Why Keurig Coffee Is Bitter And Simple Ways To Fix It

Did you just get a cup of coffee from a K-cup machine and it’s way too bitter for you? Here’s why that’s the case and what you can do about it.

Coffee from a Keurig machine is often bitter because the coffee grounds are from darkly roasted beans and the grounds are over-extracted. Using medium roast coffee cups and brewing smaller amounts reduces bitterness. Adding a tiny pinch of salt can help save an overly bitter cup.

If you’re interested in why K-cups can sometimes brew very bitter coffee and how to fix it with some of the settings on your machine below.

Two Reasons Why Keurig Coffee Is Bitter

Coffee is always going to be bitter to some degree but some coffee from Keurig machines can have a very unpleasant harsh bitterness. Especially if you’re used to coffee from a good coffee shop, there will be quite a difference. Where does that bitterness come from?

There are two main reasons why Keurig coffee is bitter over the normal bitterness of coffee.

Coffee pods
Coffee pods

1. Type of Coffee

The type of grounds in the K-cups ultimately decide the taste of the coffee. There are large differences between coffee beans and the roasting process. The type of beans, where they come from, how they’ve been washed and dried, and then how they’re roasted all have a large effect on a taste.

And all you get in a K-cup is ground coffee. That coffee can have just as much of a variety as other coffees because they are the same thing.

Suggested: How much does a K-cup brewer cost?

However, the taste most people expect from coffee usually comes from darkly roasted Arabica beans. Although that type of coffee has been losing popularity among coffee aficionados, for most people that is what they expect.

So most types of coffee that are meant for the average person who just wants caffeine will be darkly roasted. The darker you roast coffee beans, the more bitterness there is. The coffee beans become darker because of the Maillard reaction. The same that makes bread, meat, and other things darker when exposed to more heat.

The best comparison is probably caramel. The longer you let caramel go, the darker it becomes, and the more bitterness you get. Coffee beans are very similar. Lightly roasted beans taste a bit more fruity, floral, and acidic in a good way. Darker roasted beans have less acidity and more bitterness.

2. Over extraction

The second reason why Keurig coffee tends to be quite bitter is that it’s over-extracted. Think about tea; If you leave the tea leaves in the water too long or with water that’s too hot, it becomes very bitter. Coffee works in a similar way.

There are hundreds of different compounds in coffee grounds. You want to extract many of those compounds into the water and brew delicious coffee. However, not all of the compounds taste good so extracting 100% of all the soluble materials in coffee beans is not optimal.

The first compounds that extract are usually very sour while the more stubborn ones are very bitter. So you want to be somewhere in the middle so you have a balanced-tasting cup of coffee. If your cup is harshly bitter, the grounds are likely extracted too much so you get those really bitter compounds. The trick is to stop the water before you extract those bitter notes but with a Keurig machine, you have little control over this. More on that later.

Extraction is work that’s done by the water that flows through the coffee grounds. A few factors can influence the extraction:

  • Amount of water/Ratio of grounds to water
  • Grind size
  • Temperature
  • Flow rate

One way you can reduce extraction in most other brew methods is by adding more ground coffee. However, in a K-cup, you’ve got 9-12 grams of ground coffee and there is no way to change that so you have to work around that limitation.

Another way you could control extraction is by grinding the coffee coarser or finer. However, just like with the amount, in a K-cup you have no control over the grind size whatsoever so you only have the amount of water and maybe temperature to control the extraction.

How to make Keurig coffee less bitter

Above you can read the two main reasons why Keurig coffee can be quite bitter. And bitterness is personal just like other tastes. If it’s too bitter for you, that’s all that matters and you should find a solution because in my opinion coffee can be very enjoyable for most people but we all like different things.

Here are the three main things you can try to make your K-cup coffee less bitter.

Use medium/light roasted coffee

If you’re using K-cups with dark roasted coffee now (often also named ‘classic’ roast), try a medium or light roast. Medium will be a good option for most people who like the normal coffee taste but want less bitterness.

Medium roast K-cups are commonly available and shouldn’t be hard to find. Check your current cups and if it says: ‘dark’ or ‘classic, try a medium one. Light-roasted K-cups are a bit harder to find but online this isn’t a problem either. I would only go one shade lighter at a time. So if you’re using a dark roast now, try a medium roast. If that’s a step in the right direction, you can try a light roast.

Brew smaller cups

Besides the dark roast, another problem is over-extraction. What that means and does you can find above. But what can you do about it?

There are a few things you can do to reduce the extraction of the coffee grounds in your K-cup:

  • Cup size: Coffee grounds are extracted with water. The bigger the amount of water that percolates through the grounds, the more extraction happens. So if your Keurig coffee is too bitter, try brewing a smaller cup. A smaller cup means less water so lower overall extraction. The coffee you get by brewing a smaller cup might be a bit thicker and stronger in some ways but it’ll likely be more balanced and less bitter.
  • Strong button: The strong button means the water pulses into the pod instead of a constant flow. That means the water spends more time with the coffee grounds and so has more time to extract. Play around with the cup size and strong button to see what gives the best results for you.
  • Temperature: Higher temperatures extract coffee grounds faster. Especially with dark roasted coffee, high temperatures can lead to excessive bitterness. Some of the higher-end Keurig machines have an option to adjust the water temperature. Set the temperature lower if possible.

Suggested: What do the buttons on a Keurig machine do?

In the end, the changes above will make a difference but you can’t fix the taste of a type of coffee you don’t like. So playing around with the settings on your machine might give you some steps in the right direction but at some point, you might have to change to other K-cups if you’re still not happy with the results.

Pod coffee brewer

Add salt

Here’s a coffee hack you might not know, add some salt to overly bitter coffee and It’ll taste much better. The salt subdues the bitterness and enhances the other tastes in coffee so it tastes much more balanced.

You need very little salt to make a big difference. For extremely harsh, bitter coffee, 0.5 grams of salt for a 330 ml cup is enough. So really go easy because if you overshoot it, it’ll just taste salty which is not great either. Start with a very small amount, you can always add more later.

Brew method

In the end, Keurig machines are all about convenience. That does come at the cost of some taste. Sure, it’ll likely be better than 2-hour-old coffee from a drip machine but it’s not as good as coffee can be. All the things above can certainly help you to brew better coffee with K-cups but if you really want to improve your brews dramatically, another brew method is probably necessary. Of course, if you like the coffee you’re getting, that’s great but if you’re reading this, you probably feel your coffee should taste a bit better.

Recommended Keurig Equipment

  • Simple and Cheap: Just want a Keurig machine that brews coffee and does it without a confusing amount of buttons or taking up a lot of space? The Keurig K-Slim (Amazon) is the one you’re looking for.
  • Feature Rich: If you want more features like brewing more different sizes and over ice, the K-Elite (Amazon) is a better choice.
  • K-cups: Good coffee is always important but tastes are different. Try this variety pack (Amazon) with tons of different K-cups so you can figure out what you like.
  • Reusable K-cups: Prefer to use your own coffee? Filling reusable K-cups (amazon) with your own freshly ground coffee is the way to go and will likely brew even better coffee than pre-made cups.


Welcome to CoffeeImproved! Since falling in love with coffee, I've been on a journey to improve my morning cup day by day. That means I've tried many different brew methods, beans and equipment and experimented with all of them to find what I like. This is where I share what I've learned with you.

Recent Posts