IP Tools

IP Subnet Calculator

A subnet planning page for prefix, range, and host-space calculations.

IP Tools Browser shell DNSChecker inspired

What this page covers

IP Subnet Calculator helps users reason about subnet sizes and is a natural addition to the IP tool family.

  • Helpful for subnet planning and teaching.
  • Good entry point for network design tasks.
  • Matches the card-based site structure.

Why this fits the site

These DNSChecker-inspired pages keep the same header, footer, and card-based rhythm as the rest of MastreTools, so the new sections blend into the existing navigation instead of feeling bolted on.

How users reach it 
Search in the menu or open ip-subnet-calculator.html directly from the header.

Calculate a subnet

Enter an IPv4 address in the first field. Use the secondary field for a prefix like /24 or a subnet mask like 255.255.255.0. If both are filled, the secondary field takes priority.

The secondary input now helps when a network is written as a mask instead of CIDR, and it can override the prefix if you only type an IP in the main field.

Ready to calculate a subnet.

No calculation has been run yet.

Notes

This calculator is IPv4-only and runs completely in the browser, so you can plan common subnets without sending anything to a server.