About

In the world of HVAC and thermal engineering, two unit systems constantly collide: the metric/European tradition using kcal/h (kilocalories per hour) and the standard SI unit kW (kilowatts). Engineers often face the challenge of sizing a boiler rated in kcal/h against a burner or pump rated in kW. While both measure power (rate of energy transfer), the conversion factor is not intuitive.

This tool is designed specifically for thermal system sizing. Whether you are replacing an old 200,000 kcal/h burner or calculating the cooling load for a chiller, precise conversion prevents undersizing equipment. It includes high-precision outputs necessary for engineering specifications.

Formulas

The Kilocalorie is an energy unit, and Kilocalorie per Hour is a power unit. The Kilowatt is the SI unit of power.

1 kcal/h ≈ 0.0011622 kW

1 kW ≈ 860.42 kcal/h

To convert from kcal/h to kW:

P_kW = P_kcal/h860.42065

Reference Data

Nominal Power (kW)	Heat Rate (kcal/h)	Typical Application
12 kW	10,320	Small Apartment Boiler
24 kW	20,640	Standard Home Boiler
35 kW	30,100	Large Home / Small Commercial
50 kW	43,000	Commercial Heating
100 kW	86,000	Apartment Block Boiler
500 kW	430,000	Industrial Process Heat
1,163 kW	1,000,000	1 Gcal/h (District Heating)

Frequently Asked Questions

It is a unit of Power. "kcal" is energy, but "kcal per hour" is the rate of energy flow, making it dimensionally equivalent to Watts or Horsepower.

A typical domestic gas boiler is often rated at 24 kW, which corresponds to approximately 20,600 kcal/h. This is sufficient for heating and instant hot water for an average-sized home.

860 (specifically 860.42) is the number of kcal/h in 1 kW. Old engineers often memorize "divide by 860" to get kilowatts from kcal/h.

No directly, but related. Air conditioners use BTU/h. 1 kcal/h ≈ 3.96 BTU/h. This tool converts specifically between Metric Thermal (kcal/h) and SI Electric/Thermal (kW).