How Much Electricity Does an Air Conditioner Use?

The short answer is that it depends on two numbers: the aircon’s rated power input in watts and how many hours the compressor actually works. The “1 HP” or “1.5 HP” on the box doesn’t give you either one. In the Philippines, HP is a cooling-size class, so two units sold as “1 HP” can draw quite different amounts of electricity.

To estimate your aircon’s electricity use, find the rated power input on the energy label, rating plate or spec sheet. Multiply it by your daily running hours and the days in the month, then adjust for the fact that the compressor doesn’t run flat-out the whole time. The steps and worked examples are below. To skip the maths, enter your numbers in the aircon electricity cost calculator.

Horsepower is a size class, not a wattage

As a unit of power, one electric horsepower is defined as exactly 746 watts (NIST). That’s where a lot of confusion starts. People assume a 1 HP aircon uses 746 W and a 2 HP aircon uses 1,492 W. Aircon horsepower doesn’t work that way.

In the Philippine market, “HP” is a conventional label for cooling capacity, meaning how much heat the unit can remove from a room. The HP figure is a market convention that doesn’t convert exactly into a unit, and the same badge can cover a range of capacities. Carrier Philippines also notes that the kJ/hr rating is useful when comparing two units with the same HP.

So treat HP the way you’d treat “small, medium, large” on a menu. It tells you roughly what size you’re getting, not exactly what’s in the cup.

Cooling capacity vs. power input

Every aircon has two different “power” figures, and it’s easy to mix them up.

Cooling capacity is normally much larger than power input, because an aircon moves heat rather than making cold. Efficiency figures compare the two: cooling out divided by electricity in. You can convert capacity figures like this:

Cooling capacity in kW = kJ/h ÷ 3,600
Cooling capacity in W  = BTU/h × 0.2931
Efficiency (W/W)       = cooling capacity (W) ÷ power input (W)
1 W/W                  = 3.6 kJ/W·h  (the older PH label unit)

Where to find your aircon’s rated power input

Look in these places, roughly in this order:

1. The DOE energy label. New aircons sold in the Philippines carry a DOE energy label on the front of the indoor unit. The DOE guidelines state that the cooling capacity and power input shown on the label are rated values.
2. The rating plate (nameplate). This is the sticker or metal plate on the side of a window unit or on the outdoor unit of a split type. It usually lists the rated voltage, current and power input for cooling. Use the cooling input figure, not the maximum current or a heating figure if one is shown.
3. The manual or the manufacturer’s spec sheet. Search for the exact model code, which is printed on the rating plate.

Older units may still have the old yellow DOE label. That label showed the efficiency as an EER in kJ/W·h, along with cooling capacity, voltage, current and power input (CLASP, 2019). Divide a kJ/W·h figure by 3.6 to get W/W.

What the Philippine energy label shows

Energy labels are required under Republic Act No. 11285, the Energy Efficiency and Conservation Act. Section 15 directs the DOE to prescribe energy labels and says the label must, at minimum, show the product’s energy efficiency rating. The DOE runs this through the Philippine Energy Labeling Program (PELP) under Department Circular DC 2020-06-0015. That circular has since been amended, most recently (as far as we could confirm) by DC 2024-05-0017. Separate implementing guidelines for air conditioners set out what the label must show and how the figures are calculated.

For aircons, the current label design is built around these figures:

• CSPF (Cooling Seasonal Performance Factor). This is the main efficiency figure: the total heat removed over a standard cooling season divided by the electricity used over that season, both in kWh. Higher is better. Units are tested to Philippine adoptions of the ISO standards (PNS ISO 5151 and PNS ISO 16358-1).
• A 1-to-5 star rating (the “Energy Efficiency Performance Rating”) based on CSPF ranges set by the DOE. In the 2023 draft revision, the star bands are set separately for fixed-speed and variable-speed (inverter) units. If the final rules are the same, the same number of stars doesn’t mean the same CSPF across the two types, so compare the CSPF numbers themselves.
• An estimated monthly kWh figure, calculated from the rated power input with a fixed set of assumptions (below).
• A QR code linking to more product information (CLASP).

The label’s monthly kWh estimate uses this formula:

Label monthly kWh = rated power input (kW) × 9 hours × 30 days × F

F = 0.8 for fixed-speed (non-inverter) units
F = 0.5 for variable-speed (inverter) units

The DOE guidelines explain that F allows for the compressor cutting in and out on fixed-speed units, and for speed adjustment on variable-speed units. This is a standard assumption that makes labels comparable. It isn’t a measurement of how your unit behaves in your room. If you use the aircon for a different number of hours, scale the label figure:

Your monthly kWh ≈ label monthly kWh × (your hours per day ÷ 9)

The basic formula, and why duty cycle matters

If you have the rated power input, the general estimate is:

Monthly kWh = power input (W) ÷ 1,000 × hours per day × days per month × duty cycle
Monthly cost = monthly kWh × your rate (₱/kWh)

The duty cycle is the share of running time that the unit draws roughly its rated power. In a non-inverter unit, the compressor switches fully on, then off once the room reaches the setpoint, then on again as the room warms up. In an inverter unit, the compressor speeds up to pull the room down to temperature, then slows down to hold it. In both cases the average draw over a night is usually below the rated input. How far below depends on the room and the weather.

You can’t see the duty cycle on a label. To stay on the safe side, use 100% (full rated power the whole time) as an upper bound. The DOE’s 0.8 and 0.5 factors are reasonable reference points, but they’re assumptions. In a hot, sunny room on an April afternoon, an undersized unit may run near full power almost continuously.

Worked examples

All three examples use the Meralco overall rate for a typical household in October 2026, ₱15.0615/kWh, rounded to ₱15.06/kWh (The Philippine Star, 14 October 2026). This is an example rate only. Rates differ by distribution utility and change monthly, so use the rate on your own bill.

To compare scenarios side by side, such as different hours, setpoint assumptions or two candidate units, use the aircon electricity cost calculator. To see how the aircon fits into your whole bill, list your other appliances in the appliance consumption calculator.

Why your real usage will differ from any estimate

Two households with the same aircon model can see very different bills. These are the main reasons.

Room size and sizing

An undersized unit runs near full power for long stretches and may never reach the setpoint. An oversized unit cools the air quickly but can leave the room damp and clammy, because it doesn’t run long enough to remove much humidity (ENERGY STAR). Rough HP-to-room-size charts are a starting point only. Ceiling height, windows and the number of people in the room all add load.

Sun, insulation and air leaks

A west-facing room with a metal roof and single-glazed windows picks up far more heat than a shaded room under a ceiling with insulation. ENERGY STAR’s sizing guidance suggests about 10% less capacity for a heavily shaded room and 10% more for a sunny one. Gaps around a window-type unit, doors left open and unsealed openings let cool air escape, so the compressor works longer.

Thermostat setpoint

Every degree lower you set the thermostat makes the unit remove more heat, so the compressor runs longer or faster. ENERGY STAR’s advice is to set it as high as is comfortable. Lamps, TVs and other heat sources near the indoor unit’s sensor can also make it run longer than needed.

Outdoor temperature

An aircon pushes heat outdoors. The hotter it is outside, the harder the compressor works for the same cooling, and the outdoor unit needs free airflow to get rid of that heat. That’s one reason the label uses a seasonal figure (CSPF), calculated over a standard cooling season rather than at a single test point. It’s also why March-to-May bills often jump even when your habits haven’t changed.

Maintenance

Dust on the filters and coils restricts airflow. Daikin Australia recommends cleaning indoor-unit filters about every two weeks, more often in dusty areas, and says replacing a blocked filter with a clean one can lower energy use by 5% to 15%. That’s a manufacturer’s figure, and your result will depend on how dirty the filter was. Follow your own unit’s manual, and have a qualified technician handle coil cleaning and refrigerant checks.

Does dry mode use less electricity?

Not necessarily. “Dry” (sometimes shown as a water-drop symbol) is designed for days when the temperature is bearable but the humidity is high, such as during the rainy season. Daikin Malaysia notes that it isn’t a full dehumidifier.

How dry mode works varies by brand and model. Generally the compressor still runs, usually with a low fan speed, so the air passes slowly over the cold coil and more moisture condenses out. Whether that uses less electricity than cool mode depends on the situation:

• Mild, humid weather. If the room is already close to comfortable, dry mode may run the compressor less than cool mode would at a low setpoint. In that case it can use less.
• A hot afternoon. If the room is genuinely hot, dry mode may run for a long time without making it comfortable, and you may end up switching to cool anyway.
• Different designs. Some units run the compressor quite hard in dry mode, and some control it differently. The manual for your model is the only reliable description.

ENERGY STAR’s tip for humid days is to set the fan speed low in cool mode, because slower air removes more moisture. That’s an option worth trying alongside dry mode. If you want to know which mode is cheaper for your room, compare your bills or monthly kWh across similar weeks rather than relying on a general rule.

The bottom line

The HP on the box is a size, not a wattage. For an electricity estimate you need the rated power input in watts, your real daily hours, and a sensible allowance for the compressor not running flat-out. The DOE label adds a seasonal efficiency figure (CSPF), a star rating and a standardised monthly kWh based on 9 hours a day, which is useful for comparing models but isn’t a prediction of your bill. Room heat, the weather, the setpoint and maintenance can all move the real number a long way. Put your own figures into the aircon electricity cost calculator. If you’re choosing a new unit, read Inverter vs Non-Inverter Aircon: Understanding Running Costs next.