IP Subnet Calculator
Use our free online IP subnet calculator to simplify network planning. Instantly generate subnet masks, CIDR ranges, and IP address allocations for IPv4 and IPv6. Perfect for IT professionals, students, and network administrators managing IP addressing and subnetting.
IPv4 Results
Subnetting divides large networks into smaller sub-networks to improve security, performance, and address allocation efficiency. Our calculator provides comprehensive subnet information for both IPv4 and IPv6 addresses.
Key Concepts
- Network Address: First address identifying the subnet
- Broadcast Address: Last address for subnet-wide communication
- CIDR Notation: Compact IP/subnet representation (e.g., 192.168.1.0/24)
- Usable Hosts: Addresses available for device assignment
| CIDR | Subnet Mask | Hosts |
|---|---|---|
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /28 | 255.255.255.240 | 14 |
| /29 | 255.255.255.248 | 6 |
| /30 | 255.255.255.252 | 2 |
Complete Guide to IP Subnetting
IPv4 vs IPv6 Subnetting
IPv4 Subnetting
- 32-bit address space (4.3 billion addresses)
- Uses subnet masks (e.g., 255.255.255.0)
- Common private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
- Limited by address exhaustion
IPv6 Subnetting
- 128-bit address space (3.4×10³⁸ addresses)
- Uses prefix length (e.g., /64)
- Designed for hierarchical addressing
- No NAT required
Subnetting Best Practices
- Plan for future growth when allocating subnet sizes
- Use consistent subnet sizes within each network tier
- Document all subnet allocations
- Leave room for network infrastructure addresses
- Consider security implications of subnet boundaries
Frequently Asked Questions
Professional Tips
- Always document your IP allocation scheme
- Use consistent numbering for easier management
- Leave room for growth between subnets
- Consider using DHCP for dynamic address assignment
- Regularly audit your IP address usage
Fahad Ahmad
Founder of CalculatorsKit · Full-Stack JavaScript Developer · SEO & Digital Product Creator
Fahad Ahmad is the founder of CalculatorsKit and a full-stack JavaScript developer with more than 10 years of experience building modern web applications and online tools. He specializes in developing fast, accurate, and user-friendly calculators that help people make informed decisions in finance, health, education, business, mathematics, construction, and everyday life.
Every calculator published on CalculatorsKit is carefully researched, tested, and designed for accuracy and ease of use. Using modern technologies including Next.js, React, Tailwind CSS, and Shadcn UI, Fahad focuses on creating privacy-friendly tools that work instantly in the browser without requiring downloads or registration.
In addition to building calculators, Fahad writes educational articles that explain formulas, calculation methods, financial concepts, and practical examples in simple language so students, professionals, and everyday users can better understand the results they receive.