How Many kW Air Conditioner Do I Need? AC kW Calculator + Chart

In Europe, Asia, and most non-US countries, we measure the size of the air conditioner in kW (kiloWatts). Before we buy any AC unit, we have to figure out how many kW air conditioner we need. To help out everybody sizing air conditioners in kW, we have prepared these 2 easy-to-use resources:

1. Air Conditioner kW Sizing Calculator. Here you insert the size of your home (in square meters – m2), ceiling height (in Europe, we have a 2.50 m minimum ceiling height), climate, sun exposure, and inclusion of kitchen; the calculator will automatically determine how many kW air conditioner you need (rough estimate).
2. kW And Home Size Chart. Namely, we list standard sizes of air conditioners in kW anywhere from 50 m2 flats to big 1,000 m2 houses.

Now, the key to all AC sizing is that you don’t want too many kW (needless expenses, short cycling) or too few kW (inadequate cooling). The cooling load, expressed in kilowatts, you need depends on these 5 key factors (we use all of them in the AC kW calculator below, it’s useful to understand what they mean):

1. Size of your home (square meters). This is the primary factor; the bigger your home, the more kW you will need. Under minimum conditions, you would need about 0.065 kW per m2 (derived from 20 BTU per sq ft 8 ft ceiling height sizing recommendation). That means that 1 kW can cool about 15 square meters. Example: 50 m2 flat would need about 3.25 kW AC unit (0.065 kW per m2 Ã— 50 m2 = 3.25 kW). In practice, we would install a 3.5 kW unit here just to be sure.
2. Ceiling height. A higher ceiling means the AC unit will have to cool more air. That means that we will need more kW AC unit for high-ceiling rooms/homes.
3. Climate (Country). If you live in sunny Spain or Italy, you will obviously need more kW than if you live in the UK or Scandinavian countries. That’s why we add +10% cooling load for ‘Hot Climates’ or deduct -10% cooling load for ‘Cold Climates’. Bigger countries such as France, Germany, Poland have ‘Average Climates’.
4. Sun exposure. If you get a lot of sun (and have a lot of windows), we add +10% for ‘Very Sunny’ positioning. If you have a lot lower sun exposure (a lot of shade), we use ‘Heavily Shaded’. Most homeowners will have ‘Average’ sun exposure.
5. Inclusion of kitchen. If the AC unit has to cool rooms that include a kitchen, we usually add 1.2 kW to the total AC size. That’s because the kitchen includes heat-generating appliances such as an oven, stove or cooktop, electric kettles, and so on, and we need to offset that by choosing a bit bigger AC unit.

Quick example: Let’s say you have a sunny 100 m2 flat in Paris, France. Ceiling height is 2.80 meters and flat obviously includes a kitchen. Here is how we can calculate how many kW you would need for this flat:

Air Conditioner kW Capacity = 100 m2 Ã— 0.065 kW per m2 Ã— 1.12 (ceiling height correction) Ã— 1 (average climate) Ã— 1.1 (very sunny correction) + 1.2 kW (kitchen included) = 9.2 kW

For this 100 m2 flat, you would need about 9.2 kW of cooling output. Getting a 10.5 kW air conditioner would make sense in this case.

As you can see from the equation above, sizing an AC unit in terms of kW is a bit complex when done manually. To make this much easier, we have created the following Air Conditioner kW Calculator.

Below the calculator, you will also find a complete chart of how many kW you need for homes, ranging from 50 m2 flats to 1000 m2 houses. Here is the calculator:

Air Conditioner kW Calculator

Let’s solve one example to illustrate how this AC kW calculator works:

Let’s say you have a smaller 150 m2 house in Madrid, Spain, with 2.8-meter ceilings. You get average sun exposure, and the house includes the kitchen. To determine how many kW air conditioner you need, just slide the 1st square meter slider to ‘150’, the 2nd ceiling height slider to ‘2.8’, select ‘Average’ sun exposure, select ‘Hot’ climate, and tick off ‘Yes’ for kitchen. Here is the result:

For this small 150 m2 house, you would need a 14.07 kW air conditioner. In practice, you would go for a 14 kW AC unit.

Now, we have calculated how many kW AC unit you need for 50 to 1000 m2 homes, based on 2.5 m ceiling height, average sun exposure, and average climate (without kitchen). All the results, based on these premises, are summarized in the following chart:

Air Conditioner kW Size Chart

 Square Meters (Area): Air Conditioner kW Capacity: 50 m2 3.25 kW 60 m2 3.90 kW 70 m2 4.55 kW 80 m2 5.20 kW 90 m2 5.85 kW 100 m2 6.50  kW 110 m2 7.15 kW 120 m2 7.80 kW 130 m2 8.45 kW 140 m2 9.10 kW 150 m2 9.75 kW 160 m2 10.40 kW 170 m2 11.05 kW 180 m2 11.70 kW 190 m2 12.35 kW 200 m2 13.00 kW 250 m2 16.25 kW 300 m2 19.50 kW 350 m2 22.75 kW 400 m2 26.00 kW 450 m2 29.25 kW 500 m2 32.50 kW 600 m2 39.00 kW 700 m2 45.50 kW 800 m2 52.00 kW 900 m2 58.50 kW 1000 m2 65.00 kW

As you can see from the chart, you would need about 6.5 kW of cooling output for every 100 m2 of living space.

Using the calculator above and this AC kW chart, you are now well-equipped to estimate the size of the AC unit you need in terms of kW. If you need any help, you can always use the comment section below, give us some figures, and we will help you out.