Uses standard atmosphere approximation. For precise engineering work, consult local meteorological data for actual barometric pressure and temperature.
Conversion Formula
lb/ft³ to kg/m³: kg/m³ = lb/ft³ × 16.0185
Standard air density (sea level, 20°C): 1.204 kg/m³ (0.0752 lb/ft³)
Canadian City Elevation and Approximate Air Density
| City | Elevation (m) | Approx. Pressure (kPa) | Approx. Density (kg/m³) | vs. Sea Level |
|---|---|---|---|---|
| Vancouver, BC | 2 | 101.3 | 1.204 | 0% |
| Toronto, ON | 76 | 100.4 | 1.194 | -0.8% |
| Ottawa, ON | 70 | 100.5 | 1.195 | -0.7% |
| Montreal, QC | 36 | 100.9 | 1.199 | -0.4% |
| Winnipeg, MB | 239 | 98.5 | 1.171 | -2.7% |
| Saskatoon, SK | 481 | 95.7 | 1.138 | -5.5% |
| Regina, SK | 577 | 94.6 | 1.125 | -6.6% |
| Edmonton, AB | 645 | 93.9 | 1.116 | -7.3% |
| Calgary, AB | 1045 | 89.4 | 1.063 | -11.7% |
| Kelowna, BC | 456 | 96.0 | 1.141 | -5.2% |
| Whitehorse, YT | 703 | 93.2 | 1.109 | -7.9% |
Values are approximate, calculated using standard atmosphere formulas at 20°C. Actual density also varies with weather, humidity, and season. Use the calculator above for a specific elevation and temperature combination.
Altitude Effects on HVAC Systems
| System / Component | Effect at High Altitude | Typical Response |
|---|---|---|
| Gas furnace combustion | Less oxygen per unit volume; incomplete combustion risk | High-altitude derating or orifice resizing per manufacturer |
| Furnace/AHU airflow capacity | Same CFM moves less air mass; reduced heat transfer | Larger blower or oversized equipment above ~1500 m |
| Air conditioner cooling capacity | Reduced air mass flow across coil reduces capacity | Manufacturer altitude correction factor applied |
| Fan static pressure / power | Lower density reduces both pressure rise and power draw | Fan laws applied for altitude-corrected selection |
| Combustion air / venting | Larger combustion air openings may be required | Sizing per applicable gas code for altitude |
Always follow manufacturer altitude derating instructions and applicable gas and mechanical codes for installations above 1000 to 1500 m elevation. Use the Pressure Converter for atmospheric pressure work and the Airflow Unit Converter for volumetric flow calculations.
How to Use the Air Density Converter
Enter a density value in kg/m³ or lb/ft³ -- the other field updates instantly. Use the quick presets for standard sea-level air density and a Calgary-elevation approximation.
Enter your project's elevation in metres and the air temperature in the Altitude-Corrected Density Calculator. The tool computes the estimated atmospheric pressure at that elevation, the resulting air density, and the percentage reduction compared to sea level.
The city elevation table shows approximate density reduction for 11 major Canadian centres, from near-zero at Vancouver to nearly 12% at Calgary. Use this to quickly identify whether your project location requires altitude-specific equipment sizing considerations.
The HVAC implications table summarizes how reduced density affects combustion, airflow capacity, and fan performance. Always follow manufacturer altitude derating tables for gas equipment installed above roughly 1000 to 1500 metres elevation, applicable in Alberta and interior BC locations.
Air Density and Altitude in Canadian HVAC
Air density directly affects HVAC system performance because fans and blowers move a fixed volume of air (CFM or L/s) regardless of density, but the actual mass of air -- which determines heat transfer capacity and combustion oxygen supply -- varies with air density. This matters significantly for Canadian HVAC work in Alberta and other higher-elevation regions.
Standard Air Density and the Conversion
Standard air density at sea level and 20°C is commonly referenced as 1.204 kg/m³ (0.0752 lb/ft³) in HVAC calculations. The conversion factor between metric and Imperial is 0.062428: multiply kg/m³ by 0.062428 to get lb/ft³, the exact relationship set out in the NIST Guide to the SI, Appendix B. This standard density value is embedded in common HVAC formulas -- the sensible heat equation coefficient of 1.08 in Q(BTU/hr) = 1.08 x CFM x DeltaT assumes standard sea-level air density and specific heat.
How Altitude Reduces Air Density
Atmospheric pressure decreases with elevation as there's less air above pushing down. Since air density is proportional to pressure (at constant temperature), density also decreases with altitude. Calgary at approximately 1045 metres elevation has roughly 89.4 kPa atmospheric pressure compared to 101.3 kPa at sea level -- about 88% of sea-level pressure, translating to roughly an 11-12% reduction in air density. Edmonton, at a lower elevation of about 645 metres, sees a smaller reduction of roughly 7%. Environment and Climate Change Canada records station atmospheric pressure at each elevation for exactly this reason.
Impact on Combustion Equipment
Gas furnaces and boilers rely on a specific volume of combustion air to supply the oxygen needed for complete combustion. At altitude, the same volume of air contains less oxygen by mass, which can cause incomplete combustion, reduced efficiency, and higher carbon monoxide production if the equipment isn't properly adjusted. Most gas equipment manufacturers publish altitude derating tables specifying orifice size changes, input rate reductions, or other adjustments required above certain elevation thresholds, commonly starting around 600 to 900 metres and requiring changes at 1500+ metres. The Combustion Air Calculator sizes the required combustion air openings for a given appliance input.
Impact on Airflow and Cooling Capacity
An air conditioner or heat pump coil transfers heat based on the mass flow rate of air across it, not just the volumetric flow rate. At altitude, the same CFM delivers less air mass, reducing the actual heat transfer and delivered capacity below the equipment's sea-level rating. Some manufacturers provide altitude correction factors to apply to rated capacity, while others recommend selecting next-size-up equipment for installations above roughly 1500 metres, a factor worth checking against the Cooling Load Calculator results for high-elevation projects. Fan power also decreases with density (fan power is proportional to air density at constant volumetric flow and pressure rise), which can partially offset some of the capacity loss in terms of electrical demand, though not in terms of delivered heating or cooling.
Frequently Asked Questions
Multiply kg/m³ by 0.062428 to get lb/ft³. So standard air density of 1.204 kg/m³ equals 0.0752 lb/ft³. To go the other way, multiply lb/ft³ by 16.0185. Standard sea-level air density at 20°C (1.204 kg/m³ / 0.0752 lb/ft³) is the reference value embedded in common HVAC sensible heat formulas.
Air density decreases with altitude as atmospheric pressure drops. At Calgary's elevation of roughly 1045 m, air density is approximately 11% lower than at sea level. This reduces the mass of air moved for a given volumetric flow rate (CFM or L/s), affecting fan performance, heating and cooling capacity, and combustion air availability for gas appliances. Equipment rated at sea-level conditions delivers proportionally less actual capacity at altitude.
Fans move a fixed volume of air regardless of density, but the mass moved -- which drives actual heat transfer -- decreases at altitude. Equipment rated for sea-level capacity delivers less actual heating or cooling at high elevation for the same volumetric airflow. Manufacturers often provide altitude derating tables or recommend larger equipment for installations above 1500 to 2000 metres. Fan power also decreases with density, partially offsetting electrical demand even as delivered capacity drops.
Calgary, at approximately 1045 metres elevation, has an estimated air density of roughly 1.06 to 1.07 kg/m³ at 20°C, compared to 1.204 kg/m³ at sea level -- about an 11 to 12% reduction. This affects both HVAC airflow mass calculations and gas combustion air requirements, and is a factor Alberta HVAC contractors regularly account for in equipment sizing and commissioning. Use the Altitude-Corrected Density Calculator above for your specific elevation and temperature.