HVAC Load Calculator | Estimate The Size Of Your Heating / Cooling ...

HVAC Load Calculator provides an accurate real world heat load estimate for both heating & cooling.

Additionally, the HVAC Calculator provides equipment recommendations (type heating/cooling system appropriate for your home), & calculates the cost of installing the equipment, including labor & materials!

Calculate Heat Load (BTUs), HVAC Size & Cost in CA

Area Size sq. ft. HVAC System Type Cooling Only Cooling + Heating Heating Only Do you have ducts? Yes No Insulation Grade Very Well Insulated More than Average Average (R-13 walls) Less than Average Poorly Insulated Climate Region Region 1 - Blue Region 2 - Green Region 3 - Yellow Region 4 - Orange Region 5 - Red Rooms (zones) Space Height ft. Sun Exposure Strong Exposure Average Exposure Shaded or Interior Windows Average Amount More than Average Windows/Doors Air Tightness Double pane, Well sealed Average Design Single pane, Poorly sealed Do you have baseboard radiators? Yes No Estimated Load Cooling / Heating: 0 BTU Recommended Equipment Low End $0 Mid Range $0 High End $0

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We use a proprietary BTU calculation algorithm, that DOES NOT over-specify the unit capacity.

Most online tools give you a higher heat load estimate than you actually need for your home to sell you more expensive equipment.

How To Use HVAC Load Calculator

It is important that you enter accurate/appropriate details into the calculator. This tool brings you as close to a complicated Manual J estimation as possible. Otherwise, you may end up with a system that is too big or too small.

Step 1 (Climate Region): Select your Climate Region, using the Region Map at the top on the calculator. For example, if you live in NYC or NJ, select Region 3 (yellow). If you live TX, select Region 5 (red), etc.

Step 2 (Area Size): Enter square footage for your house/building or a specific area, for which you are doing the calculations.

This step is Critical for the accurate estimation of the annual heating/cooling load of your HVAC system! If you leave all settings as default, and only change the Region from 1 to 5 and back, you will see a huge change in Cooling/Heating BTU load.

Step 3 (Rooms / Zones): Enter number of Rooms/Zones where you want a new Heating/Cooling system installed.

If you plan to use a Central AC + Warm Air Furnace (ducted) system, or a Boiler for heating, the number of zones is not very important in terms of estimating heat load.

This value is most useful for figuring out which type of Ductless Mini-Split system to use.

Additionally, we discuss the PROS & CONS of using a multi-zone vs. installing multiple single-zone Ductless heat-pump systems, in our Mini Split DIY installation guide.

Typical Cost To Install a 4-zone Ductless Heat Pump Average: $11,890 - $18,910 See costs in your area

Step 4 (Space Height): Select average Ceiling Height of your house. In most cases this value should be equal to 8 ft. However if you have high ceilings, or cathedral/vaulted ceilings, the VOLUME of your space will be higher.

For cathedral/vaulted ceilings, add the lowest wall height + peak height, and divide by 2, to get the average. For example:

Your exterior wall is 8 ft. high, and the highest point on the ceiling is 12 ft. high. In that case, your average Ceiling Height is 10 ft: (12 + 8) / 2 = 10

Step 5 (Insulation Grade): Most homes in US built between 1978 and 2000 will have 4″ studs with R-13 wall insulation, and should have R-38 roof / attic insulation. If this matches your home, leave this value as default (Avg. Insulation R-13 walls).

If you have a newer home with 6″ studs, will have R-18 insulation. In this case, select “More than Average” value.

In most cases you should not use “Very Well Insulated” value, unless you have a “Super-insulated” house.

If you have partially insulated home, select “Less than Average” or “Poorly Insulated”.

These two values are most critical in terms of heating, where your heat loss will be the highest. If your primary reason for installing a new HVAC system is cooling, we recommend using “Less than Average” value, to not over-size your cooling equipment.

Step 6 (Windows): Select the average amount of windows in your home. If you have ~1 window or fewer, for every 8 feet of exterior wall length, select “Average Amount”.

If you have more than 1 window, for every 8 feet of exterior wall length, select “More than Average”

Step 6 (Windows/Doors air tightness): Select appropriate window/door insulation level. In most cases, leave this as default “Average” value.

HVAC Load Calculation Results

Unlike other online HVAC calculators, we provide estimated heat load (system size in BTU/h) for both Heating & Cooling, as well as recommended HVAC equipment type and size!

You will get TWO results:

1) Cooling & Heating Load in BTUs – this is the actual calculated number of BTUs per hour & TONs needed to heat/cool your space.

You will get an approximate BTU / TONs load for your house, based on the information you entered in the calculator and your region.

Both heating and cooling BTU results, are calculated using our optimized BTU calculation algorithm, which is more “conservative” than most HVAC contractors and equipment sellers will give you.

On average these values will be 20-30% lower than “contractor’s guestimate”. However we recommend that you use the lower numbers, for reasons discussed above.

2) Best matching Heating / Cooling equipment type for your needs.

Our calculator tries to provide the best match / recommendation for equipment to use your particular situation, based on your Climate Region and other inputs.

Equipment Recommendation needs further clarification, as each person’s situation is different. Ideally, this calculator would be perfect for a new construction home, where you have total control of design and specifications of the type of HVAC equipment that will be used.

However, most homeowners in US are dealing with existing homes, which brings certain limitations.

First of all, if you have a Duct System in your home, a Central AC + Hot Air Furnace will be the most cost-efficient system for you.

In very hot climates, a furnace can be substituted with an electric heating coil, which would provide warm air on rare cold days/nights.

If you do not have air ducts, and live in climate zones 1, 2 or 3 – the best system for heating is a forced hot water boiler (with baseboards, wall radiators or radiant floor heat), and best cooling system is a multi-zone ductless (mini-split) AC, which are economical and extremely efficient.

In Regions 3, 4 & 5, you rarely have very cold weather. In these areas, winters are very mild, and average low temps are above 0F degrees.

Therefore, a high efficiency Ductless (mini-split) Heat Pump system can (and should) be used for both heating & cooling. It is most economical* type of heating/cooling you can get.

Ductless heat pumps can both heat and cool your house, in ambient temperatures as low as -15F degrees, and they are pretty good at doing both.

Since they can provide heating, and do so using a fairly low amount of electricity (3-4 times less than electric space heaters), you may not need to install an additional heating system, be it a furnace or boiler, saving yourself about $7,000-12,000+ in installation costs.

However, these should not be your ONLY source of heating in climate zone 1 & 2, where temperatures get very cold in the winter, and power outages are frequent, as ductless heat pumps run on electricity.

If you have a backup heating system (such as old boiler or gas/pellet stove, and can last a few days without electricity in case of a power outage, then you can use Heat Pumps for primary source of heating even in colder regions.

A big advantage is that ductless systems are “modular” and operate on zone level. So if you are spending most of the day in the living room, there is no need to cool or heat the entire house!

You only need to run 1 zone. At night, you can turn off the living room zone, and turn on the zones in bedroom(s).

Moreover, ductless systems are also about 2x more efficient than even the high efficiency modern Central AC systems, which means your electric bill will be 2x lower!

Actually even more than 2x, because of zoning, which is nearly impossible to do with central air conditioning systems.

* While most southern states have very low electricity costs (around $0.10-$0.13 per kWh), places for like California, were electric costs often exceed $0.30 per kWh, and PEAK pricing can go as high as $0.50 per kWh, a ductless AC / Heating system is ideal, as these are often 2 times more efficient than a Central AC, and you can condition only the parts of your house where you actually need cool or warm air, instead of cooling/heating your entire home, while you are sitting in the living room!

Pro Tip: If your house does not currently have air ducts, and your house is single level (ranch/cape), then air ducts and the AC + Furnace could be installed in your attic, using flexible insulated ducts.

This is a lot cheaper than traditional sheet-metal ducts that have to be installed from the basement, and extended into all your rooms, especially if your house consists of multiple levels.

In this case, installing Central AIR is significantly cheaper than Ductless Heat Pumps. However, due to massive efficiency difference, a ductless system will quickly cover the initial out of pocket cost difference, by saving an average of 40% in operating costs!

How HVAC Load Calculator Can Save You Money On Home Heating

Typical Cost To Install Central AC Average: $4,070 - $5,930 See costs in your area

While there are a few BTU heat load estimators available online, many homeowners are still unsure which heating and cooling system is best for them.

This is where our new algorithm can make an intelligent recommendation, which includes both system capacity (for heating & cooling), appropriate system type, and energy/fuel costs.

PRO TIP: Improving home insulation (in walls and attic), and sealing/insulating your air ducts, will have a significant effect on the BTU load of your cooling / heating system.

Savings in energy cost savings for both cooling & heating can be as high as 15-25%!

We also recommend that IF you plan to use the results of this heat load calculation for making your purchasing decisions, you SHOULD verify the results with this long-form Manual J online estimator.

Multiple heating/cooling systems: Another important feature of our calculator is the ability to estimate the cost of multiple heating / cooling systems being installed in large homes (over 3000 sq. ft.), and specifying largest possible BTU lead HVAC system(s) and then the smallest size system for the remainder of the total BTU load.

For example, if your heat load is 150K BTUs, and maximum residential Central AC size is 60K BTUs (5 Ton) then you need two 60K BTU compressors and a 30K (2.5 Ton) system.

The calculator’s algorithm will select the full size system(s) and the smallest needed system to cover the rest of required BTU load, to give you most cost efficient estimate.

HVAC System Installation Cost Estimate: the tool will estimate total installation price for your new HVAC system, which is based off equipment cost, and national average labor + overhead + profit, that plumbers/HVAC contractors charge for each type of system.

HVAC Sizing

Getting the right size HVAC system for your home/building is essential to providing enough capacity to heat or cool your living space. If your Heating or Cooling system is too small, you won’t get enough BTUs, and the space won’t be comfortable.

If you get too big of a system, you will be overpaying for the extra capacity: Bigger system = higher cost of installation. You will also be paying too much in operating costs (be it gas, electric or oil) going forward.

Most residential HVAC/Plumbing contractors do not want to spend the time to properly calculate (using Manual J method) the heat load & heat loss of your house (or individual rooms).

So instead to cover their “bases”, 99% of pros specify oversized systems (which as explained above, costs more to install and operate).

NOTE: Most contractors and equipment distributors use INFLATED BTU/h values when calculating the heat load and unit size (in tons/BTUs), primarily to cover their backs.

Our calculator uses lower BTU/h values for both Heating & Cooling, to provide a more a “real-world” heat load estimate.

However, we strongly recommend that you (or your contractor) do a Manual J heat load calculation of your home or a specific area, before making any purchasing decisions!

This calculator should be used and is intended for Informational Purposes only!