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Adjusted BTU load
The four multipliers capture volume, weather and internal heat sources.
The Formula
BTU = area x 20 x (ceiling height / 8) x climate factor x kitchen factor
The four multipliers capture volume, weather and internal heat sources.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| Q | Cooling load | BTU per hour | The heat removal rate the unit must deliver. |
| A | Area | square feet | The floor area of the room. |
| h | Ceiling height | feet | The height of the ceiling, usually 8 to 12 feet. |
| f | Factors | unitless | Climate and kitchen adjustments, around 1 each. |
What Each Symbol Means
QBTU per hour
Cooling load
The heat removal rate the unit must deliver.
Asquare feet
Area
The floor area of the room.
hfeet
Ceiling height
The height of the ceiling, usually 8 to 12 feet.
funitless
Factors
Climate and kitchen adjustments, around 1 each.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate air conditioner size page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Air Conditioner Size, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.