Kärcher K2 vs K4

Having recently acquired a new Kärcher K4 I thought this maybe a handy comparison for others looking to buy a new pressure washer or thinking about upgrading their K2.

The Stats


1400 watts

110 bar pressure

360 l/h flow rate


1800 watts

130 bar pressure

420 l/h flow rate

In Practice

The K2 is capable of rinsing a car, producing snow foam and cleaning a patio but the extra kick of power from the K4 makes those operations quicker, thicker and cleaner.

The pressure and flow rate increase means you are getting more water onto the car at a higher force which in turn will be removing more dirt when pre rinsing and quicker at clearing suds.

Talking of suds when used with a foam lance this increase in power will also act to pick up and agitate more solution making foam thicker and quicker to apply, you may even find you can dial back dilutions slightly and still achieve a decent thickness of foam.

I demonstrated the extra force of the K4 by throughly cleaning a paving slab with the K2 first which did brighten it and remove a good amount or surface dirt but then swapped to the K4 and went back over it which removed some dark spots and ingrained dirt that the less powerful machine couldn’t shift. As you can see below there is a noticable improvement-

The down side of having more power and flow rate will be the amount of energy and water that you use, if they were running for the same time that is, but I feel that it also makes the job quicker so difference will be minimal. if your just washing one or two cars a week at home and a patio a couple of times a year I’d be surprised if you noticed a jump in utility bills.

Build Quality

The first thing I noticed when getting the K4 out of the box was the massive difference in weight. 13.5kg vs just 5.4kg of the k2. As well as having a bigger motor and less plastic internal parts a good portion of this weight gain will be because the K4 is water cooled while the K2 is air cooled, this extra system will mean the K4 motor will always have an optimal working temperature with less chance of over heating. I’ve never had a problem with the K2 over heating to the point it cuts out or anything but if you wanted to wash your car and patio so had a long running time on a hot summer day relying on the air alone to cool the motor will be putting a lot of strain on it. If you are moving it around a lot then obviously the K2 is much easier at almost a third of the weight but it also topples over easily. For me the weight isn’t an issue as it’s usually fixed in one place with a long enough hose to reach my driveway for car cleaning and patio on the odd occasion. The standard warranty for the K4 is also 3 years which is 1 more than they offer for the K2 so they are obviously confident in it more reliable.

The next most noticeable thing I found was the sound, surprisingly the more powerful K4 seemed a lot quieter so I did take a reading on each using a sound meter app which in my experience at work against dedicated, expensive and calibrated sound meters are actually quite accurate. I measured this with them both set up in the same position and stood the same distance away from machine with the trigger at arms length and the phone measuring decibels near my face so it will give a good guide on the volume you are actually hearing. The K2 is quite high pitched and runs at around 78db while the K2 has a lower hum that measured around 75db.

That doesn’t look like much of a difference in the numbers and while both are below the threshold where you need to consider ear defenders the lower pitch of the K4 make it much more pleasurable. The feel of it is different too while the K2 feels like it’s giving it’s all and powerful enough for most jobs the K4 delivers that extra power much more smoothly, it’s hard to explain but it reminds me of driving a hot hatch flat out down a country lane with the engine screaming. While that can be fun wafting along in a more powerful luxury saloon and actually getting there faster and more comfortably is more impressive.


There are lots of bundles available for both with added Kärcher accessories so depends what uses you have for them. Most of us into detailing will be looking to add a flexi hose and short trigger gun onto either of these machines so to compare cost I will just find the basic price for each. The K2 then with no additional extras is £90.19 on Amazon while the best price I can see for the K4 is £175 from B&Q. Obviously that’s a big jump to almost double the cost which would put off some weekend warriors. While I’m sure both will out last the warranties I think the K4 will last longer, As an example imagine that the warranty is the lifespan £90 for two years makes a K2 £45 a year while £175 over 3 years makes the K4 £58 a year for a more powerful and enjoyable machine, Doesn’t seem so bad put like that does it.


The K4 is obviously a big step up in quality and price, I was actually happy with my old K2 and wasn’t even considering a change until I was lucky enough to receive the K4 as a present. I’d say if you are looking to upgrade from K2 to K4 then there’s no need to rush out and do so until the K2 reaches the end of its life. If you are buying new one though and deliberating between these two, if you can afford it definitely go for the K4 and you won’t regret it.

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