Facility cost benchmarking is widely practised and frequently misapplied. The headline metric, cost per square foot per month, conceals more than it reveals. The variables that make two buildings non-comparable at identical square footage are substantial. Occupancy density changes cleaning load, washroom frequency and waste volume by multiples. A building at 1 person per 80 sq ft has a fundamentally different service requirement from one at 1 per 150. Operating hours matter equally. A 9-to-6 single-shift building and a 24x7 operation with identical area have different staffing models entirely. Surface composition affects both method and cost. Marble requires different treatment from vitrified tile. Carpet areas require different equipment from hard floors. Glass facade area drives a cost centre that a largely solid-facade building does not have. Service scope inclusion is the most common source of invalid comparison. One building's figure includes technical AMC, pantry services, pest control, landscaping and waste disposal. Another includes housekeeping alone. The comparison is arithmetically valid and practically meaningless. Compliance standard is the least visible variable and the most important. A contractor depositing full PF and ESIC against actual headcount costs materially more than one who is not. A benchmark that includes non-compliant operators sets a floor that compliant delivery cannot meet. Useful benchmarking normalises for these factors, compares like-for-like scope and treats outliers as requiring explanation rather than emulation. The most actionable benchmark is usually internal: the same building compared against itself across periods, which holds the variables constant.