How to Use a Chemex: Ratio, Grind and Technique
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Here is how to use a Chemex: place the thick, bonded filter in the top with the triple-layer side against the spout, rinse it with hot water, add medium-coarse coffee at about a 1:15 ratio, bloom for 45 seconds, then pour the remaining water in slow stages so the whole brew finishes in roughly 4 to 5 minutes. The result is a remarkably clean, bright cup with almost no sediment. Read on for exact quantities, a pouring schedule and how to keep your Chemex sparkling.
Designed by chemist Peter Schlumbohm in 1941, the Chemex is an hourglass-shaped glass flask with a wooden collar tied on with a leather thong. It is part of the Museum of Modern Art's collection in New York, but it is far more than a pretty object. Its secret is the filter.
Why Chemex Filters Matter
Chemex filters are bonded paper that is thicker than the standard filters used in most drip machines. That extra thickness slows the flow and traps most of the coffee oils and fine particles. Compared with a French press or even a V60, a Chemex cup tastes lighter in body, very clean and often more delicate, with fruity and floral notes coming through clearly.
That thickness also changes how you brew. Because water passes through more slowly, a Chemex needs a coarser grind than a typical pour over cone. Grind too fine and the filter clogs, the brew stalls and the coffee turns bitter.
Folding and placing the filter
- Pre-folded filters come as a cone with three layers on one side and one layer on the other.
- Place the three-layer side against the spout. The thicker side keeps the paper from collapsing into the spout, which would block the air channel and stall the drawdown.
- Square filters and half-moon (circle) filters both work; choose whichever you find easier to fold.
Chemex Ratio and Grind
A 1:15 ratio gives a full-flavored cup in a Chemex; 1:16 or 1:17 tastes lighter and more tea-like. Use water at 195–205°F (90–96°C), and a medium-coarse grind, a bit like kosher salt. For background on ratios in general, see our coffee to water ratio guide.
| Batch | Coffee | Water | Bloom water | Target time |
|---|---|---|---|---|
| 1 large mug | 25 g (about 4 tbsp) | 375 g / 12.7 fl oz | 50–75 g | 3:30–4:00 |
| 2 mugs | 40 g (about 6.5 tbsp) | 600 g / 20 fl oz | 80–100 g | 4:00–4:30 |
| 3–4 mugs | 50 g (about 8 tbsp) | 750 g / 25 fl oz | 100–120 g | 4:30–5:30 |
Check your model's capacity before you choose a batch size: the smallest Chemex will not hold a large batch, and the biggest ones need a bigger dose to fill properly.
How to Use a Chemex, Step by Step
This pouring schedule uses the 2-mug recipe: 40 g coffee and 600 g water.
- Heat the water. Boil a little more than you need, then let it rest for 30 seconds.
- Set the filter. Open the filter, place the triple-layer side against the spout and seat it in the top of the flask.
- Rinse thoroughly. Pour hot water all around the paper to remove paper taste and preheat the glass. Keep the filter in place and pour the rinse water out through the spout.
- Add the coffee. Grind 40 g medium-coarse, add it to the filter and shake gently to level it.
- Bloom (0:00–0:45). Start a timer and pour about 80–100 g of water to saturate all the grounds. Wait 45 seconds as the bed puffs up and releases gas.
- Pour to 250 g (0:45–1:15). Pour slowly in circles, starting from the center and spiraling out, avoiding the very edge of the paper.
- Pour to 425 g (about 1:45). Wait until the water level drops by about an inch, then pour again.
- Pour to 600 g (about 2:30). Make the final pour, keeping the water level a little below the rim of the filter.
- Let it drain. The drawdown should finish at around 4:00–4:30. Lift out the filter and discard it.
- Swirl and serve. Give the flask a swirl to mix the brew, then pour.
Watch the air channel
If the drawdown suddenly slows and bubbles stop coming up the spout, the wet filter may be sealed against the glass, cutting off air. Lift the filter slightly with a spoon to break the seal and the flow will resume.
Chemex Troubleshooting
- Brew takes 6+ minutes and tastes bitter: grind coarser. This is the most common Chemex problem.
- Brew finishes in under 3 minutes and tastes thin or sour: grind a bit finer or pour more slowly.
- Papery flavor: rinse the filter more generously.
- Cup cools too fast: preheat the flask and your mugs with hot water.
- Coffee tastes flat: check bean freshness and water quality. Our guide to the best water for coffee can help.
How to Clean a Chemex
Glass does not hold flavors, so a well-cleaned Chemex brews pure-tasting coffee for years.
- Rinse right after brewing with hot water so oils do not dry on the glass.
- Remove the wooden collar before a deep clean by untying the leather thong. The wood should not be soaked or put in a dishwasher.
- Wash with warm, soapy water and a long, soft bottle brush to reach the bottom of the flask.
- Remove coffee stains by filling the flask with warm water and a little white vinegar or a few spoons of baking soda, letting it sit, then rinsing well.
- Dry fully before retying the collar.
Best Coffee for a Chemex
The Chemex filter strips out oils and heavy body, so it showcases clarity and acidity. Light and medium roasts, especially single origins, are the stars here.
- Ethiopia Natural: berry-forward and vivid.
- Costa Rica: clean and sweet. Learn more in our article on Costa Rican coffee.
- Blonde: a light, sweet blend that tastes great through thick paper.
Chemex FAQ
What grind should I use for a Chemex?
Medium-coarse, roughly like kosher salt. It is coarser than a V60 grind because the thick Chemex filter slows the flow. If your brew stalls, go coarser.
Which way does a Chemex filter go?
Put the side with three layers against the spout. It is sturdier, so it will not collapse into the spout and block the airflow that lets coffee drain smoothly.
How long should a Chemex brew take?
Roughly 3:30 to 5:30 depending on batch size. Smaller batches finish faster. Use the total time to dial in your grind.
Can I use regular coffee filters in a Chemex?
Some people do in a pinch, but standard filters are thinner and the wrong shape, so they can collapse and give a muddier, faster brew. Chemex-shaped bonded filters give the clean cup the brewer is known for.
The Clean Cup Is Worth It
Once you know how to use a Chemex, it becomes the brewer you pull out to share coffee with friends: a medium-coarse grind, a rinsed filter with the thick side by the spout, a 45-second bloom and a few patient pours. Feel Espresso roasts every coffee order 1–5 days before delivery, so the delicate aromas a Chemex reveals are still there in the cup. Browse our single origins to pick your next Chemex coffee.