Air conditioner (1.5 ton, non-inverter): units per month in Pakistan
Short answer. A 1.5 ton non-inverter air conditioner draws roughly 1,800 watts while the compressor runs. Set to 26 °C in a reasonably insulated bedroom it runs about 5.5 hours out of an 8-hour night, which is close to 10 units a day and 300 units a month — comfortably more than an entire Pakistani household typically uses in winter.
Power draw
- Low: 1400 W
- Typical: 1800 W — the figure used in every calculation below
- High: 2200 W
Compressor plus indoor and outdoor fans. A fixed-speed unit draws close to this whenever the compressor is on and near zero when it is not, so the average over an hour depends on how hard it is working.
Units and cost by usage pattern
Each row is 1800 W × the hours shown ÷ 1,000, over 30 days. The three cost columns exist because the rupee cost of a unit depends entirely on which slab your month lands in — the same consumption costs a light user and a heavy summer household very different amounts. Rates are illustrative and not a substitute for the tariff table printed on your own bill.
| Usage pattern | Units / day | Units / month | At Rs 12.5/unit | At Rs 27.5/unit | At Rs 36/unit |
|---|---|---|---|---|---|
| Bedroom, night only (8 hours, thermostat 26 °C) | 9.9 | 297 | Rs 3,713 | Rs 8,168 | Rs 10,692 |
| Bedroom, night only (8 hours, thermostat 20 °C) | 13.5 | 405 | Rs 5,063 | Rs 11,138 | Rs 14,580 |
| Living room, evening and night (14 hours) | 18 | 540 | Rs 6,750 | Rs 14,850 | Rs 19,440 |
Rate bands: Rs 12.5 — light user, protected (≈150 units/month); Rs 27.5 — average household (≈250 units/month); Rs 36 — heavy summer month (700+ units). This appliance is seasonal — the usage patterns above assume 4 months of the year at most, so the annual figure is lower than twelve times the monthly one.
Why the thermostat setting dominates everything else
A fixed-speed compressor is either on or off. The thermostat setting decides what fraction of the hour it spends on, and that fraction is the whole bill. At 26 °C against a 40 °C afternoon the compressor might run 65 per cent of the time; at 20 °C it barely stops.
Each degree lower costs roughly 6 to 8 per cent more energy. Moving from 20 °C to 26 °C is not a marginal adjustment — it is the difference between about 450 units a month and about 300.
What a 300-unit month does to your bill
This is the part people miss. Adding 300 units to a 200-unit household does not add 300 units' worth of money at the rate you were paying, because those units land in higher slabs and, for unprotected consumers, can re-price the whole month.
It also removes protected status if you had it, and that consequence outlasts the summer by six months.
Room size, sun and sealing
A 1.5 ton unit is sized for roughly 150 to 180 square feet in Pakistani conditions. Undersizing is expensive because the compressor never reaches cut-out and simply runs continuously.
West-facing rooms and uninsulated roof slabs are the two biggest loads on any air conditioner here. A reflective roof treatment or even wet matting on a west wall changes the duty cycle measurably.
How to use less
- Set 26 °C and add a ceiling fan rather than dropping the thermostat — the fan costs about 60 watts against the several hundred that each extra degree of cooling costs.
- Clean or replace the indoor filter monthly through the season; a clogged filter forces longer run times for the same room temperature.
- Seal the gap around the pipe entry and under the door. An air conditioner cooling a room that leaks into a hot corridor never cuts out.
- Service the outdoor unit before the season. A coil packed with dust raises condensing pressure and with it the compressor's power draw.
- Use the timer to stop it two hours before you wake rather than running it until the alarm.
Frequently asked questions
How many units does a 1 ton AC use compared with a 1.5 ton?
Roughly two-thirds, at around 1,200 watts against 1,800, provided the smaller unit is adequately sized for the room. If it is undersized it runs continuously and the saving evaporates entirely.
Is it cheaper to leave the AC running all day or switch it on when I get home?
Switch it on when you need it. The idea that re-cooling costs more than maintaining is false for a building of ordinary thermal mass — the cool-down pull is real but far smaller than several hours of maintenance cycling.
Does the AC use more electricity at night?
Less, because the outdoor temperature is lower and the compressor works against a smaller temperature difference. The same unit at the same setting costs measurably less at 2 am than at 3 pm.
Compare with
- Inverter air conditioner (1.5 ton) — 1100 W typical
- Ceiling fan — 65 W typical
- Air cooler (evaporative) — 190 W typical
- Exhaust fan — 45 W typical
Go further
Filed under cooling in the full appliance index. Add your own hours in the consumption calculator, or open your actual bill with the reference number lookup.