cCalmCalc
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BTU Calculator

Area multiplied by load factor.

Choose a BTU sizing workflowEstimate a general heating load or an adjusted air-conditioning load.
3 options
GENERAL HEATING OR COOLING LOAD10,000 BTU/h

area × BTU factor. Only inputs needed by this operation are shown.

Estimate based on the values shown
Formula checkedGeneral load is area × factor; AC sizing uses room volume × 2.5 with climate, exposure, and insulation adjustments. Detailed sizing combines room volume, temperature delta, occupants, room use, insulation, sun, and climate in imperial or metric dimensions.