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Coffee filters seem like they should be the simplest part of the whole setup. After all, it’s just a piece of paper that lets water pass through. But they come in all shapes, sizes, and types. Some aren’t even made of paper.
These are just some of the questions I’ll be tackling in this guide: What coffee filter sizes should you be buying? What’s the difference between a #2 vs #4 filter? Are metal filters better than paper? What about bleached vs unbleached filters?
Grab a cup of coffee and a comfortable chair — and prepare for the unfiltered truth about coffee filters.
Coffee filter shapes
These are the filters that you are probably most familiar with. They are bucket-shaped, with flat bottoms and sides that slant outward, making the opening at the top wider than the width of the bottom section. Their sides are either smooth or contain folds like those of a cupcake liner.
This shape has earned them their other names: cupcake filters and flat-bottom filters.
Conical filters actually come in two similar shapes. The first is a true cone — just like a party hat or a waffle ice cream cone, its sides taper inward until they meet at a single point at the bottom. The second also has a round opening with two sides that taper inward, but they meet at a narrow line at the bottom of the filter instead of a single point.
Disc filters are flat, round filters that are much smaller than conical and basket filters. They are used primarily for the AeroPress, but they can also be used in percolators or to replace French Press filters.
Basket Coffee Filter Sizes
Basket-shape filters typically come in two sizes: basket and junior basket.
These are the standard 8-12 cup flat-bottom filters that you probably use in your drip coffee maker. If you don’t see a size listed on a basket filter, it’s likely the standard basket size.
Junior basket filters look like tinier versions of basket filters. They hold enough coffee grounds for 4-6 cups of coffee.
Conical Coffee Filter Sizes
Cone filter sizes follow a numbered system, with lower numbers corresponding to smaller filter sizes.
#1 size filter
This filter size is used for one-cup coffee makers, including both electric and non-electric machines. They are about 2 1/4 inches tall.
#2 size filter
These filters are used for 2–6 cup electric coffee makers and 1–2 cup non-electric coffee makers. They are about 3 1/4 inches tall.
#4 size filter
The #4 filter is used for 8–12 cup electric coffee makers and 8–10 cup non-electric coffee makers.
#6 size filter
This is the largest cone coffee filter size, and it is used for 10+ cups in electric coffee makers or drip cones. They are 5 1/4 inches tall.
Coffee Filter Thickness
Thickness is often ignored when discussing coffee filters, but it can have an important impact on quality. You’ll be fine as long as you follow one simple rule: thicker is better.
When filters are ultra-thin, they let water pass through too quickly — often before the coffee has properly extracted. Thicker filters are slightly more expensive, but their effect on coffee quality is more than worth the tiny increase in price.
Bleached vs Unbleached Coffee Filters
Bleached coffee filters
Paper is not naturally white. When first made, it’s light brown color you might see on the paper towels used in public restrooms and office kitchens. White paper has been bleached using one of a handful of processes that use cheap, harsh chemicals or more expensive, milder bleaching agents.
In the case of coffee filters, two main bleaching agents are used: chlorine and oxygen. Chlorine bleaching results in lower-quality coffee filters and it is much less environmentally friendly. No bleaching process is good for the environment, but oxygen-based bleaching is a significant step up from chlorine.
Bleached coffee filters are favored by many coffee drinkers for their appearance and the fact that they don’t impact the flavor of your coffee, even if you don’t wash them before use. The bleaching agent cannot leech into your coffee, so using bleached filters does not negatively impact the flavor of the coffee or pose any health risks.
Unbleached coffee filters
Unbleached filters still have their natural brown look. The lack of bleaching agents and the simpler manufacturing process makes them much more environmentally friendly than any bleached coffee filters.
The biggest downside of unbleached filters is that they can leave a slight, papery taste in your coffee if used wrong. You can easily eliminate this issue by pre-wetting the filter, though, so there is no real disadvantage to unbleached coffee filters when they are used properly.
Comparing bleached and unbleached filters
In the end, this is the tradeoff between bleached and unbleached coffee filters.
- Environmental impact — Unbleached filters are more environmentally friendly.
- Ease of use — Unbleached filters need to be rinsed before use, whereas bleached filters can be used as-is.
- Cost — Unbleached filters are slightly more expensive on average, even though they are less processed.
The cost difference and inconvenience of the unbleached filters are fairly minor, so I recommend unbleached for the environmental impact. However, the choice is up to you how to weigh cost, ease of use, and the environment matter in your decision.
Paper vs metal coffee filters
If you are tired of disposing of paper filters, permanent coffee filters made of metal are a potential alternative. The differences between paper and metal coffee filters fall into three categories: coffee quality, ease-of-use, and price.
Paper coffee filters have smaller holes, so they catch more of the tiny particles and oils that would otherwise make their way into the coffee. If you’ve had French press coffee, you know what these additional particles do to the flavor and body of the brew.
Metal filtered coffee is richer, bolder, and cloudier, and it tends to leave a bit of sediment in the bottom of the cup. Paper filtered coffee is crisper, often sweeter and fruitier, lighter-bodied, and more translucent.
Coffee made with a paper filter is healthier than coffee made with a permanent filter. The oils that metal filters let through can raise your cholesterol levels. Specifically, they raise LDL, the bad cholesterol that increases the risk of cardiovascular diseases.
Paper filters are much easier because you don’t have to worry about cleaning them. They are single-use, so you just throw them away when you are done.
With metal filters, you have to dump out the grounds in the trash and then rinse the filter itself in your sink. Extra caution is required to avoid dumping grounds down the drain, which can lead to a clogged sink as the grounds accumulate over time.
The upfront cost of paper filters is very cheap. Some are as cheap as about $0.01 each, and the most expensive paper filters are usually no more than $0.10 each. If you use one per day, that amounts to somewhere between $3.60 and $36 per year.
Metal filters vary quite a bit in price, with some as cheap as $5 and others as expensive as $60. Most of the time, you’re probably going to spend around $10 for a metal filter. If properly cared for, that filter can last many years.
The more frequently you make coffee, the more quickly your metal filter will pay for itself. It might take 2-3 years if you sparingly make coffee with cheap paper filters. However, a typical coffee drinker will probably find that metal filters become more cost-effective after about a year, and a good metal filter will last a lot longer than that.
Other Types of Coffee Filters
There are a few brewing methods that use their own specific type of coffee filter instead of the more common ones we’ve been discussing so far. AeroPress, Chemex, and Hario V60 all have their own unique filters.
I mentioned disc filters above, and AeroPress filters are actually the most common type of disc filters. They come in a fully compostable paper form, but you can also buy metal replacement filters for the AeroPress.
Chemex filters are extra thick, so they remove even more fine particles than other paper filters. They are also excellent at removing oils, making for a cleaner, clearer, lighter cup of coffee than almost any other type of filter. Their cone shape is designed specifically to work with Chemex pour-over coffee makers.
Hario V60 filters
The V60 uses a cone-shaped coffee filter with a large hole at the bottom of the dripper. Their standard filters are unbleached, so they have the natural brown color of pulp paper. You can use a standard cone filter with a V60 pour-over coffee maker, but the V60 brand filters provide a better result.
Frequently Asked Questions
Can you reuse coffee filters?
Paper coffee filters can be reused once or twice if they are rinsed thoroughly and used soon after. Don’t use a paper filter that has been left for too long, as mold and bacteria quickly become a concern. Also, don’t reuse paper filters more than once or twice as they will clog over time. If you want a truly reusable coffee filter, get a metal one.
What size is a standard coffee filter?
For most drip coffee machines that use basket-shaped filters, the standard size (also known as basket size) holds enough grounds for 8-12 cups of coffee.
Are coffee filters compostable?
Most paper filters are compostable, but be sure to check the packaging for specific directions. Unbleached filters are safer to compost because they don’t have any bleaching agents, and oxygen-bleached filters will be safer for composting than chlorine-bleached filters.
Coffee filters 2 vs 4: what’s the difference?
These are the #2 and #4 size cone-shaped filters. The #2 is smaller, with the capacity to brew 2-6 cups in an automatic coffee maker or 1-2 cups in a manual coffee maker. The #4 filter is larger, with an 8-12 cup capacity for automatic coffee makers and 8-10 cups for manual coffee makers.
The Filter Things in Life
Coffee filter sizes and coffee filter types can be confusing, so hopefully this guide helps you pick the right ones. Most coffee makers should give you some information about what size and type of filter to use. If they don’t, you can always contact the manufacturer for specifics.
Looking for more information about how to make coffee? Might I suggest our guides on how to make less bitter coffee? You could also check out our list of the best coffee makers under $100. Or if you really want to up your coffee game, maybe it’s time to invest in an automatic pour-over coffee maker! If you do, your mornings will never be the same.