Dishwasher buying guide: how to choose the right machine

Size and capacity: the decision that matters most

Width comes first. A full-size dishwasher is 60 cm wide and holds 13 to 15 place settings; a slimline machine is 45 cm wide and holds around 9 to 10. There are also compact tabletop units for tiny kitchens, but for most homes the real choice is full-size versus slimline. Measure your gap before anything else — the width, the height under the worktop and the depth, leaving room for the door to drop open and for the water and waste connections at the back. If you have space for a full-size machine, take it: a 60 cm dishwasher costs less per place setting and means fewer cycles than a slimline one.

Capacity is the other half. A "place setting" is a standard set of crockery and cutlery for one person, and manufacturers quote capacity in those units so you can compare machines fairly. Real life never loads that neatly, though — pans, mixing bowls and big platters eat into the figure fast. As a rule of thumb, count one place setting per person you regularly cook for, then add a couple of settings of headroom. A family of four is comfortable with a 13-setting machine; a big household that cooks from scratch will appreciate 15. More useful than the headline number is whether the racks are flexible and fold down, because that's what lets you fit awkward items in at all. Our dedicated size guide goes through this in detail, and our integrated vs freestanding guide covers the built-in question.

Noise: what the dB figures really mean

Modern dishwashers run between roughly 44 and 50 dB. Around 44 to 46 dB is genuinely quiet — fine to run overnight or in an open-plan kitchen-diner without anyone noticing. Around 47 to 50 dB is still perfectly acceptable but more noticeable, especially if your kitchen opens onto a living or sleeping space. A few decibels sounds trivial, but because decibels are logarithmic, every 3 dB is a meaningful change in perceived loudness. If your kitchen is separate from your living space, noise matters less and you can prioritise capacity and cleaning; if it's open-plan, choose the lowest dB figure you can. Our guide to the quietest dishwashers ranks the options.

Energy ratings and running cost

Since the energy label was made stricter, very few dishwashers reach the top A or B grades, and most good machines now sit between C and F. Don't fixate on the letter alone. The bigger lever on your bill is how you use the machine. The single cheapest habit is to run the eco programme: it uses less water and heats it more gently over a longer cycle, which sounds counterintuitive but genuinely costs less than a fast wash. Running a full load rather than a half-empty one, and using a delay-start timer to run overnight on a cheaper electricity tariff, save more in practice than chasing the very best energy grade. In short, a sensibly used C-rated machine will often cost less to run than a badly used A-rated one.

Drying and programmes

Drying is where machines differ most at a given price. Budget dishwashers clean well but often leave plastics beaded with water, so you'll get into the habit of leaving the door ajar to air-dry. Mid-range machines with an active drying option, such as the Bosch Series 4's ExtraDry, do noticeably better, and premium machines like the Miele G 5310 SC use AutoOpen to pop the door at the end and leave everything bone-dry. On programmes, you need fewer than the marketing suggests: a good auto cycle that judges the load, an eco wash for everyday use, an intensive cycle for pans and a quick wash for lightly soiled loads cover almost everything. Long lists of niche programmes rarely earn their keep.

Features worth paying for — and ones you can skip

A few features genuinely matter. Flexible, fold-down racks are top of the list, because they're what let you actually use the quoted capacity for real-world items. A third cutlery tray frees up basket space and is a real convenience. A good auto programme and an eco cycle are the two you'll use most. A delay-start timer lets you run the machine overnight, which saves money and noise. And on premium machines, active drying earns its place if damp plastics annoy you.

Other features are nice-to-have rather than deciding factors. WiFi and app control let you start the machine remotely, but the buttons on the front are usually quicker, so don't let connectivity pull you away from capacity, noise and drying. Brand buys you build quality, support and a longer life — well worth paying for if you value longevity, but never a substitute for getting the size and capacity right.