CIDR Subnet Calculator & IP Range Tool
Convert CIDR notation into usable IP ranges, subnet masks, and complete network details instantly. This visual subnet calculator shows you network addresses, broadcast addresses, usable host ranges, and binary breakdowns. Perfect for network administrators configuring firewalls, DevOps engineers setting up cloud infrastructure, or students learning IP subnetting. Everything runs locally in your browser - no data leaves your device. Use Cidr Calculator when you need answers fast during debugging, reviews, or incident triage. Paste your input, validate the output, then copy results into tickets or docs in seconds. Most processing runs in your browser, so you can test safely without unnecessary data exposure. Built for speed, clarity, and repeat use.
Examples: 10.0.0.0/8, 172.16.0.0/16, 192.168.1.0/24
Network Information
Network Address
Broadcast Address
Subnet Mask
Wildcard Mask
First Usable IP
Last Usable IP
Total Addresses
Usable Hosts
Binary Breakdown
IP Address
Subnet Mask
Network Address
Classification
IP Class
Network Type
CIDR Notation
How to Use the CIDR Calculator
- Enter CIDR notation - Type an IP address with prefix (e.g., 192.168.1.0/24)
- Click Calculate Subnet - Or press Enter to compute instantly
- View Network Info - See network address, broadcast address, and usable IP range
- Check Binary Breakdown - Understand how the subnet mask divides network and host bits
- Review Classification - IP class (A/B/C) and whether the range is public or private
Understanding CIDR Notation
CIDR (Classless Inter-Domain Routing) replaced the old class-based system to allow more flexible IP allocation. The number after the slash (e.g., /24) indicates how many bits are used for the network portion. A /24 means the first 24 bits identify the network, leaving 8 bits (256 addresses) for hosts.
Common CIDR blocks:/8 - 16.7 million addresses (e.g., 10.0.0.0/8); /16 - 65,536 addresses (e.g., 172.16.0.0/16); /24 - 256 addresses (e.g., 192.168.1.0/24); /32 - Single host (e.g., 192.168.1.1/32).
Why this matters: Proper subnetting improves network security by isolating traffic, reduces broadcast domain size for better performance, and optimizes IP address utilization. Cloud providers like AWS, Azure, and GCP all use CIDR for VPC configuration.