A Chemex makes one of the cleanest cups of coffee you can brew at home: bright, light-bodied and free of sediment. It is also less forgiving than it looks. The thick filter slows the water down, so the grind and the pour matter more than with most pour-over brewers.
Here is a Chemex recipe that works, the ratio for any batch size, and how to fix a cup that comes out bitter, sour or slow.
Chemex recipe at a glance
One large mug, about 12 oz in the cup.
- Coffee: 25 g, ground medium-coarse, like coarse sea salt.
- Water: 400 g at 200 to 205°F (93 to 96°C), just off the boil.
- Ratio: 1:16. Use 1:15 if you like it stronger.
- Total time: about 3:30 to 4:30, including the drawdown.
What You Need
- A Chemex and Chemex bonded filters. The 6- or 8-cup model suits most homes. A Chemex “cup” is 5 oz, so an 8-cup model holds about 40 oz.
- Fresh coffee and a burr grinder. Pre-ground coffee is usually too fine for a Chemex and will stall the filter.
- A scale, so you can repeat a good cup. See why a coffee scale helps.
- A gooseneck kettle for a slow, controlled pour. More in our gooseneck kettle guide.
- A timer, or the one on your phone.
How to Brew Coffee with a Chemex
Step by step: 25 g coffee to 400 g water
Start the timer when you start the bloom.
- Heat the water to 200 to 205°F (93 to 96°C). With no thermometer, let the kettle sit about 30 seconds off the boil.
- Fold the filter so the side with three layers faces the spout, and set it in the Chemex. The thick side keeps the paper from collapsing into the spout and blocking the air channel.
- Rinse the filter with plenty of hot water to wash out the paper taste and warm the glass. Pour the rinse water out through the spout, holding the filter in place.
- Grind 25 g of coffee medium-coarse, add it to the filter, give it a gentle shake to level the bed, and zero the scale.
- Bloom (0:00): pour about 75 g of water, enough to wet all the grounds, and give the Chemex a gentle swirl. Wait 30 to 45 seconds while the coffee releases gas. Our guide to the bloom explains why this matters.
- First pour (0:45): pour slowly in small circles from the center outward, avoiding the paper, up to 200 g.
- Second pour (1:15): pour to 300 g, keeping the water level steady rather than filling to the top.
- Final pour (1:45): pour to 400 g. Let it drain completely. The drawdown should finish around 3:30 to 4:30.
- Serve: lift out the filter, give the Chemex a swirl to mix, and pour. The coffee keeps opening up as it cools a little.
Chemex Coffee-to-Water Ratio
Keep the ratio the same and scale the batch. The same pour pattern works for every size; just split the water into a bloom of about twice to three times the coffee weight, then two or three equal pours. Bigger batches take longer to drain, so expect up to 5 or 6 minutes for a full pot.
| Batch | Coffee | Water (1:16) | Stronger (1:15) | Bloom |
|---|---|---|---|---|
| 1 large mug | 25 g | 400 g | 375 g | 75 g |
| 2 mugs | 35 g | 560 g | 525 g | 100 g |
| 3 mugs | 45 g | 720 g | 675 g | 130 g |
| Full 8-cup pot | 60 g | 960 g | 900 g | 150 g |
For other brewers and batch sizes, our coffee-to-water ratio guide and brew calculator do the math for you.
Grind Size for a Chemex
Go a step coarser than you would for a V60 or a drip machine: medium-coarse, about like coarse sea salt. Chemex filters are 20 to 30 percent heavier than most paper filters, so water passes through more slowly, and a fine grind can stall the brew and turn it bitter. Use the drawdown time to dial in: if a single mug takes much longer than 4:30, go coarser; if it is done before 3:00 and tastes thin, go finer. Our grind size guide has photos of each setting.
Grind coarser, or use slightly cooler water. A drawdown that runs long is the usual cause.
Grind finer, make sure the bloom wets every bit of coffee, and keep the water hot.
Use more coffee, moving from 1:16 toward 1:15, rather than grinding much finer.
Check that the three-layer side of the filter faces the spout so air can escape. If it does, the grind is too fine or has too much dust; go coarser.
For a fuller walk-through of what each fault tastes like, see why coffee tastes bitter or sour.
Chemex vs Other Pour-Over Brewers
- Filter
- Extra-thick bonded paper
- Cup
- Very clean, light body, bright
- Best for
- Brewing for two or more
- Filter
- Thin paper, one large hole
- Cup
- Clean, a bit more body
- Best for
- Single cups, fine control
- Filter
- Flat-bottom paper, three small holes
- Cup
- Sweet and even
- Best for
- The most forgiving pour-over
We compare the two most popular in V60 vs Chemex, and have full guides for the V60 and the Kalita Wave. For the basics that apply to all of them, start with our pour-over coffee guide.
A Little Chemex History
Chemist Peter Schlumbohm designed the Chemex in 1941, borrowing the shape from laboratory glassware: a glass flask and a funnel joined into one piece, with a wooden collar and leather tie so you can hold it while hot. The design has barely changed since. It is in the permanent collection of the Museum of Modern Art in New York, and in 1958 the Illinois Institute of Technology named it one of the 100 best-designed products of modern times.
Cleaning Your Chemex
Rinse it with hot water after each brew and wash it with mild soap every few days, using a soft bottle brush for the bottom. Coffee oils build up as a brown film over time; soak it in warm water with a little white vinegar or a coffee-equipment cleaner, then rinse well. Remove the wooden collar before putting a Chemex in the dishwasher.
Former roastery owner and coffee tour operator. Steve spent five years roasting coffee for his own shop and wholesale customers. More about Steve