> CIDR_CALCULATOR

[ Subnet calculator | IP range calculator | Network planning tool ]

CIDR Input

Format: IP/prefix (e.g., 10.0.0.0/8, 192.168.0.0/16)

CIDR Quick Guide

Common Ranges:

  • /8 = 16.7M IPs (Class A)
  • /16 = 65,536 IPs (Class B)
  • /24 = 256 IPs (Class C)
  • /32 = Single IP

Example:
192.168.1.0/24 gives you
192.168.1.0 → 192.168.1.255

🧮 CIDR Calculation Results

📖 About CIDR Notation

What is CIDR? Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and routing. It uses a suffix (like /24) to specify how many bits are in the network portion.

Common CIDR ranges:

  • /8 (255.0.0.0) = 16,777,216 addresses (Class A)
  • /16 (255.255.0.0) = 65,536 addresses (Class B)
  • /24 (255.255.255.0) = 256 addresses (Class C)
  • /32 = Single host address

Use cases: Network planning, subnet design, firewall rules, AWS/Azure VPC configuration, IP address allocation.

Related: IP Lookup · ASN Lookup

❓ CIDR Calculator FAQs

What is CIDR? CIDR represents an IP network as address/prefix (example: 10.0.0.0/8). The prefix length controls how large the range is.

How many IPs are in a /24? A /24 contains 256 total IPv4 addresses. In many cases, 254 are usable hosts (network + broadcast reserved).

What are network and broadcast addresses? The network address identifies the subnet, and the broadcast address targets all hosts on that subnet (traditional IPv4 subnetting).

What should I do with the IP range result? Use it for firewall allowlists, subnet planning, and cloud networking. Pair it with Reverse DNS and IP Lookup when investigating specific addresses.