Free homeowner tools
What size AC does your home need?
A few details about your home. A clearer picture of your heating and cooling needs. No email required.
Your home, by the numbers.
Preliminary estimateCooling load range
Heating load range
Heat needed by the home, not furnace input or heat-pump nameplate capacity.
These are illustrative scenario ranges, not measured accuracy or statistical confidence intervals.
The assumptions behind your estimate
The model assumes a simple rectangular home. Attached homes use an assumed shared-wall allowance. Room layouts, actual wall construction and window orientation can change the result.
A better starting point for your next system.
Own a home in the Phoenix metro? Ask Air Army to verify the load and help compare suitable systems.
Explore AC replacement →Bring these questions to your contractor.
Ask for a Manual J load calculation and equipment selection using manufacturer performance data. Homes with multiple systems need the load allocated to the area each system serves.
A little HVAC knowledge goes a long way.
What is an HVAC load calculation?
It estimates how much heat a home gains in summer and loses in winter. The answer is expressed in BTU per hour. Climate, windows, insulation, air leaks and ducts all affect it.
Is this a Manual J calculation?
No. This tool is a preliminary component-based estimate. It is not ACCA-approved software and does not produce a Manual J report. A professional calculation uses detailed measurements and construction information.
Before selecting equipment, have a qualified contractor verify the load and select equipment using its actual performance at local conditions.
What does a “ton” of cooling mean?
One ton of cooling equals 12,000 BTU per hour. It describes cooling capacity, not the weight of the unit. A home's equivalent cooling load does not automatically identify the unit you should purchase.
What if my home has two AC systems?
This calculator estimates the whole home. Don't divide the answer evenly between your systems: upstairs and downstairs can have very different loads. Each system needs a calculation for the space it serves.
Where do the location and climate values come from?
Postal locations come from GeoNames, licensed under CC BY 4.0. County temperature limits come from the ENERGY STAR reference guide (2019 edition, revised April 2021).
County limits can span multiple weather stations and elevations. They are not necessarily the correct design temperatures for your property. This preview uses them to demonstrate location-aware calculations; station-level verification is required before launch. Moisture profiles and home defaults are modeling assumptions, not measured data or official IECC climate zones.