Free Manual J

There are many ways to do a Manual J. Some people choose expensive software, specialized calculators, workbooks, online tutorials, and others even do them by hand. Most always they will cost you money.

A Manual J from a Manual J service like costs $79 for any size plan in any location. Other companies charge anywhere from 2-4 times this much so they can harvest more profit off of their clients.

Now, everyone knows there are also ways to do a Free Manual J. Let’s look at them below. The following are ways to do a Free Manual J:

Cool Calc: To create a free Manual J using Cool Calc you want to visit Cool Calc Free Manual J. This is an awesome software that allows you to go through all the steps to calculate your home’s heat loss and heat gain. You have the option of either measuring the home via satellite, or you can enter the data piece by piece. Whatever you prefer Cool Calc can create the Manual J for you based on your climate data and home’s construction makeup. This is a good option for a free Manual J.

Service Titan: This another great option for a Free Manual J. Service Titan allows you to enter all the data you need to create a Manual J for free. Visit Service Titan Free Manual J and then enter the following data:

Climate Region

Square Footage

Ceiling Height

Insulation Rating

Sun Exposure

Number of Windows

Door and Window tightness




Appliance Load

After you enter that data, the Service Titan calculator will output the Free Manual J and even give you an indication of the amount of tonnage needed for the structure. This in another great option for a Free Manual J that anyone can do.

Field Vibe: If simplicity is your cup of tea then the Field Vibe Manual J Simple HVAC Load Calculator will be great for you. You can visit Field Vibe Free Manual J and then you will want to enter:

Square Footage

Space Height (Ceiling Height)

Amount of Windows

Amount of Exterior Door

Number of Occupants

The Field Vibe Calculator will then give you a cooling load. This is a good option to generate the cooling load side of a Manual J for free in very little time.

HVAC Load Calculator: These guys are the original DIY Free Manual J creators. At one point they had their own software that was innovative and easy to use. Now they have moved to an online calculator model that you can find here HVAC Load Calculator Free Manual J . Their online form is simple to use and has a few more inputs some of the options above. The end report is concise and easy to read. makes a really nice free Manual J option that easy to use and love.

Manual J by Hand: If you are doing one alteration, addition, or new home construction this method may work for you. If you are doing 100 homes per year you probably need to look at another solution. Before computers, calculators, artificial intelligence, the internet, cell phones, and modern technology people did many calculations by hand. Any calculation that can be done by computer can be done by hand. The computer had to be fed the calculations and code by a human who created it by hand initially and this means that the same calculation could be reproduced by hand if you had enough knowledge and most importantly, time. The basic steps of completing a Free Manual J by hand are as follows:

Obtain the square footage of the structure. You are going to want to find the areas that will be receiving heating and cooling. Areas like sunrooms, porches, garages, and patios would be omitted from the square footage basis. This number can be found on your construction plans, hopefully. If not you can measure out the rooms one by one with an architect’s scale and add them together to generate the square footage that way.

Consider what type of insulation is being installed. Ceilings, walls, foundations, doors, and windows all contain some type of insulating qualities that protects the conditioned inside of your home from the climate zone outside. A ceiling, wall, or foundation insulation value will be measured in R Value or sometimes U Value. A window or door will be measured in U Value and SHGC. You need to have some idea of the local standards so you can decide whether what you have installed or will installed is a good barrier against your climate zone. Having a free Rescheck can help you understand what your local standards are or your building inspector may have a printout of the local insulation standards for your jobsite.

Determine the load of each construction component: This is the most complicated part of the DIY Free Manual J and impossible for me to explain in totality in this Free Manual J blog post. BTU is a British Thermal Unit and the Manual J measures the amount BTUs that will be needed to heat and cool the structure. People, doors, windows, skylights, bathroom fans, dog doors, and almost everything that separates your home from the outdoor weather has some type of load associated with it. I have read quite a few standards and many of them are baked into the Free Manual J software above. To say they are totally correct is not something that I can do, but I do think it is a good place to start. For further information on how to assign loads to each component of a home you will need a copy of Manual J Abridged Edition or Manual J full 8th Edition.

Compile the total HVAC Load: To find an estimated Free Manual J total load of a home you want to first find the following:

Volume: Square Footage of the home multiplied by height of ceiling.

Occupancy: Multiply occupants by 100 BTU

Doors: Multiply Doors by 1000 BTU

Windows: Multiply Windows by 1000 BTU

So let’s say you are building a 400 square foot bedroom addition with 2 windows, 1 door, and one occupant. The ceiling is 8′ high.

You basic hand calculated Free Manual J would look like this.

400 square foot x 8′ ceiling = 3200 BTUs

1 Occupant = 100 BTUs

2 Windows = 2000 BTUs

1 Door= 1000 BTUs

The total load in this DIY Free Manual J method would be: 6300 BTUs

Please take this method and most of the above free Manual J methods with a grain of salt. Here are the limiting factors of the hand calculated by hand DIY Free Manual J and many of the previous free Manual J calculations above.

It does not provide a heat loss or heating load.

It does not take into account your climate zone

It does not take into account your elevation

It will not be accepted as legitimate if your building permit requires a Manual J

It could result in under sizing

It could result in oversizing

The component values used in the calculation are one size fits all

It does not account for outdated doors or windows with broken or missing seals

It does not account for missing or inadequate insulation

It does not account for negligent construction or installation

Overall, the free Manual J method can get you by in a pinch. You also need to proceed with caution, it can also put you in a bind. It is not the best way to go about a Manual J.  Especially if a Manual J Heat Loss and Heat Gain calculation is required for a permit. If a Manual J is not required, and you are just using the free Manual J methods described above to double check a subcontractor, then maybe it is right for you. Just like if you use a Manual J service each Free Manual J Calculator above will give you a different answer.  You have to contend with different data points as well. Many of the them lack heat loss or heating load for structure.  They simply give a slight glimpse at cooling load with no real consideration of the climate zone or altitude. Knowing which one is correct can be a challenge.

If you need help having a Manual J created for you we can do it. We charge $79 and can have it back to you in 4-6 hours. Simply email us your order number, pdf plans, jobsite address, and square footage to and we will get you taken care of.

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Free Manual J Residential Load Calculation PDF

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