Manual J Load Calculations



Right-Draw® is highly recommended, but is not required.

Manual J Load Calculations & Manual S:

Right-J® is the industry leading residential load calculation software since 1986. It enables designers of all skill levels to perform ACCA and ANSI approved Manual J calculations quickly and with ease. Right-J® also includes Manual S, with expanded data from some manufacturers, which automates the equipment selection process.


In conjunction with Right-Draw®, Right-J® will instantly calculate your load once building details are selected. Once the load is calculated, choose the desired equipment using the included (automatic or manual) Manual S feature. With our exclusive Hotlink™ technology, Right-J® will recalculate instantly as you enter figures enabling you to play “What If?” just by changing one value in the easy-to-understand worksheet.
**Using Right J vs using Right J, Right Draw  View overview video.

Right-J® Applications:

Build extensive libraries, or use our pre-loaded libraries. These libraries contain hundreds of building material types for building surfaces and offers the ability to create unlimited custom material types. Building material types already within the program range from standard frame materials to structural insulated panels, insulated concrete forms, log walls, encapsulated attics, sealed craws (spray foam/dense packed cellulose applications, and so much more. This program can also can accommodate custom materials which can either be built as layers of components or entered with pre-engineered numbers and can be saved and reused.

Easily assign air handlers as you need them. With our easy-to-use drag and drop multi-zone tree, choose to specify equipment type easily. Each space may have its own thermostat and can be grouped with other spaces simply by dragging from one piece of equipment to another within the multi-zone tree.

Use any of 4 different infiltration systems. Right-J® supports ACCA 5-option Simplified Method, ACCA Detailed Method, single point blower door (CFM-50), and multi-point blower door (Test-C / Test-N).

Calculate fresh air requirements using Manual J or ASHRAE 62 methods. Right-J® supports centrally introduced and room introduced ERV, HRV, ventilating dehumidifiers, and untreated outside air. (ASHRAE 62 is required by Energy Star and other building codes and programs.)

View the shape of load peaks and valleys. Right-J® offers a colorful Load Meter which shows the shape of load peaks showing you a large range of possible conditions effecting your load. These visuals are also shown on the Right-J® reports.

Add or view NFRC performance data. Right-J® has dedicated fields to keep up with modern window technology.

Instantly set or find the worst-case-scenario house orientation. In a single click of a button, choose to view or print the load for every orientation on a single report. This program uses only the 8 approved orientations of the Manual J8 to avoid unnecessary over-complications with extra orientation choices.

View and print submittal reports. Choose to view reports for plan review or inspection.   View sample report.

Contains complete international ASHRAE weather database.

Automate Manual S selection. This tool equipped with most manufacturer data, and includes an interpolator tool for manufacturers not included. The Manual S form for submittals is also included in this section of Right-J®.

Additional Technical Features

  • Calculates ACCA certified Manual J 7th and 8th edition load calculations, including addenda A,B,C and D.
  • Work with blazing speed as the worksheets instantly recalculate onscreen with any changes made in Right-Draw®.
  • All Manual J tables are included, including mobile homes with improved sizing loads for:
    • Single-family detached homes
    • Small multi-unit structures, condominiums, and townhouses
    • Manufactured homes
  • Links with ARI/GAMA electronic equipment directory built into the program.
  • Loads can be broken down by whole house or room-by-room with BTUs and CFMs and viewed as pie charts with the Load Meter.
  • Multi-zone capability with single central VAV or multi-equipment, including the calculation of peak loads.
  • Handles hydronics including high and low density baseboards.
  • Fast links to ResCheck, Rem/Rate and Florida Engage for easy code compliance, sold separately.
  • Both ACCA and sales-oriented reports and printouts for submissions, detailed analysis, and more.
  • Thousands of material types for walls, windows, doors, roof types, window shading and more including custom surface library for unusual materials.
  • Contains a complete international ASHRAE weather database.
  • Calculations including:
    • Improved duct loss and gain models
    • Heat loss and gain for log walls, structural foam panels, aerated concrete block, insulated form concrete panels, brick walls, concrete walls, wood foundation walls, below grade walls, and many other types of walls and insulation
    • Heat gain sensitivity to roofing material, roof color and the use of radiant barriers
    • Cooling loads for glass rated by the National Fenestration Rating Council (NFRC)
    • Improved methods for estimating the effect of internal and external shading devices, including insect screens
    • Sensitivity to skylight glazing material, curb construction and light shaft construction
  • Equipment Sizing Loads for:
    • Single-family detached homes
    • Small multi-unit structures, condominiums and townhouses
    • Manufactured homes
  • Many Sensitivities in:
    • Cooling loads for glass rated by the National Fenestration Rating Council (NFRC)
    • Improved duct loss and gain models
    • Improved methods for estimating the effect of internal and external shading devices, including insect screens
    • Infiltration estimated based on blower door test
    • Sensitivity to latitude and altitude
    • Sensitivity to skylight glazing material, curb construction and light shaft construction
    • Heat gain sensitivity to roofing material, roof color and the use of radiant barriers
    • Heat loss and gain for log walls, structural foam panels, aerated concrete block, insulated form concrete panels, brick walls, concrete walls, wood foundation walls, and many other types of walls and insulation
  • Calculations in:
    • Below grade walls
    • Radiant barriers in attics
    • Peak loads for zoning
  • Thousands of Material Types such as walls, windows, doors, roof types, window shading types and more
  • AED Load Meter within Right-Draw/Right-J:
    • As you draw, the Load Meter shows the total heating and cooling loads for the building and the total loads for walls, glazing, doors, ceilings, floors, infiltration, ducts, ventilation and hydronic piping.


As the original ACCA Technical Partner, MiTek-Wrightsoft’s 30+ year relationship is longer than all other software partners combined, giving you the peace of mind you need when calculating loads. Join the tens of thousands of contractors and HVAC designers utilizing Right-J® to quickly and easily calculate heating and cooling loads. Combined with Right-Draw®, you can save even more time and increase accuracy with the most reliable load calculation tool and equipment selection tool on the market.


What Our Customers Are Saying

"As a business owner, one of the things I like is that Right-Draw gives us a level of professionalism whether it’s a specialty home or a basic starter home. Within the past year, we have actually picked up new accounts because our customers were so impressed by the professionalism of our designs, particularly when we go up against contractors who are giving them what amounts to a crayon rendition on a napkin."

Mike Douglas

from Advent Air Conditioning

"I’ve always been a proponent of proper sizing of air conditioning equipment. For a standard 3,000 square foot, 4 bedroom house, doing the load calculations manually would take many hours. Then I found Wrightsoft, and by using their Right-J and Right-D, I was able to produce load calculations and duct design in about an hour."

Bob Pietrangelo

from Comfort Solution

“Hands down, the best tool for the job. Our HVAC partners love the 2-line mode drawings, and the export to REM/Rate module saves me at least 2 hours per project! That's a real game changer for us in terms of billable hours and revenue. Mike (sales) and Donald (tech support) have been there for us for over 10 years! Keep up the good work and thanks again guys. - Just another loyal happy customer.”

Mike Truitt

Resnet Rater from This Efficient House

“We are primarily a residential replacement air conditioning and heating company in Clearwater, Florida.  We found a serious issue with improperly sized air conditioning systems in existing homes that was causing issues with humidity, or lack of cooling.  We have used Manual J for over 30 years, but due to the time-consuming process of entering information manually, it was not done unless we had a consumer complaint.  We partnered with Wrightsoft over 15 years ago and can now do a Manual J Load Calculation in less than 30 minutes. Wrightsoft is always there for us, with tech support staff that answers the phone quickly, and offer advice when needed.  There is also a library of how to videos available 24 hours a day on their website. Wrightsoft has continued to be the best option for us for Manual J load calculations.”

Jim Heinz

President of Heinz Air Conditioning and Heating, Inc.

“I reached out to technical support [to complete an advanced task].  [Technical support] responded within an hour or two, guided me through the process, and even QC’d my spreadsheet (making corrections needed).  I was really impressed… I’ve found that my questions are always answered, usually within hours, and there’s never an attempt to dodge an issue. Wrightsoft’s responsiveness on the support side is what truly sets you apart.  Your team has made my life easier and using RSU has become an integral cornerstone to the work I do guiding our teams in the design and construction of high performance, soon to be ZNE affordable housing.”

Tim Kohut

Director of Sustainable Design National Community Renaissance

“I've been using Wrightsoft since the late 80’s. Public Service Company in Oklahoma's "Good Cents" program required an ACCA Manual J load calculation and ACCA Manual D duct design to qualify as a "Good Cents" structure. As long as the information is entered correctly, Wrightsoft takes all of the guesswork out of the equation. It has given me peace of mind and keeps our quality of installation above the rest. I can't imagine doing an install without it, it's as important to us as the rest of the tools on our trucks.”

Steve Paxton

from Air-Dynamics

“The Wrightsoft experience has been great from the beginning to end.  Their support staff are patient and professional.  Proper equipment sizing is imperative regarding our customers comfort. We have been able to provide our customers with accurate professional data to backup our proposals awarding us multiple projects over our competitors. Well worth the investment of time and money.”

Tom Tumminelli

from Brothers Plumbing, Air & Electric

"If you're a Wrightsoft user and have been wanting to go to the next level, Right-CAD is it. I'm not conversant with CAD but I was up and running with 3D almost immediately, importing some of my more complex duct designs already created with RSU, and amazed at seeing what I could only imagine before. The 3rd dimension takes the guesswork out of interstitial duct runs, navigating dropped ceiling areas, dropped girders, etc. Learning curve is simplified by utilizing the familiar tools & tabs already within RSU, and yet with lots of bells and whistles for rainy day exploration and further fine tuning of design presentation. I see this as the future of professional & field ready HVAC design, without the cost and lengthy learning curve of Revit."

Rick Blair

Certified Home Energy Rater & Thermographer Performance Point, LLC

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