How do I choose a dishwasher and what actually matters in the specification?

A dishwasher is bought roughly twice in a lifetime and used every day, so the things that matter are the ones you meet daily: how loud it is when you are in the room, whether the crockery comes out dry, and whether your actual dishes fit. Almost every specification argument online is about place settings and energy class, which are the two numbers least likely to change your experience.

Step by step

1. Measure the aperture before anything else — width, depth and height.Full size is 598-600mm wide, slimline is 448-450mm. Height matters more than people expect: a standard machine is about 815-820mm and many have adjustable feet giving 870mm, but an integrated one has to fit under the worktop with the door panel on.
2. Decide freestanding, integrated or semi-integrated.Integrated hides behind a cupboard door and costs more for the same internals. Semi-integrated leaves the control panel visible, which is genuinely easier to use. Freestanding is cheapest and easiest to replace later.
3. Treat the noise figure as a primary spec, not a footnote.Anything from 39-44dB is quiet enough to hold a conversation next to. 46-48dB is audible but tolerable. Above 50dB in an open-plan kitchen means the machine only runs when the room is empty, which changes when you can use it.
4. Find out how it dries, because this is the biggest single difference between machines.Condensation drying is standard and is why plastics come out wet. Heated drying dries better and uses more electricity. Zeolite drying (a mineral that releases heat as it absorbs moisture) dries best and is the reason some machines cost more. Auto-open doors, where the door pops ajar at the end, are a cheap and effective compromise.
5. Look at the basket layout rather than the place-setting count.Place settings are measured to a standard that assumes small plates and no mixing bowls. What matters is whether the lower basket takes your dinner plates upright, whether tines fold flat for pans, and whether the upper basket height adjusts with the basket loaded.
6. Decide whether a third cutlery rack is worth the lost height.A flat cutlery drawer at the top washes cutlery better than a basket and frees the whole lower basket. It costs 40-50mm of upper basket height, which matters if you wash tall glasses or stick blenders.
7. Check the cycle length of the programme you will actually use.The eco programme is the one the energy label is measured on, and on many machines it runs three to four hours. If you need dishes back in an hour, look at the length of the machine's 1-hour or auto programme instead, and accept it uses more energy.
8. Check what the machine wants in the way of consumables.Most have a salt reservoir and a water softener. A few cheap models do not, which is a real disadvantage in a hard water area. Check the rinse aid dispenser is refillable from inside the door rather than needing the door removed.
9. Confirm it is cold fill and that there is a socket, not an extension lead.Almost every modern dishwasher is cold fill only and heats its own water. It needs its own switched socket. If there is no socket in the run, adding one is fixed electrical work for an electrician, not a job to solve with a trailing lead under a worktop.
10. Check the leak protection before you buy an integrated one.A full AquaStop-type system has a valve at the tap end of the hose and a float switch in the base tray. On an integrated machine under a wooden worktop, that is worth paying for — a slow leak behind a cupboard door is discovered by the floor rather than by you.

Tips

• Take a dinner plate and your largest mixing bowl to the showroom, or check the basket dimensions against them. Plate diameter is the single most common regret.
• Half-load and zone-wash functions are worth much less than they sound: on a modern machine, waiting until it is full and running eco beats running half loads.
• Wi-Fi connectivity on a dishwasher is close to useless day to day. A delay-start timer, which every machine has, does the one genuinely useful thing.
• If the machine will sit next to a bedroom wall or under a bedroom floor, weight and build matter as much as the dB figure — a heavy machine transmits less through the floor.

Common mistakes

• Buying on place settings — The place-setting figure is measured against a test standard with small plates and no serving dishes. Two machines rated at 14 place settings can differ enormously in what they actually swallow.
• Ignoring the noise rating because the kitchen has a door — Kitchens increasingly do not, and dishwashers increasingly run overnight or during the evening. A 52dB machine dictates when you are allowed to use it.
• Assuming the energy class describes the programme you use — The label is measured on eco. If you run a one-hour programme every day, the machine's real consumption can be double the label figure, and the class tells you nothing about it.

Questions people ask