The Best (and Easiest) Way to Clean Stained Coffee Mugs

published Apr 12, 2023
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dirty bottom of a coffee mug
Credit: Ashley Rodriguez

Whose bright idea was it to make all insides of coffee mugs white? As a coffee expert, I’m all too familiar with coffee stains in general, but especially the ones that mar the insides of my favorite mugs, thus making them look embarrassingly dirty. “Thanks for coming over for dinner! Here’s coffee in a gross-looking mug!”

While these stains don’t come out with regular hand-washing or stints in the dishwasher, there are a few different things you can do lift them. Which one is best and easiest? I was determined to find out! So I tried five different methods and recorded my results. Here are my findings.

Credit: Photo: Sarah Crowley

How I Tested the Methods for Cleaning Coffee Stains Inside Mugs

I rooted around in the cabinet and found my five favorite mugs, which, with near-constant use, also happened to be the most stained. I brewed a strong batch of coffee and poured about two ounces of liquid in the bottom of each one. Then, I let it all sit on the counter to soak in. Once the liquid had evaporated and the coffee oils had left a nice, tough layer on top of the already-lingering stains, it was time to get to work by cleaning each one using five popular and proven methods!

The ratings: I ranked each stain-removal approach from 1 to 5, with 5 being the easiest and/or most efficient and 1 being the hardest and/or least efficient. While each technique and tool managed to leave the mugs clean, some required more work either during or after the job was done. Along with the rating, you’ll find more detailed notes from my tests.

Credit: Sarah Crowley

Mug Cleaning Method: White Vinegar

  • Total time: 8 minutes (3 active minutes)
  • Rating: 1 / 5

The method: Fill the stained mug halfway with boiling water, and top with white vinegar. Allow to sit for five minutes, then scrub using a sponge. Wash when done.

How it went: Vinegar can be an effective cleaning agent because of its mild pH, which helps break down tough grime and grease. Unless it’s used in relatively high concentration — like, high enough to make your kitchen smell like a pickle factory — it’s not powerful enough to cut through those deep-down coffee stains and requires quite a bit of scrubbing. While the mug did eventually come clean, it took too much work to achieve the white gleam I was looking for — and way too long to air out the house. Also, this method requires thorough cleaning after the fact to remove the smell and taste of white vinegar. 

Credit: Sarah Crowley

Mug Cleaning Method: Denture Tablet

  • Total time: 20 minutes (5 active minutes)
  • Rating: 1.5 / 5

The method: Fill the mug with warm (not hot) water, and drop an effervescent denture-cleaning tablet inside. Let sit for 15 minutes, or until the water turns clear. Then, clean the mug as usual.

How it went: Because I love anything that feels like a science experiment, I was drawn to the bubbling, foaming, and color-changing process. Once the bubbling stopped I was slightly disappointed: The blue water just sat there looking a bit off-putting while I distracted myself with other dirty dishes. Coming back, I still had to scrub with a bit of gusto — not unlike when I brush my teeth after a marathon espresso-tasting session. Points for being fun and unusual, but this method came up on the low side in this test and also required a thorough washing afterward.

Credit: Sarah Crowley

Mug Cleaning Method: Lemon Wedge

  • Total time: 3 minutes
  • Rating: 2 / 5

The method: This method works exactly like how you might imagine. Cut up a wedge of lemon and rub it vigorously along the inside of the mug. Then, wash as usual.

How it went: The only smell that comes close to being as lovely as coffee is the smell of fresh lemon, which is a perk of this technique — but that’s about the only one. It was awfully awkward to try to fit a whole adult human hand and a sizable lemon wedge into a standard-size coffee mug. Plus, that lovely smell also means you need to give the mug a thorough washing after the fact, as it might linger in your next latte. 

Credit: Sarah Crowley

Mug Cleaning Method: Bar Keepers Friend and Steel Wool Pad

  • Total time: 11 minutes (1 active minute)
  • Rating: 4 / 5

The method: Wet the inside of the mug, then sprinkle Bar Keepers Friend powder inside. Allow it to sit for up to 10 minutes, then scrub using a steel wool pad. Wash when done.

How it went: This miraculous cleaning powder does the trick like almost no other, which is why it’s a friend indeed! It cut through tough, soaked-in stains after sitting in the mug for just a short time and took almost no elbow grease to get it done. However, these results were also due, in part, to the steel wool scrubber, which can be a foe to your cherished heirloom mugs, as scrubbing too vigorously can scratch ceramic or remove decorative paint and glaze. You could absolutely use a softer sponge, but your results won’t be as effective.

Credit: Sarah Crowley

Mug Cleaning Method: Baking Soda

  • Total time: 3 minutes (1 active minute)
  • Rating: 5 / 5

The method: Mix a bit of tap water into baking soda so that you get a thick paste. Dab your scrubby sponge into the paste and use it to clean the mug. (You can also make the paste right in the mug if you don’t want to dirty another dish!) Rinse when you’re done.

How it went: Of course baking soda wins here; it’s such a great cleaner! While the baking soda paste did get a little gloopy in the mug, it was endlessly satisfying to watch it work. Baking soda’s grittiness makes a paste that’s just abrasive enough to get the job done and leaves behind no odor or flavors that could ruin your next brew. Plus, you probably already have a box in your pantry and it’s inexpensive!

Do you have a method you love for cleaning coffee stains out of mugs? Tell us about it in the comments below.