Find the correct AC capacity for your room — based on size, floor, climate, sunlight and occupants.
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The basic rule is 60 BTU per sq ft for Indian conditions. A 150 sq ft room needs about 1 ton, a 250 sq ft room needs 1.5 tons, and 350 sq ft needs 2 tons. Adjustments are made for floor level, climate, sunlight, and occupants.
Too high: short-cycles, causing humidity problems and higher bills. Too low: runs continuously without reaching target temperature, reducing efficiency and lifespan.
In Indian conditions, 1 ton is typically sufficient for 100–150 sq ft. In very hot cities like Delhi, consider 1 ton per 100–120 sq ft.
Use this calculator. Roughly: up to 150 sq ft = 1 ton, 150–250 sq ft = 1.5 ton, 250–400 sq ft = 2 ton. When in doubt, go slightly higher — undersized AC costs more to run.
5-star ACs consume 25–30% less electricity than 3-star models. The upfront cost is higher but saves ₹3,000–6,000/year on electricity. Inverter split ACs are the most efficient choice.
Buying an underpowered air conditioner means it runs continuously, never really cools the room, and burns out prematurely. Buying an oversized one wastes money upfront and on electricity — a 2-ton AC cooling a small room short-cycles (switches on and off too quickly) and fails to dehumidify properly. Getting the tonnage right is the single most important decision when buying an AC in India.
AC capacity in "tons" refers to tons of refrigeration — not weight. One ton of refrigeration = 3,517 watts of cooling = 12,000 BTU/hour. This unit originates from the amount of heat needed to melt one ton of ice in 24 hours. A 1.5-ton split AC provides 5,275 watts of cooling capacity. Most Indian homes use 1-ton, 1.5-ton, or 2-ton ACs.
The standard thumb rule of "1.5 tons per 150 sq ft" applies to a temperate climate. In Indian conditions, this needs adjustment:
A 5-star 1.5-ton inverter AC uses approximately 1,200–1,400 units (kWh) per year (8 hours/day, 6 months). A 3-star non-inverter uses 1,800–2,200 units. At ₹7/unit average electricity cost, the 5-star model saves ₹4,200–5,600 per year. The price premium for 5-star is typically ₹5,000–8,000 — it pays back in 1–2 seasons.