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AC BTU Calculator

AC BTU Calculator

You can enter the ceiling height, sun exposure, the number of people, climate, square footage and room dimensions in the AC BTU calculator to calculate the AC size for your room or house.🙂

I want to calculate:

Area Length:


Area Width:


Area Ceiling Height:



Number of People Inside Regularly

Insulation Condition:

Sun Exposure:


Desired Temperature:



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Our AC BTU calculator will instantly estimate the heating and cooling capacity of your air conditioner (inverter) for a particular room or area. Now calculating BTU for a room or house is no more a daunting chore! Whether you are using a window AC or a central AC, our advanced AC calculator will recommend you the actual size of it you need to install.

What Is AC BTU?

BTU is an acronym used for “British Thermal Unit” and is defined as:

“The maximum energy range of your air conditioner that may be required to expel heat in your room or house”

Alternatively, it is the amount of heat that may be needed to increase the heat of 1 pound of water by 1℉. BTU is a fundamental entity to consider while calculating air conditioner size for a particular area. If you do not select the right AC, it may create problems for you if it lacks BTUs needed to cool certain area. This is why we programmed this smart AC size calculator that may assist you in estimating your cooling needs to avoid any hindrance later.

BTU Equivalent Units:

British Thermal Unit Equivalent Units
1 BTU 1055.06 Joules
1 BTU 1.05506 Kilo Joules
1 BTU 252.164 Gram Calorie
1 BTU 0.252164 Kilo Calorie
1 BTU 0.293071 Watt Hour
1 BTU 0.000293071 Kilowatt Hour
1 BTU 6.585e+21
1 BTU 1.002e-5 US Therm
1 BTU 778.169 Foot Pound

How Many BTU Do I Need?

If you know the footage of your room or covered area of the house, you can add it to our AC BTU calculator to know the BTU you need. Otherwise, the rule of thumb states that your AC must have at least 20 BTU to heat or cool 1 square footage of the area.

For instance, if the total area of your room or house is about 600 sq ft, then you may need:

AC BTU Needed = 20 * 600

AC BTU Needed = 12,000

There are two rules you need to remember always:

Not Too Big:

If you buy a bigger AC unit, it will operate as an overpowered system. Such an AC will turn on and off its PCB Kit which may overheat it. It will burn the kit thereby making the unit useless.

Not Too Small:

If your AC is underpowered, it will be difficult for it to cool the area from which you have installed it. In such a case, it will try to consume more wattage to meet the cooling needs of your room.

Furthermore, you may better go through the air conditioner BTU chart below to know the actual heat or cool capacity of your room.

Room area (Square Feet) Recommended air conditioner capacity (BTU/hr)
100-150 5000
150-250 6000
250-300 7000
300-350 8000
350-400 9000
400-450 10000
450-550 12000
550-700 14000
700-1,000 18000
1,000-1,200 21000
1,200-1,400 23000
1,400-1,500 24000
1,500-2,000 30000
2,000-2,500 34000

Factors Affecting AC Size:

A few factors affect the heating and cooling conditions of your room. That is why they play a role in deciding the perfect air conditioner size you need to buy. Among these include:

  • Physical Condition
  • Roof Ceiling
  • Sunlight Exposure
  • Family Members
  • Temperature Increase & Decrease

How AC BTU Calculator Works?

Our air conditioner room size calculator makes AC size calculations quite easy, fast, and near to accurate. Let’s find how it works!


  • First, select if you want to calculate either “AC BTU” or “General Cool & Heat BTU”
  • Now enter the required values in their respective fields
  • Also, select the climate, air conditioning area, and ceiling type from their designated lists
  • Click on calculate icon


  • AC BTU in various capacity units
  • General BTU required for heating and cooling a certain room area


The BTU ratings calculated by our AC BTU calculator are just estimations. We do not recommend you rely only on these results while going to purchase an air conditioner. You may better appoint an HVAC expert and consider the factors aforementioned to buy a perfect unit for your room or house.


From the source of Wikipedia: British thermal unit, Prefixes, Conversions, Associated units