BTU/hr and Refrigeration Tons Converter

What Is a 'Ton' of Refrigeration?

The term Ton of Refrigeration (TR) originates from the late 19th-century ice harvesting and cold storage trade prior to electric mechanical refrigeration.

The Latent Heat of Ice

A ton of refrigeration is defined as the rate of heat removal required to freeze 1 US short ton (2,000 lbs) of liquid water at 32°F (0°C) into ice at 32°F over a 24-hour period:

• Latent heat of fusion of ice = \

• Total heat for 2,000 lbs = \

• Rate per hour = \

Common AC Sizing Equivalents

• 1.5 Ton: 18,000 BTU/hr (5.28 kW thermal, 600 CFM)

• 2.0 Ton: 24,000 BTU/hr (7.03 kW thermal, 800 CFM)

• 2.5 Ton: 30,000 BTU/hr (8.79 kW thermal, 1,000 CFM)

• 3.0 Ton: 36,000 BTU/hr (10.55 kW thermal, 1,200 CFM)

• 3.5 Ton: 42,000 BTU/hr (12.31 kW thermal, 1,400 CFM)

• 4.0 Ton: 48,000 BTU/hr (14.07 kW thermal, 1,600 CFM)

• 5.0 Ton: 60,000 BTU/hr (17.58 kW thermal, 2,000 CFM)

How to Use This Calculator

Enter your Conversion Direction — choose from Tons of Refrigeration (TR) ➔ BTU per Hour (BTU/hr), BTU per Hour (BTU/hr) ➔ Tons of Refrigeration (TR), Cooling / Refrigeration Capacity (e.g. 3.5), and AC Efficiency Rating (SEER / SEER2) for Power Draw — choose from 14 SEER (Standard Base Efficiency), 16 SEER (High Efficiency / Modern Standard), 18 SEER (Premium Two-Stage System). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Conversion formulas between Tons of Refrigeration (TR) and BTU/hr:/hr = Tons of Refrigeration (TR) × 12,000 of Refrigeration (TR) = (BTU/hr) / (12,000) HVAC engineering sizing formulas:- Thermal kW: kW_thermal = TR × 3.5168528- Airflow Rate: CFM = TR × 400 CFM/ton- Estimated Electrical Draw: Watts_electric = (BTU/hr) / (SEER) (or COP = (SEER) / (3.41214))

Worked Example

For example, converting a 3.5-ton central air conditioner: . This system produces 12.31 kW of thermal cooling, requires 1,400 CFM of blower airflow, and under a 16 SEER rating draws approximately 2.63 kW of electrical power to condition 1,400 to 2,100 sq ft.

Understanding Your Result

Percentages are relative values — context determines what is "good" or "bad." A 50% discount is significant; a 50% failure rate is alarming. Percentage change and percentage points are different: moving from 4% to 5% is a 1 percentage point increase, but a 25% relative increase. When comparing percentages across different base values, always check whether absolute differences are meaningful — a 10% improvement on a large base creates more absolute value than 10% on a small base.