Between 8, 9 and 10 kg, what matters is how much you fill the drum, not the maximum stated capacity. The grid to choose the right capacity based on your household.
Between an 8, 9 or 10 kg washing machine, the difference is not "how much it washes", but how full you actually fill it. The capacity on the label is the maximum weight of dry laundry that the drum can handle at full load: choosing a larger size than necessary won't improve washing, but costs more and encourages you to run half-full loads, wasting water and energy.
The rule is simple: start with the number of people and how many washes you do per week, then choose the size that gets your drum to 80-100% full.
In brief: what you'll find in this guide
The short answer
For most families, the most balanced size is 9 kg: it covers a week's laundry for four people, handles double bed sheets and a single duvet, and remains efficient because it fills easily. The 8 kg is especially suitable for couples and households of 2-3 people; the 10 kg makes sense for large families or those who often wash bulky items. The deciding factor is not the theoretical maximum, but your actual average load.
What 8, 9 or 10 kg really mean
The kilograms indicate dry laundry that can be loaded at full capacity. To get a concrete idea: a shirt weighs about 200-300 g, a medium towel 400-500 g, a single duvet 1.5-2 kg. This helps you understand that a "full load" is actually more spacious than it seems, and that almost nobody fills a 10 kg drum with just everyday laundry every time.
An often overlooked detail: two washing machines with the same declared capacity can have drums of different volumes. A larger drum, with the same kg capacity, treats bulky items better and wrinkles them less. If you often wash duvets and blankets, also look at the drum volume in litres, not just the kilos.
When to choose 8 kg
The 8 kg is especially suitable for couples and households of 2-3 people, or for those with limited space. It's the size that lets you do full loads regularly without ever having to run a half-full drum. It also makes sense for a single person who washes sheets and towels together with other items, avoiding a machine too small that forces frequent washes.
When to choose 9 kg
The 9 kg is the most flexible compromise for a four-person family. It handles a week's laundry, double bed sheets and a single duvet, and at the same time it fills easily: this keeps it efficient in everyday use. It's the size we recommend when you're unsure, because it covers the most situations without waste.
When to choose 10 kg (or more)
The 10 kg — and larger sizes up to 11-12 kg — makes sense for large families (5 or more people) or for those who often wash bulky items: double duvets, blankets, curtains. The advantage is getting everything done in one cycle. The downside is that if your average load remains small, the machine will almost always work below its optimal capacity: more space and more expense, without real savings.
Capacity and consumption: the link that matters
A washing machine is efficient when the drum is 80 to 100% full. Energy and water consumption don't grow in proportion to the kilos washed: washing a half load doesn't halve consumption. This is why the right capacity is the one you'll fill, not the larger one.
In practice: an 8 kg machine always full uses less, per kilo of laundry, than a 10 kg machine always half full. If you're unsure about the size, choose the slightly smaller one that you'll actually fill. For other parameters — energy class, functions, noise level — you'll find the full picture in our reference guide: How to choose a washing machine.
Mistakes to avoid
Getting the larger size "just to be safe": this is the most common and costly mistake over time.
Confusing kg and drum volume: for bulky items, the volume in litres also matters.
Thinking about exceptional loads: choose based on your average laundry, not the duvet you wash three times a year.
Forgetting about space: larger sizes are often deeper; check your available space.
Portos' choice
If we had to suggest a single size for the average Italian family, it would be the 9 kg: a balance between capacity and consumption, suitable for four people and able to handle occasional bulky loads. Drop to 8 kg if there are two or three of you, go to 10 kg only if a full load is your everyday reality.
Once you've decided on the size, you can compare prices and availability on SniffaPrezzi or check models on OpportunityCommerce.
What choosing 9 kg practically means: consumption, cycle duration, residual moisture and actual dimensions of a nine-kilogram machine are analyzed in detail in the analysis of the Bosch Serie 6 WGG244ZRIT, compared to the 8 kg version of the same range.
Sources
European Commission — new energy label (from 1 March 2021) and consumption per 100 cycles on the Eco 40-60 program.
What about the dryer? It should be sized to match the washing machine, not the other way around: if the washing machine is 9 kg, an 8 kg dryer will split every full load in two. The reasoning with the declared data is in 8 or 9 kg dryer: which one to really choose.
