About this calculator This calculator determines the altitude correction factor for cooling equipment. Reduced air density at higher elevations affects heat transfer across cooling coils and reduces effective capacity. Apply this factor when sizing cooling equipment for installations above 1,000 feet to ensure the system meets the design load at altitude.
Use when You need to adjust cooling capacity for installations at high altitudes.
Formula Density Factor = (1 - 0.00000687 × Altitude) ^ 5.256
Variables
Altitude Elevation above sea level in feet
Altitude (ft)
Elevation above sea level in feet
Density Factor 1.0000

What is a density correction factor?

A density correction factor adjusts HVAC capacity calculations for air density changes caused by altitude. At higher elevations, air is less dense, which reduces the mass flow rate through equipment for a given volumetric airflow (CFM). This means cooling coils, heating elements, and fans all deliver less capacity than their sea-level ratings. The correction factor is calculated using the barometric formula: Factor = (1 - 0.00000687 × Altitude)^5.256, where Altitude is the elevation in feet above sea level. At 5,000 feet, the factor is approximately 0.83, meaning equipment delivers roughly 83% of its rated capacity. Most HVAC manufacturers rate equipment at standard conditions (sea level, 70°F), so this correction must be applied during equipment selection for any installation above approximately 1,000 feet to avoid undersizing.

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