Review: Ratio Four Coffee Maker

The Ratio Four coffee maker does one of two things: It will make one delicious mug of coffee. Or it will make two delicious mugs of coffee.

Technically, you could also make one and a half mugs of delicious coffee, or a half a mug. But this is where it stops. This is the end of what the device will accomplish.

What a rare and wonderful achievement.

Here’s the thing. Your classic drip coffee maker is a wonderfully simple and useful device, but it shuns the singleton. It looks sideways, even, at a couple. A 12-cup coffee maker makes large batches fit instead for offices, diners, and church socials.

It’s not a big problem, per se. But it is a bigness problem. If, like many of us, you live in a one- or two-adult household, even an eight-cup carafe can be a real responsibility unless you take your coffee in IV form or leave it on a burner all day to get oxidized and weird. I think about this every time I pour out the sad remains of a half-full carafe. Small wonder people resort to pod coffee, even while sacrificing flavor.

Photograph: Matthew Korfhage

This is the situation the Four is designed to solve. Released in November, the Four is the third and smallest coffee maker designed by well-regarded Portland, Oregon, company Ratio.

The device fits easily under a cabinet, and its form is elegant in the modern-minimalist style that involves plenty of BPA-free polymer. Its carafe, made of borosilicate glass, is shapely in familiar ways. But otherwise its specs can look like limitations. Its biggest batch measures a mere four cups, big enough for two steaming mugs. There’s only one button, and no heating element under the carafe. Plus, the machine costs north of $200.

And yet after weeks of testing, I'm convinced. No device I know makes single-mug drip coffee this delicious, with such ease and simplicity.

The coffee that comes from the Ratio can be astoundingly good. On light and medium roasts in particular, my cups have been satisfyingly full-bodied while still whispering sweetly of berries or toffee. I’ve brewed beans I know well, only to discover new flavors.

All the Single Ladies Put Your Mugs Up

But what makes the Four distinctive is the abject ease with which it delivers that terrific single mug—for one, or for two.

When I’ve tried smaller batches on drip machines made for larger brews, it usually doesn’t work out. It requires futzing, and the results taste like compromise. The coffee winds up underextracted, or I have to make too strong a cup. This has been true even on fancy batch devices, including Ratio’s previous eight-cup machines. Most large machines simply aren’t designed to make a great single mug. Single-serve pod coffee doesn’t tend to taste great, either.

(Note: Aeropress is a terrific, but slightly different brewing method for single cups. We also recommend it with all our hearts.)

If you want genuinely good immersion coffee in single servings, the alternative is usually to enter the priestly single-cup coffee world of pour-over, of infinite customization, and of complicated devices that assume you want to meditate over your coffee.

Sometimes, this is exactly what I want to do. But first thing in the morning, I often just want a mug. I want it fast, easy, and terrific, and I don’t want to have to think about it.

Using the Four is simple: Pour the water, add a standard flat-bottom filter and coffee to the brewing basket. Push the basket in, and push the device’s only button. Voilà: something perfect. A half-batch takes three minutes for a single mug. A full batch for two takes four minutes.

The process, essentially the same as on a Mr. Coffee from the 1970s, means I could give the Four as a gift to my dad, and he’d already know how to use it.

In Full (and Half) Bloom

If the button-press operation of the device is easy, there’s a surprising level of sophistication in the Ratio’s brewing method.

For those who’ve followed previous coffee machines by Portland coffee company Ratio, the coffee’s deliciousness will be the smallest surprise. For a decade, the company has devoted itself to recreating the poetry of pour-over coffee in automated form. Its first device was a wildly expensive eight-cup Ratio Eight (8/10, WIRED Recommends), made with all-natural materials to mirror the sumptuous hourglass pour-over of a Chemex. The next was a charmingly midcentury-modern Ratio Six, made more affordable with the use of 21st century modern polymers. Despite its name, the Six is also an eight-cup device.

Ratio’s signal technology is a showerhead that mimics the agitation of a pour-over, allowing for uncommonly full-bodied and full-flavored extraction, hewing tightly to the Specialty Coffee Association’s recommended optimal brewing temperature of 201 degrees Fahrenheit. The Six received SCA certification attesting to this. The Four is not yet certified the same way, and the closed brewing basket makes its temperature difficult to verify.

I should also note the water reservoir. It’s odd. It’s attached by a plastic tube to the exterior of the device, like an organ you keep outside your body or a test tube for an alien baby. This makes the device a bit funny to transport, and sometimes funny to look at. That said, the flexible setup is convenient for the countertop Jenga of small kitchens, as is the fact you can pull the reservoir off its base to fill it in a sink or from a water purifier.

Photograph: Matthew Korfhage

And I’ll always forgive weirdness in the face of flavor. The Four’s brew hovers somewhere between pour-over and classic drip. Same as baristas do, the Four blooms its coffee grounds by dappling a small amount of hot water to release carbon dioxide trapped in fresh-roasted beans. The showerhead also offers a bit of agitation, to help extraction. Meanwhile, the Four’s enclosed brewing chamber allows for consistent temperature. The mix leads to a whompingly flavorful cup.

To start the process, you just pass your finger across the button, and the light that says “Bloom” will light up on the coffee display, setting in motion a series of quiet gurgles and pump noises and light coil whine like the sound made by an old monitor, as water is heated and drawn into the brewing chamber. This activity is nonetheless significantly quieter than your average electric kettle.

For single-mug batches, you can hold the button down until the “bloom” light turns on: This will set in motion a smaller bloom cycle optimized for smaller batches. It’s a thoughtful touch. It also might be the key to the Four’s rare success at single-mug drip coffee.

An Imperfect Ratio?

But there are some catches. First off, the Four’s brew button can be oversensitive and trigger accidentally, especially when you push in the brew basket. This mostly means pressing down the button again to stop the brew before it starts. Annoying, but trivial.

More significant is that coffee brewed with the Four pretty much has to be drunk right away. The carafe, while handsome, does not preserve temperature well. And as with manual pour-over, the coffee is pretty much already at optimal drinking temperature at the moment it's done brewing. Wait too long to drink it, it’ll be closer to lukewarm.

Photograph: Matthew Korfhage

This means if I’m making coffee just for me, I’ll make single mugs only. If I’m brewing for two—or plan to fill up a big coffee thermos on my way out the door—that’s when I’ll make a full batch.

Temperature is also a trouble point for a coffee-geek-friendly “alternate” brewing method most users probably won’t play with. Basically, the device allows pour-over fans to remove the brewing basket and put their favorite pour-over device under the spout. In theory, the Four pours at appropriate temperature. But as assessed by my own taste buds and an infrared thermometer, it wasn’t clear the brewing temperature on this method stayed high enough.

Perhaps it’s a minority who’d want to graft another brewing device onto a coffee machine that already makes lovely coffee with minimal effort—but if that’s you, take heed. Though also note that one can up the brew temp by first running an extra bit of water through the machine before brewing.

But for drip coffee lovers who don’t want to brew a full pot and also don’t want to try too hard, the Ratio will be a lovely companion. The triple-figure price tag offers a steep price of entry, sure. But in the words of Dale Cooper, it’s a damn fine cup of coffee.

Be sure to check out WIRED's other coffee coverage,