BTU Heating Load Calculator
Estimate an early-stage heating load in BTU per hour from room measurements. A planning aid with clear limits, not a Manual J HVAC sizing calculation.
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How to use BTU Heating Load Calculator
- Enter the room length, width and height in feet.
- Choose the room use, insulation level and glazing type.
- Add the number of exposed walls and other relevant room factors.
- Review the rough planning load in BTU per hour, then obtain a room-by-room heat-loss design.
Why use this tool
- Provides an early BTU/h planning figure from simple room information.
- Uses feet and cubic feet on the US route.
- Makes the need for a complete heat-loss calculation explicit.
This is not a final radiator, baseboard or HVAC equipment selection. A real room-by-room heat-loss calculation needs measured assemblies and thermal values, infiltration and ventilation, local outdoor design temperature and the intended indoor temperature. Select equipment from manufacturer output data at the actual operating conditions and have a qualified HVAC professional verify the complete system.