AC BTU Calculator

Calculate the exact BTU and recommended AC tonnage for any room. Enter room dimensions, occupancy, windows & insulation — instant results and energy cost estimates.

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Recommended AC Size

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How to Use the AC BTU Calculator

Our AC BTU calculator helps you determine the perfect air conditioning size for any room. By considering factors like room dimensions, occupancy, ceiling height, and insulation quality, you get an accurate BTU recommendation.

Understanding BTU Requirements

BTU (British Thermal Unit) is the standard measurement for cooling capacity. The basic formula starts with 25 BTU per square foot, but real-world conditions require adjustments:

  • Occupancy: Each additional person adds 600 BTU of heat
  • Kitchen: Cooking appliances add 10% heat load
  • Windows: West-facing windows add 10% solar heat gain
  • Ceiling Height: Ceilings above 9 feet add 15% cooling load
  • Insulation: Poor insulation adds 20% heat transfer

BTU to Tonnage Conversion

Air conditioners are often rated in "tons" of cooling capacity. One ton equals 12,000 BTU. Common residential sizes include:

  • 0.75 Ton = 9,000 BTU
  • 1.0 Ton = 12,000 BTU
  • 1.5 Ton = 18,000 BTU
  • 2.0 Ton = 24,000 BTU

Frequently Asked Questions

What is BTU and why does it matter?▼

BTU (British Thermal Unit) measures cooling capacity. Higher BTU = more cooling power. Choosing the right BTU ensures efficient cooling without wasting energy.

How do I calculate AC BTU for my room?▼

Multiply room length × width × 25 for base BTU. Add 600 BTU per extra person, 10% for kitchens, 10% for west-facing windows, and 15-20% for high ceilings or poor insulation.

What size AC do I need for a 12x12 room?▼

A 12x12 room (144 sq ft) typically needs around 3,600-5,000 BTU or a 0.5-1 ton AC, depending on occupancy and other factors.

Is a bigger AC always better?▼

No. An oversized AC cools too quickly without removing humidity, causing discomfort and higher bills. Right-sizing is essential.

What is the difference between BTU and tonnage?▼

1 ton of cooling = 12,000 BTU. Tonnage is simply BTU divided by 12,000, making it easier to compare larger AC units.