HVAC Calculators

Air conditioner sizing, insulation R-value, and duct calculators.

HVAC sizing follows a simplified Manual J load calculation — the industry standard method for determining heating and cooling requirements. The BTU calculator chains together room area, ceiling height, climate zone, insulation level, and window area to estimate the minimum tonnage needed. Undersizing an AC unit means it runs constantly and never dehumidifies properly; oversizing causes short cycling and humidity problems. The R-value calculator uses DOE climate zone maps to recommend insulation thickness for attics, walls, and floors.