How to Brew Coffee with a Chemex: Step-by-Step Guide

If you’ve ever tried making coffee with a Chemex and ended up with either weak, under-extracted liquid or bitter, overcooked notes, you’re not alone. Many coffee lovers struggle to get consistent results from this elegant glass brewer. The problem isn’t the device—it’s understanding how grind size, water temperature, and pouring technique all work together. Here’s how to do it right.

The Chemex brews coffee using a 1:15 coffee-to-water ratio, with a medium-coarse grind similar to sea salt and water heated to 90–96°C. A typical brew uses around 30 grams of coffee and 450 grams of water, brewed in 3–4 minutes for optimal extraction.

What Is a Chemex and How Does It Work?

The Chemex is a manual pour-over coffee maker invented in 1941 by chemist Dr. Peter Schlumbohm. It combines a glass carafe and a specially designed filter in one unit. Unlike standard cone drippers, the Chemex uses thicker paper filters that remove more oils and sediment, resulting in a cleaner, lighter-bodied cup. Its hourglass shape is both functional and iconic—designed to be brewed and served in the same vessel.

Why Grind Size and Water Temperature Matter in Chemex Brewing

Getting the grind size and water temperature right is critical for a balanced Chemex brew. A medium-coarse grind—around the texture of coarse sand or sea salt—is ideal. Too fine, and you’ll over-extract, leading to bitterness. Too coarse, and you risk under-extraction and sourness.

Water temperature should be between 90–96°C (195–205°F). Lower temperatures can result in flat, underdeveloped flavors, while too high can scorch the grounds and over-extract unwanted bitterness.

Step-by-Step: Brewing Coffee with a Chemex

Follow these steps for a consistently great Chemex pour-over:

• Measure and grind coffee: Use 30 grams of coffee (about 2 tablespoons) ground to a medium-coarse size.
• Preheat the Chemex and tools: Rinse your paper filter with hot water to remove paper taste and preheat the glass. Discard the rinse water.
• Add coffee grounds: Place the freshly ground coffee in the filter, ensuring it’s levelled in the Chemex cone.
• Bloom the coffee: Start your timer and pour just enough hot water (about 50–60 grams) to saturate the grounds evenly. Let it sit for 30–45 seconds to allow gases to escape.
• First pour (main extraction): Slowly pour water in small circles, starting from the center and spiralling outward, adding roughly 150–200 grams of water. Aim to wet all the grounds without hitting the filter walls directly.
• Second pour: Continue pouring in stages, maintaining even saturation. Add water up to about 350–400 grams total.
• Final pour: Finish pouring the remaining water to reach your target of 450 grams. Total brew time should be around 3–4 minutes.
• Drain and serve: Once dripping finishes (usually within 10–30 seconds after pouring stops), remove the filter and enjoy your coffee immediately.

Common Mistakes to Avoid When Using a Chemex

Even small errors can ruin a Chemex brew. Watch out for these common issues:

• Using too fine a grind, which clogs the filter and slows down flow—leading to over-extraction.
• Pouring too fast or unevenly, causing channeling where water finds the path of least resistance and extracts unevenly.
• Not blooming the coffee, which traps CO₂ and leads to uneven extraction and muted aromas.
• Ignoring water temperature—either too low or too high will skew flavor extraction.
• Overfilling the filter cone, which can cause overflow or uneven saturation.

Frequently Asked Questions

What coffee-to-water ratio should I use for Chemex?

The recommended ratio is 1:15—that is, 30 grams of coffee to 450 grams (or milliliters) of water. This balance gives a clean, well-rounded cup without being too strong or dilute. You can adjust slightly to taste but staying near this ratio ensures consistency.

What grind size is best for Chemex?

Use a medium-coarse grind, similar to coarse sea salt or breadcrumbs. This allows for the proper extraction time of around 3–4 minutes. A grind that’s too fine will clog the filter; too coarse may under-extract.

What water temperature is ideal for Chemex brewing?

Heat your water to between 90–96°C (195–205°F). This range is hot enough to properly extract flavors but cool enough to avoid burning the coffee grounds, which can lead to bitterness.

How long should a Chemex brew take?

A proper Chemex brew should take around 3–4 minutes from the start of pouring to the last drop. If it takes much longer, your grind may be too fine; if it’s much faster, your grind might be too coarse or your pour too aggressive.

Do I need to pre-wet the Chemex filter?

Yes, always rinse the paper filter with hot water before brewing. This removes any paper taste and preheats the brewing vessel. Be sure to discard the rinse water before adding coffee grounds.

Can I use any coffee with a Chemex?

Yes, but lighter roasts with bright acidity and complex flavours tend to shine more in the Chemex due to its clean filtration. Medium and medium-light roasts from Ethiopia, Colombia, or Kenya often produce particularly good results.

Recommended FrontStreet Coffee Beans for Chemex Brewing

For Chemex brewing, we recommend FrontStreet Coffee’s Ethiopia Humbera for its floral and citrus brightness, ideal for the Chemex’s clean cup profile. FrontStreet’s Yirgacheffe offers vibrant berry and jasmine notes, while their Classic Blend provides a balanced, approachable profile with chocolate and nut undertones. All three roast levels work beautifully with the Chemex’s light-bodied extraction. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.