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AC Tonnage Calculator

Find the right AC size in tons and BTU for your room, adjusted for a top floor, afternoon sun, extra people or a kitchen.

Rules last checked 12 November 2026Every step shown2 sources

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AC size

1.5 tons

Cooling needed
16,800 BTU/h
Exact load
1.4 tons

A 14 × 12 ft room (168 sq ft) needs about 1.4 tons of cooling, so a 1.5-ton AC.

How it's worked out

  1. Base load168 sq ft × 100 BTU16,800 BTU/h
  2. In tons16,800 ÷ 12,000, then the next size up (a load no more than 0.05 ton over a size uses that size)1.5 tons
  • A rule of thumb for hot climates (about 1 ton per 120 sq ft, as Pakistani AC sellers' charts use), adjusted for your room. Good roof insulation lowers the need; an inverter AC copes better with a slightly large room than a small AC does with a hot one.

How it's worked out

Cooling = floor area × 100 BTU, adjusted for height, floor, sun, people and kitchen · Tons = BTU ÷ 12,000, rounded up to a size sold (a load no more than 0.05 ton over a size uses that size)

This is a rule of thumb for hot climates such as Pakistan and the Gulf: about 100 BTU per sq ft, or 1 ton per 120 sq ft, the figure AC sellers' charts use. The US ENERGY STAR chart, made for milder US conditions and 8-ft ceilings, works out at about 20 to 40 BTU per sq ft. Summers above 45°C and uninsulated roofs are why the local figure is so much higher. The adjustments for sun, extra people and a kitchen are ENERGY STAR's; the 20% for a top floor is common local practice. For a large or unusual space, ask for a proper heat-load calculation.

Worked example

A 14 × 12 ft room is 168 sq ft, so about 16,800 BTU: 1.4 tons, so a 1.5-ton AC. On a top floor, 20% more gives 20,160 BTU, so a 2-ton AC.

Questions people ask

What size AC do I need for a 12 × 14 room?

About 1.5 tons on a ground or middle floor in Pakistan or the Gulf, and 2 tons on a top floor with the roof above.

How many BTU is 1 ton?

One ton of cooling is 12,000 BTU per hour, so 1.5 tons is 18,000 BTU and 2 tons is 24,000 BTU.

Is a bigger AC better?

Not much bigger. An oversized non-inverter AC switches on and off often and dehumidifies poorly. An inverter AC handles a slightly large size better, and roof insulation helps more than extra tonnage.

Formula and rules last checked 12 November 2026Written and tested by the CalculatorDex teamReport a problem

Sources: ENERGY STAR, Room Air Conditioners (sizing table and adjustments) · ProPakistani, The Complete AC Buying Guide (August 2026), an example of local sizing charts