How compare.ac works

Our method, in plain sight

compare.ac is an independent buying advisor for real air conditioners. We do not sell the units, and no manufacturer or retailer can pay to rank higher. This page explains exactly where our numbers come from, how we decide what to show you, and how we make money, so you can trust the comparison.

Only real air conditioners, never fans

compare.ac lists units that actually remove heat with a refrigerant cycle. We exclude desk fans, tower fans, evaporative or 'air' coolers, and humidifiers that get marketed beside real AC. If it cannot lower the room temperature below the outdoor air, it does not appear on compare.ac.

We explain the system types so you pick the right shape

A portable monobloc, a window unit, a single split, and a multi-split solve different problems and cost very different amounts to install and run. compare.ac shows what each type is, where it fits, and the trade-offs in plain language before you spend a cent.

Specs you can actually compare

We normalize every listing to the four numbers that decide comfort: cooling power in BTU (with kW shown alongside), noise in dB(A), energy efficiency as CEER or SEER2, and the room area it realistically covers in square feet. No marketing watts, no peak-only figures presented as continuous, and no ASHRAE headline BTU passed off as a portable's real capacity.

We tell you if you are even allowed to install it

A split system is a structural change to the building. Its refrigerant may only be handled by an EPA Section 608 certified technician, most US jurisdictions want a permit for the outdoor unit and its circuit, and renters and condo owners usually need written permission from a landlord or HOA first. compare.ac flags this before you buy, so you do not end up with hardware you cannot legally mount.

Efficiency and running cost, explained honestly

A cheap portable can cost noticeably more to run than a quiet split for the same cooling, because much of its capacity leaks back through the single exhaust hose. We surface the efficiency rating (SEER, CEER or the energy label) wherever the manufacturer publishes it, and explain how the system types compare on running cost, so it is part of your decision rather than a surprise. We never invent a figure the maker does not state.

Adapts to where you install

Sizing, regulations and running costs adjust to where you actually live: the ENERGY STAR room air conditioner chart as the sizing base, your state's climate as the adjustment, and the install rules that apply in your city and building. BTU and kW are always shown side by side, so nothing is lost in translation.

From your room to a decision

How the tool works

1

Tell us your room and your situation

Enter the room area in square feet, how sunny it is, whether it is a bedroom you need quiet for, and whether you rent or own. This is enough to rule out the wrong system types immediately.

2

See only real AC, matched and explained

We show genuine air conditioners sized for your room, grouped by type (portable monobloc, window, single split, multi-split), each with cooling in BTU and kW, noise in dB(A), and efficiency as CEER or SEER2 on the same scale.

3

Check whether you are allowed to install it

For split and multi-split units we flag that an EPA 608 certified technician must handle the refrigerant and that a permit plus landlord or HOA permission is usually needed. For monobloc and window units we explain the much lighter requirements.

4

Compare what matters and decide

Compare purchase price, the efficiency rating where the maker publishes it, and whether it needs a professional install, then pick the unit that fits your room, your noise tolerance, and your tenancy.

Where the data comes from

  • Specs and images come from Open Icecat, matched to each unit by its GTIN or model number, so the cooling power, noise, dimensions and energy rating are the manufacturer's own published figures.
  • Prices and stock come live from the retailer's own product feed through CJ Affiliate, refreshed on a schedule, so the price you see next to Buy is the price the retailer is charging, not a number we set.
  • Price history and deals. We record each unit's price at every retailer once a day. That lets us tell you honestly when a price is at the lowest in our available history from the last 120 days, always dated and named to one seller, never a market average or a forecast. A unit reaches the deals page only when its current in-stock price is that tracked low AND it is a real markdown of at least 5% and $20 off a higher price we genuinely observed, never off a manufacturer list price.
  • Efficiency for US window and portable units is matched to the ENERGY STAR certified-products database by barcode, so for a certified unit its CEER and annual energy use are the official certified figures, not ours. For the few units the manufacturer publishes a CEER outside that database, we show the manufacturer's own rating, still a real published figure, never one we invented.
  • Running cost is the one number we estimate rather than read off a source, and we say so: for those ENERGY STAR units we price their published annual energy use at the average US residential electricity rate (EIA) to get a standardized dollars-per-year for comparison. We keep it national on purpose (pricing it by your state would read backwards, since the hottest states have the cheapest power), show it only where the data exists, and never convert a mini-split, which is rated on the different SEER2 scale, to a dollar figure.
  • If a maker does not publish a figure, it stays blank. We mark it "Not published" rather than estimate it. A number you see is a number a real source states.

How we rank and sort

  • The default view leads with units you can actually buy in stock, then the ones with the most complete specs, because a decision needs the numbers to be there.
  • Tell us your room and every unit shows whether it fits, sized from the maker's stated coverage or, where none is published, estimated from cooling power and clearly marked as an estimate.
  • When you pick your region, we also size for its climate: a hot or humid place needs more cooling per square metre than a mild one, so we scale the need using published ASHRAE design temperatures and Manual-J regional practice. We always show both your real room size and the figure we size against, and when your climate is unknown we make no adjustment.
  • A whole-home system gets no room verdict. A multi-zone or central ducted system splits its cooling across several rooms or through ductwork, so matching its total capacity to one room would overstate what that room actually gets. We label it a whole-home system and leave the sizing to the installer, who sizes each room.
  • A blank cannot satisfy a noise limit. Set one and units whose maker publishes no decibel figure drop out, with the count shown, because we cannot claim a unit is quiet enough when nobody has said how quiet it is. A missing price is treated differently and kept in view: it is a gap in what we know, not an unverified claim about the unit.
  • You can re-sort by price, by quietest, by cooling power, or by efficiency where it is rated. Units with no efficiency rating are shown last, never given an invented score.
  • No one can pay for placement. Ranking is the same for every unit.

How we make money

When you click Buy and purchase from a retailer, compare.ac may earn an affiliate commission. It comes out of the retailer's margin, so it never changes the price you pay.

Most US models also carry a Search Amazon link, which opens Amazon's search for that exact model number (never a generic "air conditioner" search, which is mostly fans and coolers). We do not show Amazon's price or stock, because Amazon shows its own. As an Amazon Associate I earn from qualifying purchases.

It also never changes how we rank or which units we show. We would rather send you to the right unit once than the wrong unit repeatedly, so the incentive and the advice point the same way.

Why this exists

Why searching 'air conditioner' online mostly returns things that are not air conditioners

Type 'air conditioner' into a large marketplace and most of the first page is not air conditioning. You get tower fans, USB desk fans, evaporative 'air coolers', and water-tank 'mini coolers' that simply blow air over a wet pad. None of them can pull the temperature of a closed room below the outside air, because none of them has a refrigerant compressor. They sit in the same search results, use the same blue-and-white packaging, and quote a low price, so they look like the affordable option.

On top of the mislabelling, the spec sheets are written to confuse. Cooling is quoted in BTU on one listing and kW on the next, efficiency hides behind CEER, SEER2 and EER, a portable's real SACC capacity is replaced by a flattering ASHRAE number, and noise is sometimes omitted entirely. Two units that look identical can differ by half their running cost. Without a common scale, you cannot tell a strong, quiet, efficient machine from a loud, thirsty one.

The final trap is installation. Many buyers assume any AC is plug-and-play. A portable monobloc is, but a split or multi-split is a permanent installation: it needs an EPA 608 certified technician for the refrigerant, a hole drilled through the wall, an outdoor unit, usually a permit, and in most apartments and rentals the written permission of the landlord or HOA. People discover this only after the box arrives. compare.ac exists to surface all three problems before you buy.

What it looks likeWhat it actually isWhy it matters
A 'portable air cooler' or 'evaporative cooler' with a water tank, sold for a fraction of an AC priceA fan blowing air over a wet pad. It cools only by evaporating water and adds humidity to the roomIn a closed room, or anywhere humid like the Southeast or the Gulf coast, it barely lowers the temperature and can make the air feel clammy. It cannot hold a set temperature like a real AC. It needs a window open to work at all, which defeats the purpose.
A sleek 'cooling tower fan' marketed with snowflake icons and 'ice' brandingA tower fan. It moves air across your skin but does not remove any heat from the roomOn a 35 C day the room stays at 35 C; you only feel a breeze. There is no compressor and no refrigerant, so the actual air temperature never drops. Useful for airflow, useless for genuine cooling.
A tiny 'personal mini AC' or 'desktop air conditioner' under 50 eurosA small evaporative humidifier with a fan, designed to cool a hand-sized space directly in front of itIt has no capacity rating in kW or BTU because it has no refrigeration cycle. It cannot cool a bedroom or living room. The 'AC' in the name is purely marketing.
A real-looking 'portable air conditioner' with an impressive BTU number and no exhaust hose picturedSometimes a genuine monobloc AC, but often the listing hides that a real unit must vent hot air outside through a hose and windowA true portable AC needs the exhaust hose run to a window, or it just recirculates its own heat. If the listing has no hose, no window kit, and no kW or dB(A) figure, it is almost always an evaporative cooler in disguise.
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