Ratio Four Coffee Maker: Terrific Single-Serve Drip

The Ratio Four coffeemaker 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 coffeemaker is a wonderfully simple and useful device, but it shuns the singleton. It looks sideways, even, at a couple. A 12-cup coffeemaker 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 coffeemaker 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.