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.
Subnet Calculator
IPv4 Results
Enter IPv4 address and click Calculate
About Subnetting
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
Common Subnets
| 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