Find Your Perfect AC Size in Seconds
Free AC tonnage calculator: answer a few quick questions and get the right AC size in tons and BTU instantly
Room & Cooling Details
Fill in your room details below to calculate the ideal AC tonnage.
Best fit for your room
Why this size?
This is a quick estimate based on standard HVAC sizing rules of thumb. For homes with poor insulation, large glass windows, or unusual layouts, get an on-site load calculation from a technician.
Table of Contents
Quick Answer: AC Size by Room Size
AC Tonnage Chart by Room Size
This AC tonnage chart shows the AC size for common room sizes. Every row is worked out with the same formula as the AC tonnage calculator above, so the chart and the calculator give the same answer.
| Room (sq ft) | Room (sq m) | Normal: BTU/hr | Normal: AC size | Hot: BTU/hr | Hot: AC size |
|---|---|---|---|---|---|
| 50 | 4.6 | 5,000 | 0.75 ton | 6,000 | 0.75 ton |
| 75 | 7.0 | 7,500 | 0.75 ton | 9,000 | 0.75 ton |
| 100 | 9.3 | 10,000 | 1 ton | 12,000 | 1 ton |
| 120 | 11.1 | 12,000 | 1 ton | 14,400 | 1.5 ton |
| 150 | 13.9 | 15,000 | 1.5 ton | 18,000 | 1.5 ton |
| 180 | 16.7 | 18,000 | 1.5 ton | 21,600 | 2 ton |
| 200 | 18.6 | 20,000 | 2 ton | 24,000 | 2 ton |
| 250 | 23.2 | 25,000 | 2.5 ton | 30,000 | 2.5 ton |
| 300 | 27.9 | 30,000 | 2.5 ton | 36,000 | 3 ton |
| 400 | 37.2 | 40,000 | 4 ton | 48,000 | 4 ton |
| 500 | 46.5 | 50,000 | 5 ton | 60,000 | 5 ton |
| 600 | 55.7 | 60,000 | 5 ton | 72,000 | Above 5 ton |
Chart settings: ceiling up to 9 ft, medium sunlight and 2 people. A high ceiling or direct sun adds 15% each, a shaded room takes off 10%, and each extra person adds 600 BTU/hr. The AC size is the smallest standard size that covers the load.
AC Tonnage per Square Foot
This AC tonnage calculator starts from 100 BTU/hr for every square foot of floor area, then adjusts for your room. The steps are:
Extra people load = 600 x (number of people - 2), only when there are more than 2 people
Tons = BTU/hr / 12,000
- Ceiling factor: up to 9 ft = 1.00, above 9 ft = 1.15
- Sunlight factor: shaded = 0.90, medium = 1.00, direct sun = 1.15
- Climate factor: normal = 1.00, hot (Gulf or desert) = 1.20
The result is rounded up to the nearest standard AC size: 0.75, 1, 1.5, 2, 2.5, 3, 4 or 5 ton. Above 5 ton, use more than one unit or a ducted system.
Example 1: a 150 sq ft bedroom in the UAE with direct sun, a normal ceiling and 2 people. 150 x 100 x 1.00 x 1.15 x 1.20 = 20,700 BTU/hr. 20,700 / 12,000 = about 1.7 ton, so the recommended size is 2 ton.
Example 2: a 20 sq m living room in a normal climate with medium sunlight, a normal ceiling and 4 people. 20 sq m = 215.3 sq ft. 215.3 x 100 = 21,528 BTU/hr. Two extra people add 2 x 600 = 1,200 BTU/hr. The total is 22,728 BTU/hr. 22,728 / 12,000 = about 1.9 ton, so the recommended size is 2 ton.
AC Ton, BTU/hr and kW Conversion Table
One ton of AC cooling equals 12,000 BTU/hr, or about 3.52 kW of cooling capacity. The kW figure is cooling capacity, not the electricity the AC uses. The table also shows the largest room each AC size can cover with this calculator's standard settings.
| AC size | Cooling (BTU/hr) | Cooling (kW) | Room area, normal climate | Room area, hot climate |
|---|---|---|---|---|
| 0.75 ton | 9,000 | 2.64 | 90 sq ft (8.4 sq m) | 75 sq ft (7.0 sq m) |
| 1 ton | 12,000 | 3.52 | 120 sq ft (11.1 sq m) | 100 sq ft (9.3 sq m) |
| 1.5 ton | 18,000 | 5.28 | 180 sq ft (16.7 sq m) | 150 sq ft (13.9 sq m) |
| 2 ton | 24,000 | 7.03 | 240 sq ft (22.3 sq m) | 200 sq ft (18.6 sq m) |
| 2.5 ton | 30,000 | 8.79 | 300 sq ft (27.9 sq m) | 250 sq ft (23.2 sq m) |
| 3 ton | 36,000 | 10.55 | 360 sq ft (33.4 sq m) | 300 sq ft (27.9 sq m) |
| 4 ton | 48,000 | 14.07 | 480 sq ft (44.6 sq m) | 400 sq ft (37.2 sq m) |
| 5 ton | 60,000 | 17.58 | 600 sq ft (55.7 sq m) | 500 sq ft (46.5 sq m) |
To convert other HVAC units, use the HVAC Unit Converter.
How This AC Tonnage Calculator Works
AC tonnage tells you how much heat an air conditioner can remove per hour. One ton of cooling equals 12,000 BTU/hr. A common HVAC rule of thumb is roughly 100–120 BTU per square foot of room area, adjusted upward for high ceilings, strong sunlight, hot climates like the UAE and Gulf region, and extra occupants. This calculator applies those adjustments automatically to recommend the nearest standard AC size (0.75, 1, 1.5, 2, 2.5, 3, 4, or 5 ton).
For a deeper technical reference on how professionals size cooling equipment, see the U.S. Department of Energy's guide to central air conditioning. In Gulf countries like the UAE, actual field practice often runs slightly higher than U.S. rule-of-thumb numbers because of longer, more intense summer heat loads — which is why this calculator applies an extra hot-climate adjustment on top of the base BTU-per-square-foot figure.
HVAC Tonnage, Condenser Size and Commercial Use
HVAC tonnage is the cooling capacity of an air conditioning system, and one ton equals 12,000 BTU/hr. This HVAC tonnage calculator finds the tonnage a room needs, so you can use it as an AC size calculator for a bedroom, living room, shop or small office.
The outdoor condenser is not sized on its own. It is paired with the indoor unit, and the manufacturer's matching chart shows which condenser goes with which indoor unit. If the calculator gives 2 ton, look for a 2 ton matched system.
The calculator covers sizes from 0.75 to 5 ton. For a commercial space that needs more than 5 ton, use more than one unit or a ducted system, and get a full load calculation from a technician.
Using the Calculator for a Shop or Office
The AC tonnage calculator also works as a starting point for a small shop, office or clinic. Enter the floor area, choose the climate, and set the number of people in the Occupants field. Each person above two adds 600 BTU/hr.
Shops and offices usually have more heat from lighting, computers, display fridges and fresh air than a bedroom, and this calculator does not count that equipment heat. Treat the result as a starting size. For restaurants, kitchens, server rooms and large open spaces, ask a technician for a full load calculation (Manual N or an ASHRAE method) before you buy.
Frequently Asked Questions
How many square feet does a 1 ton AC cool?
A 1 ton AC (12,000 BTU/hr) typically cools around 100–120 sq ft under normal conditions. In hot climates like the UAE, or rooms with high sunlight exposure, the safe coverage is closer to 90–100 sq ft.
How do I calculate AC tonnage for my room?
Multiply your room's square footage by 100–120 BTU, then adjust for ceiling height, sunlight, climate, and occupants. Divide the result by 12,000 to get tons. Use the AC Tonnage Calculator above to do this instantly with your exact room details.
What happens if I install an oversized or undersized AC?
An oversized AC cools too fast without removing enough humidity, leaving the room feeling clammy, and it short-cycles, which wears out the compressor faster. An undersized AC runs constantly and still fails to reach the set temperature during peak heat. Getting the tonnage right avoids both problems.
Is this calculator accurate enough to buy an AC unit?
This AC Tonnage Calculator gives a reliable estimate based on standard HVAC sizing rules of thumb, suitable for most homes and offices. For large spaces, poor insulation, unusual layouts, or commercial installations, get an on-site Manual J load calculation from a licensed HVAC technician before purchasing.
What is the difference between AC ton and BTU?
BTU/hr measures how much heat an AC removes in one hour. A ton is a bigger unit equal to 12,000 BTU/hr. The name comes from the cooling power of melting one ton of ice in 24 hours.
How many BTU is a 1.5 ton AC?
A 1.5 ton AC is 18,000 BTU/hr (1.5 x 12,000), which is about 5.3 kW of cooling capacity. With this calculator's standard settings it suits a room of up to 180 sq ft in a normal climate or 150 sq ft in a hot climate.
How many square feet does a 2 ton AC cool?
With this AC tonnage calculator's standard settings, a 2 ton AC (24,000 BTU/hr) suits a room of up to about 240 sq ft (22 sq m) in a normal climate and about 200 sq ft (18.6 sq m) in a hot climate.
Why does a hot climate need a bigger AC for the same room?
In hot weather more heat enters through the walls, roof and windows, so the AC has more work to do. This AC tonnage calculator adds 20% to the cooling load for hot climates like the UAE and Gulf region, and another 15% for a room with direct sun most of the day.
Can I use this AC tonnage calculator for a shop or office?
Yes, as a starting point. Enter the floor area and the number of people. The calculator does not count heat from lighting, computers or display fridges, so a real shop or office may need more. For restaurants, kitchens, server rooms or large spaces, get a full load calculation from a technician.
What is an HVAC tonnage calculator?
An HVAC tonnage calculator estimates the cooling capacity, in tons, that a room needs. It turns floor area, ceiling height, sunlight, climate and number of people into BTU/hr, then divides by 12,000 to give tons.
How do I size an air conditioner condenser?
Use the tonnage this calculator gives for the room, then choose a matched system where the outdoor condenser is rated for the indoor unit. Check the manufacturer's matching chart before you pair units of different sizes.
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