FREE AC SIZING TOOL
Air Conditioner Size Calculator
Find
The Right Cooling Capacity
Determine the correct cooling capacity (BTU/hr or tons), power requirement, and recommended AC type for your room to ensure energy efficiency and comfort.
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Optimal Comfort
Power Saving
Calculate AC Needs
Enter your room details below for a precise recommendation.
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How to Use the Air Conditioner Size Calculator
- Enter Room Dimensions: Measure and input the room length, width, and ceiling height.
- Select Occupancy: Choose the number of people who will typically be in the room.
- Choose Sunlight & Insulation: Rate the room's sunlight exposure and insulation quality.
- Identify Heat Sources: Indicate if there are major heat sources like a kitchen or servers.
- Select Climate & Type: Pick your climate zone and the room application (e.g., Bedroom).
- Calculate: Click button to see the ideal AC size in BTU/hr and Tons.
How to Calculate Air Conditioner Size (Step-by-Step)
1
Room Area
Room Area (sq.ft) = Length × Width
The first step is to calculate the total floor area to gauge the volume of air that needs cooling.
2
Base Cooling Capacity
Base BTU/hr = Room Area (sq.ft) × 25
We use a multiplier of 25 BTU per square foot to establish a baseline for an average room with standard ceiling height.
3
Adjustments for Room Factors
Apply these correction factors for accuracy:
- Sunny room: +10%
- Shaded room: -10%
- Kitchen / heavy appliances: +4,000 BTU/hr
- Occupancy: +600 BTU/hr per person (if > 2 people)
- High ceiling (>10ft): +10–15%
- Poor insulation: +15%
4
Convert to Tons & Power
Tons = BTU/hr ÷ 12,000
Power (kW) = (BTU/hr ÷ 3.412) ÷ 1000
Power (kW) = (BTU/hr ÷ 3.412) ÷ 1000
Real-Life Calculation Scenarios
1
Scenario: Master Bedroom (Sunny)
Room Details
- Dimensions 12 ft × 15 ft
- Sunlight Direct Sun (+10%)
- Occupancy 2 People (Standard)
Step-by-Step Calculation
1.
Calculate Area
12 × 15 = 180
sq.ft
2.
Base BTU (× 25)
180 × 25 = 4,500 BTU
3.
Sunlight Adjustment (+10%)
4,500 + 450 = 4,950 BTU
Recommendation:
0.5
Ton (5,000 BTU)
2
Scenario: Living Room + Open Kitchen
Room Details
- Dimensions 20 ft × 15 ft
- Heat Source Kitchen (+4,000 BTU)
- Climate Temperate
Step-by-Step Calculation
1.
Calculate Area
20 × 15 = 300
sq.ft
2.
Base BTU (× 25)
300 × 25 = 7,500 BTU
3.
Kitchen Adjustment
7,500 + 4,000 = 11,500 BTU
Recommendation:
1.0
Ton (12,000 BTU)
3
Scenario: Busy Office Space
Room Details
- Area 600 sq.ft
- Occupancy 4 People
- Heat Sources Computers
Step-by-Step Calculation
1.
Base BTU (600 × 25)
15,000 BTU
2.
Occupancy Adjustment (Extra 2 people)
2 × 600 BTU = 1,200 BTU
15,000 + 1,200 = 16,200 BTU
Recommendation:
1.5
Ton (18,000 BTU)
Room Size to AC Capacity Guide
| Room Size (m²) | BTU/hr Needed | Tons | Recommended AC Type |
|---|---|---|---|
| Up to 10 | 5,000–6,000 | 0.5 | Small room |
| 10–15 | 7,000–9,000 | 0.75 | Bedroom |
| 15–20 | 9,000–12,000 | 1.0 | Living room |
| 20–30 | 12,000–18,000 | 1.5 | Medium room |
| 30–40 | 18,000–24,000 | 2.0 | Large room |
| 40–60 | 24,000–36,000 | 3.0 | Hall / office |
| 60+ | 36,000+ | 4.0+ | Central AC |
Adjustments for Room Factors
To refine accuracy, consider these correction factors based on your specific room conditions:
| Condition | Adjustment |
|---|---|
| Sunny room | +10% capacity |
| Shaded room | -10% capacity |
| Kitchen or heat-producing area | +4,000 BTU/hr |
| More than 2 people | +600 BTU/hr per extra person |
| High ceiling (>10 ft / 3 m) | +10–15% |
| Poor insulation | +15% |
Air Conditioner Size by Room Size
| Room Area (sq.ft) | Recommended BTU/hr | Tons | Example Usage |
|---|---|---|---|
| 100 | 2,500 | 0.25 | Small office cabin |
| 150 | 3,750 | 0.31 | Bedroom |
| 200 | 5,000 | 0.42 | Guest room |
| 300 | 7,500 | 0.63 | Living room |
| 400 | 10,000 | 0.83 | Studio |
| 600 | 15,000 | 1.25 | Hall |
| 800 | 20,000 | 1.66 | Large hall |
| 1,200 | 30,000 | 2.5 | Office floor |
Conversion Formulas
| Conversion | Formula |
|---|---|
| sq.ft to m² | m² = sq.ft × 0.0929 |
| m² to sq.ft | sq.ft = m² × 10.764 |
| BTU to Tons | Tons = BTU ÷ 12,000 |
| Watts to kW | kW = W ÷ 1000 |
Key Factors Affecting AC Sizing
- Ceiling height: Higher ceilings (over 10 ft) increase the volume of air, requiring more BTUs.
- Windows & insulation: More windows or poor insulation allow heat to enter, increasing the cooling load.
- Location / climate: Tropical or hot areas require significantly higher BTUs per square foot than temperate zones.
- Appliance heat load: Devices like computers, ovens, or extensive lighting generate heat, raising cooling needs.
- Occupancy: Each additional person in the room adds approximately 600 BTU/hr of heat.
Buying & Efficiency Tips
Energy Efficiency
- • Choose Inverter AC: Variable speed compressors save significant energy.
- • High Ratings: Look for EER ≥ 3.2 or SEER ≥ 15.
- • Avoid Oversizing: Too large a unit wastes power and cools unevenly (short cycling).
Installation & Maintenance
- • Placement: Install on a shaded wall away from direct sunlight.
- • Sealing: Use proper insulation and keep doors/windows closed.
- • Service: Regular filter cleaning ensures optimal airflow.
Air Conditioner Size Calculator FAQs
What AC size do I need for my room?
It depends on the room area and heat load. A general rule is 20-30 BTU per square foot. Use our
calculator for a precise estimate that factors in ceiling height, sunlight, and occupancy.
Is a bigger AC always better?
No. An oversized AC cools the room too quickly without dehumidifying it, leading to a clammy,
uncomfortable environment and short-cycling which wears out the compressor.
How does ceiling height affect AC sizing?
Standard calculations assume an 8-10 ft ceiling. For ceilings higher than 10 ft, you should
increase the capacity by approximately 10-15% to cool the larger volume of air.
What is the difference between BTU and ton?
BTU (British Thermal Unit) measures heat energy. One 'Ton' of cooling is equivalent to 12,000
BTU/hr. Large ACs are often rated in tons.
Which AC type is best for bedrooms?
Split ACs are generally best for bedrooms because they are quieter and efficient. Inverter Split
ACs offer the best temperature stability for sleeping comfort.