Aircon Horsepower: How Many BTU, Watts & What Room Size?

If you shop for air conditioners in Malaysia, the Philippines, Singapore, Thailand or Hong Kong, units are labeled in horsepower. In India and the US, the same machines are labeled in tons or BTU. This guide translates between all three systems and shows how to size a unit for your room — with the math visible at every step.

What "Horsepower" Means on an Air Conditioner

It is not the motor's mechanical power. Decades ago, a room air conditioner with a 1 HP compressor motor delivered roughly 9,000 BTU/hr of cooling, and the label stuck as a capacity shorthand long after compressors improved. Today "1 HP" on a spec sheet simply means ≈9,000 BTU/hr of cooling output, whatever the compressor actually draws. Our AC horsepower calculator does the conversion instantly.

HP → BTU → Ton → Watts Conversion Table

Aircon HP	BTU/hr	Tons	Cooling watts	Typical input watts*
0.5	4,500	0.38	1,320	400–550
0.75	6,750	0.56	1,980	550–800
1.0	9,000	0.75	2,640	750–1,100
1.5	13,500	1.13	3,960	1,100–1,600
2.0	18,000	1.50	5,280	1,500–2,100
2.5	22,500	1.88	6,600	1,900–2,600
3.0	27,000	2.25	7,900	2,200–3,100

*Electrical consumption depends on the unit's EER/SEER rating; inverter models draw much less at part load. Cooling watts = BTU/hr × 0.293.

HP vs. Ton: The Same Machine, Two Labels

One cooling ton = 12,000 BTU/hr, so 1 ton ≈ 1.33 aircon HP. This is why an Indian "1.5 ton" split and a Malaysian "2 HP" split are essentially the same air conditioner (both ≈18,000 BTU/hr). Watch for marketing rounding: some "2 HP" units actually deliver 17,000–19,000 BTU/hr — the BTU figure on the energy label is the number that matters. For the exact power-to-power conversion (a different question entirely), see our HP to ton converter.

Two Kinds of "Watts" — Don't Mix Them Up

An air conditioner moves heat rather than converting electricity into cooling, so it delivers 2.5–3× more cooling power than it consumes. A 1 HP unit outputs ~2,640 W of cooling while drawing perhaps 900 W from the wall. When sizing a generator, extension cord or solar system, use the input watts (and allow 3–5× briefly for compressor start-up on non-inverter units). When sizing for a room, use BTU/hr or cooling watts. To estimate input watts: divide BTU/hr by the EER (e.g. 9,000 ÷ EER 10 ≈ 900 W).

What Size Aircon for Your Room?

The working rule for typical bedrooms and living rooms is ~600 BTU/hr per square metre (≈55 BTU per sq ft), adjusted upward for sun-facing rooms, top floors, high ceilings, many occupants or kitchens:

Room size	Recommended	BTU/hr
Up to 14 m² (150 sq ft) — small bedroom	1.0 HP	9,000
15–22 m² (160–240 sq ft) — master bedroom	1.5 HP	13,500
23–30 m² (250–320 sq ft) — living room	2.0 HP	18,000
31–37 m² (330–400 sq ft) — large living/open plan	2.5 HP	22,500
38–45 m² (410–480 sq ft)	3.0 HP	27,000

Don't oversize. A too-big unit cools the air quickly but cycles off before dehumidifying, leaving the room cold and clammy while wasting energy on start-stop cycling. A correctly sized inverter unit running steadily is more comfortable and cheaper to run. Undersizing is equally bad: the unit runs flat-out continuously and never reaches temperature on hot afternoons.

Quick Buying Checklist

• Find the BTU/hr figure on the energy label — it's the truth behind the HP marketing number.
• Match it to your room area with the table above, rounding up for sun exposure or crowds.
• Prefer inverter models — the same HP rating with 30–50% lower running cost at part load.
• Check the EER/SEER (higher = cheaper to run) and derive input watts if you're on a generator or solar.
• Verify your circuit: a 2.5–3 HP unit may need a dedicated line — an electrician's job, not a guess.

Run your own numbers with the AC horsepower calculator, convert capacity units with HP to BTU, or compare labeling systems with HP to ton.