Working out what size air conditioner you need for a 15×20 ft room? A 15×20 room is 300 sq ft, and the calculator below is pre-set to that size for an instant answer. As a quick guide, a 15×20 ft room with an 8-foot ceiling needs about a 0.75 Ton AC (6,534 BTU/hr, 1.9 kW) in a moderate climate.
🧊 Find the Right AC Size for Your Room — in Tons & BTU
Convert room size (sq ft or m²) to the exact AC tonnage you need — 0.5, 1, 1.5, 2 Ton and up. ACCA Manual-J inspired, in tons, BTU/hr and kW, for the US, UK, Europe, India, UAE, Saudi Arabia & Australia.
🌍 Prefer metric? Switch units here
🏠1. Space Type
📐2. Floor Area & Ceiling
Range: 50 – 10,000 sq ft
Range: 7 – 20 ft
Range: 0 – 50 people
🌍3. Country / Climate
The base factor assumes a 30 °C / 86 °F design day. Change the chip above to match your region.
🧱4. Insulation
☀️5. Sun Exposure
🪟6. Windows / Glazing
➕Advanced loads (kitchen, appliances, exhaust) — optional
Wattage × 3.4 = BTU/hr. e.g. 500 W ≈ 1,700 BTU/hr
For office IT, gym gear, lab equipment
AC Size for a 15×20 Room (300 Sq Ft) — Summary
A 15×20 ft room works out to 15 × 20 = 300 sq ft. With an 8-foot ceiling and average insulation, that needs a 0.75 Ton AC (6,534 BTU/hr) in a moderate climate. Size up if the room is on a top floor, faces heavy afternoon sun, or sits in a hot region:
| Condition | Recommended Capacity | Approx. BTU/hr |
|---|---|---|
| Standard insulation / moderate climate | 0.75 Ton | 6,534 BTU/hr |
| Top floor / heavy afternoon sun | 0.75 Ton | 7,425 BTU/hr |
| Hot climate (Dubai, Texas, India) | 0.75 Ton | 7,514 BTU/hr |
How to Size an AC for a 15×20 Room
Multiply the room’s length by its width to get the floor area — 15 ft × 20 ft = 300 sq ft — then apply an ACCA Manual-J–style heat-gain factor per square foot, adjusted for ceiling height, climate, insulation, and sun, with a 10% safety margin. For a 300 sq ft room, a 0.75-ton inverter split or mini-split is usually the right choice: large enough to cool fast, small enough to dehumidify and avoid the short-cycling of an oversized unit. Use the calculator above to adjust ceiling height, sun exposure, and climate for your exact 15×20 room.
Frequently Asked Questions
What size AC do I need for a 15×20 room? A 15×20 ft room (300 sq ft) needs about a 0.75 Ton AC (6,534 BTU/hr) in a moderate climate. Top-floor, high-sun, or hot-climate rooms should size up to 0.75–0.75 Ton.
How many square feet is a 15×20 room? 15 × 20 = 300 square feet.
How many BTU for a 15×20 room? Roughly 6,534 BTU/hr for standard conditions; adjust for ceiling height, insulation, and sun in the calculator above.
Related: refrigeration cycle diagram and components explained.
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Figures are reviewed by the Refcon HVAC engineering team using U.S. DOE, ENERGY STAR & ACCA Manual J data. Estimates only — confirm with a licensed pro.