The short answer
Use 30 g of medium-coarse ground coffee (like rough sand or sea salt) and 500 g of water at 200 °F (93 °C) for a 1:17 ratio. The total brew time — bloom plus pours — should land around 4:00–4:30. The Chemex’s thick bonded filter removes oils and fine particles, producing the cleanest, brightest cup of any pour-over method.
If your brew drains faster than 3:30, grind finer. If it stalls past 5:00, grind coarser. That one adjustment fixes 90% of Chemex problems.
What you need
• Chemex (6-cup or 8-cup; the 6-cup is most common for home use).
• Chemex bonded filter (square or half-moon). The thick filter is what makes a Chemex a Chemex — don’t substitute a thinner filter.
• 30 g coffee, ground medium-coarse (sea salt texture). A burr grinder is strongly recommended for consistent particle size.
• 500 g water at 200 °F. A gooseneck kettle gives you pour control; a regular kettle works but makes an even pour harder.
• Scale and timer. Use the Brew Ratio Calculator to scale the recipe for different doses.
Step-by-step recipe
1. Prep the filter. Open the Chemex filter into a cone (3 layers on one side, 1 on the other). Place it in the Chemex with the thick side over the pour spout. Rinse with hot water to remove paper taste, then discard the rinse water.
2. Add coffee. Pour 30 g of ground coffee into the filter. Shake gently to level the bed.
3. Bloom (0:00–0:45). Start your timer. Pour 60–75 g of water in a slow spiral, wetting all the grounds. Wait 30–45 seconds. You’ll see the bed rise and bubble as CO₂ escapes — this is the bloom, and it lets water contact the coffee evenly during the main pour.
4. First pour (0:45–2:00). Pour in slow, steady spirals from the center outward, avoiding the walls of the filter. Add water until the scale reads about 300 g. Keep the water level about 1 inch below the rim.
5. Second pour (2:00–3:00). Continue pouring in spirals until you reach 500 g. Maintain a steady, thin stream.
6. Drawdown (3:00–4:30). Stop pouring and let the water drain through. The bed should look flat and even when done. Total time from first pour should be 4:00–4:30.
7. Serve. Remove the filter, swirl the Chemex once to mix, and pour. You’ll have roughly 14–15 oz of clean, bright coffee — enough for two mugs.
Troubleshooting
• Sour, thin, drains under 3:30? Grind finer (one notch toward medium). The water is passing through too fast to extract enough sweetness.
• Bitter, heavy, drains past 5:00? Grind coarser (one notch toward coarse). The thick Chemex filter already slows flow; too-fine a grind chokes it.
• Uneven flavor? Your pour is hitting the filter walls. Keep your spiral within the coffee bed. Water running down the glass bypasses the grounds entirely.
• Flat or papery taste? Rinse the filter more thoroughly, or switch to a fresh box of filters. Old filters absorb moisture and develop off-flavors.
For a detailed grind reference, see the coffee grind size chart.