Convert BTU/hr (British Thermal Units per hour) to tons of refrigeration and kilowatts. Essential for HVAC, air conditioning, and cooling system sizing and comparisons.
Last updated: March 2026 | By Patchworkr Team
A ton of refrigeration (TR) is a unit of power describing the heat absorption capacity of an air conditioning or refrigeration system. One ton of refrigeration equals 12,000 BTU/hr—the amount of heat energy needed to melt 1 short ton (2,000 pounds) of ice at 32°F in 24 hours.
This unit originated from the early days of refrigeration when large ice-production facilities defined cooling capacity by how much ice they could produce. Today, it's still widely used in North America for HVAC systems, but kilowatts (kW) and BTU/hr are also common.
Understanding TR helps when sizing air conditioning units, comparing system efficiency, and interpreting manufacturer specifications. For example, a "2-ton AC unit" absorbs 24,000 BTU/hr of heat from indoor air.
Values are based on standard HVAC and thermodynamic references
To convert BTU/hr to tons of refrigeration, divide by 12,000:
Example: 36,000 BTU/hr = 36,000 ÷ 12,000 = 3 Tons
To convert BTU/hr to kilowatts, divide by 3412.142:
Example: 36,000 BTU/hr = 36,000 ÷ 3412.142 = 10.55 kW
Sizing an Air Conditioning Unit
Actual electrical power consumption depends on the unit's efficiency (SEER/EER rating). A typical 4-ton AC unit draws 15–25 kW depending on efficiency. You'll need adequate electrical service (typically 240V) and proper circuit breaker sizing for the compressor unit.
| BTU/hr | Tons | kW |
|---|---|---|
| 6,000 | 0.5 | 1.758426 |
| 12,000 | 1 | 3.516852 |
| 18,000 | 1.5 | 5.275279 |
| 24,000 | 2 | 7.033705 |
| 36,000 | 3 | 10.550557 |
| 48,000 | 4 | 14.06741 |
| 60,000 | 5 | 17.584262 |
| 120,000 | 10 | 35.168525 |
The term originated from ice production. A "ton" referred to the amount of ice produced (1 short ton = 2,000 lbs). The heat required to melt that ice in 24 hours became the standard unit of cooling capacity, even though it's really a unit of power, not weight.
BTU is a unit of energy (total heat). BTU/hr is power (rate of heat transfer per hour). For cooling systems, we care about BTU/hr—how fast the system removes heat. A 12,000 BTU/hr system removes heat at that rate continuously.
In countries using the metric system and for electrical engineering, kilowatts are the standard. BTU is North American. Both measure power: 1 kW ≈ 3,412 BTU/hr. Using both lets engineers and customers communicate effectively worldwide.
A general rule: 20–30 BTU/hr per square foot. A 2,000 sq ft home typically needs 40,000–60,000 BTU/hr (3.3–5 Tons). Hot climates may need more; mild climates may need less. Your HVAC technician considers climate, insulation, and ductwork for exact sizing.
SEER (Seasonal Energy Efficiency Ratio) and EER (Energy Efficiency Ratio) measure how efficiently an AC unit operates. Higher = better. A 4-ton system with SEER 16 uses electricity more efficiently than one with SEER 10, even though both have the same cooling capacity.
No. Oversized units short-cycle (turn on/off frequently), wasting energy and not dehumidifying properly. Undersized units run constantly without reaching target temperature. Proper sizing requires matching capacity to actual cooling load.
1 kW = 3,412.142 BTU/hr (precise), or 1 BTU/hr = 0.000293071 kW. This ratio is fixed—perfect for precise conversions. It comes from the definition of BTU relative to the joule (SI unit of energy).
No. This conversion applies to any refrigeration or heat removal system: portable ACs, heat pumps, refrigerators, freezers, industrial chillers, etc. Any system with a BTU/hr or ton cooling rating can be converted using these relationships.
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