Air Conditioner Size (BTU) Calculator

Free AC BTU calculator. Find the right air conditioner capacity in BTU or kW for any room size, accounting for insulation, sun exposure, and occupancy.

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Required Cooling Capacity (BTU/hr) hesaplanacak
Required Capacity (kW) hesaplanacak
Suggested AC Class hesaplanacak
Estimated Annual Energy Cost hesaplanacak

What Is BTU and Why Does It Matter?

BTU (British Thermal Unit) measures an air conditioner's cooling or heating capacity. Choosing the correct BTU size is critical — an undersized unit runs continuously and cannot reach target temperature; an oversized unit short-cycles, leaving air humid and uncomfortable.

Basic Sizing Rule

A general starting point: 20 BTU per square foot of floor space (or 215 BTU per m2).

Example: 20 m2 room = 20 x 215 = 4,300 BTU minimum

Adjustments for Room Conditions

ConditionAdjustment
Heavily shaded roomReduce capacity by 10%
Very sunny roomIncrease capacity by 10%
Room with more than 2 occupantsAdd 600 BTU per extra person
Kitchen / cooking areaAdd 4,000 BTU
High ceiling (over 2.7 m)Increase by ceiling height ratio
Poor insulation / old buildingAdd 10–20%

BTU to kW Conversion

1 kW = 3,412 BTU/hr | 1 BTU/hr = 0.000293 kW

Common sizes: 9,000 BTU = 2.6 kW | 12,000 BTU = 3.5 kW | 18,000 BTU = 5.3 kW

Energy Efficiency (EER / SEER)

Higher EER (Energy Efficiency Ratio) means lower running costs. Modern inverter ACs with SEER ratings of 14+ are significantly more efficient than older fixed-speed units. An inverter AC can reduce cooling costs by 30–50%.

How to Use This Calculator

Using our calculator is simple: enter the required values into the input fields and click the calculate button. Results are displayed instantly on screen. You can adjust the values and recalculate to compare different scenarios and find the best option for your situation.

Frequently Asked Questions

QuestionAnswer
How accurate are the results?We use standard formulas and up-to-date 2025 rates. Individual circumstances may vary slightly.
Is this calculator free?Yes, completely free and no registration required.
What should I do for exact figures?For precise information, consult a relevant professional or official authority.
Does it work on mobile devices?Yes, it works seamlessly on all devices and screen sizes.

Important Notes

This calculator is provided for informational purposes only. For legal, financial, or medical decisions, always seek advice from qualified professionals. Calculation results do not constitute official documents. Legislative changes may affect results; please visit the relevant official website for the most up-to-date information. Our calculators are regularly updated to reflect current regulations and rates.

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Frequently Asked Questions

A rough guide is 100-150 BTU per square meter for average insulation. Sunny rooms or poor insulation require 150-200 BTU/m². This calculator applies all these factors.
No. An oversized AC cools too quickly, shuts off before dehumidifying, and short-cycles (frequent on/off) which wastes energy and reduces lifespan.
1 ton = 12,000 BTU/hr. It originally referred to the cooling effect of melting 1 ton of ice in 24 hours. Common residential sizes are 1, 1.5, 2, 2.5, and 3 tons.