Ratio Six review: the coffee maker that tells you what it's made of

Ratio's pitch is that the Six brews like a careful pour-over, with a bloom phase and steady flow, from a single button. The part that sets it apart for many buyers is less romantic: Ratio writes down exactly which materials touch hot water.

That disclosure is rare. Most coffee maker listings say nothing at all, which is why the Ratio holds our no-plastic slot.

Ratio's FAQ is specific. The cold-water tank is Tritan, a BPA-free plastic. Once brewing begins, Ratio says water only touches stainless steel, borosilicate glass, die-cast aluminum (the heating element) and FDA-approved silicone.

Two places still involve plastic or polymer in the standard kit: the tank before heating, and the liner in the filter holder. Ratio's own answer is to pair the Six with the Ratio Eight Series 2 stainless dripper and thermal carafe, which it says creates a fully plastic-free hot water path. That setup needs Ratio's brew mat to line up the showerhead.

We report this exactly as Ratio states it. We haven't inspected the inside of a machine, and this site doesn't make health claims about plastics.

Ratio's own documentation is the main evidence here, which is why the card carries a "Maker spec" badge.

Some retailers describe the Ratio Six as SCA certified. When we checked the SCA's certified home brewer list on Oct. 27, 2026, the Ratio Six wasn't on it. Older certifications can lapse when a license isn't renewed, so this may not mean anything about performance, but we only report what the list shows today.

The Amazon listing had a problem: its bullet points describe the Ratio Four, a smaller machine for 5 to 20 oz brews. We ignored those bullets entirely and used only the title, the spec table and Ratio's own pages.

The Ratio Six specs from the listing's table: 1.25 liters, 15 in tall on a 7 by 12.5 in footprint, 1,400 watts and a 5-year manufacturer warranty. The table also says borosilicate glass for the carafe, which conflicts with the thermal carafe in the title; Ratio's own page describes the stainless thermal carafe as standard on the Six.

Ratio says 44 oz of water yields about 40 oz of brewed coffee. Filters can be Ratio's own basket papers, Melitta 8 to 12-cup basket filters, or Ratio's stainless Able basket.

The Six suits households that brew one pot and drink it over a morning:

• Two people who drink slowly. Two 10 oz mugs each before noon is 40 oz. The thermal carafe keeps the second round warm without cooking it, about $445 a year in beans at site defaults.
• A kitchen with open shelving. The Six looks good, which matters when the machine lives in view.
• Someone avoiding plastic but unwilling to pour by hand. It's the most convenient route we found to a mostly glass and steel brew path.

It's 15 in tall, so check the space under cabinets. The listing gives the weight as 17 lb, which seems high for this size; plan for a solid machine either way.

Daily cleaning on the Ratio Six is a rinse of the filter holder and the carafe. The water lines are glass, so you can actually see scale forming, which almost no other machine allows.

When those tubes turn hazy, it's time. How to descale the Ratio Six: follow Ratio's manual with a coffee maker descaler, then run plain water through twice. In a hard-water town, look at the glass once a month.

Hand-wash the thermal carafe with a long brush. Ratio's Series 2 carafe has no moving parts in the lid, which makes it easier to clean than older designs.

On Oct. 27, 2026, the listing was sold by Ratio Coffee as a third-party seller on Amazon, which our rules mark for a closer look but which is normal for smaller brands.

Ratio deals tend to appear on Ratio's own site as bundles with the Eight Series 2 accessories, sometimes discounted as a set. If plastic is your reason for buying, that bundle may be better value than the Six alone. The Ratio Six price on Amazon and Ratio's site can differ, so compare before you buy.

More lower-plastic options are on the best coffee makers without plastic page.

Buyers who read material lists. Kitchens where the coffee maker sits in plain view. Couples who drink slowly and hate burnt coffee.

The Six is also a quiet argument for paying more once. A five-year warranty, a carafe with no moving parts and glass water lines you can inspect make it a machine you can keep and maintain rather than replace, which suits people who would rather fix a thing than throw it away and start over.

It's less suited to anyone who needs a timer. The Six has one button and no clock.

Ratio says 44 oz of water yields about 40 oz of coffee:

Rows over 100 percent mean a second brew. The thermal carafe holds the first pot while the second runs.