AC Tonnage Calculator
Which AC size suits your room: 1, 1.5 or 2 ton?
A 1.5 Ton AC Suits This Room
Usual AC size by room area
| Room area | AC size |
|---|---|
| Up to 90 sq ft | 0.75 ton |
| 90–125 sq ft | 1 ton |
| 125–180 sq ft | 1.5 ton |
| 180–240 sq ft | 2 ton |
| 240–300 sq ft | 2.5 ton |
| 300–360 sq ft | 3 ton |
- 1Enter the room sizeLength, width and ceiling height
- 2Describe the roomSun, people, kitchen
- 3See the AC sizeIn tons, BTU and kW
How is AC tonnage chosen?
A ton of cooling removes 12,000 BTU of heat an hour (3.517 kW). In Indian conditions, a common guide is about 1 ton for every 120 sq ft at a 10-foot ceiling, more for hot, sunny rooms.
Tons ≈ area ÷ 120 × (height ÷ 10) × sun factor + 0.1 per extra person
1 ton = 12,000 BTU/hr = 3.517 kW of cooling
Too small or too big
An undersized AC runs flat out and still can't cool a hot afternoon. An oversized fixed-speed AC cools quickly but switches on and off a lot, leaving the room clammy. Inverter ACs handle a small oversize better.
Power use
A ton describes cooling, not electricity. A 1.5 ton 5-star inverter AC typically draws about 1–1.5 kW at full load and much less once the room is cool. Check the label's yearly units and use our Electricity Bill Calculator for running costs.
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- Inverter Battery Backup CalculatorHow long your inverter battery will last on your load
Frequently asked questions
Is 1.5 ton enough for a 12 × 12 room?
Yes. 144 sq ft usually needs about 1.2–1.5 ton, so a 1.5 ton AC is the common choice, especially on a top floor.
Is 1 ton enough for 120 sq ft?
Usually yes for a shaded or middle-floor room. Choose 1.5 ton if it's west-facing, on the top floor or has many people.
What is 1 ton in watts?
1 ton of cooling is 3,517 W of heat removed. The electricity it uses is lower: roughly 0.8–1.2 kW for a 1 ton AC, depending on star rating.
Last reviewed: October 2026