Subnetting Tools

Divide networks efficiently, optimize address allocation, and master network design with our comprehensive subnetting toolkit.

IPv4 Subnet Calculator

Calculate subnet masks, network addresses, broadcast addresses, and host ranges

IPv6 Subnet Calculator

Calculate IPv6 subnets and network prefixes

VLSM Calculator

Variable Length Subnet Mask calculator for splitting networks into smaller subnets

Supernet Calculator

Aggregate multiple networks into supernets for route summarization

Subnet Planner

Design VLSM networks with drag-and-drop planning

What's Subnetting?

Subnetting is the process of splitting a large network into smaller, easier-to-manage pieces. Each subnet has its own network address and range of IPs, which helps organize devices, improve security, and reduce wasted addresses. It's core to network planning (both small home labs, or managing a large office or campus).

These tools aim to make this easier for you, handling the math and planning for you. They calculate network and broadcast addresses, host ranges, and help design or summarize networks so you can focus on building, not IP crunching.

Common Subnet Masks

CIDRSubnet MaskUsable Hosts
/8255.0.0.016,777,214
/16255.255.0.065,534
/24255.255.255.0254
/25255.255.255.128126
/26255.255.255.19262
/27255.255.255.22430
/28255.255.255.24014
/30255.255.255.2522
/32255.255.255.2551

Best Practices

  • Plan for growth \u2014 choose subnet sizes that accommodate future expansion
  • Document your addressing scheme for team reference
  • Use private RFC 1918 addresses for internal networks
  • Reserve space for infrastructure (routers, switches, servers)
  • Use /30 or /31 for point-to-point links

Common Mistakes

  • Forgetting that network and broadcast addresses are not usable
  • Overlapping subnet ranges in the same network
  • Using subnets that are too small for future growth
  • Mixing up subnet mask and wildcard mask
  • Not considering IPv6 for new deployments