Home Beginner 8 min read
How to Choose the Right Air Conditioner Without Regret
Practical guide to calculating BTUs, choosing the right type, and avoiding mistakes when buying an air conditioner
Before anything else: what do I really need?
Before buying anything, I stop and think:
- What do I want it for? Just cooling on hot days, or also humidity and air quality control?
- Where will it be installed? Bedroom, living room, office, home office?
- How many hours per day will I use it? This directly impacts the electricity bill.
If I have rhinitis, asthma, or allergies, I note this first — it matters when choosing filters and features.
Calculating the right size (BTUs)
This is where most people mess up. Buying an AC that’s too weak or too strong is wasting money.
Basic calculation
First, measure the room: width × length = area in m².
Then use this table as a baseline:
| Room size | Recommended BTUs |
|---|---|
| Up to 12 m² | 9,000 BTU |
| 12–18 m² | 12,000 BTU |
| 18–25 m² | 18,000 BTU |
| 25–30 m² | 22,000 BTU or more |
Adjustments I always consider
- Direct sunlight? → Add 10–15% BTUs
- Many people using the room? → Increase capacity
- Heat-generating appliances? → Increase even more
Rule of thumb: better to slightly oversize than undersize and run it at max all the time.
Types of units: which to choose?
Window AC
- ✅ Cheaper
- ✅ Easier installation
- ❌ Noisier
- ❌ Less efficient
Split
- ✅ Quieter
- ✅ Cleaner look
- ❌ Higher installation cost
Split Inverter
- ✅ Real energy savings with long use
- ✅ Stable temperature
- ❌ Higher price
Filters and fresh air
Fresh air allows external air intake instead of only recirculation.
Important if:
- The room is closed
- Many people stay inside
- AC runs for long hours
Filters matter especially for allergies.
Power and installation
Before buying:
- Check home voltage
- Dedicated circuit?
- Indoor unit position
- Outdoor unit ventilation
Energy consumption
Cheap ACs can be expensive monthly.
Check:
- Energy efficiency label
- kWh consumption
- Real monthly cost
Final checklist
- Correct BTU calculation
- Right AC type
- Installation viability
- Energy efficiency
- Filter needs
Summary
Focus on:
- Correct BTUs
- Usage-based type choice
- Energy efficiency
- Filters and air renewal
- Proper installation