Ratio Four: one-minute review

The Ratio Four is a drip-coffee machine focused on smaller batches. That means it fulfils a valuable niche in the market, making it perfect for anyone likely to want just a few cups of coffee at a time.

Instead of leaving your brew to stew for hours over a heating element, you can quickly whip up a small batch of coffee on demand, so there's less waste than with some traditional drip machines. While it may not be optimal for offices or big families, it’s great for couples or coffee fans who are flying solo.

The smaller capacity has an extra benefit: its footprint takes up far less space on your counter than many of the best coffee makers. Instead, it cuts a sleek figure on your counter, with its clamp-shaped form and smoky-colored glass carafe looking at home in any kitchen. The only exception here is the water tank. While I understand the design helps keep its size down, I’m not the biggest fan of the way it’s hooked up to the machine via an umbilical cord pipe: I much prefer the built-in tanks of the more premium Ratio Six and Ratio Eight.

Using the Ratio Four couldn’t be easier. Once I’d filled the water tank, all I had to do was slip a compatible filter into the basket, grind my beans to medium-coarse, and pour them in. Pressing the single button on the front first runs a bloom cycle to pre-wet and stir up the grounds – a step many traditional drip machines skip – and then the Ratio Four gets to work running water through your grounds to fill the carafe with sweet Costa Rican crude.

So how did my coffee turn out? Once I found the best grind for the Ratio Four, it made very solid coffee – it wasn’t too bitter, and there was at least a hint of some of those volatile flavors that make speciality coffees so fantastic. But I wouldn’t say it packed the rich bouquet I associate with wonderfully extracted coffee. I’ve definitely experienced pour-over and pressure-extracted coffees that expressed more character out of similar beans.

That doesn’t mean the Ratio Four isn’t worth buying, though. Pour-over coffee requires developing the knack for it, while many of the best espresso machines require you to spend more money and a lot of time cleaning. When you just need a couple of cups of tasty coffee in mere minutes, the Ratio Four is definitely worth your time.

Ratio Four review: price and availability

• Launched November 2024
• Retails for $279

Launched in November 2024, the Ratio Four is available now. It retails for a list price of $279 (around £205) – unfortunately, unlike its larger stablemates, the Ratio Six and Ratio Eight, it’s not currently available in the UK. So those based on that side of the pond might have to content themselves with drip machines like the Sage Luxe Brewer Thermal or Ninja DualBrew Pro instead.

While the black version featured here isn’t currently available on Amazon, the white colorway is, and it looks just as classy. For that price, you get pretty much everything you need included – such as the carafe and filter basket – with the exception of compatible Ratio or Melitta filters. I’d recommend you grab some at the same time if you’re going to purchase the Ratio Four.

Ratio Four review: specs

Ratio Four review: design

• Sleek, attractive styling
• Perfect for just one or two cups
• Water tank looks less elegant

For some reason, not every brand seems to have gotten the memo about coffee maker design. Some manufacturers seem to think that just because an appliance is bulky, it has to be squat and utilitarian. Fortunately, Ratio is way ahead of the crowd here: all of its drip coffee machines are gorgeous, and the Four is no exception.

Despite measuring 10.6 x 7.5 x 11.5 inches / 26.9 x 19.1 x 29.2cm, this coffee maker looks pretty sleek to my eye. Both its matt black finish and bracket-shaped form meant it cut a bold silhouette in my kitchen and stood out among all the chrome and squat boxes of my other appliances.

As the smallest product in Ratio’s range, the Four’s water tank only holds 20.3oz / 0.6l, which is approximately enough for two full mugs. There aren’t many drip machines that cater to this size, making this a great choice for individuals or couples. However, that does mean that if you need to brew enough for a family brunch or your coworkers’ coffee order, you’ll probably want to size up.

The water tank is the one area where this machine loses some style points. The discrete reservoir and hose hookup looks a little goofy to me, like it's connected to the device with an umbilical cord. Personally, I prefer the built-in tanks of the more premium options.

By their very nature, drip coffee machines are far simpler affairs than espresso machines, so you don’t get a lot in terms of accessories here, but it includes everything you need. The packaged carafe is nicely made, and its darkened, heat-proof glass gives it a smoky, sophisticated look. And it comes with a filter basket, although you can swap in your Hario V60, Kalita Wave, or Origami basket if you prefer.

Beyond this, you’re on your own. So, to get the right coarseness of grind – pre-ground is unlikely to give you either the freshness or precision you’ll need here – you’ll want a coffee grinder too. It’s also worth getting some compatible, flat-bottom filter papers. Ratio sells its own, but the Ratio Four is also compatible with Melitta filters if those are more convenient for you.

• Design score: 4.5/5

Ratio Four review: performance

• Quick to use and clean
• Easier than pour-over to get consistent results
• Flavor is good, but not top tier

If you’re looking at automatic drip-coffee machines, your biggest priorities are likely to be speed and convenience. I’m happy to say that the Ratio Four offers both of these things in spades.

Larger drip-coffee machines can take 5 to 10 minutes to brew, but thanks to the Ratio Four’s smaller batch sizes, it often takes far less time. While the first brew I did took 1 minute 52 to bloom and 5 minutes 16 for the total pour, once the boiler had warmed up, this time shrank considerably. My final brew took 1 minute 29 to bloom and 4 minutes 28 for total pour time, so pretty much bang on what I’d expect.

So, how easy is it to use? All told, I felt the process was pretty straightforward. Once you’ve ground your beans, just insert a compatible filter, fill it up, and top up the tank – then you’re good to go. Press its single button, and it’ll automatically bloom and brew your coffee. Compared to the more finicky process I’ve come to expect from my pour-over or espresso machine, using the Ratio Four is a breeze.

And it achieves decent results… as long as you’re willing to experiment with dialing in the right grind. While you’ll be broadly fine with a medium-coarse grind – somewhere between sand and sea salt in texture – I found brewing a few test batches allowed me to really zero in on the right grind for the machine and filters I was using.

Case in point, for my first batch, I set TechRadar’s Mazzer Philos testing grinder to 100 (on a scale of 0 - 140). While the initial bloom of the grounds seemed to go well, the resultant pour looked a little weak to my eye – something I confirmed when I tasted it. Honestly, it was insipid, tasting indistinguishable from a stewed French press. Back to the grindstone then.

This is where I went down a bit of a rabbit hole. I brewed about eight more batches, dialing the grind down 60 microns at a time, producing more flavorful brews each time. I did eventually hit a sweet spot of richness and acidity, but this came at a finer grind than I expected and didn’t quite produce the flavor-forward caffeine hit I was looking for. Don’t get me wrong: it makes a tasty cup of joe, but I honestly feel like pour-over or an espresso machine would have extracted more of those mouth-watering, floral flavor notes I was hoping for.

But barring a little grind calibration, I have to hand it to the Ratio Four for being incredibly easy to use. And it’s similarly easy to clean. All I had to do was bang the used filter and grounds into the trash, wash out the filter basket, carafe, and water tank, wipe down the shower, and it was ready to go again. Compared to espresso machines, with their milk-encrusted steam wands and silt-clogged portafilters, it’s much easier to get the Ratio Four looking spotless.

All in all, the Ratio Four makes good coffee while being simple to operate. It ekes a little bit more flavor out of your grind than a standard drip coffee, and it’s cheaper and easier to use than the best espresso machines – it just can’t reach the same heights of flavor.

• Performance score: 3.5/5

Should I buy the Ratio Four?

Buy it if…

Don't buy it if…

Ratio Four review: also consider

How I tested the Ratio Four

• Tested it over a week
• Made around 8 - 10 batches of coffee
• Have several decades of experience making coffee

I tested the Ratio Four over the course of a week. As it’s exclusive to the US and I’m testing in the UK, I used a voltage transformer to step down our 240V mains power to 120V. I exclusively used fresh-roasted beans ground right before brewing to ensure as much of the delicate flavor profile was preserved as possible.

When it came to testing, I brewed 8 - 10 batches of coffee at a range of grinds from coarse to medium, covering a much wider range of grinds than would usually be used for drip coffee. I followed the exact grounds-to-water ratio suggested by the manufacturer. I created multiple batches one after another, then made sure to compare the results to see how variations in the grind affected the finished results.

In terms of my experience, I’ve been making and drinking coffee on a daily basis for over two decades. My go-to brew methods are espresso using my Breville Bambino and cold-brew extracted at room temperature over 18 hours and then filtered through a fine mesh. However, I’ve used an enormous array of coffee-making devices over the years, from the Aeropress to a stove-top moka pot.

• First reviewed: February 2026
• Read more about how we test