When brewing coffee, filter size and shape does make a difference.
Since most brewing methods require some sort of filter, it’s vital to know which filter size and shape you need for the method you use.
In this article, I’ll demystify those filter sizes you see on the filter boxes so you can choose the right one for your coffee maker.
And if you wound up with the wrong size or shape filter? I’ll walk you through how to still brew the best coffee possible.
Coffee Filter Sizes Are Dictated by Numbers
Filters are essential when brewing coffee. Think about when you brew coffee. You set up the filter and add the coffee grounds.
You then pour water into the grounds and through the filter, either manually or through an electric coffee maker.
Along the way, the water absorbs the good things about coffee, like the flavors and aromas. But, on the other hand, the coffee grounds stay where they should – inside the filter and not in your cup or carafe.
Filters can be made of metal, mesh, cloth, or paper. Filters should be fine enough to allow the water to pour through while thick enough to retain the coffee grounds. Whichever you use, the filter is essential to getting a good cup of coffee.
Types Of Coffee Filters
How can you decide which shape of filter you need?
Actually, it’s often not up to you to decide. Your brewing method already has a filter holder, and you need to use the filter that fits into that holder.
What kind of filter holder came with your coffee maker? Two common filters are:
- Cone filter holders: round at the top and narrow towards the bottom
- Basket filter holders: flat on the bottom and wide at the top
The first thing you run into when deciding on the right coffee filter size is what those little numbers on the packaging mean.
You’ll find more sizes for conical filters or those cone-shaped ones than for the basket type filters.
Let’s quickly talk about sizes.
Universal Coffee filter sizes
Before we start going over the specifics of filter shapes and sizes, let me just mention that there are universal coffee filters.
You’ve probably seen them – made of mesh. They can come in a conical shape or a flat-bottomed basket shape. They fit most standard coffee makers, and all you have to decide is if you need a conical or basket filter.
2 VS 4 Coffee Filter Size
When you talk about cone filters, you start getting into more specific sizes. The common cone filters are the #2 size and the #4 size.
The difference between these paper coffee filters is the height and the diameter. In other words, when you choose between sizes, you’re deciding how tall your filters should be and how wide they are.
Those two common filter sizes are popular for a range of manual coffee brewers, such as the Clever Dripper, Bee House Dripper, and V60. They are also used in some automatic coffee makers.
But now, I’m going to throw a wrench in your understanding of filter sizes. These numbers are sizes and not specific cup amounts. Let me explain.
While the #1 size filter brews one cup of coffee, a #2 filter size can be used to brew just one cup of coffee, or you can use it to get two cups. And while the #4 size filter sounds like it can brew a lot, you can also use it to brew just one cup of coffee or just two cups. But it can reach up to four cups of coffee.
If you’re at the supermarket and you really can’t remember which size filter you need, you could always go for a #4 size coffee filter.
After all, if you buy a size that’s too small by mistake, you can’t make it larger. But if you have a filter that’s larger than your filter holder, it shouldn’t be a major problem to brew coffee.
What can you do if you bought a filter that’s too big?
Depending on your filter holder, you may be able to just fold the top edges down. Or you could tweak the size with a pair of scissors, making sure you only cut around the top (and not the bottom).
As I said, the filter shape you use has to do with your brewing method. Filters come in many shapes, but the basic ones are:
- Round disk filter
Conical filters are more often used in pour-over brewing methods.
Basket filters are what you’ll see in large electric coffee makers, although you can also find them in small coffee makers. And round disk filters are what you use when you brew in a French Press or AeroPress. I’ll tell you more about each type of filter later in this article.
Can you use them interchangeably?
Not with great results. If you try to fit a basket filter into a cone-shaped filter holder, you’re going to wind up with folds and creases in a filter that’s not the right shape for the holder.
Those little corners will trap coffee grounds, which won’t extract evenly. The resulting brew might be underexactracted and sour.
What about that other filter I mentioned, the round disk one? You’ll find that type used in the AeroPress coffee method and in French Press brewers.
They’re flat, small, and look like a wafer. The AeroPress filter is generally made of paper, although I love using metal ones.
Then I don’t have to carry around a pack of paper filters when I travel, and I’m fine with the extra sediment in my coffee.
Conical Coffee Filter Sizes
Conical filters are often preferred because they keep the coffee and water moving throughout the brewing process.
The coffee grounds get evenly saturated, and more positive flavor notes can be extracted. Also, total dissolved solids can be higher in brews made with conical-shaped filters, which can contribute to the intensity of the brewed coffee.
Now let’s get specific about sizes. What sizes are available for conical coffee filters, and what do they mean?
You’ll find #1, #2, #4, and #6 size conical filters. How do you know which is right for your brewing method?
While all brewing methods (and filters) might have slight differences, here are the general sizes:
- No. 1 coffee filter – for a single cup of coffee or single serve cone basket coffee maker
- No. 2 coffee filter – for one to four cups of manually brewed coffee. If using a coffee maker, for 2-6 cups
- No. 4 coffee filter – for automatic coffee makers, 8-12 cups
- No. 6 coffee filter – for large 10 cup coffee makers
Note: Keep in mind that these cup sizes refer to 5 ounces, which is smaller than many American mug sizes.
Basket Paper coffee filters
Basket coffee filters are easy to recognize. They have a wide, flat bottom and are ruffled around the edges. They look like cupcake liners waiting for an enormous cupcake to fill them.
Basket coffee filters are used in commercial coffee makers and some home coffee makers.
When you use a basket coffee filter, the coffee grounds are spread along the wide filter bottom. When you add water during brewing, it can be tough to make sure all the grounds get saturated evenly.
Also, the water doesn’t have the same flow as in a conical filter. The water may pool inside the filter as it’s brewing rather than flow out of the filter.
What sizes are available, and what do they mean? In general, there are two sizes for basket filters, small and large. The small holds less than 6 cups, and the large is for more than 6 cups.
Should you use a basket coffee filter? Take a look at the filter holder in your coffee maker. If it has a flat bottomed basket, then you need a basket filter.
Which are better, cone or basket filters? This is hotly debated in the world of coffee brewing. Let’s try to find some answers.
Cone VS Basket Filters
What makes cone filters different from basket filters?
In deciding which to use, availability might be the issue. Where you live, you might only find conical filters for smaller cup sizes. You might also find that the prices vary between the two, and that may define which you’ll use.
Do cone and basket filters create a difference in the brewed results? Yes.
Many coffee experts feel that if you keep everything else stable (such as roast level, water temperature, brew time, etc.), cone filters simply brew better coffee.
Coffee saturation is optimal since all the coffee grounds are in a smaller space, not spread out along the wide basket bottom. The shape of the filter allows the coffee grounds to move freely and the water to flow.
Since this is a debated subject, the Specialty Coffee Association (SCA) partnered with Breville Corporation to give the final word in this dilemma. They found that, based on the filter shape, there is a big difference in perceivable flavors in the cup.
This has to do with how the flavors are transferred from the grounds to the water when using the filter. What differences did they find when using the filters?
- Conical filters accentuate notes of citrus and berry
- Basket filters bring out the dried fruit, chocolate, and cocoa notes
Of course, the key to good coffee is not just the filter. The coffee itself and the skills of the one brewing it makes a huge impact. Combine all these factors, and you’ll be brewing fantastic coffee.