BTU Calculator
Calculate the right BTU capacity for your air conditioner or heater based on room size and conditions.
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AC Unit Size Guide
Window AC
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Portable AC
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Mini-Split
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Heating Estimate
Space Heater BTU
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Wattage Equivalent
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BTU Sizing Guide
What is a BTU?
BTU (British Thermal Unit) measures heating and cooling capacity. One BTU is the energy needed to raise 1 pound of water by 1°F.
Quick Sizing Reference:
- 100-150 sq ft: 5,000 BTU
- 150-250 sq ft: 6,000 BTU
- 250-350 sq ft: 8,000 BTU
- 350-450 sq ft: 10,000 BTU
- 450-550 sq ft: 12,000 BTU
- 550-700 sq ft: 14,000 BTU
- 700-1000 sq ft: 18,000 BTU
Why Proper Sizing Matters:
- Undersized unit: Runs constantly, can't keep up, higher bills
- Oversized unit: Short cycles, poor humidity control, wasted energy
- Right size: Efficient operation, comfortable temperature, lower costs
Additional Factors:
- Add 600 BTU per additional person beyond 2
- Add 4,000 BTU for kitchens
- Add 10% for sunny rooms, subtract 10% for shaded
- Consider ceiling height for rooms over 8 feet