🍽️What does a dishwasher cost to run?

Usually yes, on both water and energy, provided you run it full and do not pre-rinse under a hot tap. A modern machine uses roughly 10 to 12 litres per cycle; a sink filled twice uses more, and washing under a running tap uses far more. The heat in that water is the cost either way.

About 30% of the electricity, so roughly 0.3 kWh a cycle on a machine that uses 1.0 on normal. Across six cycles a week that is 94 kWh a year — $16, £23 or €33. It takes longer because it holds a lower temperature for more time, which is exactly why it uses less.

Scrape, do not rinse. Modern detergents need some soil to work against, and machines have sensors that adjust the cycle to how dirty the water is — a pre-rinsed load can trigger a shorter, weaker cycle. Rinsing under a hot tap can use more energy than the whole wash.

It depends what heats your water. Most dishwashers take a cold feed and heat internally with an electric element, which costs whatever electricity costs. If your machine takes a hot feed from a gas-heated cylinder, some of that energy moves to the gas bill instead — cheaper per unit almost everywhere, though standing losses eat into the gain.

Only if you genuinely cannot wait. It saves some water and a little electricity, but not half — the machine still heats, still pumps and still runs a programme. A full load on eco is the cheapest way to wash any given number of plates.

The energy label. EU labels give annual consumption over 280 eco cycles — divide by 280 for the per-cycle figure. US labels give estimated annual energy use. Either way, a plug-in monitor across one real cycle on the programme you actually use is the most accurate answer.