N - 2 (subtracting the network and broadcast addresses).
What is a /24 subnet mask?
A /24 subnet mask translates to 255.255.255.0. It provides exactly 254 usable host IP addresses within that specific network block.
Can I use this tool for AWS or Azure virtual networks?
Absolutely. Cloud providers like AWS VPC and Azure VNets rely heavily on CIDR blocks to define internal subnets, making this calculator perfect for cloud architects.
What is the network address in a CIDR block?
The network address is the very first IP address in a subnet block. It is reserved to identify the network itself and cannot be assigned to a host.
What is the broadcast address?
The broadcast address is the very last IP in a subnet block, used to transmit messages to all devices within that specific subnet.
Does this calculator transmit my network topology?
No, all subnet bitwise logic and calculations happen exclusively in your browser. No backend server is involved.