BEFORE A MANUAL J CALCULATION
Better planning.
Room by room.
Explore a preliminary cooling load range for the rooms in your home. See how space, ceiling height, insulation and sunlight change the starting point.
PRELIMINARY HVAC LOAD CALCULATOR
Let’s map your comfort.
A planning estimate, not a Manual J calculation. This tool uses broad area-based assumptions for cooling only. It does not calculate heating or replace a professional load calculation or equipment selection.
UNDERSTAND THE NEXT STEP
What is a Manual J calculation?
Manual J is ACCA’s residential heating and cooling load calculation method. A professional assessment accounts for details such as building materials, windows, orientation, air leakage and local design conditions.
This free tool helps you organize room measurements before that conversation. It is not ACCA-approved software and does not implement the Manual J standard.
Learn about Manual J from ACCA ↗How is this preliminary estimate calculated?
For each room: length × width × a climate range × a ceiling-height factor × insulation × sun exposure. Hot climates use 22–34 BTU/h per sq ft; warm use 18–30; mild use 15–25. Ceiling height uses height ÷ 8, with a minimum factor of 1. Insulation factors: well insulated 0.85, average 1, poor 1.2. Sun factors: shaded 0.9, some sun 1, strong sun 1.1. These are illustrative planning assumptions, not validated Manual J factors. Room values are rounded outward to 100 BTU/h and then added.
What does the tool leave out?
It does not model wall and roof assemblies, window area or performance, orientation-specific solar gain, occupancy, appliances, ventilation, infiltration, duct losses or humidity loads. Actual loads may fall outside the displayed range; it is not a statistical confidence interval.
Can I choose an A/C tonnage from this result?
No. Dividing a cooling rate by 12,000 converts BTU/h to a tons equivalent, but it does not select equipment. Adding rough room ranges is not a whole-house design load. A professional needs to evaluate your home and equipment performance before recommending a system.
Is this useful for heating or commercial buildings?
This estimator is for preliminary residential cooling planning only. It does not calculate heating loads and is not suited to commercial, industrial or specialized spaces.
YOUR LOCAL COMFORT TEAM
Good measurements. Better conversations.
Bring your room list and comfort concerns. We’ll help you understand the next step for your home.