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Room AC Size Calculator

Your answer

Unit size to buy

1.5 ton

That is 18,000 BTU.

Cooling the room needs
13000 BTU
Exact tonnage
1.1 tons
Base for the room and floor
12000 BTU
Added for glass, sun and use
1200 BTU

This gives you a size to shop with. For a whole villa, a double height room or any commercial space, have somebody survey it properly.

Room AC Size Calculator for Dubai and the UAE

This tool is for people who do not want to work in BTU. You pick what kind of room it is and a few things about it, and it gives you a unit size.

It is the same maths as the BTU calculator underneath, but you never have to see it. Everything is a choice from a list.

Use it when you are standing in a shop or looking at a listing and just need to know whether you want a 1.5 or a 2 ton.

How to use this

Five choices and you have an answer. Nothing needs measuring precisely.

  • Pick the closest room

    You do not need the exact size. Pick whichever description sounds most like your room and the answer will be close enough to shop with.

  • Be honest about the floor

    Top floor is the single biggest jump on this list. Heat comes through a roof all day and it makes a real difference.

  • Look at the glass

    Not the window frame, the glass itself. A full height sliding door is a lot of heat coming in.

  • Check which way it faces

    Stand in the room in the afternoon. If the sun is coming in and the room feels warm, pick the west facing option.

The rooms people get wrong

Some rooms need much more than their floor size suggests. These are the common ones in the UAE.

  • Top floor bedrooms

    They feel fine in winter and become impossible in July. The roof above them is in full sun all day and the heat comes straight down.

  • Rooms with balcony doors

    A wall of glass is not the same as a wall. Even with the door shut, heat comes through it far faster.

  • Open plan kitchen and living

    The cooking heat goes into the living space, and there is no door to stop it. This space always needs more than its floor area suggests.

  • Majlis rooms

    Often double height, often a lot of glass, and used by a lot of people at once. This is the room most likely to be undersized in a villa.

  • Home offices

    A computer, a monitor and a person is a surprising amount of heat in a small closed room.

  • Rooms above a garage

    Heat rises out of a hot garage into the room above it, which is a source most people never think about.

What to check before you buy

The size is only part of the decision. Three other things decide whether you are happy with the unit in two years.

Whether it is an inverter. A fixed speed unit runs at full power or nothing. An inverter slows down instead, so it holds a steadier temperature and uses less power once the room is cool. In a place where the AC runs most of the year, that is money.

The efficiency rating. Two units of the same tonnage can differ noticeably in what they cost to run. The rating is on the label and it is worth two minutes of comparing.

Who is fitting it. A good unit fitted badly is a bad unit. Pipe runs that are too long, poor insulation on the pipe, or the wrong gas charge will all rob you of cooling you paid for.

Signs the unit you have is the wrong size

If you already have an AC and it is not working well, the symptoms point at which way it is wrong.

  • Runs all day and never reaches the temperature

    Too small, or losing performance. Check the filter and the gas first, because a dirty filter looks exactly like an undersized unit.

  • Cools fast then switches off, room feels clammy

    Too big. It has not run long enough to pull the water out of the air, so you are cold and damp at the same time.

  • Switches on and off every few minutes

    Short cycling, usually from oversizing. It wears the compressor out and it uses more power than running steadily would.

  • One end of the room is cold and the other is warm

    Usually placement rather than size. Where the unit sits and where the air lands matters as much as its capacity.

  • It was fine and now it is not

    That is not a sizing problem. That is a service problem: filter, coil, gas or fan. Sizing does not change over time.

One unit or two

For a large or awkward space, two smaller units are often better than one big one.

A long living room, or an L shaped open plan space, is hard to cool from a single point. The air simply does not reach the far end well, so you end up running the unit colder than you need to make the far corner comfortable.

Two units also give you control. You can cool the part of the space you are using and leave the rest, which in a villa can save a real amount over a summer.

And there is the failure case. If one unit goes down in August with a single unit covering everything, the whole floor is unusable. With two, you are uncomfortable rather than stuck.

The cost is higher to buy and to service. For a normal bedroom or a square living room, one correctly sized unit is the right answer.

Questions people ask

What size AC do I need for my room?

Pick your room type above and it gives you the size in tons and BTU. As a rough guide, a normal bedroom in Dubai takes 1 to 1.5 tons and a living room takes 2 to 2.5.

What size AC for a living room in Dubai?

A 30 square metre living room on a middle floor usually needs about 2 tons. Add a top floor, a lot of glass or afternoon sun and it moves to 2.5.

Do I need a bigger AC on the top floor?

Yes. Heat comes through the roof all day, so a top floor room commonly needs around a quarter more cooling than the same room lower down.

Is it better to have two small units or one big one?

For a long or L shaped space, two is usually better. The air reaches everywhere, you can cool only the part you are using, and one failure does not leave the whole area unusable.

My AC runs all day. Is it too small?

Maybe, but check the simple things first. A dirty filter, a blocked coil or low gas all make a correctly sized unit behave like an undersized one, and all three are cheap to fix.

Does this replace a proper survey?

No. It gives you a size to shop with and to check a quote against. A whole villa, a double height room or any shop or office should be surveyed properly.

Need the job done

We do this work across Dubai

Use the numbers above to plan, then let us quote the real thing.

Call +971 54 381 1897WhatsApp Us

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