AC Buying Guide for India: Tonnage, Star Rating and the Cheapest Month

An air conditioner is unusual among household purchases: the sticker price is the smaller number. Over five years of Indian summers, the electricity a badly-chosen unit consumes will comfortably exceed what you paid for it.

Which means the discount you negotiate matters far less than three decisions made before you look at any prices — and one decision about when to buy, which is worth more than all the negotiating combined.

Decision 1: Tonnage, matched to the room

Tonnage is cooling capacity, and getting it wrong is expensive in both directions.

Rough guidance for Indian conditions:

• Up to about 110 sq ft → 1 ton
• About 110–160 sq ft → 1.5 ton
• About 160–250 sq ft → 2 ton

Then adjust upward — usually to the next size — if any of these apply: the room takes direct afternoon sun, it sits directly under a terrace or a metal roof, it has large windows, more than two or three people are usually in it, there's a kitchen adjoining, or you're in a hot-dry region where peak temperatures run very high.

Undersized is the more common error. The unit runs continuously, never quite reaches the set temperature, and consumes power constantly while under-delivering. People conclude their AC is faulty when it's simply too small for the room.

Oversized has a subtler failure. It cools the air quickly and shuts off before it has removed the humidity, so the room ends up cold and clammy — and the frequent on-off cycling wastes power and wears the compressor. This is why "just buy bigger to be safe" isn't good advice.

Decision 2: Inverter, in almost every case

A non-inverter compressor has two states: full power and off. It reaches the target temperature, switches off, drifts warm, and slams on again. That cycling is where the electricity goes.

An inverter compressor varies its speed, running gently to hold a temperature rather than repeatedly restarting. The result is meaningfully lower consumption for the same comfort, quieter operation, and steadier temperature.

The premium is real but modest, and if you use the AC for more than a few weeks a year it pays for itself. The only scenario where a non-inverter unit makes sense is very occasional use — a guest room used a handful of nights annually — where the running cost never accumulates enough to matter.

Decision 3: Star rating, ISEER, and what they actually mean

The BEE star rating is the label everyone reads, with one important complication: the rating thresholds are periodically re-normalised. A 5-star unit from an older rating cycle is not equivalent to a 5-star unit under current standards. Comparing star ratings across model years can mislead you.

The number underneath is ISEER, and it is directly comparable: higher means more efficient. If you're choosing between two units, comparing ISEER figures tells you what the stars can obscure.

How much does it matter? For heavy summer use — several hours a day through the season — the gap between a 3-star and a 5-star unit is typically a few thousand rupees a year in electricity. Over a five-to-seven-year life, that comfortably exceeds the price difference between the two units. For light use, the payback is longer and a 3-star unit can be the rational choice.

The rule of thumb: the more you'll use it, the more efficiency is worth paying for. Bedroom AC running nightly all summer — buy the efficiency. Living room unit used on weekends — the calculation is closer.

The specifications worth checking

Copper condenser. Insist on it. Copper transfers heat better, is repairable rather than requiring wholesale replacement, and lasts longer in humid and coastal conditions. Some cheaper units use alloys and describe them creatively — if the listing doesn't say copper, assume it isn't.

Anti-corrosion coating if you're within reach of coastal air. Salt destroys condensers, and this is one of the few add-ons genuinely worth paying for.

Noise level in decibels, for a bedroom unit. Published figures are measured optimistically, but they're comparable between models, and the difference between a quiet unit and a loud one is something you'll notice every night.

Stabiliser requirement. Many modern units claim stabiliser-free operation within a voltage range. If your supply fluctuates outside that range, you need a stabiliser, and it belongs in the price you're comparing.

The costs that appear after checkout

This is where AC purchases most often exceed their budget, and it's entirely predictable.

Installation. "Free standard installation" covers a specific, minimal scenario. Anything else — a longer copper pipe run, core drilling through a thick wall, a high or awkward outdoor unit position, a stand or bracket — is charged separately.

Copper piping beyond the included length. Usually a few metres are included and the rest is per-metre. If the outdoor unit sits far from the indoor one, this alone can run into thousands.

Stabiliser, if needed.

Old unit removal, if you're replacing.

Realistically, budget an additional several thousand rupees beyond the unit price, and more if the installation is at all complicated. Two "prices" that include different things are not comparable at all — this is the single most important adjustment when comparing AC listings across stores.

Split, window or portable?

Worth a short detour, because the format choice comes before everything above.

Split AC is the default for good reasons: quieter indoors because the compressor sits outside, more efficient models available, better air distribution, and it doesn't consume a window. The trade-offs are higher installation cost and a permanent outdoor unit that needs a viable location.

Window AC is cheaper to buy and much cheaper to install, and it's a single unit so servicing is simpler. It's noisier, generally less efficient at the top end, and it needs a suitable window opening. For a rented flat, a small room, or a situation where an outdoor unit isn't permitted, it's a perfectly sensible choice that gets dismissed too quickly.

Portable AC is the option to avoid unless you genuinely have no alternative. They're inefficient, loud, they need a hose vented out of a window anyway, and they cool poorly compared to a fixed unit of nominally similar capacity. The convenience is real; the performance rarely justifies it.

For renters specifically: a window unit or a split with a straightforward installation is worth thinking about, since split installation costs are largely non-recoverable when you move, and re-installation at the next place costs again.

Running it cheaply once it's installed

Since electricity is the larger cost, a few habits are worth more than the star rating difference people agonise over.

Set it to 24–26°C rather than 18°C. The unit doesn't cool faster at a lower setting — it simply runs longer before stopping. Each degree lower increases consumption noticeably, and 24°C is comfortable for most people once the room has settled.

Clean the filters every few weeks in season. Clogged filters restrict airflow, which makes the unit work harder for less cooling. This is the single highest-impact maintenance task and it takes ten minutes.

Use a fan alongside. Circulating cooled air lets you sit comfortably at a higher thermostat setting, and a ceiling fan's consumption is trivial next to a compressor's.

Get it serviced before the season, not during. Cheaper, faster, and you find out about a problem in March instead of in the third week of May when nobody is available.

The price window: when to buy

Here the calendar is unusually clear, and it's worth a lot of money.

Worst time: April and May. Peak demand, tight stock, installation teams booked solid. Prices reflect all of it. Buying an AC in the second week of May is close to the most expensive way to do it.

Best times: late June through August, once the season breaks and warehouses are full with nobody buying; and the festive sales in September–October, when last season's stock is cleared and bank offers stack on top.

If you can tolerate one uncomfortable summer, buying in July for the following year is one of the highest-return timing decisions in Indian retail. Installation teams are also free, so you get the job done properly rather than rushed.

Comparing across stores properly

Two specific difficulties with AC comparison, both solvable.

Model numbers are long and nearly identical between variants. A single character often separates a 3-star from a 5-star, or a 1.5-ton from a 1-ton. Copy the full model string exactly, and verify the tonnage and star rating on each listing rather than trusting the title.

What's included varies. One store's price includes installation and a stabiliser; another's doesn't. Compare the delivered, installed total, not the listed number.

With those two handled, the comparison is genuinely worth doing — the spread between stores on large appliances is one of the widest in retail, commonly ₹2,000 to ₹6,000 for the identical unit, plus different installation terms and different exchange values on your old machine.

Searching the full model string on 7Compare matches that exact unit across the stores that carry it, so you're comparing the same tonnage and the same star rating rather than three similar-sounding models. The installation terms still need reading on each listing — but by then you're only reading two.

The short version

Match the tonnage to the room, honestly, accounting for sun and roof. Buy an inverter unless the unit will barely be used. Pay for efficiency in proportion to how much you'll run it, and compare ISEER rather than stars across model years. Insist on copper. Budget properly for installation. And buy in July, not in May.

Get those right and the discount becomes what it should be — a bonus on a good decision, rather than the decision itself.