Guide · Chemex

Chemex: a recipe by weight, and the 1941 design behind it

The Chemex is an hourglass of borosilicate glass that works as dripper and carafe at once, with a thick bonded paper filter. Start at about 49 g of medium-coarse coffee for a full six-cup brewer (887 ml of water, the SCA’s 55 g/L reference), pour in stages, and expect the bed to drain in roughly 4–5½ minutes.

Updated 2026-10-15 · sources listed at the end · brand names appear only where a cited recipe or the history requires them

Recipes compared

The maker measures by spoon, two roasters publish gram recipes, and the SCA gives targets for any brewer. Each column is shown as published.

	Chemex (Six Cup page)	Counter Culture	Blue Bottle	SCA best practice
Coffee	1 rounded Tbsp per 5 oz cup, more for stronger	45 g	36–46 g	55 g/L ± 10%
Water	5 oz per cup; 30 oz for 6 cups	750 g	600 g	—
Ratio	— (by volume)	1:17 as stated (≈1:16.7)	≈1:13–1:17	≈1:18
Grind	Medium-coarse	Medium-coarse, like kosher salt	Medium-coarse	—
Water temp	Off the boil, once it stops boiling vigorously	200°F	200–210°F	200°F ± 5° (93°C ± 3°)
Bloom	Enough to wet the grounds, ≈30 s	100 g, 30 s	80 g; next pour at 0:45	—
Pours	Slowly, level at least ¼ in below the top	Every ≈30 s (or when the level drops ≈1 cm) to 750 g	To 300 g at 0:45, 400 at 1:20, 500 at 1:50, 600 at 2:20	—
Total time	Not given	4:00–5:00	4:30–5:30	—

Wikipedia’s Chemex article gives 93–96°C (199–205°F) and a coarse grind “resembling kosher salt”. The SCA’s 55 g/L works out to about 1:18; both roaster recipes run stronger. For any other amount, use the ratio calculator.

How much coffee for each Chemex size

Chemex rates its brewers in 5 oz cups. The table treats the rated capacity as water poured (1 fl oz = 29.57 ml, NIST); the grounds hold some back, so the carafe ends a little under. Figures match how much coffee per cup.

Brewer (maker’s page)	Rated	Water (ml)	55 g/L (g)	1:16 (g)	Filters listed
Three Cup Classic (CM-1C)	15 oz	444	24	28	FP-2 / FP-2N half moons
Six Cup Classic (CM-6A)	30 oz	887	49	55	FP-1, FC-100, FS-100, FSU-100
Eight Cup Classic (CM-8A)	40 oz	1183	65	74	FC-100, FS-100, FSU-100*
Ten Cup Classic (CM-10A)	50 oz	1479	81	92	FC-100, FS-100, FSU-100*

*These pages list FP-1 in the description but FP-2 in the page summary; check the box. A “rounded tablespoon” has no fixed weight — weigh one spoonful of your coffee once.

Brewing, step by step

Heat the water. Aim for 200°F ± 5° (SCA). Without a thermometer, the maker’s cue works: take the kettle off once it stops boiling vigorously.
Fold the filter. A round filter is folded in half, then in half again, and opened into a cone with three layers on one side and one on the other. Put the three-layer side against the spout; pre-folded squares and circles go in the same way.
Rinse. Wet the paper with hot water to remove paper taste and preheat the glass, then pour that water out through the spout.
Add coffee. Weigh it (table above), grind medium-coarse, and shake the filter gently to level the bed.
Bloom. Pour just enough water to wet all the grounds — 80 g and 100 g in the two roaster recipes — and wait 30–45 seconds.
Pour in stages. Slow circles, keeping the level at least ¼ in below the rim, until the scale reaches your total.
Drain and serve. Lift out the filter once dripping stops; Chemex says the filters are compostable. The two roaster recipes expect a 4:00–5:30 finish.

Paper filter, folded into a cone with three layers on the spout side so it cannot collapse into the spout. The patent’s claims describe upper walls diverging at about 60° to hold a 60° filter cone.
Air channel and spout: a groove running from the rim past the neck, described in the 1941 patent as “a pouring spout as well as an air passage” for air displaced by the coffee.
Coffee bed: medium-coarse grounds.
Neck: the filter tip reaches into it; the patent claims a wide opening here so a brush can clean the flask.
Collar: a heatproof wooden collar in two halves, held by a tied leather thong.
Lower flask: shaped like an Erlenmeyer flask, which the patent says makes it stable and easy to pour and clean.
Halfway mark (“bellybutton”): half full on 5–10 cup models, the full line on the 3 cup.

Drawn by pourxlab.com for this page from US patent 2,241,368, the Chemex FAQ and folding instructions, and Wikipedia’s Chemex article (sources 5, 6, 13, 15). Generic schematic with no brand marks. Not to scale.

The filter: thick paper, three layers

Thicker than standard. Wikipedia describes the bonded filters as thicker than ordinary drip filters, removing most of the coffee’s oils. The maker cites the paper’s “heavy weight and texture” but gives no thickness figure.
Why three layers face the spout. The FAQ: the filter must not collapse into the spout, which doubles as the air channel. If brewing floods, it advises a coarser grind or checking the three layers are on the spout side.
White or natural. The maker says both perform the same; white filters get an oxygen cleansing bath plus hot-water baths, natural ones only the hot-water baths. No bleach is used, and both are compostable.
Cafestol. Wikipedia says the thicker paper may also remove more cafestol, a cholesterol-raising compound. In a 2017 study of paper-filtered coffee (filter type not specified), 87.45% of the cafestol stayed in the spent grounds, 12.41% in the paper and 0.15% reached the brew. More context in the French press guide.

Troubleshooting checklist

☐ Drains slowly or floods: grind coarser; check three filter layers sit on the spout side (FAQ). Blue Bottle notes a finer grind slows flow and can over-extract.
☐ Drains fast, tastes thin or sour: grind one step finer — see the grind size chart.
☐ Too strong or weak but balanced: change the ratio, not the grind.
☐ Keeping it warm: the FAQ lists a low gas flame, a warm water bath, a low glass-top setting or a wire grid on a low electric coil — never the microwave.

History: from patent to museum

Peter Schlumbohm, a German-born chemist, designed the brewer around lab glassware: MoMA’s label says it was inspired in spirit by the Bauhaus and in form by laboratory equipment such as the Erlenmeyer flask. MoMA calls it the most successful of the more than 300 designs he patented.

Year	Event	Source
1896	Born 10 July in Kiel; later a chemistry doctorate from the University of Berlin	Lemelson-MIT
1931	First US trip to sell patent rights; vacuum-bottle designs sold to the American Thermos Bottle Company	Lemelson-MIT
1935 / 1936	Moves to the US — MoMA’s text says he immigrated in 1935; Lemelson-MIT says he moved to New York City in 1936	MoMA; Lemelson-MIT
1939	US application for a “Filtering device” filed 13 April (claiming a German filing of 13 April 1938); Chemex Corporation incorporated in New York	Google Patents; Lemelson-MIT
1941	US patent 2,241,368 granted 6 May	Google Patents
1942	On the cover of MoMA’s Useful Objects in Wartime bulletin; Corning Glass Works agrees to manufacture	Lemelson-MIT
1943–46	“Decanter flask” patent 2,411,340 (filed 1943, granted 1946): a side groove lets liquid pour past ice held back by the neck. Its number is stamped on the base of a Corning Museum of Glass example	Google Patents; Corning Museum of Glass
1956 / 1958	Illinois Institute of Technology names it among the best-designed products of modern times — 1956 per Lemelson-MIT, 1958 per Wikipedia	Lemelson-MIT; Wikipedia
1962	Schlumbohm dies	Lemelson-MIT; Wikipedia

At MoMA: the museum’s Architecture and Design collection lists Chemex Coffee Maker, 1941, in borosilicate glass, wood and leather, 9½ × 6⅛ in (24.2 × 15.5 cm), object number 51.1943, gift of Lewis & Conger. It was listed as not on view when checked on 15 October 2026.

For the other drippers — V60, Kalita Wave and the Melitta-style cone — see pour-over technique.