Straight to the Point
Believe it or not, brewing one cup of coffee at a time is controversial amongst coffee professionals. “If the brewing method isn’t tailored to handle that amount of coffee, you don’t get quite the bed depth that you need and channeling is going to be a potential issue,” says Jaymie Lao, who has spent more than a decade in specialty coffee education. Her thoughts echo my own concerns. Essentially, if your bed depth of coffee isn’t deep enough, water has an easier time flowing unevenly through the coffee grounds, extracting good and bad flavors all at once. This means that even our favorite pourover brewers are not quite suited for brewing eight to 10 ounces at a time. Lao likes to brew closer to 12 ounces at a time, just slightly larger than the average coffee mug, and even adding just five grams of coffee to the bed depth can make a big difference. “The higher it is, the more you can observe the evenness of the coffee bed and make sure it’s level.”
However, other coffee pros like to go small. “I pretty much only brew one cup at a time,” said Umeko Motoyoshi, owner of umeshiso.com. “I like to brew tiny cups of coffee because they are cute, and I also like to brew an amount that I can enjoy very quickly. If I brew a large batch then sometimes it can get cold and I’m not able to enjoy it all the way to the end.” I reached out to Motoyoshi for this piece because they were the first person I saw demonstrating the Fellow Prismo Attachment. “I love to brew with the Prismo attachment for the Aeropress. I have a different relationship to brewing a single cup of coffee because I’m making it just for me, or just for you, and it feels more special to me, and I pay closer attention to the brewing.”
With the pros of brewing a single cup in mind, I set out to find the best manual coffee maker that can brew 8 to 10 ounces of coffee at a time, compiling a list of brewers that use pourover, immersion, and even pressurized brew processes. When searching for the best single-serve coffee makers, I intentionally left out the Keurig and other pod-based coffee machines. Aside from being expensive and creating more waste than brewing your own coffee, these types of machines are designed for convenience over quality, resulting in thin, bitter, and watery coffee—no matter what style of K-Cup or pod you purchase. (Editor’s note: Nespresso machines are another matter and we’ll have a review published on them soon.) I also did not include any espresso makers, as these were covered in their own review.
The Winners, at a Glance
The Best Single-Cup Brewer: Kalita Wave 155 Dripper
I loved the Kalita Wave 155 Dripper for many of the same reasons its bigger sibling won our pourover brewers testing: the brewer’s simple flat-bottom design along with the size of the filter bed make it perfectly suited for brewing a single cup at a time. It can be paired with these filters and the Kalita 300-G server, if you don’t want to brew directly into your mug.
The Best Single-Cup Brewer If You Like to Tinker: Aeropress with Fellow Prismo Attachment
While the Aeropress is a great brewer on its own, the Prismo attachment’s pressure actuated valve allows for even more control and customization. With a rubber stopper that stays closed until you press it, the Prismo allows the Aeropress to act as a full immersion brew method. Because the base of the Prismo is wider than most pourover brewers, we recommend the Fellow Mighty Small Glass Carafe to make sure there is enough clearance for the brewer.
- Brewing Test: Each brewer was tested with an 8-ounce brew to assess bed depth, temperature stability, and brew time.
- Each brew used 15 grams of coffee and used 250 grams water total.
- Brew water was heated to 210ºF in an temperature-control electric kettle and then immediately used to start each brew cycle.
- Pourover brewers had a 45-second bloom, and water was added in 25-50 gram pulses every 10-15 seconds.
- Immersion brewers had all the water added at once, and were stirred for 10 seconds at the one-minute mark and allowed to steep five minutes.
- The Aeropress was brewed inverted, and treated like an immersion-style brew with a two-minute, 45-second steep time.
- The Prismo attachment was treated like an immersion style brew with a two-minute, 45-second time
- Temperature Stability Test: Each brewer was tested for temperature stability throughout the brew cycle.
- Two waterproof probes from a Thermocouple were inserted in the coffee bed before brewing started.
- The thermocouple recorded the temperature curve for the duration of the entire brew time.
- Each brewer had its temperature assessed at the highest peak and heat loss was recorded during the entire brew cycle.
- Taste Tests: Each brewer was then dialed in to produce the best tasting coffee.
- Based on multiple brewing test, each brewer was assigned a custom brew ratio, grind size, and brew time to reflect the recipe that yielded the best results.
- Each recipe was then adjusted to produce the best tasting coffee each brewer was capable of making.
- Usability and Cleanup Tests: Each brewer was assessed in usability and design.
- Brewers were evaluated on ease of use, picking up, filter attachment, handle comfort, and other tactile evaluations.
- Brewers were evaluated on how easy they were to clean, including discarding of spent grounds and removal of coffee oils and residues.
What We Learned
Small Brews Lacked Thermal Mass
Across the board, these single-cup coffee brewers lost a lot of heat during the brew cycle. One of the main advantages of an automatic drip coffee maker is a closed brew basket and a boiler delivering water directly into the coffee bed. When I tested pourover devices, the full-sized devices couldn’t quite match the temperature stability of an automatic drip brewer…and single-cup brewers fared even worse.
The ideal zone for coffee brewing is between 195-205ºF, and almost every single-cup brewer dropped below 190ºF before the brew cycle was finished, potentially leaving the coffee poorly extracted. This is because larger quantities of coffee in a filter contain more mass, and so do larger quantities of brew water: when brewing with only 15 grams of coffee and 250 grams of water, it was difficult for the coffee bed to hold onto heat.
Bed Depth Mattered
It’s not a surprise that the best brewer in this review has the most narrow brew base. The Kalita Wave’s base was only five centimeters wide, while the Pure Over (one of the poorer performers) had a 10-centimeter diameter. With a narrower base, the small dose of coffee was able to create a deeper bed depth, which encouraged more even saturation, better flow restriction, and more consistent extraction overall. In comparison, the wide base of the Pure Over meant that coffee towards the edge of the brew bed dried out significantly earlier than coffee at the bottom of the filter disc, making it all but impossible to brew consistently at smaller volumes.
Precision Was Key
Shrinking down to a single-cup brew puts a microscope on the whole brewing process. If you’re off by a gram or two of coffee when brewing 60 grams of coffee and one-liter of water, the overall ratio of coffee to water remains more or less intact. But if you’re off by a gram when your desired dose is 15 grams of coffee? Your brew ratio is massively disrupted.
The standard brew ratio for brewing is a 1:16.667 ratio of coffee to water: 1000g of water divided by 60 grams of coffee. Add a gram, and your ratio shifts to a 1:16.39 ratio. Add a gram to a 15-gram dose, and your 1:16.667 ratio drops to 1:15.625. Now, this seems finicky, but these ratios do matter! The lower the ratio of coffee to water, the stronger the brew gets, and the harder it becomes to extract the sweeter flavors you’re looking for. When brewing in the 8- to 10-ounce range, an extra coffee bean or two falling in the grinder, or an errant pour that adds a half-ounce of volume to your brew can throw the whole thing off. This is why, when brewing single-serve amounts, it’s very important to weigh everything in grams, even if you’re used to imperial measurements.
More Coffee Made a Big Difference
In our conversation, Lao highlighted the fact that five grams of coffee could make a huge impact in creating a more stable brew environment and coffee bed depth. None of the brewers really produced a stellar coffee at an 8-ounce volume, so in the second round of testing, I pushed the total brew volume as close to 10 ounces as I could, always brewing into the same mug to make sure it was never too full. With this larger amount, I found brew times were more consistent, and the brews themselves ended up tastier with a more balanced sweetness and body. At the end of the testing cycle, it’s hard to recommend anyone try brewing eight ounces of coffee—ever.
The Criteria: What We Look for in a Single-Serve Coffee Brewer
The best single-serve brewers were simple in design, easy to clean, had comfortable handles, and simply brewed great coffee in small volumes. They held onto brew temperature better than their competitors, and were more forgiving during the brewing process. A narrow base was also key to a well-functioning single-serve brewer: it encourage deeper coffee bed depth which in turn promotes a more even, better tasting extraction from the coffee.
The Best Single-Cup Brewer: Kalita Wave 155 Dripper
What we liked:The Kalita Wave 155 just simply brewed great-tasting coffee. With a flat-bottom design, the coffee was evenly distributed across the filter base which allowed the coffee to be saturated evenly during the pouring process. With such a narrow diameter, it was easy to maintain a coffee bed depth that allowed for even and consistent extraction, brew after brew. The short height of the brewer’s walls also made it easy for the spout of the kettle to get closer to the coffee bed, promoting higher brew temperatures. I also really appreciated that the brewer could feasibly brew up to 14 ounces of coffee, making it a more versatile brewer overall. Since the main body of the brewer is glass, the Kalita Wave 155 was easy to rinse off and wipe clean, with no coffee oils or residues left hanging on. With a base wide enough to rest easily on top of most mugs or glass servers, the Kalita Wave 155 is a utilitarian brewer.
What we didn’t like: While the glass version is cheaper than the stainless steel version, it also felt significantly more fragile. The plastic base helped protect the glass bottom of the brewer from dense, stone countertops, but the base also felt cheap to the touch when compared to the brewer’s solid steel cousin. The handle on the glass version was rounded, which caused it to rotate slightly when picked up.
Price at time of publish: $21.
- Materials: Glass and plastic
- Weight: 4 ounces
- Surface diameter: 5 centimeters
- Base diameter: 11 centimeters
- Number of pieces: 2
- Compatible with: Kalita Glass 300-G Server
The Best Single-Cup Brewer If You Like to Tinker: Aeropress with Fellow Prismo Attachment
What we liked: With the pressurized rubber value on the attachment’s base and a micromesh metal filter, the Prismo transforms the upright Aeropress into a full immersion chamber that lets coffee steep for as long as you’d like before pressing the coffee through the filter itself. The Aeropress with Prismo attachment actually brewed my favorite tasting cup out of all of the models — it just took some tinkering, and was not as repeatable as the Kalita Wave 155.
The Aeropress itself has a huge following due to its compact nature and the many ways to brew with it. (There’s even a yearly competition to see who can develop the best tasting coffee with an Aeropress, and custom recipes are highly encouraged.) One issue with the Aeropress, however, is that when brewing right side up, coffee tends to trickle through the filter because, well, gravity. This is pretty common when blooming any pourover brewer, but since the brewer only allows so much brew water to be used at one time, most people find the best results by inverting the brewer and turning it into an immersion chamber, with the stopper precariously holding the brewing coffee at bay. With the Prismo attachment, you can achieve the same full immersion chamber without the delicate and dangerous flip method.
My favorite thing about the Prismo is truly how much more customization it adds to the Aeropress. My best tasting recipe with it used a slightly higher dose of coffee, which suits immersion brew methods, and a full 4-minute steep time before pressing down. Oh, and one more secret: even though the Prismo comes with a built-in metal filter, I added two of the standard Aeropress paper filters, which provided more resistance during the pressing period and helped filter out any lingering coffee grit. It’s the perfect set up for the coffee fan that loves to tinker.
What we didn’t like: The Aeropress with Prismo attachment’s biggest strengths are also its biggest weaknesses: to get the best coffee, you have to tinker. With hundreds of different ways to set up a recipe, it can be difficult selecting which brewing bits and pieces you want to add into your own custom brew guide. It can also be tricky to properly seat a paper filter, if you want to go that route, and with a brewer that comes apart into four separate pieces, there are just a lot of moving parts to keep clean. Speaking of cleanup: puck removal from an Aeropress can be messy at times, as you have to unscrew the filter cap and press the grounds out. If you’re lucky, they’re fully compacted, but sometimes the grounds are loose and can spill all over. As the body of the Aeropress and Prismo are both plastic, they will tend to pick up more coffee oils and residues over time and will require deeper cleaning. And, lastly, this setup also requires you to buy two separate brewing devices.
Price at time of publish: $35 (for Aeropress) and $30 (for attachment).
Key Specs (Together)
- Materials: Plastic, rubber, metal
- Weight: 8 ounces
- Surface diameter: 6 centimeters
- Base diameter: 9.5 centimeters
- Length: 17 centimeters
- Number of pieces: 2
- Aeropress: The Aeropress is a great brewer with lots of fun ways to brew but cup quality and usability is hard to match against an Aeropress with a Prismo attachment. It performed admirably at brewing small amounts of coffee, but had some temperature stability issues and required some tricky maneuvers.
- OXO Brew Single-Serve Pourover Coffee Maker: The OXO Brew featured an auto-drip water tank designed to make pour-over more novice friendly, with measurements built-in. The issue is that water starts dripping through immediately, so if you’re trying to add exactly eight ounces to the reservoir, you likely have seen at least two ounces drip through already. The brewer is based off of the Melita cone shape, so the coffee bed can spread out wide along the bottom ride, but the auto-drip dispersion holes only let water drip in a narrow circle, leaving the edges of the coffee bed high and dry in comparison.
- Espro Travel Press: Designed to be a French press on the go, the Espro travel press brewed some tasty coffee. The main issue, however, is the effectiveness of its dual wall vacuum construction. While it held the highest brew temperature out of all the single -cup brewers tested, it also held that temperature in what was now designed to be a drinking vessel. Unless you need a more compact French press for travel or camping, it’s likely you would have a better experience with a standard sized french press, since it has to be decanted anyways.
- Pure Over: Unfortunately, the Pure Over suffers from a massive design flaw: with such a wide and flat bottom that tapers to a narrow exit glass filter, the Pure Over creates an extremely shallow bed depth with a showerhead lid that is half the size of the base. This leads to an extremely uneven saturation of the coffee and guarantees channeling. The design of the brewer was just so flawed that I didn’t even move it to the second round of testing. On top of that, the brewer has a glass on top of glass on top of glass construction, and even included a ceramic coaster, which is all just begging for parts to chip and crack against each other. Plus, it was a pain to try and dump the coffee grounds and the straight handles on the pour over and mug were awkward to hold.
What about Keurig or other K-Cup and pod coffee machines?
Single-pod machines tend to be very wasteful, but at their core, they’re just not good at making good-tasting coffee. Great drip coffee requires a standard ratio of coffee to water, a medium to mediu- fine grind, water temperatures between 195-205ºF, and a sustained brew time of around three to four minutes. Pod machines cheat these brew specs all in the name of convenience: there’s not enough coffee in the pods for the amount of water being used, so the coffee will be ground extra-fine, the machines will use boiling water to create pressure, and the brew times are forced too short. The end result is usually weak and bitter and the method makes it impossible the match the quality of a freshly brewed coffee.
Can my drip coffee maker be used to make a single cup?
Some modern drip coffee makers have a single cup setting, but it’s not usually what that changes about the brew cycle. At the end of the day, the filter basket size on a drip coffee maker is designed for larger brews, so it would likely be difficult to achieve the right bed depth of coffee for a single cup on these machines. One option might be the OXO 8-cup coffee brewer, which actually features a smaller basket insert for brewing smaller volumes, though this basket is around the same size as the Kalita 185 brewer, and better designed for a minimum brew of 16 ounces.
How much coffee should I use when making a single-cup pourover?
The standard ratio for coffee to water is 60 grams per liter of water, or 1:16.667—that means you should start with one part coffee and about sixteen parts water. That could be one ounce of coffee and sixteen ounces of water, but measurements are much more accurate in grams when brewing smaller amounts. It’s also recommended to weight coffee out on a scale, and then place your whole pourover brew rig on the scale afterwards. This way, when you add water to the filter, you can measure exactly how much water you are adding to the grounds. An 8-ounce cup of coffee should use 15 grams of coffee and 250 grams of water.
What type of coffee works best in an Aeropress?
Any high quality coffee should brew well in an Aeropress. In order to brew well, the coffee should be ground at a medium-fine setting, or just slightly finer than what you would use for drip. While there are some recipes that suggest brewing an espresso-style concentrated brew in an Aeropress, we recommend using a standard brew ratio and steep time.