Free online tool to calculate sensible, latent, and total heat load instantly. Determine Sensible Heat Ratio (SHR) for precise HVAC cooling coil sizing. No sign-up required.
Heat load is the amount of cooling or heating power an AC needs. Like knowing how big an oven you need to bake a giant pizza.
SI: Q_s = 1.21 × L/s × ΔT(K), Q_L = 3010 × L/s × ΔW(kg/kg). Imperial: Q_s = 1.08 × CFM × ΔT(°F) (sea-level air density 0.075 lb/ft³ — at ~1500m altitude divide by ~0.83).
Rule of Thumb: Sensible heat drops the temperature; latent heat removes the moisture.
Checklist: Enter airflow rate. Input temperature and humidity differences. Review the Sensible Heat Ratio (SHR).
Quick Tip: A low SHR (< 0.7) means your AC spends a lot of its capacity just wringing water out of the air.
SHR is the ratio of sensible heat to total heat. It tells you how much of the cooling energy is spent lowering temperature versus removing moisture.
Higher airflow increases the total heat transfer capacity. The heat load calculation relies heavily on the mass or volume flow rate (CFM or L/s) of the air.
If you only account for sensible heat, your system won't remove enough moisture, leading to a cold but clammy and uncomfortable environment.
Yes, while typically used for commercial air handler calculations, these exact same thermodynamic principles apply to sizing residential air conditioners and heat pumps to ensure they are matched perfectly to the cooling load.