VLAN Capacity Calculator
The VLAN capacity calculator answers a design question that comes up in every network build: given a number of VLANs and an average number of devices per VLAN, what subnet size should you allocate?
Add a growth factor and the calculator accounts for future endpoints, then returns the required prefix length, its subnet mask, and the number of usable hosts per subnet - so you can size every VLAN once and stop guessing.
VLAN Capacity Calculator
Determine the subnet size you need for a given number of VLANs and devices.
Enter values above to see results.
Read More
Guides that go deeper on the same topic.
What Is a LAN? LAN vs WAN, Ports, and How They Connect
A plain explanation of a LAN: what a local area network is, how it differs from a WAN, what LAN and WAN ports on a router mean, and how LANs scale from a home to a campus.
What Is a VLAN? A Plain Explanation for Beginners
A clear beginner guide to VLANs: what they are, why networks use them, how 802.1Q tagging and trunk ports work, and how devices on different VLANs talk to each other.
How to Set Up VLANs in a Homelab
Set up homelab VLANs step by step: plan subnets, configure router and switch ports, map Wi-Fi, add firewall rules, and test isolation.
More Tools
Explore the other tools in the toolkit.
Subnet Calculator
Free subnet calculator: enter an IP address and CIDR prefix to get the network address, broadcast address, subnet mask, usable IP range, and host count instantly.
CIDR Calculator
Free CIDR calculator: convert any prefix length from /0 to /32 into its dotted-decimal subnet mask, binary mask, wildcard mask, and total usable hosts.
IPv4 Range Calculator
Free IPv4 range calculator: enter a start and end IP address to find the smallest set of CIDR blocks covering the range, plus the total number of addresses.
Rack Power Calculator
Free rack power calculator: estimate total watts, BTU/hr, amps at 120V and 240V, cooling tons, and watts per feed for the equipment in your racks.
Rack Unit Calculator
Free rack unit calculator: convert rack units (U) to inches and millimetres, check 1U and 42U heights, and see how many devices fit in a rack after reserved space.
UPS Runtime Calculator
Free UPS runtime calculator: estimate how long your UPS battery will run under load based on wattage, battery capacity, voltage, and inverter efficiency.
BTU Calculator
Free BTU calculator: convert electrical watts to BTU/hr and the tons of cooling required for your data center, server room, or network closet.
Subnet Overlap Checker
Free subnet overlap checker: paste a list of CIDR blocks and instantly see every pair that shares addresses, before conflicts cause routing or IP assignment problems.
IPv6 Subnet Calculator
Free IPv6 subnet calculator: enter an IPv6 address and prefix length to get the network address, expanded form, total addresses, and the number of /64 subnets.
Batch CIDR Converter
Free batch CIDR converter: paste a list of subnets as CIDR, IP + mask, or bare IP and convert them all to network address, subnet mask, usable range, and host count in one click.
IP Allocation Planner
Free IP allocation planner: assign CIDR blocks inside a supernet to sites, VLANs, or teams and see used, free, and overlapping address space instantly.