Skip to main content
Calcimator

VLAN & Subnet Calculator

Calculate IP address allocation across VLANs with optimal subnet sizing, growth margin, and utilization analysis.

Inputs

%

Results

Subnet CIDR

25 bits

Hosts per Subnet

126

Total Usable IPs

504

Devices per VLAN50
Devices + Growth65
Total IPs Allocated512
IP Utilization39.7 %
Supernet CIDR (All VLANs)23 bits
Subnet Mask255.255.255.128
Wildcard Mask0.0.0.127
How to Use This Calculator
  1. Enter Total Devices, Number of VLANs, and Growth Margin.
  2. Set Second Octet (10.X.0.0).
  3. Review Subnet CIDR (bits), Hosts per Subnet, and Total Usable IPs.
  4. Use Devices per VLAN and Devices + Growth to inform your decision.
  5. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Total Devices

Total DevicesSubnet CIDRHosts per SubnetTotal Usable IPs
10,00120 bits4,09416,376
35,00118 bits16,38265,528
65,00016 bits65,534262,136
90,00016 bits65,534262,136

What each input means

Total Devices
Total number of network devices/endpoints to address
Number of VLANs
Number of VLANs to distribute devices across
Growth Margin
Additional address space for future device growth
Second Octet (10.X.0.0)
Second octet for the 10.X.0.0/Y addressing scheme

How this is calculated

Formula

Hosts = 2^(32-CIDR) - 2; CIDR = smallest where Hosts ≥ Devices × (1+Growth)

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Total Devices = 200, Number of VLANs = 4, Growth Margin = 30, Second Octet (10.X.0.0) = 168 = 4 input(s) provided
  2. Calculate Subnet CIDR
    Subnet CIDR = 30
    25 = 25
  3. Calculate Hosts per Subnet
    Hosts per Subnet
    126 = 126
  4. Calculate Total Usable IPs
    Total Usable IPs
    504 = 504
  5. Calculate Devices per VLAN
    Devices per VLAN
    50 = 50
  6. Calculate Devices + Growth
    Devices + Growth
    65 = 65

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

Related Calculators

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

Network Design

Bandwidth Capacity Planner

Calculate required network bandwidth from user count, application profiles, concurrency, and protocol overhead.

Network Design

Switch Port Density Calculator

Calculate access, distribution, and core switch count from endpoint count, port requirements, and uplink oversubscription.

Technology & Computing

Subnet Calculator

Calculate subnet mask, network address, broadcast address, usable host range, and CIDR notation for any IP address.

Technology & Computing

IP Subnet Calculator

Calculate IP subnet information including subnet mask, hosts per subnet, and network configuration.

Technology & Computing

Network Tools Calculator

Subnet calculator, bandwidth estimator, and VLSM network planning.

More in Technology & Computing.