Tamper Showdown: Flat vs Convex Tampers

Tamper Showdown: Flat vs Convex Tampers - Comiso Coffee

There are many debates in the espresso-making world. Some debates seemingly never end, perhaps because the truth often lies somewhere in the middle or it's simply a matter of personal preference.

It is possible to prevent watered-down shots with an espresso tamper and tamping technique practice. It's not as easy as it seems to find the right espresso tamper. Flat and convex espresso tampers are the two most popular types. They're both popular, but there are differing opinions on which is best.

A tamper is a necessity for anyone who makes espresso for any length of time. The device compresses espresso grounds in your espresso machine's portafilter into a coffee puck, allowing you to create a balanced shot every time.

Because water channels, packing the espresso grounds evenly is crucial to brewing balanced espresso. Water prefers to flow where it finds least resistance. During the brewing of espresso, this can pose a problem.

Espresso grounds that are not packed tightly or poorly packed are more likely to have water flowing down the sides of the basket or taking the channels of least resistance through the loosely packed grounds, causing uneven distribution of water. This way of channeling water allows the flavor to be extracted more quickly from the beans. As a result, the shot turns watery.

You should choose a tamper whose diameter perfectly matches the size of your basket. Check the product page of your espresso machine for the right size or reach out to us. If you use an undersized tamper, you will end up with uneven tamping, which means a water channel will form and the water will not be extracted evenly.

Tampers of the highest quality are also heavier. Heavier tampers tend to be made of sturdy stainless steel. However, many of the free tampers included with an espresso machine purchase tend to be plastic and considered temporary solutions.


When you apply even pressure to a flat tamper, they create a straight and even puck. The purpose of this is to stop any water channeling and create an exquisite shot.

Those who favor flat bases claim that they provide a more consistent final product and are easier to use. There is also a bit of evidence to suggest that they provide better extraction than convex bases.

However, flat tampers may have one small problem. The edges of the packed ground and the basket are prone to water leaking through. Some flat tamper advocates believe that this risk does not exist at all or that it can be easily mitigated with the proper technique and base diameter.


The bases of convex tampers are rounded just a bit. Convex coffee tampers are designed to create tight seals between the espresso beans and basket, preventing water from seeping down the sides of the basket.

The ability of convex tampers to prevent side-channeling is what many baristas believe makes them superior. Many people swear that convex tampers ensure an even brew, especially when combined with proper technique.

Convex tampers, however, have drawn criticism due to their difficulty in applying even pressure. Additionally, they do not offer the same amount of extraction capacity.

Alternatively, for baristas who do not wish to have their fingers touch the grounds, a convex tamper may be more suitable. As a result of a convex tamper, the beans will push toward the edges of the portafilter, crushing any central accumulation.


It really doesn't matter which tamper you choose; the one that feels most comfortable to you is the best. Many people find flat tampers easier to use, and they may also provide better extraction. Despite this, convex tampers are preferred by many baristas because of their ability to prevent side channeling.

What are your thoughts? Let us know below!


  • My machine uses a 58mm portafilter. I’ve made hundreds of shots using fine quality flat tampers. The pucks were never as consistently solid, as when I switched to an American curve tamper.

    - Jeffrey Frumkin
  • I have always used a flat tamper, everyone I know only uses a flat tamper

    - Calvin H Hamilton
  • Having used the ‘CONCEPT-ART" variable setting from 6 to 20 pounds of pressure flat 58mm flat tamper for hundreds and hundreds of espressos that it is excellent. Made with extremely well engineered stainless and aluminum parts, and a heavy nice long lasting rubber upper ’gasket’ also serving as a ‘stopper’ to retain the coffee as pressure is applied…works perfectly and we have had no problems with any ‘side channeling’ or improper flow. It comes in beautiful anodized lasting colors as well and in simple uprignt position almost provides a ‘pre-tamp’ as you fit it into the basket. If set for high pressure you can use it also without pressing down as you would a regular tamper, if that be plastic cheapie to fancy one. Recommended tamper and quite attractive, and pops up when the set handle pressure is executed thus releasing it each time w/ internal spring and heavy machined parts having a screw on cap that secures solid too…making it essentially waterproof for internal parts and is easily washed when needed for grounds that do not affect the ‘gasket’ stopping most any overflow of coffee in the basket. D.Curtis

    - Dve Curtis
  • I have never try a convex tamper because
    Common sense tells me that a flat surface
    Produces better extraction,
    This is my personal opinion.

    - Juan Perez

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