JAEN

CIDR Calculator

Calculate network address, broadcast, subnet mask, and usable hosts from an IP/CIDR.

Input data is processed in your browser
Data is never sent to a server

Tool

Presets:

What is the CIDR Calculator?

This tool calculates all the network information you need from an IP address and CIDR prefix length. It supports subnet design, firewall rule configuration, and routing setup — essential tasks for network engineers.

What It Calculates

  • Network address and broadcast address
  • Subnet mask and wildcard mask
  • Usable host count and total address count
  • IP class (A / B / C / D / E)
  • Address type (private, public, loopback, link-local, multicast, etc.)
  • Binary representation with visual network/host bit separation

How to Use

  1. Enter an IP address with prefix length in CIDR notation (e.g. 192.168.1.0/24).
  2. Click "Calculate" to see all network details.
  3. Use the preset buttons to quickly fill in common network ranges.
  4. Copy individual values with the row copy button, or use "Copy All" to copy everything.

FAQ

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a notation that combines an IP address and a network prefix length separated by a slash. For example, "192.168.1.0/24" specifies the IP address "192.168.1.0" with a prefix length of 24 (equivalent to subnet mask 255.255.255.0).

How many hosts can a /24 network hold?

A /24 network (subnet mask 255.255.255.0) has 256 total addresses. Excluding the network address and broadcast address, it can accommodate 254 usable hosts.

What are private IP addresses?

Private IP addresses are ranges reserved for internal networks that are not directly routable on the internet. Defined by RFC 1918, there are three blocks - 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

What is a wildcard mask?

A wildcard mask is the bitwise inverse (logical NOT) of a subnet mask. It is commonly used in router configurations such as Cisco ACLs and OSPF. For example, the wildcard for subnet mask 255.255.255.0 is 0.0.0.255.

How are /31 and /32 used?

/32 is used to specify a single host (e.g. host routes or route aggregation). /31, defined in RFC 3021, is used for point-to-point links and allows both addresses to be used as valid hosts.

More Tools in This Category

Text

Count, clean, compare, and transform text in the browser.

Generators

Generate UUIDs, hashes, passwords, QR codes, and more.

Web

Inspect user agents, IP details, meta tags, and CSS gradients.

YAML

Format, validate, and diff YAML configuration files.