A watt is a rate, while a kilowatt-hour is an accumulated quantity. The numbers cannot be converted without knowing how long the device operates. A 1000 W appliance running one hour uses 1 kWh; the same appliance running six minutes uses 0.1 kWh. This distinction is the foundation of a defensible cost estimate.
Account for kilo and time units
One kilowatt equals 1000 watts, one hour equals 60 minutes, and one kWh equals 1000 Wh. Convert both power and duration before multiplying. A calculator can perform the conversion, but visible input units remain essential when checking a label, manual, plug meter, or result.
Prefer known energy when a cycle varies
Some appliances cycle heaters, compressors, or motors instead of drawing nameplate power continuously. If a manual, energy label, smart plug, or meter provides Wh or kWh for a full cycle, use known-energy mode. It removes the assumption that rated power remains constant, though the measurement still describes only the measured conditions.