HVAC Calculators

Estimate heating and cooling load with Manual J-style inputs for a quick HVAC sizing check.

Estimate the BTUs needed to heat or cool a room based on size, ceiling height, insulation, and room conditions.

Estimate cooling load, AC size, and tonnage from room or home conditions.

Estimate furnace BTU size from floor area, ceiling height, climate, insulation, and furnace efficiency.

Estimate single-zone mini split BTU size from room size, ceiling height, insulation, sun exposure, and heating or cooling use.

Estimate heat loss in BTU/hr, W, or kW from room size, temperature difference, insulation, glazing, and air leakage.

Estimate room airflow from air changes per hour, or calculate duct CFM from duct size and air velocity.

Calculate room air changes per hour from airflow and room volume, or estimate the CFM needed for a target ACH.

Estimate round and rectangular duct sizes from airflow, duct use, and target velocity.