Free HVAC Calculator

HVAC Heat Load Calculator

Calculate heating and cooling loads for any room or zone and get a recommended AC or heat pump size.

Room / Zone Details

Frequently Asked Questions

How many kW do I need to cool a 60 m² room?

For a typical 60 m² room in a temperate climate (Wellington, Sydney) with average insulation, you need approximately 7–9 kW of cooling capacity. Enter your specific details above for an accurate calculation.

What is the rule of thumb for AC sizing in NZ?

A common rule of thumb is 100–150 W per m² for cooling in NZ, but this varies significantly with climate zone, insulation, window area, and occupancy. This calculator applies climate zone and insulation adjustments for more accurate results.

What is the difference between cooling kW and heating kW?

Cooling load is driven by solar gain, occupant heat, and external temperature. Heating load depends on heat loss through walls, windows and roof. In NZ's mild climate, the cooling load often governs sizing, but colder regions like Queenstown may be heating-dominated.