What does a washing machine (warm/hot wash) cost to run?

A warm or hot wash costs several times more than the same load run cold, and the reason is simple. Heating the water dominates the machine's energy use. The hotter the wash and the bigger the load, the more power goes into the water instead of the cleaning. For most everyday laundry, that heat is not doing much work that cold water and a good detergent could not.

This is the flip side of the cold-wash saving. The motor and pump barely sip electricity; it is the element warming the incoming cold water up to temperature that turns a cheap cycle into an expensive one. Choose a 60-degree wash out of habit and you are paying to heat water that a modern detergent never needed heated.

There is a place for hot washes. Heavily soiled work clothes, bedding and towels, or illness in the house, where the temperature really does help lift grime and knock back bugs. Used deliberately, for the loads that genuinely earn it, a hot wash is money well spent and no cause for guilt.

The waste is using warm or hot as the default for normal loads out of habit. A basket of lightly worn everyday clothes does not need it, and running every load hot simply because the dial was left there is one of the quietest ways to inflate a laundry bill without getting cleaner clothes in return.

If your machine connects only to cold and heats internally, dropping the temperature setting is a direct saving, because every degree you do not ask it to reach is power you do not spend. It is the simplest lever in the laundry, a one-off nudge of a dial that pays off on every load from then on.

If your machine can take a hot-water feed from a cylinder on a night rate, that hot water is cheaper than heating it in the machine, since the cylinder did its heating overnight on cheaper power. Either way, run full loads to make each heat-up count, and try a few hot cycles in the calculator against the same loads run cold to see exactly what the heat is costing you.