Free HVAC sizing calculators, BTU tools and Texas HVAC resources
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Free HVAC Sizing Tool

HVAC Size Calculator

Estimate a preliminary HVAC cooling load in BTUs and tons using conditioned square footage, Texas climate, ceiling height, insulation, windows and sun exposure.

Calculate HVAC Size
HVAC Sizing Estimate

Estimate BTUs and HVAC tonnage.

This tool is designed for preliminary planning. Before equipment is selected for a real HVAC installation , the home's actual heating and cooling loads should be evaluated.

Calculate Approximate HVAC Size

Enter basic home characteristics to generate a preliminary sizing range.

Enter conditioned square feet.
Preliminary HVAC Size Estimate - -

This is an early planning estimate rather than equipment-selection advice. Actual HVAC capacity can change materially after a proper residential heating and cooling load calculation.

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Approx. Nominal Size
Home Size -
Climate -
Insulation -
Ceiling -

Planning an HVAC installation?

Open the short form below to send your location and HVAC installation request.

Important sizing note: this calculator deliberately provides a broad preliminary estimate. Square footage alone is not sufficient for final HVAC sizing. Building orientation, insulation, windows, infiltration, duct location, construction, humidity and design temperatures can materially change the actual heating and cooling load.
Compact HVAC Lead Form
HVAC System Sizing

Why the right HVAC size matters.

Oversized HVAC Equipment

Bigger equipment is not automatically better. Oversized systems may cycle frequently and can affect comfort and humidity control. That is why a final system should be sized for the home's actual load before an HVAC installation .

Undersized HVAC Equipment

Equipment with insufficient capacity may struggle during high-load conditions. HVAC size should account for more than floor area, including insulation, windows, air leakage, ducts and climate.

HVAC Tonnage

Residential cooling capacity is commonly discussed in tons, with one ton representing approximately 12,000 BTU per hour. Use our HVAC tonnage calculator for a tonnage-focused estimate.

BTU Cooling Capacity

BTUs describe heating or cooling capacity. For a more detailed capacity-focused calculation, compare the result with our whole-home BTU calculator .

Planning New HVAC Equipment

Sizing connects directly to installation cost and efficiency.

Once you have a preliminary capacity estimate, the next questions usually involve equipment efficiency and project cost. Review our AC installation cost in Texas guide when budgeting for new equipment.

If you are comparing equipment types rather than just capacity, our heat pump vs AC in Texas guide explains key differences between conventional air conditioning and heat-pump systems.

Proper HVAC Sizing

Why this calculator is only the starting point.

U.S. Department of Energy

DOE guidance explains that heating and cooling loads should be determined before equipment is selected and warns that simple rules of thumb can lead to oversized systems. Read DOE HVAC sizing guidance .

ENERGY STAR Quality Installation

ENERGY STAR recommends sizing equipment using the actual characteristics of the home and also highlights airflow, refrigerant charge and duct-system condition as part of HVAC quality installation. Review ENERGY STAR HVAC installation guidance .

HVAC Size Calculator FAQs

Common HVAC sizing questions.

What size HVAC system do I need?

The appropriate system size depends on the home's heating and cooling load. Square footage is useful for preliminary planning, but insulation, windows, air leakage, ducts, orientation and climate can materially affect the actual requirement.

How many BTUs are in one ton of AC?

One ton of nominal air-conditioning capacity corresponds to approximately 12,000 BTU per hour.

Can I size an HVAC system using square footage alone?

Square footage alone does not capture enough information for final equipment selection. A proper residential load calculation considers additional building and climate characteristics.

Is a bigger AC system better in Texas?

Not automatically. An oversized system may cycle more frequently and can affect comfort and humidity control. Equipment should be matched to the home's actual load.

Does insulation affect HVAC size?

Yes. Insulation affects heat transfer through the building enclosure and can materially change heating and cooling loads.

Do high ceilings affect AC size?

Ceiling height can affect the volume of conditioned space and should be considered along with other load factors rather than relying only on floor area.

What is a Manual J load calculation?

Manual J is a residential load-calculation methodology used to estimate the heating and cooling requirements of a home using climate and building-specific inputs.

Can this HVAC size calculator replace Manual J?

No. This calculator is intended for early research and comparison. Final HVAC equipment selection should be based on a detailed load calculation and the actual characteristics of the property.

HVAC Installation

Planning a new HVAC system?

Use the HVAC help form to provide your service type and Texas location after reviewing the preliminary sizing estimate.

Request HVAC Help