A one-formula answer, worked examples for six cities, and the one number most people get wrong when estimating their aircon costs.
Running cost per hour = Unit power draw (kW) × Electricity rate ($/kWh)
That's it. The only two numbers you need are your unit's actual power draw and your local rate. Both have a catch:
| Unit size | Cooling capacity | Typical input (inverter) |
|---|---|---|
| 0.75 HP | ~7,000 BTU | ~0.6–0.7 kW |
| 1 HP | ~9,000 BTU | ~0.75–0.9 kW |
| 1.5 HP | ~13,000 BTU | ~1.1–1.4 kW |
| 2 HP | ~18,000 BTU | ~1.5–2.0 kW |
Input power at steady-state operation. Startup draw is higher for all types; inverter units sustain the high draw longer during the initial ramp-up.
Using a typical 1HP inverter unit drawing 0.85 kW at steady state:
| City | Rate (approx.) | Cost per hour | Cost per 8h night |
|---|---|---|---|
| Singapore | 34.78¢/kWh | ~29.6¢ SGD | ~$2.37 |
| Kuala Lumpur | ~12¢/kWh (TNB base) | ~10.2 sen | ~RM 0.82 |
| Jakarta | ~8¢/kWh (PLN R-1) | ~Rp 1,228/hr | ~Rp 9,820 |
| Bangkok | ~11.5¢/kWh (MEA avg.) | ~0.39 THB | ~3.10 THB |
| Manila | ~26.5¢/kWh (Meralco Jul 2026) | ~₱2.25 | ~₱18 |
| Honolulu | ~47¢/kWh (HECO Jul 2026) | ~$0.40 USD | ~$3.19 |
All figures are reference estimates. Rates change; check your own bill for the current figure. Honolulu: subtropical climate, not equatorial — heavy nightly aircon use less common.
People often divide their monthly bill by their unit size in HP and conclude that aircon "doesn't cost that much per hour." The error is using HP as if it were kW. A 2HP unit is not 2,000 watts of electrical draw — it is roughly 1,500–2,000 watts, meaning the correction isn't dramatic, but it is real. More importantly, the monthly bill reflects all household electricity, not just aircon. Isolating the aircon cost requires either a smart plug with energy monitoring on the indoor unit, or using this formula with the nameplate input power.
For the percentage-savings version — which applies regardless of your local rate — try the savings calculator. For the physics behind how dry mode reduces that hourly cost by ~43%, see Does Dry Mode Really Save Electricity?