How Much Electricity Does an Air Conditioner Use?
The actual consumption of an air conditioner depends on its cooling capacity (BTU or kW), the outdoor temperature, and how often it runs. A typical portable unit (9,000–12,000 BTU) consumes between 800 and 1,200 W during operation.
The Formula: Calculate Your Electricity Cost
Daily cost = Power (kW) × Hours used per day × Electricity price (€/kWh)
Example: 1.0 kW × 6 h × €0.25 = €1.50 per day — or about €45 per month during summer.
| Unit size | Typical power draw | Cost at 6h/day (€0.25/kWh) |
|---|---|---|
| 7,000 BTU | 700 W | €1.05 / day |
| 9,000 BTU | 900 W | €1.35 / day |
| 12,000 BTU | 1,200 W | €1.80 / day |
| 14,000 BTU | 1,400 W | €2.10 / day |
Energy Efficiency Classes: A+++ vs A+
An A+++ model is approximately 35–40% more efficient than an A+ model. Over a summer of 90 days (6h/day) this can save €20–40 in electricity — not enough to justify replacing a functioning unit, but important when buying new.
Tips to Reduce Running Costs
- Set 24–26 °C instead of 18–20 °C — each degree colder increases consumption by ~6%
- Use the timer — avoid running the AC when no one is home
- Close blinds during peak sun hours to reduce heat gain
- Clean the filter monthly — a dirty filter can increase consumption by 10–15%
How many kWh does an air conditioner use per day?
A 9,000 BTU portable unit running 6 hours uses approximately 5.4 kWh per day, costing around €1.35 at average European electricity rates.
Does leaving the AC on 24/7 save money vs. cycling?
No — running continuously generally costs more. The energy needed to cool a room back down after a break is less than the continuous running cost. Use a timer or schedule feature instead.