Manual J Calculator (Simplified) – HVAC Load Calculation USA

Yes, Manual J is required in many US states for HVAC system design and installation permits.

What is Manual J Calculation?

Manual J is a standard HVAC load calculation method used in the USA to determine accurate cooling and heating requirements.

Total Cooling Load = Area Load + People Load + Window Load + Infiltration Load

Room Area (sq.ft) Ceiling Height (ft) Number of People Window Area (sq.ft) Insulation Quality Climate

Manual J is a standard HVAC load calculation method used in the USA to determine accurate heating and cooling requirements.

This simplified version provides a close estimate. For exact design, a detailed Manual J calculation is recommended.

Typically, 20–30 BTU per square foot is used depending on climate and insulation.

Yes, many states require Manual J calculations for HVAC system installation and permits.