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Pakistan’s Smartest AC Tonnage Calculator
Apne room ka sahi AC size seconds mein janein — sirf length aur width enter karein. Advanced mode mein top floor, sun exposure aur room occupancy ke factors bhi shamil karein.
BTU Auto-Calculation
Advanced Heat Load
Top Floor Factor
0.75 – 2.0 Ton Range
100%
Free
<5s
Result Time
±5%
Accuracy
6+
Heat Factors
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⚡ AC Tonnage Calculator
Enter room size — get instant AC size recommendation
⚙ Advanced Factors
⚠ Please enter valid room dimensions (length & width).
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Recommended AC Tonnage
How to Choose the Perfect AC Size for Your Room?
Buying an air conditioner is a significant investment — and choosing the wrong capacity is one of the most common and costly mistakes homeowners make. An AC that is too small will run continuously, struggle to cool the room, and drive up your electricity bill. On the other hand, an oversized AC cools the room too quickly without adequately removing humidity, leaving the air feeling damp and clammy — while still wasting energy.
Our free AC Tonnage Calculator eliminates this guesswork. By entering your room’s dimensions — and optionally advanced factors like sun exposure and occupancy — you receive an accurate, data-backed recommendation in seconds.
What is BTU and How Does It Relate to AC Tonnage?
BTU stands for British Thermal Unit — the standard measure of heat energy. In air conditioning, BTU indicates how much heat the unit can remove from a room per hour. The higher the BTU, the more powerful the AC.
AC tonnage is derived directly from BTU: 1 Ton of cooling = 12,000 BTU/hr. This is why you’ll see residential ACs sold as 0.75 ton, 1 ton, 1.5 ton, or 2 ton models. Our Room Size AC Calculator uses your square footage to compute the required BTU, then converts it to the nearest standard tonnage.
BTU Chart: Room Size vs. Recommended Tonnage
Use this quick-reference chart to get a baseline estimate before using the calculator above for precision results.
| Room Size (sq ft) | Room Size (approx) | BTU Required | Recommended Tonnage |
|---|---|---|---|
| Up to 100 sq ft | 10×10 ft | ~9,000 BTU | 0.75 Ton |
| 100–150 sq ft | 10×15 ft | ~9,000–12,000 BTU | 1.0 Ton |
| 150–200 sq ft | 12×15 ft | ~12,000–14,000 BTU | 1.0–1.5 Ton |
| 200–250 sq ft | 14×18 ft | ~14,000–18,000 BTU | 1.5 Ton |
| 250–350 sq ft | 16×20 ft | ~18,000–21,000 BTU | 1.5–2.0 Ton |
| 350–450 sq ft | 18×25 ft | ~21,000–24,000 BTU | 2.0 Ton |
| 450+ sq ft | Large Room | 24,000+ BTU | 2.0+ Ton / Multiple Units |
Factors Beyond Square Footage That Affect Cooling Load
Square footage gives a starting point, but real-world heat load depends on several additional variables — which is exactly why our calculator includes an Advanced Mode:
Sun Exposure & Top Floor: Rooms on the top floor absorb radiant heat from the roof throughout the day. Similarly, west-facing rooms receive intense afternoon sunlight. These can increase heat load by 10–15%, requiring a higher-capacity unit for energy efficient cooling.
Number of Occupants: Each person in a room generates approximately 600 BTU/hr of body heat. A room regularly occupied by 4–5 people may need an additional half-ton of capacity compared to a single-occupancy bedroom.
Windows & Glass Walls: Large windows — especially untreated glass — allow significant solar heat gain. Rooms with large or multiple windows typically need 400–800 BTU more than similarly sized rooms with minimal glazing.
Proximity to Kitchen: Kitchens generate substantial heat during cooking. A bedroom adjacent to a kitchen, or a studio apartment where cooking and sleeping share space, requires noticeably higher cooling capacity.
Energy Saving Tips for Smarter Cooling
- ✓Right-size your AC: Oversized units short-cycle (turn on and off rapidly), wasting energy and reducing dehumidification. Use our BTU Chart and calculator to select the correct tonnage — not one size bigger “just in case.”
- ✓Use a programmable or inverter AC: Inverter technology automatically adjusts compressor speed based on room temperature, consuming up to 30–50% less electricity compared to conventional fixed-speed units.
- ✓Seal gaps and insulate properly: Even the most energy efficient cooling system performs poorly in a poorly insulated room. Seal window gaps, use thermal curtains on sun-facing windows, and ensure proper roof insulation on top floors.
- ✓Set the thermostat at 24–26°C: Each degree below 24°C increases energy consumption by approximately 6–8%. For most climates, 24–25°C provides comfort without excessive load on the compressor.
Frequently Asked Questions
Is 1.5 ton AC enough for a 12×15 room?
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A 12×15 ft room covers 180 square feet, which typically requires between 9,000 and 12,000 BTU — placing it right in the 1.0 to 1.5 ton range. For a shaded ground-floor room with normal occupancy, a 1.0 ton unit may suffice. However, if the room is on the top floor, has large windows, receives direct afternoon sun, or is regularly occupied by 3+ people, a 1.5 ton AC is the more appropriate and energy-efficient choice. Our AC Tonnage Calculator accounts for all these variables in its Advanced Mode for a precise recommendation.
What happens if I install an AC that is too small for my room?
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An undersized AC will run continuously at full capacity attempting to reach the set temperature — and often fail to do so on hot days. The consequences are significant: electricity bills rise sharply because the compressor never gets rest cycles, the unit wears out faster due to mechanical stress, indoor humidity remains high making the air feel uncomfortable even if temperatures drop slightly, and the overall cooling quality is poor. An undersized AC is not a cost-saving measure — it is a false economy that increases both running costs and early replacement expenses.
How does being on the top floor affect my AC requirement?
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Top-floor rooms absorb heat continuously from the roof, which acts as a large thermal mass during peak summer hours. This radiant heat load can increase the effective cooling requirement by 10–15% compared to the same room on a middle floor. In practical terms, a room that would need a 1.0 ton AC on the second floor may require a 1.5 ton unit on the top floor. Our calculator’s Advanced Mode includes a “Top Floor / Direct Sun” factor that automatically applies this correction to your BTU and tonnage calculation.
