What size washing machine do you really need?

If you’re in the market for a new machine, what capacity should you go for? Is a larger machine necessary and worth the extra cost?

We wondered what 9kg of washing looks like, and whether it was even possible to fit it into a 9kg-rated machine? If we did get it in, how well do washing machines perform anyway, at full load capacity?

How heavy is your washing?

I weighed every load we did at home for two weeks. We’re a fairly typical family of four, with two boys aged 10 and 13 who produce a reasonable amount of dirty (and stinky!) washing every few days.

I recorded the weight and type of each load; measuring the weight using handheld luggage scales.

• Thirteen loads were weighed and washed over the fortnight.
• The average weight of all the loads was 3.39kg.
• Mixed loads weighed from 2.38kg to 4.91kg, with the average being 3.76kg.
• Towel-only loads ranged from 3.21kg to a max of 5.26kg (this load had very wet towels).
• A single duvet cover, single fitted sheet, pillowcase and two towels weighed 2.64kg.
• A queen duvet cover, queen fitted sheet and four pillowcases weighed 3.04kg.
• A double-layered queen duvet weighed 4.17kg.
• Swimming gear for one of the boys (a wet towel, togs and rash shirt) weighed 1.3kg.

It’s a limited survey, but we can still conclude that an average family of four can probably get by with a fairly small capacity machine – a 7kg front loader would suffice, or even a 6kg top loader. (Although, in general, we don’t recommend top loaders as their performance is not as good as front loaders.)

Your money would be better spent on a smaller capacity, but better performing machine (check our results). Indeed, we perform our tests with 3.5kg loads, as research shows this is the average load weight of most household washes.

How much can you fit in a washing machine anyway?

Our current machine is rated for 9kg, but what does 9kg of washing look like? Well, here it is.

It’s a lot – pretty much my whole wardrobe! Fitting it into the machine was possible, but not particularly easy!

“It fits!” I exclaimed. Then I remembered the glass door on a front loader protrudes into the drum a fair way and can make it hard to shut. I had to hold the door shut until the program started and the door lock activated, or it kept popping open again.

If you’re regularly doing basket loads of this size, a bigger machine is clearly what you need.

But if you’re considering a new machine, we’d recommend investing in a $25 luggage scales first. That way, you can weigh your laundry for a few weeks before you jump in to buy a 12kg machine.

And if you’ll only use the extra capacity occasionally (e.g., for washing a large duvet), don’t forget the laundromat could be a significantly cheaper option in the long run.

A bit about drum sizes

Buying a larger capacity machine doesn’t always get you a bigger drum to stuff your washing into.

Often manufacturers will use the same size drums for a range of capacities. For example, Miele 7kg- and 8kg-rated machines all have 59L drums, while the 9kg models have 64L drums.

There is clearly a limit on the maximum drum size based on the overall dimension of the machine, especially with front loaders. Often the difference between machines with different capacities will be electronic, rather than physical. Modern machines will adjust cycle times to suit load weight, and the difference between the 7kg and 8kg machine might only be a circuit board.

So, check before you buy – that extra-large duvet you’re hoping to wash at home may still not fit in your new 12kg washer!

What does our testing show?

As stated, our ongoing washing machine tests use 3.5kg loads, representing an average load size. But we wanted to know; how does a machine perform if you stuff it to the max?

To satisfy our curiosity, the lab ran extra tests with full loads. It compared the performance of a full load in an 8.5kg-capacity front-loading machine with the results for a 3.5kg load in the same machine.

The results were surprising.

• Dirt removal performance was very similar.
• Cycle time increased from 2.75 hours for the 3.5kg load, to over 5 hours for the 8.5kg load, an 80% increase.
• Using full 8.5kg loads over the course of a year would save around 20% in electricity costs and use nearly 50% less water (nearly 10,000 litres) than doing the same amount of washing in 3.5kg loads.
• Rinsing performance score did drop, though, and was 33% worse with the larger load.

(Bear in mind this was a modern machine, able to sense the load’s weight and adjust cycle times accordingly. Older machines may not have this functionality.)

Our standard test calculations are based on doing a single 3.5kg load per day for a year. So, if you can save up your loads and wash a larger load every third day or so, and put up with extended cycle times, you will save money and a significant amount of water. You may need to run an extra rinse cycle at the end though.

Of course, hanging out 8.5kg of washing might not be your idea of fun. And the 5-hour wash cycle means you may need to plan your wash day in advance too.

Detergent dosage

It’s common sense to use less detergent for smaller loads, but it isn’t always obvious what size load a standard dose of detergent is for. And it also goes without saying that detergent manufacturers aren’t bothered if you use too much of their product anyway.

Some detergents state to use 50gm for small loads between 4kg and 7kg. But many liquid detergents just state 50ml for a standard load. If we assume a “standard load” is between 4kg and 7kg, this suggests we should be using less detergent than we think for many of our washes.

For testing, we use 12.5gm of detergent powder per kg of washing, which equates to a 50gm dose for a 4kg load. If you’re using powder, then a similar ratio should be fine for your washes. Level of soiling also plays a part here, as more heavily soiled clothes may require more detergent.

If you can do fuller loads, you’re going to save detergent as well as electricity and water, as you’ll be washing less often.

Automatic dosing

Many newer machines now come with an auto-dosing system that will dispense the correct amount of detergent depending on load volume and degree of soiling, taking the guesswork out of dosing.