If you make a purchase using our provided links, we may receive a commission. Learn more here.
Trying to make a Chemex brew taste right?
I like Chemex because it gives me enough control over the pour to steer the cup without making the process complicated.
The first thing I get right is the water-to-coffee ratio.
I usually start around 15:1 and adjust from there by taste.
In this guide, I explain why that ratio matters and how I build a balanced Chemex cup.
What is the perfect Chemex coffee to water ratio?
The ideal Chemex coffee ratio is between 12:1 and 17:1 (water to coffee), and many people argue that a ratio of 15 grams of water for every 1 gram of coffee (15:1) is best.
That balance affects strength, flavor, and body.
The optimal ratio will vary depending on the brewing process, but for Chemex coffee brewing, it should stay within this range.
So what does the Chemex ratio actually mean?
For every 1 gram of ground coffee, I aim for about 15 grams of water. I measure by weight because it is more consistent than scooping, and I use the 1 gram equals 1 ml shortcut only for water, not coffee grounds.
That works out to about 0.5 fluid oz of water per 15 grams, so a 5 oz cup comes to roughly 150 ml of water and 10 grams of coffee.
If I do not have a scale, I treat 3 tablespoons of grounds as a rough fallback, not an exact conversion.
How does the ratio of ground coffee beans to water impact the taste?
A lower ratio of water to coffee grounds will make your coffee stronger, and a higher ratio of water to coffee grounds will make your coffee weaker.
There is no hard rule with Chemex brewing. I usually let taste and brew strength decide where I land.
I start at 15:1, then move only after I know whether the cup needs more strength or feels a little too light.
Most of the time I stay somewhere between 12:1 and 17:1. Outside that range, the cup can become harder to balance and may drift flat or harsh.
How does Chemex pour over coffee work?
The origins of Chemex
Chemex is a type of pour-over coffee made with a distinctive glass brewer.
The brewer was invented in 1941 by Dr. Peter Schlumbohm, who wanted to make household objects more effective and easier to use.
Peter Schlumbohm designed it to be simple and effective, and the shape has stayed recognizable for decades.
What I notice most is how quickly small changes in flow, grind, or saturation show up in the cup.
That is why it still feels like an easy way to change strength and flavor without making the process complicated.
What is a Chemex coffee maker?
A Chemex brewer has just 3 parts:
Chemex brewing is popular because it is as straightforward as it looks.
How to brew Chemex coffee
It is a pour-over method, so I manually pour hot water over the grounds and let gravity do the rest.
The hands-on process only requires the following:
Then there are 8 easy steps:
- 1Weigh the coffee to suit your Chemex coffee recipe, usually with a Chemex ratio of 15:1. You can use pre-ground coffee or whole coffee beans and a coffee grinder.
- 2Place the coffee filter in the Chemex coffee maker, and for the best results, gently pour hot water over it to remove the paper taste.
- 3Place the ground whole coffee beans in the triple-fold portion of the filter. Separately heat water ready for brewing (you can use tap or filtered water).
- 4Start brewing the coffee by pouring hot water over the coffee beans and through the filter. You traditionally use a gooseneck kettle, but as most people don't have gooseneck kettles, an electric kettle works just fine.
- 5Start pouring from the center of the coffee bed and use a spiral pattern going outwards to cover the grounds. The hot water picks up the flavor as it passes through the grounds and causes them to bloom.
- 6Leave the grounds to bloom and brew for a few minutes, and then start the second pour. A good starting point for the next pour is in the middle, and you should use the same circular motion.
- 7Repeat the process for 2-5 total pours with the remaining water until the water level is almost full.
- 8Remove and rinse filter, pour the coffee out, and enjoy your perfect cup of homemade coffee.
Why is Chemex so popular?
Chemex is popular with beginners and experienced coffee drinkers for a few simple reasons:
How to adjust your Chemex ratios
As a rule of thumb, I start at 15:1. When I brew multiple cups, I keep the ratio the same and scale only the coffee and water.
When the ratio is close, the cup is much easier to balance.
Below is a quick Chemex brewing guide. I have assumed about 200 ml per serving so the numbers stay easy to follow, but I still check brewer capacity and target yield.
Coffee to water ratio for 2 cups
You can buy a 3-cup Chemex, but it also works if I partially fill a larger model. Here are the ratios:
Coffee to water ratio for 4 cups
Coffee to water ratio for 6 cups
A 6-cup Chemex is fairly large, so I check the brewer size before I plan the recipe. The batch still has to fit comfortably.
Coffee to water ratio for 8 cups
If I am brewing for 8 people, I need a larger Chemex so the batch fits properly. I would not force that amount through a small brewer.
Making the best Chemex coffee (Bonus Barista tips)
Pour-over coffee leaves more room for experimentation than most brewing methods, which is part of why I keep coming back to it.
It still takes a little time to learn a good cup, and these are the things I adjust first:
Get the right water temperature
The first variable I watch is water temperature. I keep mine around 195 to 205 degrees Fahrenheit, which usually gives full flavor without pushing the cup too far toward bitterness.
Keep an eye on the brew time
Brew time matters too. With a Chemex, I aim for about 3 to 5 minutes and usually work in 3 to 5 pours so the extraction stays even.
If I pour too fast, the cup can taste thin and underdeveloped. If I slow everything down too much, it usually feels heavier and more bitter.
Think about grind size
With Chemex, water passes through the grounds fairly quickly. I start with a medium-coarse grind so the water moves at a sensible pace without dragging the brew down.
A finer grind usually slows drawdown and can push the cup toward bitterness. A coarser grind can leave it weak or sharp.
Use filtered water
Filtered water has been shown to be healthier and can keep any impurities out of the brew. This will give you a purer and smoother taste.
FAQs
How much water do I put in a 20g coffee Chemex?
If I use the standard 15:1 ratio, 20 grams of coffee calls for 300 grams of water. I weigh both ingredients on a scale so I am not guessing at the final yield.
What is the 4:6 method coffee ratio?
The 4:6 coffee method uses 40% of the water in the first two pours, then divides the remaining 60% across later pours. I treat it as a starting pattern, because pour timing still depends on how the bed is flowing.
What are the best pour over coffee bean brands?
Lavazza, Lifeboost, Atlas, Caribou, and Volcanica all make beans people use for pour-over coffee, but I pay more attention to roast and grind than the name on the bag, because those are the parts that change how the Chemex tastes and flows. A medium-coarse grind is still where I start.
What is the ideal water temperature for Chemex?
195 to 205 degrees Fahrenheit is a solid target for Chemex pour-over brews.
Conclusion
Chemex coffee sits somewhere between science and art. The ratio of coffee to water is usually between 12:1 and 17:1, and I still start at 15:1 when I am dialing one in.
From there, I adjust the coffee amount and fine-tune the balance until the cup tastes right.
The basic pattern is simple: set the ratio first, then change grind, temperature, or pour flow one at a time if the cup tastes off. That is usually enough to get the cup back into balance without chasing too many variables at once.
