Chemex Ratio 1:15 vs 1:17: Taste, Grind, and a 30 g Recipe

Chemex ratio 1:15 vs 1:17 comes down to how concentrated you want your coffee, but the Chemex’s thick paper filter changes how that difference feels in the cup. We’ll compare the taste, calculate two 30 g recipes, and show you how to adjust grind and flow without changing several variables at once.

Key Takeaways

• Which ratio makes stronger coffee? A 1:15 brew uses less water per gram of coffee, so it produces a more concentrated cup than 1:17.
• What is the 30 g recipe at 1:15? Use 30 g coffee and 450 g water, including 60 g for the bloom.
• What is the 30 g recipe at 1:17? Use the same 30 g coffee with 510 g water, including 60 g for the bloom.
• What grind should you start with? Use a medium-coarse grind for both ratios, then make a small adjustment only if the drawdown or taste points to a grind problem.
• Why does the Chemex make this comparison distinctive? Its thick paper filter holds back oils and fine particles, creating a clean cup in which the extra concentration of 1:15 can stand out.
• The ratio numbers are familiar, but the Chemex filter and flow deserve their own dialing-in approach.

What Chemex Ratio 1:15 vs 1:17 Changes in the Cup

A brew ratio describes coffee dose compared with brew water by weight. At 1:15, every gram of coffee gets 15 grams of water; at 1:17, it gets 17 grams, so the 1:15 cup is more concentrated and the 1:17 cup is lighter.

The Chemex’s proprietary paper filter is thick and tightly structured. It holds back more oils and fine particles than a metal filter, which contributes to the brewer’s clean, clear cup and leaves less of the oily texture people associate with metal-filter coffee.

That filtration makes the concentration difference especially noticeable. Depending on the coffee, 1:15 may feel fuller and make its sweetness, acidity, or roast more prominent; 1:17 may feel lighter and let delicate notes stand out. These are tendencies, not guaranteed flavor changes: the coffee and brew quality shape what you taste.

Ratio changes beverage strength, not extraction by itself. Extraction also depends on grind size, water temperature and quality, and brewing technique, so changing from 1:15 to 1:17 will not automatically fix a sour, bitter, or slow-draining brew.

The Chemex filter also slows flow compared with less restrictive filter materials. Grind size, coffee-bed depth, and the way you pour all affect drawdown, so a ratio change alone cannot promise a particular brew time or solve a flow problem.

Choose a starting ratio and calculate the water

Choose the ratio by the cup you want, not by a universal rule. For a fuller, more concentrated Chemex, start with 30 g coffee and 450 g water at 1:15; for a lighter, more delicate cup, use 30 g coffee and 510 g water at 1:17.

To scale either recipe, multiply your coffee dose by the second number in the ratio. For 20 g coffee, 1:15 takes 300 g water and 1:17 takes 340 g.

Water weighs close to a gram per milliliter, so the gram amounts are also practical approximations in milliliters. Weigh both coffee and water rather than measuring scoops; scoop volume varies with bean size, roast, and how loosely the grounds sit.

A coffee scale turns the ratio into a repeatable input. If you’re running the same 1:15-vs-1:17 test on a V60 instead, our V60 pour-over ratio guide walks through the same math for that brewer.

Set a Chemex grind that works with each ratio

Start with a medium-coarse grind for both recipes. The thick Chemex paper already slows water, so grinding very fine can stretch the drawdown and push the cup toward harsh or bitter flavors.

Keep the grind consistent when comparing the two ratios. At 1:15, the larger amount of coffee relative to water can make the bed drain more slowly; if the drawdown is sluggish or the cup tastes harsh, make a small move coarser.

At 1:17, begin with the same grind. If water runs through unusually quickly and the coffee tastes sour or underdeveloped, move slightly finer to increase extraction rather than changing the ratio and grind together.

If a 1:17 brew tastes weak but the flow and flavor are otherwise balanced, try a tighter ratio before grinding much finer. A substantially finer grind can slow the Chemex and introduce bitterness when the real issue is simply that you prefer a more concentrated cup.

Grinder markings are not universal, so a numbered setting will not transfer reliably between grinders; use a medium-coarse, coarse-sand-like texture as your starting reference. Change the setting in small steps, and record the result so each adjustment is a useful commit rather than a guess.

Brew both recipes with a consistent Chemex pour

Rinse the Chemex paper filter thoroughly with hot water, then discard the rinse water. This wets and seats the paper against the brewer and clears away its papery taste before the coffee reaches the filter.

For either 30 g recipe, add 60 g water for the bloom and let the grounds sit for 30–45 seconds. Then pour the remaining water: 390 g more for 1:15, or 450 g more for 1:17. The bloom water counts toward the total.

Pour steadily in controlled pulses with a gooseneck kettle rather than a wide-spout pot — the narrow stream makes it easier to keep water on the coffee bed instead of sheeting down the filter wall. Avoid aggressive swirling or stirring, since extra agitation can shift fine particles toward the thick filter and slow the drawdown.

Keep grind, pour pattern, water temperature, and water quality consistent during a ratio test. For a practical starting point, use clean-tasting water and brew water around 93–96°C (199–205°F); the key is to hold the temperature steady while comparing the cups. For more on water temperature and timing fundamentals, see the National Coffee Association’s overview of pour-over brewing.

Treat each recipe like a controlled test: keep the inputs stable, change the ratio, and taste the output.

Diagnose flavor and drawdown before changing the ratio

A strong-tasting 1:15 cup is not automatically better extracted. If it tastes balanced but simply too intense, move toward 1:17 instead of changing grind or temperature.

Sourness can point to insufficient extraction, especially when the drawdown is very fast. Try a slightly finer grind and keep the ratio, pour, and temperature steady while you assess the result.

Harsh bitterness or an unusually slow drawdown can indicate a grind that is too fine, a filter that is clogging with fines, or excessive agitation. Coarsen slightly or pour more gently before blaming the ratio.

Change one variable at a time. Taste the coffee as it cools, too: acidity, sweetness, and bitterness can become easier to distinguish when the cup is no longer piping hot.

Compare the cups fairly and account for brew yield

For a useful side-by-side test, brew the same coffee at 1:15 and 1:17 with the same dose, grind, water temperature, bloom, and pour pattern. Change only the total water, then compare the cups as they cool.

The water you pour is not the finished beverage yield. Some water stays in the coffee grounds and filter, so the amount of brewed coffee you collect will be less than the 450 g or 510 g you added.

The ratio itself does not change with Chemex size. A much smaller or larger batch changes the coffee-bed depth, however, and that can alter drawdown; judge each batch by its own flow and taste rather than expecting identical brew times.

When choosing a Chemex, match its stated capacity to the batch you make most often, not the largest batch you might occasionally brew. Your usual dose and water should fit comfortably; an oversized brewer used for a small batch can change bed depth and flow, while a brewer that is too small limits the amount you can make. If you are between sizes, prioritize everyday use, then check whether it can accommodate your occasional larger brew. Still deciding between brewers? Our V60 vs Chemex vs Kalita Wave comparison breaks down how each one drains and tastes.

Frequently Asked Questions

Is 1:16 a good middle ground between 1:15 and 1:17?

Yes. For 30 g coffee, a 1:16 recipe uses 480 g water, placing it directly between the two recipes in concentration.

It makes a useful third point in a tasting if 1:15 feels too intense and 1:17 feels too light.

Does roast level affect whether 1:15 or 1:17 tastes better?

Yes, roast level can change how quickly coffee extracts and how prominent its roasted flavors seem. A darker roast may feel more forceful at 1:15, while some lighter coffees can benefit from the extra concentration, so taste the particular coffee rather than assigning a ratio by roast alone.

Can I reuse a Chemex paper filter for another brew?

Use a fresh filter for each brew. A used filter retains spent grounds and oils, and the damp paper can fold or clog differently on a second pass, making both flavor and flow less predictable.

Should I stir Chemex coffee after it finishes draining?

There is no need to stir the drained coffee bed. If you want to even out the collected beverage before serving, gently swirl the coffee in the Chemex or serving vessel instead.

Does a 1:17 Chemex brew have less caffeine than a 1:15 brew?

With the same coffee dose, the 1:17 cup is more diluted, so caffeine is less concentrated per sip; that alone does not mean the entire brew contains proportionally less caffeine.

What are the 1:15 and 1:17 recipes for 15 g of coffee?

For 15 g coffee, use 225 g water at 1:15 or 255 g at 1:17. Those amounts make a smaller brew, but the Chemex’s bed depth and drawdown can differ from the 30 g recipes.

Conclusion

The practical choice in Chemex ratio 1:15 vs 1:17 is a fuller, more concentrated cup at 1:15 or a lighter cup with more room for delicate flavors at 1:17. Start with a medium-coarse grind, use the 30 g recipes as written, and keep the filter, pour, temperature, and other variables steady while you compare.

When the cup misses the mark, diagnose grind and flow before changing several inputs at once. Precision turns the Chemex from a guessing game into a repeatable ritual, one careful brew at a time.