Building Construction, Renovation & Maintenance

Air Conditioner Size Calculator

How to calculate the size of air conditioner you need

Here you will find a calculator to help you work out the size of air conditioner you need for different room sizes, sizes are provided in BTUs (British Thermal Units), kilowatts, watts and HP (horsepower) or Peka (Dutch horse power).

See the full Fixed Abode article "How Big's Your Peka" here

See also:

How big an air conditioner do you need?

It is important to select the correct size of air conditioner for a room. Too small and the air conditioner will be working too hard, the room will not be cool enough and you may get condensation problems. Too large and your air conditioner may be constantly switching on and off.

This is a simple calculator to help you decide what size of air conditioner you will need. This is based on the most commonly used air conditioners these days which are split units with a CoP of 4. CoP stands for Coefficient of Performance - how efficient the air conditioner is and modern air conditioners can move 4 kilowatts of heat by using only 1 kilowatt of electricity.

To find the size of air conditioner you will need enter your room size in metres:

metres long by metres wide = square metres.

The estimated size of air conditioner you will need is:

PK or HP
Watts input
Well insulated room
Medium insulated room
Poorly insulated room


Standard air conditioner sizes available for domestic use:

The range of sizes varies between companies. Having said that they do tend to fall into specific preferred sizes. Generally speaking standard air conditioner sizes available for domestic use are:

0.5PK 0.75PK 1PK 1.5PK 2PK 2.5PK


Sizes measurement watts, BTUs horsepower and PK:

Different brands of air conditioners use different ways of indicating their size, for this reason 3 different size equivalents are given above:

1. PK (pronounced peka is Dutch for Horse Power or HP) which is the common sizing of air conditioners in Indonesia.

2. BTUs (British Thermal Units) the common sizing used in America.

3. The electrical power rating in watts (this is watts of input power not output watts).

Input power versus output power

It is important to note that the PK, HP and watts figures indicate the amount of power input, the BTU figures indicate the amount of cooling output achieved. The actual cooling achieved in BTUs depends on the efficiency of the air conditioner. The above figures are given as an approximate guide of what you might expect with normal modern air conditioners.

How insulated is your room? It makes a difference

Insulation makes a huge difference. The better a room is insulated the less air conditioning you will need. As a rough guide:

Well insulated room

A might have thick solid walls, an insulated ceiling, close fitting doors and few or double glazed windows and not many people in it.

Medium insulated room

A medium insulated room might have solid concrete walls, close fitting doors, an insulated roof and few standard windows.

Poorly Insulated Room

A poorly insulated room might have large window area, poorly fittng doors, a roof or walls that give off heat or a lot of people in it.

See also:

Site last updated 8 September 2019 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali, Indonesia
WhatsApp:+62-8123-847-852 Tel:+62-8123-847-852 or +62-81-558-000-860