We've taken our proven formulas and designed this easy-to-use BTU calculator.

Fill out the fields below to calculate the BTU/hr (imperial) or Watts (metric) required for your worksite. Use this number as a guideline when choosing what size of industry heater you will need.

Select an R-Value number between 1-40 for each input field below. R-Value is a measure of the capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power. If you are unsure of your site’s R-values, we recommend using the standard unit of “1” in all input fields, which will assume moderate insulation. We have provided approximated R-Values for standard materials as a guide.

Building tightness is a measure of the leakage of air from a building. It is defined as the fraction of the air volume of a building that leaks out of the building per hour (units: 1 / hr). The lower the value, the tighter the building is.

0.33 = Very Tight 0.5 = Tight 1 = Moderate 2 = Loose 3 = Very Loose



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American Rental Association