One kilocalorie per hour is 1.1622222 watts. The unit is a survival from an era when heating output was calculated in calories, and it lingers in older radiator specifications and in exercise equipment.
About the units
A kilocalorie per hour is a rate of energy delivery: 4,184 joules spread over 3,600 seconds. It was the standard unit for heating output across continental Europe before the switch to watts, and radiators manufactured before roughly the 1980s often carry ratings in kcal/h. The watt replaced it for the same reason SI replaced most legacy units — it connects directly to every other quantity in the system without a conversion constant. In exercise physiology the unit persists because energy expenditure is discussed in kilocalories, so a rate naturally comes out per hour.
The exact factor
The derivation is 4,184 J ÷ 3,600 s = 1.16222222 W. Reference points: a radiator rated at 1,000 kcal/h delivers 1,162 W; a person at rest produces about 100 W of body heat, which is 86 kcal/h; and a hard workout at 700 kcal/h is 814 W of metabolic power, of which only around a fifth becomes mechanical work. That last figure is why a gym gets warm — most of the energy leaves as heat.
Where you meet this conversion
Renovation and heating system replacement, where an old radiator's rating in kcal/h has to be matched against a modern boiler specified in kilowatts. Older European technical documentation uses it throughout. Exercise machines display kilocalories per hour, and comparing that to a cycling power meter in watts requires both this conversion and an assumption about metabolic efficiency — the machine is reporting energy burned, not mechanical output.