What is a VLSM calculator?

A VLSM calculator (variable length subnet mask calculator) is an IP subnet calculator that sizes each subnet to a different host requirement. Our free online VLSM calculator takes a base IPv4 CIDR network and host list, then outputs a VLSM table with masks, networks, and usable ranges.

How do I calculate VLSM step by step?

Sort host requirements largest to smallest, pick the smallest CIDR block that fits each need (including network and broadcast addresses), place that subnet on a valid boundary, then repeat with the next free address. Use this VLSM calculator with steps to check your manual work.

Can I use this as a subnet calculator for 192.168.100.0/24 divided into 6 subnets with VLSM?

Yes. Enter 192.168.100.0/24 as the base network and six host counts (for example 50, 30, 20, 10, 5, 2). The VLSM subnetting calculator allocates six non-overlapping subnets and shows each CIDR mask and usable range.

Is this an IPv4 VLSM calculator or does it support IPv6?

This tool is an IPv4 VLSM calculator / VLSM calculator IPv4 using CIDR notation. VLSM ideas still apply to hierarchical design, but IPv6 address planning is usually handled with different prefix conventions; we focus on the IPv4 VLSM problems used in CCNA labs.

What is the difference between a VLSM calculator and an FLSM calculator?

FLSM (fixed-length) gives every subnet the same size. VLSM (variable-length) lets each subnet have its own mask. This page is a VLSM and FLSM learning aid: use it when requirements differ so you do not waste addresses.

Is this a CCNA / Cisco VLSM calculator?

Yes, it is built for CCNA-style VLSM subnetting: largest-first allocation, CIDR prefixes, and a clear VLSM calculation table. It complements Cisco Packet Tracer labs and exam practice without needing a downloadable app.

Do I need to download a VLSM calculator Excel sheet or APK?

No. This is a free VLSM calculator online that runs in your browser. There is no Excel template, Android APK, or install required, calculate VLSM instantly on any device.

Does the calculator show a VLSM table with block sizes?

Yes. Results include each subnet’s network address, CIDR / subnet mask, broadcast, usable hosts, and sequential placement so you can verify block size and avoid overlaps, like a VLSM table calculator with working.

VLSM Calculator Online, Free IPv4 CIDR Subnet Calculator

VLSM Calculator Online, Free IPv4 CIDR Subnet Calculator | Binary Tech