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Air Conditioner Size Calculator

Calculate the perfect AC capacity (Tonnage and BTU) for your room to ensure efficient cooling and lower electricity bills.

Feet
Meters

Room Dimensions

Heat Factors

Each extra person generates roughly 600 BTU of heat.

HVAC Expert Tips

1
Right-Sizing is Critical

An oversized AC cools the room too fast without removing humidity, leaving you cold but clammy. An undersized AC runs constantly, burning electricity and wearing out the compressor.

2
The Top Floor Factor

If your room is directly under the roof terrace, the concrete absorbs solar heat all day. You must increase your AC capacity by 15% to compensate.

3
Inverter Technology

If you fall between sizes (e.g. 1.2 Tons), buy a 1.5 Ton Inverter AC. The inverter compressor can automatically slow down to act like a 1.0 Ton AC once the room is cool, saving power.

Enter your room size to calculate exact cooling load.

The Ultimate AC Size & Tonnage Calculator for India (2026-2027)

Choosing the right air conditioner capacity is one of the most critical decisions for maintaining thermal comfort and managing electricity bills in Indian summers. Whether you are living in a humid coastal city like Mumbai or a dry-heat region like Delhi, knowing your exact cooling load is essential. An undersized AC will struggle to cool the room, running continuously and hiking up your power bills, while an oversized unit cools the room too fast without dehumidifying the air, leaving you feeling cold and clammy. Our advanced AC Size Calculator takes the guesswork out of HVAC sizing by considering your room dimensions, sun exposure, and occupancy to recommend the perfect AC tonnage and BTU requirements.

How to Calculate AC Size (Step-by-Step)

  • Measure Room Dimensions: Enter the length and width of your room in feet or meters. The calculator will automatically determine the square footage.
  • Select Heat Factors: Choose the level of sun exposure. If your room is on the top floor directly under the roof or has large west-facing windows, the cooling requirement increases significantly.
  • Enter Occupancy: Specify the number of people who will regularly occupy the room. Human bodies generate heat, and each additional person adds to the cooling load.
  • Get Your Recommendation: Click calculate to see the precise cooling load in British Thermal Units (BTU) per hour and the recommended AC capacity in Tons.

Engineering Formulas & Thumb Rules for AC Sizing

The fundamental metric for cooling capacity is the British Thermal Unit (BTU). A general thumb rule in India is that you need about 20 BTU per square foot of living space for a standard room. For instance, a 150 sq.ft. room requires approximately 3,000 BTU for base cooling. One Ton of refrigeration equals 12,000 BTU/hr. So, a basic formula is: Room Area (sq.ft.) x 20 / 12,000 = Base AC Tonnage. However, this is just the baseline. If the room is heavily shaded, the capacity can be reduced by 10%. If it receives direct sunlight or is on the top floor, the required capacity increases by 10% to 20%. Additionally, you must add 600 BTUs for each person in the room beyond the first two occupants.

Current Market Rates in India & 2027 Projections

  • 1.0 Ton Split AC (3-Star): ₹28,000 - ₹32,000
  • 1.0 Ton Inverter Split AC (5-Star): ₹34,000 - ₹38,000
  • 1.5 Ton Inverter Split AC (3-Star): ₹35,000 - ₹40,000
  • 1.5 Ton Inverter Split AC (5-Star): ₹42,000 - ₹48,000
  • 2.0 Ton Inverter Split AC (3-Star/5-Star): ₹48,000 - ₹56,000
  • Installation & Copper Piping (per meter): ₹1,200 base + ₹800/m extra pipe

Frequently Asked Questions (FAQ)

What happens if I install an oversized AC?

An oversized AC cools the room rapidly and shuts off before it has a chance to circulate air properly and remove humidity. This results in a "swampy" feeling where the air is cold but uncomfortably damp. It also causes excessive wear on the compressor due to short-cycling.

Do I need a larger AC for a top-floor room?

Yes, significantly. The roof absorbs intense solar heat throughout the day and radiates it into the room below. You typically need to increase the AC capacity by 15% to 20% compared to a middle-floor room of the same size to ensure effective cooling.

Is a 5-star AC worth the extra cost over a 3-star AC?

If you use your AC for more than 4-5 hours a day for several months a year, a 5-star inverter AC is absolutely worth the investment. The energy savings will offset the higher initial purchase price within 2 to 3 years.

What is an Inverter AC?

An inverter AC features a variable-speed compressor. Instead of shutting off when the desired temperature is reached (like a traditional AC), it slows down, continuously maintaining the temperature while consuming much less electricity. This makes it highly energy-efficient and quieter.