ac tonnage calculator

🧊 AC Tonnage Calculator

Convert room size (sq ft or m²) to the exact AC tonnage you need — 0.5, 1, 1.5, 2 Ton and up. ACCA Manual-J inspired, in tons, BTU/hr and kW, for the US, UK, Europe, India, UAE, Saudi Arabia & Australia.

🌍 Prefer metric? Switch units here


🏠1. Space Type

📐2. Floor Area & Ceiling



sq ft

Range: 50 – 10,000 sq ft



ft

Range: 7 – 20 ft



people

Range: 0 – 50 people

🌍3. Country / Climate


The base factor assumes a 30 °C / 86 °F design day. Change the chip above to match your region.

🧱4. Insulation

☀️5. Sun Exposure

🪟6. Windows / Glazing

➕Advanced loads (kitchen, appliances, exhaust) — optional

Wattage × 3.4 = BTU/hr. e.g. 500 W ≈ 1,700 BTU/hr


For office IT, gym gear, lab equipment



AC Tonnage Chart by Room Size (sq ft & m²)

Use this quick-reference table to find the AC tonnage you need for a typical room. Then drop your exact dimensions into the calculator above to factor in sun exposure, ceiling height, climate, and insulation.

Room Area (sq ft) Room Area (m²) Recommended AC Tonnage Cooling Capacity (BTU/hr)
Up to 120 sq ft Up to 11 m² 0.8 to 1.0 Ton 9,000–12,000 BTU/hr
120 – 180 sq ft 11 – 17 m² 1.2 to 1.5 Ton 12,000–18,000 BTU/hr
180 – 250 sq ft 17 – 23 m² 1.5 to 2.0 Ton 18,000–24,000 BTU/hr
250 – 400 sq ft 23 – 37 m² 2.0 to 2.5 Ton 24,000–30,000 BTU/hr
400 – 600 sq ft 37 – 56 m² 3.0 Ton 36,000 BTU/hr
600 – 900 sq ft 56 – 84 m² 3.5 to 4.0 Ton 42,000–48,000 BTU/hr

These are consumer-grade estimates for split AC, window AC, and mini-splits in standard 8 ft ceilings. Hot climates, west-facing glass, kitchens and top floors push you one size higher — verify with the calculator above.

How to Calculate AC Tonnage for Your Room

Finding the right AC size is a four-step process. The calculator above automates all of it, but here’s the reasoning behind the number so you can sanity-check the result.

1. Calculate Room Area (Length × Width)

Multiply the room’s length by its width to get the floor area. For an L-shaped room, split it into rectangles and add them. A 12 × 12 ft bedroom = 144 sq ft (≈ 13 m²). A 15 × 20 ft living room = 300 sq ft (≈ 28 m²).

2. Account for Sun Exposure & Roof Heat

Top-floor rooms and west-facing walls get a lot of radiant heat through the roof and glass. The calculator adds a sun-exposure multiplier of 10% (normal afternoon sun) to 20% (constant direct sun). If your room has a flat roof with no insulation, add another 0.25 to 0.5 Ton on top of the calculator’s result.

3. Climate Factor (Humid, Arid, Desert)

Coastal humid climates (Miami, Houston, Singapore, Dubai) carry a high latent load — the AC has to remove moisture as well as heat, which needs more capacity than dry climates at the same temperature. Desert climates (Riyadh, Phoenix, inland Australia) need extra sensible capacity. The calculator’s climate chip picks the right multiplier for your region; pick from the country dropdown above to auto-set it.

4. Inverter AC Sizing Rule

If you’re buying an inverter (variable-speed) split AC, you can size closer to the calculated load — the compressor modulates down to match demand, so a 1.5 TR inverter on a 1.2 TR load is fine and saves electricity. With a fixed-speed (non-inverter) AC, always round UP to the next standard size (1, 1.5, 2, 2.5, 3 TR), because short-cycling kills the compressor and the unit never dehumidifies properly.

Frequently Asked Questions

What size AC do I need for a 12×12 room?
A 12×12 ft room (144 sq ft / ≈13 m²) typically requires a 1.0 Ton (12,000 BTU/hr) AC in standard climates, or up to 1.25–1.5 Ton on top-floor, west-facing, or desert-climate installations. A small window or mini-split unit will cover it.
How many sq ft does a 1.5 ton AC cool?
A 1.5 Ton AC covers roughly 150 to 250 sq ft (14 to 23 m²) in average residential conditions. In hot-humid or top-floor settings it leans toward the smaller end of that range; in cool-marine climates it can stretch to 300 sq ft.
What happens if I buy an oversized or undersized AC?
Undersized: the AC runs constantly, never reaches setpoint on hot days, and burns out the compressor early. Oversized: the AC cools the air too fast without running long enough to remove moisture — the room feels cold but clammy, and you get higher electricity bills for the same comfort.
Is 1 ton AC enough for a 100 sq ft room?
A 1 Ton (12,000 BTU/hr) AC is technically too big for a 100 sq ft room in a moderate climate. A 0.75 or 0.8 Ton unit is a better match. However, in very hot, top-floor, or west-facing rooms, going up to 1 Ton is fine — especially with an inverter compressor that can modulate down.
What size AC for a 200 sq ft bedroom?
A 200 sq ft (≈19 m²) bedroom typically needs a 1.0 to 1.5 Ton (12,000–18,000 BTU/hr) AC. Standard climate and good insulation → 1 Ton. Top floor, west sun, or hot climate → 1.5 Ton. Use the calculator above to factor in your exact conditions.
How many tons of AC for a 1,000 sq ft house?
A 1,000 sq ft (≈93 m²) home in a moderate climate typically needs a 2.0 to 2.5 Ton (24,000–30,000 BTU/hr) central or ducted system. In hot Sun Belt, Gulf, or Indian summer climates, plan for 3.0 to 3.5 Ton. Always calculate per-room if you have a multi-split setup.
What’s the difference between tonnage and BTU?
1 Ton of cooling = 12,000 BTU/hr. The “ton” comes from the heat absorbed by melting one ton of ice in 24 hours. When you see a “1.5 TR” or “1.5 Ton” AC, that means it removes 18,000 BTU per hour at full output. Use the calculator above to switch between tons, BTU/hr, and kW.
Do I need a stabilizer with my split AC?
In areas with frequent voltage fluctuations (many parts of India, Middle East, Africa, rural areas), yes — a dedicated AC stabilizer rated for your unit’s kW is cheap insurance against compressor damage. Most modern inverter ACs have built-in voltage tolerance (160–270 V) and don’t strictly need one, but it extends compressor life.

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Last updated: 2026. Maintained by the Refcon HVAC engineering team. Found an error or have a suggestion? Tell us.

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