How to calculate how much ton AC will be suitable for a room

When buying an AC in India the most important question that many consumers have in mind is how much ton AC should they buy and whether the AC will be sufficiently enough keep the room cool. If you ask this question to the salesman most probably they will try to sell you the maximum ton AC, which in fact will be more than required to cool the room.

So how does one calculate how much ton AC a room requires?

The answer is very simple. To find the ton AC required you should know the length, breadth and the height of the room. Once you have the figure (in feet) just multiply all of the three to get a total.

So the formula goes Total = Length (feet) x Breadth (feet) x Height (feet)

Now compare the total that you have arrived according to this chart.

Total Ton AC Required
Less than 729 0.75
Between 729 and 810 0.75
900 0.75 to 1
1000 1
1089 1
1210 1 to 1.5
1296 1 to 1.5
1440 1.5
1690 1.5
1960 1.5 to 2
2250 2


There are several other factors that you also need to consider for effective AC cooling.

  • The number of Windows in the room.
  • Application that produce heat such as TV, Desktop etc.
  • If the room gets too much sunlight.

Once you know the total you can easily find the Ton AC required for your room.

{ 4 Responses }

  1. kiran kumar says

    hi my room is lenth 15 feet breath 11 feet and hight 10 feet now pls tell us which ac is sutable for my room 1.5 or more

  2. Pius says

    I am planning to put an a/c in a room of size 50L x 20W with a room height of 11 ft. Please advice how much tonnage of a/c is required to cool this room and the ideal temperature. The required room temperature is 24 degree Celsius.

  3. mainsh sharma says

    hi gogi,

    i m thinking to buy a AC this summer………but getting confuse.
    i my room dim is 11*10*10 so plz suggest me which ac is best for me in term of electricity efficiency……

    • PRASAD says

      What ever is available just above 1ton would be fine. If the next higher one available is 1.5 t only, I would advise to for a 1 t unit.