Mode
The baseline rule assumes an 8 ft (about 2.44 m) ceiling and adjusts proportionally for taller or shorter rooms.
The calculator adds 600 BTU/h for each regular occupant above two.
Kitchen mode adds 4,000 BTU/h because cooking spaces often generate extra heat.
This is a planning estimate. It is not a replacement for a professional HVAC load calculation.
Use this mode when you already know the room’s floor area and want a quick cooling-capacity estimate.
Use this mode when you know room length, width, and ceiling height but not the total area yet.
Use this mode when you already know the AC size and want an approximate maximum room area.
What this calculator is for
- Room / window / portable / single-room AC planning.
- Rough BTU/h and kW sizing from room size and simple adjustments.
- Reverse coverage checks from a known AC capacity.
What this calculator does not do
- No Manual J or equivalent professional HVAC load calculation.
- No whole-home central HVAC design.
- No detailed humidity, glazing, insulation, or duct-loss model.
- No product database, electrical sizing, or energy-bill estimate.
How the estimate is calculated
- The baseline rule uses 20 BTU/h per square foot of floor area, which is converted consistently for metric input.
- Ceiling height adjusts the base estimate proportionally against an 8 ft (about 2.44 m) reference ceiling.
- Sun exposure applies a simple factor: shaded rooms use less capacity, while sunny rooms use more.
- Regular occupants above two add 600 BTU/h each, and kitchen mode adds 4,000 BTU/h.
- A suggested common size is then chosen by rounding the estimate up to the next room-AC size on the built-in ladder.
FAQ
Why does the calculator use 20 BTU per square foot?
That is a common room-AC sizing rule of thumb used for simple planning. It is useful for quick estimates, but real homes can need more or less cooling depending on insulation, windows, humidity, and layout.
Why does ceiling height change the estimate?
Taller ceilings usually mean more room volume to cool. This tool adjusts the baseline proportionally against an 8 ft reference ceiling.
Why does a sunny room need more capacity?
Rooms with stronger sun exposure often gain more heat during the day. This calculator applies a simple +10% sunny adjustment or -10% shaded adjustment for quick planning.
Why does kitchen mode add 4,000 BTU/h?
Cooking spaces often add noticeable heat from appliances and meal preparation, so the estimate includes an extra fixed adjustment when kitchen mode is on.
Is this a replacement for professional HVAC sizing?
No. This page is a quick room-AC planning tool, not a full HVAC load calculation. For larger spaces, unusual layouts, or major purchases, confirm the result with a qualified professional.
Next steps
- Universal Unit Converter for Length, Area, Volume & MoreConvert feet, meters, area, volume, energy, and many other units with a shareable result URL.
- Temperature Converter (Celsius, Fahrenheit, Kelvin)Convert °C, °F, and K quickly when you want to compare thermostat or weather values.
- Length Converter (m, km, cm, mm, inch, foot, yard, mile)Convert room dimensions between metric and imperial units before sizing the cooling estimate.
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Comments
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