How do you find BTU for gas furnace?

To find the BTU (British Thermal Unit) rating for a gas furnace, you can check the manufacturer's label or specifications, usually found on the unit itself or in the user manual. The BTU rating indicates the furnace's heating capacity, typically measured in BTUs per hour. If this information is not available, you can estimate the required BTUs by calculating the heating needs of your space, considering factors like square footage, insulation, and climate. Online BTU calculators can also assist in determining the appropriate size for your specific needs.