Keurig K-Slim vs K-Classic: Which Brewer is Better?

We provide you with everything you need to know about the Keurig K-Slim and K-Classic to help you brew your best cup!

With a legion of devoted followers, Keurig is one of the most popular manufacturers of single-serve coffee machines. Creating a hot delicious drink in your cup is truly as simple as pushing a button with a Keurig! Due to its popularity, it is no wonder that there are a wide variety of Keurig models available on the market today. It can be intimidating trying to figure out which model will best fit your coffee drinking needs! To help simplify your decision, we are comparing two popular models, the newly released Keurig K-Slim vs K-Classic, so you can easily determine which model is meant for you. The best selling K-Classic is Keurig’s popular flagship model whereas the K-Slim is a newly released Keurig model.

The Keurig K-Slim and the K-Classic are both designed to be slim and compact, making them optimal for areas where space is limited. Let’s take a look at what each of these brewers can do:

Keurig K-Slim vs K-Classic

Dimensions12.14” H x 4.76” W x 15.2” D13.0″ H x 9.8″ W x 13.3″ D
Type of Compatible PodsK-Cup (both Keurig Official and compatible pods)K-Cup (both Keurig Official and compatible pods)
ColorsBlackBlack and Rhubarb
Single Cup Brew Sizes                           8, 10 and 12 oz.6, 8, 10 oz.
Water Reservoir46 oz. removable reservoir48 oz. removable reservoir
Automatic Turn Off YesYes

Want to learn even more about single serving brewers? Find out more about two of the most popular brands in single serving coffee by checking out our thorough review of Nespresso vs Keurig.

Keurig K-Slim vs K-Classic Similarities

Coffee brewed by Keurig's K-Slim and K-Classic side by side.
Keurig’s K-Slim and K-Classic offer similar features to one another.

The Keurig K-Slim and K55 Classic come with several features that are the same, including: 

  • Ability to brew K-Cups as well as your own coffee beans (Using a K-Cup Reusable Filter) 
  • Removable water reservoir 
  • Indicator lights such as “Add water”
  • A removable drip tray to accommodate larger mugs
  • Auto-off function
  • Easy to use
  • Brewing time under one minute

Below we provide an overview of the similarities for both models in more detail so you can get to know each brewer and the features they both offer better:

K- Cups

With over 400 varieties for 60 brands there will never be a shortage of K-Cup drinks and flavors to try. One of the major selling points of a Keurig machine is the versatility in drinks and drink types offered. For more details about top Keurig models click here.

For those who are not familiar, all Keurig machines use K-Cups which is basically coffee that comes ready made in a pre-measured capsule. All you need to do when brewing with a Keurig is select which K-Cup you want to brew, insert it in the machine, choose your brewing options and let it do its magic! Just don’t forget to place your favorite mug underneath.

If you crave the best freshly ground coffee or prefer a more environmentally friendly alternative to the K-Cup, the K-Slim and K-Classic both have the ability to brew with a reusable filter. 

A reusable filter can be re-used in a Keurig multiple times and can be filled with your favorite freshly ground coffee before brewing.

Water Tank 

Both the Keurig K-Classic and K-Slim come with a removable water tank. The K-Classic has a 48 ounce water tank and the K-Slim features a 46 ounce water reservoir.

Although there is a two ounce difference between the two models, it is such a slight difference we opted to put this under similarities versus differences. Two ounces is not big enough of a differential to make a huge impact in your day to day when brewing with either model.

The removable feature for the water tank makes refilling the machine with water very convenient. With a removable water tank you can remove it from the Keurig machine and bring it to your water source to refill it. Once filled, you simply place the water reservoir back into the machine. 

For a smaller model, a 46 to 48 ounce water reservoir is generously sized. It will allow you to brew multiple cups of coffee before having to refill.

Indicator Lights

Another useful feature of both the K-Slim and K-Classic are indicator lights. Indicator lights on the Keurig tell you when something on the machine requires maintenance.

Each brewer has indicator lights on the top of the machine that light up when the Keurig needs to be refilled or when it needs to be descaled. 

Descaling is the process used to clean the Keurig so it can continue running properly. For full details on how to descale your Keurig, check out our step by step guide here.

Removable Drip Trays

The K-Classic and K-Slim are equipped with a very convenient removable drip tray. The function of the drip tray is to catch any extra drops of coffee your cup may not catch so that your counter stays nice and clean.The removable drip tray is also designed to hold a full accidental brew! 

Another advantage of a drip tray is that it acts like a shelf for your mug, raising it up higher so it is closer to the coffee being dispensed. When the drip tray is removed, it creates extra room so you can fit taller cups under the machine such as travel mugs. 

One other benefit of having the ability to remove the drip tray is that it allows for easier cleaning. Instead of having to clean the drip tray while still attached to the machine, you can remove it and clean it off in your sink.


Turning off appliances when not in use is a great way to save money on your monthly electric bill. With most homes having several appliances it can be easy to forget to switch them all off when not in use. 

The Keurig K-Slim and K-Classic both come with an auto off function which turns off the brewer automatically when it hasn’t been used for a period of time. To turn the brewer back on you simply hit the power button and it is ready to brew!


A lot of features on a coffee maker can be very useful, but there is such a thing as overcomplicating appliances to the point that they can be difficult to use. Oftentimes having a lot of features and buttons to push can be overwhelming. For most a straightforward machine with intuitive functionality is ideal so that your brewing experience is easy and convenient.

The Keurig K-Slim and K-Classic have a streamlined interface that is as simple as pressing a button to brew your cup. There is no feature that is overly complex or difficult to find. The Keurig is designed to make operating your machine and brewing a warm cup as easy as possible. 

Keurig K-Slim vs K-Classic Differences

Two cups of coffee side by side brewed by the K-Slim and K-Classic.
There are several key differences between the Keurig K-Slim and K-Classic. Read on to discover more.

Drink Sizes

The Keurig K-Slim and K-Classic have multiple drink sizes you can opt to brew. Each machine has slightly different options as far as sizes to choose from.

The K-Slim has three drink sizes you can choose to brew: an 8, 10 or 12 ounce cup. The 12 ounce option is great to have if you are looking to regularly fill a larger travel mug when you are heading out the door. 

The K-Classic also offers three drink sizes but its largest brew option is 2 ounces smaller than the K-Slim’s with the ability to brew drink sizes in 6, 8 or 10 ounce cups. 

If you are wanting to make larger drinks more regularly the K-Slim is a better option for you. If larger drink sizes are not important to you, then either model should fit your needs well. 


The K-Classic has a bit more variation in brewer color to choose from then the K-Slim. 

The K-Classic comes in basic black or for a pop of color in your kitchen it is also available in a bright red Keurig has named Rhubarb. 

The K-Slim is available in black, a sleek and modern choice. 

Compact Design

The K-Slim was named with the word “slim” in it for a reason! With a total width of under 5 inches it is one of the slimmest single serve coffee makers on the market.

The advantage of having a slim coffee maker is that it does not occupy a lot of counter space. This makes the K-Slim a great option anywhere you need to optimize space whether that is in between items on your counter, on a small counter top or even in your RV.

By most standards the K-Classic is still a modestly sized brewer. However, at almost 10 inches wide it is close to double the width of the K-Slim. 

If space is at a premium for you, the K-Slim is the better choice.

Heating Light

As mentioned, both the K-Slim and K-Classic come with indicator lights. The K-Classic has one additional indicator light that the K-Slim does not have, a heating light. The heating light indicates that the K-Classic is getting ready for the next brew cycle by heating another batch of water.

Although this is a nice feature to have, it really will not have much impact on your overall brewing experience. 

Keurig K-Slim Summary

With a 5 inch wide profile the Keurig K-Slim is designed to fit perfectly in small places. The K-Slim is designed to be simple and easy to use, without sacrificing the high quality the Keurig brand is known for. 

Despite its small size, the K-Slim does not fall short on size where it counts. With a sizable 46 ounce water reservoir you will be able to brew four eight ounce cups before having to refill! 

For those who are looking for a tiny machine that can make a larger than life brew, the K-Slim is the right fit for you!

Keurig K-Classic Summary

Economical Choice

The Keurig K55 K-Classic is Keurig’s longtime flagship model. The K55 K-Classic is an economical choice that is capable of brewing a hot, quick and delicious cup of coffee in 6, 8 or 10 ounce sizes.   

Equipped with all of the basic features you would need in order to enjoy your coffee machine, the K-Classic is a perfect fit for those who are looking for a single serve brewer that is reliable and easy to use. 

Cozy’s Bottom Line

Both the K-Slim and K-Classic are easy to use, economical Keurig machines designed to give you a delicious cup of coffee with the simple press of a button. Both of these machines offer close to the same features and will be sure to meet your quick coffee brewing needs.

The K-Classic is a great option if you are in the market for a traditional, no frills coffee brewer. With an easy user interface and just the right amount of features this is a great option to consider if you are looking for simple and user friendly. 

If you take your coffee on the go using a travel mug, you will need to weigh if the max brewing size of 10 ounces for the K-Classic will fit your needs. However, if you want to fill larger mugs regularly, the K-Slim may be a better fit with the ability to brew up to 12 ounces at one time.

When it comes to color choices the K-Classic offers a colorful rhubarb which may be the selling point between these two coffee machines.

If you are looking for a coffee maker that offers a great brewing experience without taking up much real estate, the K-Slim hands down is the right machine for you. Its tiny size shouldn’t fool you, it still has the ability to make a generous sized cup. 

Whether you choose tradition over size, or vice versa, we have no doubt that either of these popular Keurig models will meet all of your coffee drinking dreams! Enjoy!

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