How the figure is calculated
For US machines we take the annual kWh from the ENERGY STAR list. It includes the energy to heat the hot water the washer draws, so it is not just the motor. The DOE uses 295 cycles a year under Appendix J2 and 234 under the newer Appendix J; which one the list uses is not confirmed, so you choose and we divide accordingly. British models use the measured energy of a 60 °C cotton full load from the EU fiche, multiplied by the washes you enter.
The Samsung WW80K6210RW only publishes an annual figure, so for it we show the year alone.
What drives the cost
Temperature above all: heating water is most of the bill, so a 30 °C wash costs much less than the 60 °C test cycle. Then load size, programme length and spin speed. Front-loaders generally use less water, which is why the 4.5 cu ft LG WM4000 lists 105 kWh a year against 133 kWh for the GE GTW490 top-loader.
Worked example
US: the LG WM4000 front-loader lists 105 kWh a year. At 295 cycles that is 0.356 kWh a wash, or 6.52¢ at 18.31¢/kWh; at 234 cycles it is 8.22¢. The year comes to $19.23 either way.
GB: the Bosch WAN28K00 used 0.74 kWh for a 60 °C cotton full load, 19.48p at 26.32p/kWh. Four such washes a week is £40.62 a year.
Washing for less
Wash at 30 °C when the clothes allow, fill the drum, and skip the pre-wash. A high final spin also cuts drying cost later.
Questions
Why does the US figure include hot water?
The DOE efficiency metric counts the energy to heat the water the machine draws, so the label cannot be split into motor and heating.
Is the 60 °C figure what every wash costs?
No, it is the hottest standard test. Cooler washes cost less, so treat it as an upper estimate.
Why no default number of washes for British machines?
We could not verify the cycles per year behind the EU figure, so type how many washes you run.