Convert kW to BTU: Air Conditioner Calculator & Charts

Letting your AC unit run unchecked can be a costly error if you’re trying to budget your energy usage. Therefore, it is vital to determine the AC’s actual power capacity based on your room size.

Maintaining the required cooling – and not exceeding it –  will help you ensure lower energy consumptions, and in turn, save a decent chunk of money!

That’s why you should always keep an eye on your air conditioner’s kilowatts and BTU ratings.

But what are they exactly? Read on as we explain kilowatts and BTUs in detail:

What Is A Kilowatt?

Kilowatt or kW is a globally recognized standard for measuring electricity. It measures how much power (watts) you consume.

To put it simply, power companies charge households by the amount of energy they use per kilowatt-hour. In other words, you are charged according to the amount of kW you use over a certain period.

One kilowatt is equivalent to 1000 watts. And if you want to find kW, all you have to do is: divide your appliance’s wattages by 1000. After that, multiply by the total number of hours you intend to use.If you’re still confused, here’s an equation to simplify things:

Kilowatt-hour (kWh) = (watts / 1000) x number of hours used

As an example: let’s suppose you want to use a 500-watt radio unit for one hour. Put this into the formula:

Kilowatt-hour kWh = 500/1000 x 1 = 0.5

What Are BTUs?

BTU is short for the British Thermal Unit. It’s used for measuring thermal energy. Specifically, one BTU means the amount of power required to raise one pound of water temperature by 1° F.

BTU is typically used when talking about air conditioners and home heaters. Therefore, all AC units come with BTU ratings that tell you how powerful your units are.It measures how much heat your unit removes from indoor air per hour. So, to calculate BTU/hr, use the following equation:

BTU/hr = heat dissipation (wattages) x 3.4192

Let’s suppose you have a server with a 500-watt heat dissipation output. Put the value in the equation:

BTU/hr = 500 x 3.4192 = 1709.6

Importance Of BTU Calculation In Your AC System

BTU is one of the most important factors to consider when looking for the ideal sized cooling or heating system for a house.

For instance, if you purchase an air conditioning system with insufficient cooling power, constantly using it will drive your energy bills through the roof and not even provide adequate cooling.

Knowing the right BTUs will help you determine the size of the air conditioner you need and how much space it will cover.

Importance of BTU Calculations

BTU Recommendations Based On Cooling Needs

At this point, you’re probably wondering how many BTUs are enough to cool down the particular square footage of a room.

Remember that determining the right BTUs depends on several factors: room size, heat load, ceiling height, etc.

Having appropriate BTUs is essential: you don’t want a 14,000BTU AC unit for the 12×12 small room as it may boost your utility bills. You also don’t want to choose too small, like 6000BTU AC unit for 1000 sq. ft space as it will be ineffective.

Take a look at the BTU chart to know what size of an AC unit you need:

Room/Area SizeExamplesRecommended BTU
100 – 200 sq.ft10 x 10 room5000 BTU AC unit
200 – 300 sq.ft16 x 16 room6000 BTU AC unit
300 – 400 sq.ft18 x 18 room8000 BTU AC unit
600 – 700 sq.ft2 rooms small apartment14,000 BTU AC unit
800 – 900 sq.ft3 rooms average apartment18,000 BTU AC unit
900 – 1000 sq.ft3 rooms large apartment20,000 BTU AC unit
1000 – 1200 sq.ft4 rooms large apartment24,000 BTU AC unit

How To Convert Kilowatts To BTU

Suppose you have a 5 kW air conditioner; do you know how many BTUs of power it amounts to?  The answer is 17,060.71 BTU/hr!

Knowing how to convert kW to BTUs/hr is highly beneficial for many homeowners in the US and the world over.

Luckily, you can convert kilowatts to BTUs using three easy, helpful ways:

Manual Conversion

The First method to convert kW to BTU is through an equation. It’s the most basic method used by HVAC users worldwide.

Note: Before jumping to the formula, you should know that 1 kW is equivalent to 3412.12 BTU/hr.Hence, the conversion formula of kW to BTUIT/hr is:

P (BTU/hr) = 3412.142 x P (kW)

For example, let’s suppose you have a 5 kW AC unit. Insert the value to the above formula:

P (BTU/hr) = 3412.142 x 5 = 17060.71 BTU/hr

Watts to Amps Table

The second method is comparatively more straightforward than the equation method and is preferred by most as it avoids the added annoyance of calculations and computations.

It is the chart or table method.

Here’s a kW to BTU conversion chart:

Power (kW)Power (BTU/hr)
1 kW3412.142 BTU/hr
10 kW34121.420 BTU/hr
100 kW341214.200 BTU/hr
1000 kW3412142.000 BTU/hr
10000 kW34121420.000 BTU/hr
Online Calculator

The third and the easiest method among all is through the online calculator. Use it to convert kilowatts to BTUs within no time.

It’s easy to use: input the kilowatts, and you’ll have your required BTUs!

Factors To Consider That Determine The Correct BTU Rating

Size Of The Space

The size of the area is the primary factor when determining the adequate BTU rating for your appliance. It tells you how much indoor air you need to cool down a place.

Therefore, you should consider the room’s length, width, and height to find the space’s correct square footage.

Ceiling Height

Technically, ceiling height provides you a figure regarding the total air space that needs cooling.

BTU recommendations based on sq. ft. assume the standard 8-foot ceilings; however, if the ceiling height is bigger, you’ll need a greater amount of air and an AC unit with a high BTU rating.


Suppose you’re living in a relatively warmer climate. In that case, you’ll need an air conditioner with a high BTU rating as there will be a significant difference in your preferred temperature and ambient air.

In short, the size of your air conditioner depends greatly on how warm your region is.

Unit Location

There are two ways your home naturally heats: direct sunlight inside your house or if you’re living on the hotter second story of a building.

In conditions such as these, you need to add 10% more BTUs to your actual choice. More heat load means more BTUs are required.


Insulation is vital to your cooling process. For example, if you’re living in an insulated home – mostly a newer house – low BTUs may suffice.

However, if the house is poorly insulated, you’ll need powerful AC units to maintain cool air inside the home. Otherwise, your air conditioner will run continuously and increase energy bills.


Your windows don’t have the same insulation power as your walls. That’s why they detract from the overall house insulation ratings.

If your house has large windows, make sure to add 10% more BTUs for adequate cooling.

BTU Ratings for Windows

Room/Home Shape

If your house is compact, it will need less energy to cool. But if you have a ranch house, you’ll need more power and potential.

In simple terms, more BTUs are required if the house is sprawled.

People Also Ask (FAQ)

How many BTUs are in a kilowatt?

There are 3412.14 BTUs in a kilowatt (kW).

What is 30kW in BTU?

30 kilowatt (kW) is 102,364.2 BTUs of power.

Does a higher BTU mean higher aircon efficiency? How does it affect price?

Although more BTUs mean more power to cool down space, it depends on the room size. If you have a small room and a unit with higher BTUs, it will cool the area faster and leave it humid. And besides, when you use more BTUs, it will automatically increase your energy bills.

How many BTUs do I need for an outdoor heater?

Though it depends on the area you want to cover, you can still choose a heater with 30,000 to 50,000 BTUs.

Related Article Best Outdoor Electric Heater


When you’re buying an air conditioner, you should pay keen attention to BTU and kilowatt ratings.

Securing a unit with the right BTUs will help you acquire your desired room temperature and save money on your monthly utility bills.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.