Tons to Kilowatts

How Many Kilowatts in a Ton of Refrigeration?

One ton of refrigeration equals approximately 3.5169 kilowatts (3,516.9 watts). To convert tons to kW, multiply the tonnage by 3.517. This conversion bridges American HVAC sizing in tons with the international standard of kilowatts. It is particularly relevant for multinational companies specifying cooling systems for facilities worldwide, for engineers working with global equipment manufacturers, and for energy analysts comparing cooling infrastructure across countries. A 100-ton chiller in the US would be described as a 352 kW cooling system internationally, while a 3-ton residential system is roughly 10.55 kW of cooling output. The important distinction is that HVAC documents may show two different kW values: thermal output in kW of cooling or heating, and electrical input in kW consumed by the equipment. The tons-to-kW conversion refers to thermal capacity, not utility draw. Actual electrical demand depends on COP, EER, IPLV, or related efficiency metrics. As the global HVAC market consolidates and manufacturers increasingly publish dual-unit specifications, the tons-to-kW conversion helps professionals translate between the two dominant rating systems without confusing capacity with energy use.

How to Convert Ton of Refrigeration to Kilowatt (thermal)

1. Start with the cooling capacity in tons of refrigeration.
2. Multiply the ton value by 3.517 to get kilowatts.
3. For example, 5 tons x 3.517 = 17.58 kW.
4. For a quick estimate, multiply tons by 3.5. This underestimates by less than 0.5%.
5. Chain conversion: tons x 12,000 = BTU/hr, then BTU/hr / 3,412 = kW. Or simply tons x 3.517 directly.

Real-World Examples

History of Ton of Refrigeration and Kilowatt (thermal)

The disconnect between tons and kilowatts reflects the broader divergence between American and international engineering standards. When the SI system formalized the watt and kilowatt as universal power units in the 1960s, the American HVAC industry was already deeply invested in the ton-based system inherited from the ice trade. Attempts to metricate the US HVAC industry in the 1970s and 1980s failed, partly because the installed base of equipment, training materials, building codes, and contractor knowledge were all built around tons and BTU/hr. Today, the conversion between tons and kW is most relevant in global commerce, where equipment must be specified in both systems for different markets.

Common Mistakes to Avoid

• Confusing thermal kW (cooling output) with electrical kW (power consumption). A 3-ton (10.55 kW thermal) air conditioner might consume only 3 kW of electricity due to the heat pump cycle's COP. These are two different kW figures describing different things.
• Using 3.5 instead of 3.517 for precise engineering calculations. The error is 0.48%, which matters for large systems. A 200-ton system at 3.5 kW/ton gives 700 kW; at 3.517 it gives 703.4 kW — a difference of 3.4 kW.
• Forgetting that tonnage refers only to cooling capacity. Heating capacity for heat pumps is rated separately and may differ significantly from cooling capacity, especially at low outdoor temperatures.
• Using converted thermal kW to size electrical feeders or generators. Tons-to-kW gives the cooling capacity delivered by the machine. Electrical infrastructure must be sized from the equipment's input kW, amps, and starting characteristics instead.

Frequently Asked Questions