What’s The Best Coffee Grind Size For a Moka Pot? +Adjustment


Grind size is always an important part of the puzzle that is brewing good coffee. So which grind size is good for a moka pot? Here’s what you want to know.

The best grind size for a moka pot is fine to medium-fine. Most particles should be around 0.8mm in diameter. Don’t use an espresso grind setting, this is too fine. When using pre-ground coffee, use an espresso grind since pre-ground espresso is usually slightly coarse which is good for a moka pot.

Of course everyone has a different taste so let’s dive into what you can do to really get your percolator coffee how you like it.


Best Coffee Grind Size For Moka Pot

The best grind size for a moka pot is a little bit coarser than you would use for an espresso machine. So while a moka pot is also called a stovetop espresso maker, a slightly coarser grind is actually better.

Untamped grounds in a moka pot

Where you would use a fine grind for an espresso machine, for a moka pot you should use a medium-fine grind size. This is comparable to the size of table salt or slightly smaller.

If you grind your own coffee, set your grinder quite fine. Especially lower quality grinders aren’t capable of grinding super fine espresso grounds anyways so their almost finest settings will actually get you into the right ballpark, size wise.

Everyone likes their coffee a little different and every type of coffee brews a little differently. That means that like with any other brew method, there isn’t an exactly set grind size that will result in the perfect coffee every time. If you have your own grinder, it’s good to experiment a little and see what works best for you. Of course with pre-ground coffee you don’t really have that option.

If the grind size is too large for a moka pot, the coffee will flow into the collector quite quickly and be weaker than ideal. It might also be a bit sour. If it’s too fine, the coffee might not come out at all or be overly bitter. Ideally you get something that flows slowly into the collector (especially the first liquid) and is not too bitter nor too sour although it should pack a punch.

Of course if you’ve got a high quality grinder, it will be capable of grinding finer so, a few steps above the finest setting should do. How many steps really depends on the grinder since they are all a bit different.


Pre ground coffee

If you’re buying ground coffee from the supermarket, it’s a bit more difficult. The best grind size is in between the espresso (fine) and filter coffee (medium) grind. If you like your coffee strong, start with the espresso version.

Most pre-ground espresso coffee is actually slightly coarser than you would use in a high-end espresso machine. That’s because people that buy pre-ground coffee are highly unlikely to have a high-end espresso machine. Most consumer level home espresso machines have pressurized baskets which work better with a slightly coarser grind size than an espresso machine you’d find in a coffeeshop. These machines are more focused on brewing acceptable espresso consistently and easily. High-end espresso machines are not easy to use to their full potential.

That means most supermarket espresso grounds are slightly coarser than for ‘real’ espresso machines which actually makes it very close to the perfect grind size for a percolator.

Suggested post: Does a moka pot brew espresso?

With a medium (filter) grind you can expect slightly weaker coffee because the water can pass through the grounds a bit easier. And while the taste is weaker, it’s probably on the sour side. See if you like it, if not change to espresso grind next time or buy your own grinder and massively improve your coffee by using fresh beans.

Of course everyones taste is different. The recommended medium-fine grind size is a good place to start off from for the average coffee and coffee drinker. But of course you can change things up if that doesn’t fit your taste.


Adjusting Grind Size For a Moka Pot

The grind size outlined above is just a guideline to start off with. Of course you can always adjust the grind size to your taste. Everyone likes their coffee differently and in a percolator, the best place to start adjusting the taste of your coffee is in the grind size.

There isn’t much harm you can do by changing the grind size except ruining your cup of coffee. So if you find it fin to chase that elusive ‘perfect cup’ just experiment a little bit. Just make small adjustments and keep track of what you like.

If you’re serious about experimenting with grind size, it’s important to keep all other factors the same so you can really figure out what effect the change in grind size has on the taste and texture of the coffee. If you change the grind size but also the ratio and beans, it’s very difficult to know which change had which effect.

So here’s what you should try to keep the same if you change the grind size;

  • Amount of grounds in the filter basket (grams)
  • Amount of water in the boiler
  • Starting temperature
  • Stove temperature setting
  • Beans

When you keep those factors the same and adjust your grind size in small steps, you can track precisely which change is a step in the right direction.

Suggested post: Why does my moka pot coffee taste sour/bitter/burnt?

Below you’ll find which way to adjust in to get the result you want.


When To Use a Bigger Grind Size For You Percolator

Maybe you’re not happy with how your moka pot coffee is coming out. One of the first things to adjust is the grind size. So what can you expect when you grind your beans a little bigger?

  • Water will flow through the coffee bed easier. This means less heat and pressure is required.
  • There is also less surface area that water touches.
  • This combination means there is less extraction of the grounds.
  • This can cause the coffee to be more acidic.

If you think your coffee is a touch too bitter, try making the grind size a little coarser. This will reduce the extraction and thus reduce the bitterness. It will make the coffee a bit sourer if you go too big so increase the size slowly. That way you can find the right balance for you. It might take a few tries to get it right but it’s worth it.


Potential problems with bigger grind

Of course the slightly-coarser-than-espresso recommendation is there for a reason. It hits the right balance of taste and practical use in a percolator. If the grind is too coarse, you will make the coffee less strong. That might be what you like but it’s something to keep in mind.

With grind size, the weight per volume of grounds is different. (A scoop of espresso grind is heavier than a scoop of whole beans). That means if you go by volume, you will change the ratio of grounds to water.

Suggested post: What’s the right coffee ratio for a stovetop espresso maker?

So it’s better to use a scale to measure out the same weight of grounds. Once you get everything dialed in, it will be easier to do it by eye but while you’re adjusting the grind, you’ll want to keep other factors as similar as possible and that includes weighing out your grounds.


When To Use a Smaller Grind Size For You Percolator

Maybe you want to go the other way. What can you expect?

  • A smaller grind has more surface area
  • That leads to more pressure and a higher temperature in the boiler of your moka pot
  • This means a higher extraction
  • Higher extraction can reduce sourness but increase bitterness.

As you can see, it’s all about balancing the taste. You don’t want too little extraction but also not too much. That’s one of the keys when making coffee.

So if you find your medium-fine grind is a bit too sour/acidic and you want a bit bolder taste. Trying a finer grind is a good thing to adjust first.

Suggested post: Should you tamp the grounds in a moka pot?


Potential problems with smaller grind

Going too fine can cause some problems though. If the granules are too fine, they can block the holes in the filter. This will cause the pressure to rise higher in the boiler. At some point there are a few things that can happen;

  • There is enough pressure to start the water flowing through the coffee.
  • The pressure finds a ‘weak spot’ in the coffee bed and burrows through it. This means the water doesn’t extract the coffee and all goes through the gap in the coffee bed.
  • The pressure valve opens to relieve the pressure
  • If none of the above happens, bad things can happen. It’s unlikely but a possibility. Read more here.

Favorite Moka Pot Products

You don’t need many things to brew good coffee with a Moka pot. Here are the few things you need to make the best possible coffee.

  • Moka Pot: Just buy a high quality Moka pot from the get go. The cheaper ones can be messy when brewing. Bialetti is the original and still one of the best with it’s classic looks. They cost a bit more than the cheap ones but these can last for decades and the parts that wear out are easily available for the Bialetti Moka pots. The 3 cup size is good for a single person (Amazon)
  • Beans: Good coffee starts with good beans. You can’t make bad beans taste good. Espresso roast beans are good for a Moka pot and will get you closer to that typical espresso taste. Peet’s coffee does a great 100$ Arabica espresso roast. Give it a try, you can get it here on Amazon
  • Grinder: Using whole beans means you need to grind them at home. This improves the taste because the grounds are much fresher. A Hario Slim (Amazon) is a great starting point for the starting home barista. If you want a good hand grinder for a good price, check out the TimeMore C2 (Amazon)
  • Scales: To get consistent results, a set of accurate scales is essential. Check out this Apexstone scale (Amazon). I’ve been using it for more than a year and while it doesn’t look the sleekest, it’s cheap and just as accurate as more expensive coffee scales. It just reacts a little slower.

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