Mini Split Sizing Calculator
Calculate the required BTU/h cooling capacity for a mini split air conditioner based on room area, ceiling height, insulation, sun exposure, and number of occupants.
Published by:
isCalculator Editorial Team
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How to use this tool?
Mini Split Sizing Calculator Guide
This calculator estimates the cooling capacity (in BTU/h) needed for a room. All measurements are in imperial units (square feet, feet).
- Enter Room Area (sq ft) – Required. Example: 400 for a 400 sq ft room.
- Enter Ceiling Height (ft) – Default is 8 ft. Adjust if taller or shorter (e.g., 10 ft).
- Select Insulation – Choose Poor, Average (default), or Good based on wall/attic insulation quality.
- Select Sun Exposure – Choose Low, Moderate (default), or High based on window sunlight.
- Enter Number of Occupants – Default is 2. Each occupant adds 600 BTU/h.
- Click "Calculate" – The recommended capacity and a detailed breakdown appear below.
Output: The result shows total BTU/h needed. The breakdown includes base load (20 BTU/h per sq ft), ceiling adjustment, insulation and sun factors, and occupant load. Use this value to select a mini split unit (e.g., 12,000 BTU for a 400 sq ft room with average conditions).
Previous Results
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Frequently Asked Questions
It estimates the required BTU/h cooling capacity for a mini split air conditioner based on room characteristics.
Base load (area x 20) plus ceiling adjustment, multiplied by insulation and sun factors, plus 600 BTU per occupant.
Oversized units cycle too often, reducing efficiency and humidity control. Undersized units run constantly and may not cool adequately.