1. What is CIDR Notation?

CIDR (Classless Inter-Domain Routing) notation is a compact representation of an IP address and its associated routing prefix. It shows the number of bits in the network portion of the address.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( cidr \) — Number of bits in network prefix (1-31)
• \( 32 \) — Total bits in an IPv4 address
• \( -2 \) — Subtracting network and broadcast addresses

Explanation: The formula calculates how many host addresses are available in a subnet by determining how many bits are left for host addressing.

3. Importance of Subnet Calculation

Details: Proper subnet calculation is essential for network design, ensuring efficient IP address allocation and proper network segmentation.

4. Using the Calculator

Tips: Enter the CIDR value (1-31) to calculate the number of available hosts in that subnet. The calculator automatically excludes network and broadcast addresses.

5. Frequently Asked Questions (FAQ)

Q1: Why subtract 2 from the total?
A: The first address is the network identifier and the last is the broadcast address, which cannot be assigned to hosts.

Q2: What's the maximum CIDR value I can use?
A: For host calculation, the maximum meaningful value is 30 (leaving 2 bits for hosts). A /31 is special case (point-to-point) and /32 is a single host.

Q3: How does this differ for IPv6?
A: IPv6 uses a different approach with much larger address spaces. This calculator is for IPv4 only.

Q4: What's a typical CIDR for a home network?
A: Typically /24 (255.255.255.0) which provides 254 usable addresses.

Q5: Can I use this for subnet mask calculation?
A: While related, this specifically calculates host count. You'd need additional calculations for the actual subnet mask.