Cost Allocation by Square Footage Calculator

About this calculator

Splitting a shared cost by square footage is the standard method for common-area maintenance (CAM) charges, shared utility bills, and joint repair costs in commercial leasing, multi-tenant buildings and condo/HOA arrangements: each unit pays a share proportional to how much of the total floor area it occupies — Unit share = Total cost × (Unit area / Total area).

This pro-rata approach is considered the fairest default when usage can’t be metered individually, since a larger unit is assumed to draw proportionally more heating, cooling, cleaning and shared-service resources than a smaller one; commercial leases typically spell out this formula explicitly under a CAM or “operating expense” clause. Property managers, landlords and HOA boards use it to bill tenants or owners transparently and defensibly. This calculator takes the total cost, a unit’s area and the total area and returns that unit’s allocated share.