CIDR Notation Calculator Net Guides, December 19, 2024December 21, 2024 This CIDR Notation Calculator is a simple yet powerful tool that helps network administrators, IT professionals, and students work with IP addresses and subnets. It converts CIDR notation (like 192.168.1.0/24) into easily understandable network information. CIDR Calculator CIDR Notation Calculator Enter IP address with CIDR notation (e.g., 192.168.1.0/24): Please enter a valid CIDR notation Calculate Network Address: – Broadcast Address: – First Usable IP: – Last Usable IP: – Subnet Mask: – Number of Usable Hosts: – 1. What is CIDR Notation? CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP addresses and their associated routing prefix. It’s a fundamental concept in IP networking that replaced the older system of IP address classes. A CIDR notation looks like this: 192.168.1.0/24 The part before the slash is an IPv4 address The number after the slash (called the prefix length) indicates how many bits are used for the network portion Common CIDR prefix lengths: /32 – Single IP address /24 – 256 addresses (traditional Class C network) /16 – 65,536 addresses (traditional Class B network) /8 – 16,777,216 addresses (traditional Class A network) 2. Understanding the CIDR Calculator Our CIDR Calculator helps network administrators and IT professionals by: Converting CIDR notation into detailed network information Calculating usable IP ranges Determining broadcast and network addresses Computing the total number of available hosts Key Features Simple, user-friendly interface Instant calculations Comprehensive network information Input validation Mobile-responsive design 3. How to Use the CIDR Notation Calculator? Basic Usage Locate the input field at the top of the calculator Enter an IP address followed by a forward slash and the prefix length Click the “Calculate” button Valid Input Formats IP Address: Four numbers between 0-255, separated by periods Prefix Length: A number between 0-32 after the forward slash Example: 192.168.1.0/24 Common Input Examples Small network: 192.168.1.0/24 Medium network: 172.16.0.0/16 Large network: 10.0.0.0/8 Single host: 203.0.113.1/32 4. Understanding the Results The calculator provides the following information: Network Address The first address in your network range All host bits are set to 0 Cannot be assigned to a device Broadcast Address The last address in your network range All host bits are set to 1 Used for network broadcasts First Usable IP The first IP address that can be assigned to a device Usually the Network Address + 1 Last Usable IP The last IP address that can be assigned to a device Usually the Broadcast Address – 1 Subnet Mask Shows which bits are used for network vs. host portions Displayed in dotted decimal format Number of Usable Hosts Total number of IP addresses that can be assigned to devices Excludes network and broadcast addresses 5. Example Calculations Example 1: Small Office Network Input: 192.168.1.0/24 Results: Network Address: 192.168.1.0 Broadcast Address: 192.168.1.255 First Usable IP: 192.168.1.1 Last Usable IP: 192.168.1.254 Subnet Mask: 255.255.255.0 Usable Hosts: 254 Example 2: Medium Business Network Input: 172.16.0.0/16 Results: Network Address: 172.16.0.0 Broadcast Address: 172.16.255.255 First Usable IP: 172.16.0.1 Last Usable IP: 172.16.255.254 Subnet Mask: 255.255.0.0 Usable Hosts: 65,534 6. FAQ about the CIDR Notation Calculator Q: What’s the difference between network address and first usable IP? A: The network address identifies the network itself and cannot be assigned to devices. The first usable IP is the first address that can be assigned to a device. Q: Why do I see fewer usable hosts than total addresses? A: Two addresses in each network are reserved: the network address and the broadcast address. Exception: /31 networks are used for point-to-point links and can use both addresses. Q: Can I use this calculator for IPv6? A: No, this calculator is designed for IPv4 addresses only. IPv6 uses different notation and requires different calculations. Q: What’s the smallest/largest network I can calculate? A: You can calculate from a /32 (single host) up to a /0 (entire Internet) network. Enjoyed this CIDR Notation Calculator? Then be sured to check out our other network guides. Best Wi-Fi 7 Router Best 10Gb Router Network Tools network