Prices
What an AC actually costs to run
Multiply the unit's running draw in kilowatts by the hours it runs, then by your tariff band's rate — not the average rate. A 1.5 ton inverter unit settles at roughly a third to a half of its startup draw once the room is cool, which is where the inverter saving actually comes from.
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The arithmetic, and the figure people get wrong
Cost is kilowatts multiplied by hours multiplied by your marginal tariff rate. The mistake is using an average rate. Domestic tariffs here are banded, and air conditioning pushes a household into the top band, so those units are billed at the highest rate you pay — which makes AC consumption disproportionately expensive relative to everything else in the house.
Rated power is not running power
The figure on the box is closer to maximum draw than to what the unit consumes once the room has reached temperature. A non-inverter unit runs at full draw then stops, repeatedly. An inverter unit settles to a fraction of that and holds. Estimating from the rating plate alone overstates an inverter's cost badly and understates the gap between the two types.
What changes the number most
Set point, first and by a wide margin — each degree lower costs meaningfully more to hold. Then condenser condition, because a clogged outdoor coil makes the compressor run longer for the same cooling. Then the room itself: an uninsulated top-floor room under an exposed roof can cost twice what an identical middle-floor room does.
Measuring rather than estimating
A plug-in energy meter on the unit's supply for a week gives you the real number for your unit, your room and your habits, and it usually surprises people in one direction or the other. It costs very little and settles arguments that no general figure can, including whether an upgrade would actually pay back.
How much does it cost to run an AC in Pakistan?
How much does it cost to run an AC all night?
Take the unit's steady running draw in kilowatts, multiply by the hours, and multiply by your top-band rate rather than an average. For most households an inverter unit holding a moderate set point overnight costs materially less than the same unit at its minimum setting, which is the single cheapest change available.
Does raising the temperature by one degree really save much?
Yes, more than most people expect, because the unit spends less time working to hold a smaller gap against the outside. It is the highest-return adjustment available and it costs nothing. Combining a moderate set point with a ceiling fan feels cooler than a low set point in still air, and costs a fraction.
Is it cheaper to run one big AC or two small ones?
One correctly sized unit, where the room shape allows it — two units mean two compressors, two standby draws and two sets of losses. Two smaller units only win where one cannot serve the space, such as a long narrow shop, and there the alternative is not cheaper but simply inadequate.
Rather have it done?
A service is a deep clean of both coils, the filters and the drain, plus a set of measurements that show whether the unit is actually healthy. Servicing starts at PKR 3,000, and gas refilling starts at PKR 6,000 — but a unit needing gas has a leak, and refilling without finding it is a yearly bill, not a repair.
AC servicing and gas refilling in Islamabad — prices and scope