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What size air conditioner do I need?
The question that opens every installation conversation — and the one most often answered wrong. Here is the honest table, the factors that shift it, and why "bigger is better" is the most expensive mistake.
Quick summary
Quick rule for Valencia: ~115 W per m². A 12 m² bedroom ≈ 1.4 kW (a 2.0 kW unit), a 25 m² living room ≈ 2.9 kW (a 3–3.5 kW unit). Add 15–25% for west orientation, big glazing or a top floor. Our calculator does it for you.
The sizing table by square metres
For Valencia's climate and a standard room (~2.5 m ceilings, normal insulation, no extreme orientation), this is the reference we use in real calculations:
| Area | Capacity (kW) | Typical unit |
|---|---|---|
| Up to 12 m² | 1.5–2.0 | 2.0 kW split |
| 12–20 m² | 2.0–2.5 | 2.5 kW split (the best seller) |
| 20–30 m² | 2.5–3.5 | 3.5 kW split |
| 30–40 m² | 3.5–5.0 | 5.0 kW split or cassette |
| 40–60 m² | 5.0–7.0 | Cassette / floor-ceiling / ducted |
| Whole home 80–120 m² | 9–14 | Zoned ducted system |
Worth remembering locally: Spain still quotes "frigorías" — 1 kW = 860 frigorías. A "3,000-frigoría split" is a 3.5 kW unit.
The factors that raise (or lower) the calculation
The table is the starting point; these factors adjust it — and they are what a phone quote never asks about:
- West or south orientation: +15–20%. Valencia's afternoon sun is every unit's final exam.
- Large glazing: +15–25%. Each m² of sunlit glass adds 200–300 W of radiation — a glazed living room can need double what its floor area suggests.
- Uninsulated top floor: +15–20%. A hot roof radiates all day.
- High ceilings (>2.8 m): +10–15%. You condition cubic metres, not square ones.
- Open kitchen: +0.3–0.6 kW for the appliances.
- High occupancy (a 4-person office, an academy): +0.1–0.15 kW per person.
- North orientation and recent insulation: −10–15%. Sometimes the calculation drops — and so does the unit's price.
The expensive mistake: buying "spare capacity"
Intuition says a bigger unit cools better. Physics says otherwise: an oversized unit reaches the setpoint too fast, stops before dehumidifying the air, and restarts minutes later. The result is the classic "it's 24° but the air feels sticky" — more consumption, more start cycles (the thing that wears a compressor most) and less comfort.
A correctly sized unit runs long, low and quiet: it dries the air, sips power in the inverter's efficient band and lasts years longer. That is why we calculate before we sell — and why we sometimes recommend a smaller unit than the client asked for.
Sizing for heating: the forgotten calculation
Every modern split is a heat pump, and more and more Valencia homes run it as primary heating. But the winter load is not the summer one: in January the unit fights a bigger temperature gap (8 °C outside to 21 inside) than in August (34 to 25). Practical rule for the area: if the unit will be your main heating, size for the winter load — it usually asks for half a step more capacity. Figures on our air-to-air heat pump page.
FAQ
What size air conditioner do I need? — FAQ
What size AC do I need for 20 m²?
About 2.3–2.5 kW under normal Valencia conditions; with west orientation or lots of glass, 3–3.5 kW. The exact calculation from your details is free via WhatsApp.
Is an oversized air conditioner bad?
Yes: it stops before dehumidifying (cold but sticky air), multiplies the start cycles that wear the compressor, and runs outside the inverter's efficient band. The right unit is the calculated one, not the biggest one.
Are frigorías and kW the same thing?
They measure the same thing (cooling capacity) in different units: 1 kW = 860 frigorías. Spanish shops still quote frigorías; manufacturers quote kW.
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