If you’re looking for a decent pressure washer but don’t want to spend an absolute fortune, then the Karcher K2 and K4 models are two solid options to consider. But which is the best choice?
In this article, I’ll directly compare these two pressure washers and their variants (power control, compact, home etc.) so you can figure out which is the best option for you.
Karcher K2 vs K4 Summary
The Karcher K4 has a maximum flow rate of 420 litres/ hour and pressure of 130 bar whereas the Karcher K2 has a maximum flow rate of 360 litres/ hour and pressure of 110 bar. The Karcher K4 also has a longer hose compared to the K2. The K2 is smaller, lighter and cheaper than the K4 pressure washer.
| Specification | Karcher K2 | Karcher K4 |
| Maximum Pressure | 110 bar | 130 bar |
| Maximum Flow Rate | 360 litres/ hour | 420 litres/ hour |
| Motor | Air-Cooled | Water-Cooled |
| Hose Length | 4m for Compact and 5m for Power Control Model | 6m for Compact and 8m for Power Control Model |
| Compact Version Weight | 3.7 kg | 4.7 kg |
| Power Control Version Weight | 4.0 kg | 11.5 kg |
Still considering other Karcher models? Make sure you check out my guide to the Karcher pressure washer range to make sure you’re choosing the best option for your requirements.
Pressure and Flow Rate
The Karcher K4 is a more powerful machine than the Karcher K2. The K2 has a maximum pressure rating of 110 bar and a maximum flow rate of 360 L/ hour. The K4 on the other hand has a maximum pressure rating of 130 bar and a maximum flow rate of 420 L/ hour.
This means the K4 has around 18% more pressure and a 17% higher flow rate compared to the K4.
Both machines are powerful, but if you plan on using the pressure washer for more heavy duty tasks such as cleaning outdoor furniture, fences or flagstones.
If you plan on using the pressure washer to clean a car or bicycle, then either machine is capable, but of course the K4 is more effective. I have personally used both machines to clean a car and have not struggled at all using the K2 despite this application not being explicitly listed by Karcher on their website.
You will notice a difference between the two models if you are using a snow foam cannon though. You’ll be able to get better quality, thicker foam from the K4 due to it’s higher pressure and flow rate. However, it’s still possible to get thick snow foam from a K2 if you pair it with a good quality foam cannon.
Dimensions and Weight
The Karcher K2 is smaller and lighter than the Karcher K4. There are 4 models to consider here though as there are “compact” and “power control” variants of both the K2 and K4.
The Karcher K2 Compact, K2 Power Control and K4 Compact are all a fairly similar size, with the K4 Compact being the heaviest and longest, and the K2 Power Control being the widest and tallest. The Karcher K4 Power Control however is much larger than the other three units and weighs more than double.
Here are some tables to show the differences between each model in terms of their size.
Metric Units
| Karcher Model | Length | Width | Height | Weight |
| K2 Compact | 18.0 cm | 21.9 cm | 38.9 cm | 3.7 kg |
| K2 Power Control | 24.6 cm | 28.0 cm | 58.6 cm | 4.0 kg |
| K4 Compact | 27.3 cm | 25.6 cm | 45.7 cm | 4.7 kg |
| K4 Power Control | 40.2 cm | 30.6 cm | 58.8 cm | 11.5 kg |
Imperial Units
| Karcher Model | Length | Width | Height | Weight |
| K2 Compact | 7” | 8.6” | 15.3” | 8.2 lbs |
| K2 Power Control | 9.7” | 11.0” | 23.1” | 8.8 lbs |
| K4 Compact | 10.7” | 10.1” | 18.0” | 10.4 lbs |
| K4 Power Control | 15.8” | 12.0” | 23.1” | 25.4 lbs |
Other Key Differences
In addition to the differences in size and power between the K2 and K4, there are also several other notable differences between these models.
- Hose Length: the K2 Compact has a 4m hose, the K2 Power Control has a 5m hose, the K4 Compact has a 6m hose and the K4 Power Control has an 8m hose.
- Motor: the K2 Compact/ Power Control, and K4 Compact models have air-cooled motors whereas the K4 Power Control has a water-cooled motor which is designed to be more durable.
- Power Rating: the K2 has a power rating of 1400W whereas the K4 has a power rating of 1800W so will use more electricity.
- Detergent Application: the K2 Power Control/ Compact and K4 Compact use suction to apply the detergent whereas the K4 Power Control uses the more advanced plug and clean system.
- Trigger: the K4 Power Control has a more premium trigger with LED display compared to the K2 model.
Model Variants
I’ve already touched on a couple of variants of the K2 and K4, but in this section I’ll go into a bit more detail about the differences.
Both the Karcher K2 and Karcher K4 have two main versions: power control and compact.
Power control models have longer hoses and are larger and heavier compared to the compact models. All Compact models use suction to apply the detergents whereas the K4 Power Control uses the “plug and clean” system.
The K4 Power Control also has an LED display on the trigger, unlike the K4 Compact version. Finally, the Compact versions all use air-cooled motors, whereas the K4 Power Control (and higher priced models) have a water-cooled motor.
However, there is no difference between the flow rate and pressure rating between the power control and compact versions of the Karcher pressure washers and they both have a 5 meter mains cable.
| Pressure Washer | Compact Model Hose | Power Control Model Hose |
| Karcher K2 | 4 meters | 5 meters |
| Karcher K4 | 6 meters | 8 meters |
The short hoses on the the K2 models, and even the K4 compact can be a bit limiting when washing a car and you’ll likely need to move the pressure washer at least once to get around the entire vehicle which can be a bit inconvenient. The 8 meter hose on the K4 Power Control is a bit more freeing but not overly long so doesn’t cause problems when packing it away.
There are also two other model variants “home” and “car and home”. These simply refer to the extra accessories that come with the pressure washer:
- Home: patio cleaner and detergent also included.
- Car and Home: patio cleaner and detergent, rotating car wash brush, foam jet and shampoo.
I’ve found the patio cleaner to be quite useful, but I strongly advise against buying the “car kit”. These accessories are poor quality and the brush in particular will cause scratches in the paintwork. I always recommend using a microfiber wash mitt instead of a sponge or brush if you don’t want to ruin the car’s finish!
You can also find much better quality aftermarket foam cannons and car shampoos from dedicated car cleaning stores. Check out my car cleaning product recommendations if you’re looking for some suggestions.
Similarities
Despite there being numerous differences between the Karcher K2 and K4 models, there are also some features that both these pressure washers and their variants (Compact and Power Control) share. Here’s a list:
- Both the K2 and K4 Power Control and Compact models include two nozzles: the vario lance and dirt blaster lance.
- All models have a telescopic handle.
- All models have a quick connect on the machine for the hose.
- All models have a 5 meter main cable.
- The maximum water feed temperature is 40°C.
- The minimum pressure is 20 bar.
Specification Comparison Table
Here is a table comparing the specifications of the K2 Power Control and K4 Power Control.
| Feature | K2 Power Control | K4 Power Control |
| Current Type | 220-240 V | 230-240 V |
| Minimum Pressure | 20 bar | 20 bar |
| Maximum Pressure | 110 bar | 130 bar |
| Max Flow Rate | 360 L/ hour | 420 L/ hour |
| Area Performance | 20 m2/ hour | 30 m2/ hour |
| Water Feed Max Temp | 40°C | 40°C |
| Power Rating | 1400 W | 1800 W |
| Power Cable Length | 5 meters | 5 meters |
| Hose Length | 5 meters | 8 meters |
| Weight (without accessories) | 4 kg | 11.5 kg |
| Dimensions (L x W x H) | 24.6 x 28.0 x 58.6 cm | 40.2 x 30.6 x 58.8 cm |
| Motor | Air Cooled | Water Cooled |
| Detergent Application | Suction | Plug and Clean System |
| LED Display on Trigger | No | Yes |
| Telescopic Handle | Yes | Yes |
| Quick Connect on Machine | Yes | Yes |
Check out my complete guide to the Karcher pressure washer range to find out all the differences between each model.
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