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The great composer Beethoven reportedly counted exactly 60 coffee beans to make his cup of coffee. We don’t know how Beethoven brewed his coffee or how much water he used. His brew ratio remains a mystery.
When we asked how many coffee beans are used per cup, there isn’t a straightforward answer. This is because coffee beans can vary in species, shape, size, age, and roast. The amount of coffee you use also depends on the brewing technique and the brew ratio. Just counting the number of coffee beans will not give you a consistently good-tasting cup of coffee.
However, if you want a ballpark figure to answer the question of how many coffee beans per cup, then we need to make some assumptions. Let us say you want to make one 8 oz cup of coffee with a brew ratio of 1:15 (see below for more information on the brew ratio).
In this case, you need 15.8 g of coffee.
Assume that the weight of one medium roast Arabica coffee bean is 0.14 g (I weighed 100 coffee beans to calculate this weight).
The number of coffee beans required to make one 8 oz cup of coffee is therefore
15.8/0.14 = 113
You need about 113 medium roast coffee beans to make one 8 oz (237 ml) cup of coffee!
It seems that Beethoven liked his coffee a bit weaker or used less water for his brew.
If this calculation was all that there was to this article then it wouldn’t be very long. Consequently, we are going to expand a little further on the topics of coffee brew ratios and whether you need to weigh coffee beans or coffee grounds.
The Golden Ratio?
In mathematics, two quantities have a golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. Confused?
If there is quantity a and quantity b where a is greater than b. The ratio a/b is the same as the ratio of (a+b)/a
OK. The mathematics lesson is over!
We are talking about coffee in this post and the golden ratio has a different meaning. The golden ratio is supposedly the perfect brew ratio of coffee grounds to water to create the best-tasting coffee. It doesn’t exist for at least three reasons.
1. The ‘perfect cup of coffee’ is whatever suits your taste. No one can say that you are wrong if the coffee you brew is perfect for you.
2. Some people seem to have confused the Specialty Coffee Association’s (SCA) ‘Golden Cup’ standard and misinterpreted it as a ‘Golden Ratio’.
3. The coffee to water brew ratio can vary depending upon the type of coffee and the coffee brewing method. If it can vary then it isn’t a ‘golden ratio’.
The SCA ‘Golden Cup’ standard is a standard for a cup of coffee after it has been brewed. In particular, the standard states
Coffee shall exhibit a brew strength, measured in Total Dissolved Solids, of 11.5 to 13.5 grams per liter, corresponding to 1.15 to 1.35 “percent” on the SCA Brewing Control Chart, resulting from a solubles extraction yield of 18 to 22 percent*.
The SCA does have a coffee to water brew ratio standard for cupping and it is about 1:18. The standard is stated as follows:
When cupping, the ratio of 8.25 grams (whole bean) coffee (± 0.25 grams), to 5.07 fluid ounces (150 ml) water shall be used.
Divide 150 ml by 8.25 g and you get 18.18 which is about 18 and the brew ratio is 1:18.
There are some coffee to water brew ratios that have been shown to make a good cup of coffee and have been accepted as de facto standards. A brew ratio is also known as coffee to water ratio.
Too much water or too little coffee will over-extract the coffee, making the resulting coffee unbalanced, watery, dull, and bitter. Too little water or too much coffee will under-extract the coffee making the resulting coffee unbalanced, strong, and sour.
These commonly used coffee to water ratios use enough coffee and water to brew a balanced, flavorsome coffee without being overpowering.
The most often used ‘Golden Ratio’ is 1 gram of coffee for every 18 g of water and this is base on the SCA cupping standard. Brew ratios are usually written as 1:15 and 1:18 which means that 1 part of coffee is added to 15 parts or 18 parts of water respectively.
Did you know that a dilution ratio written as 1:15 can also be written as a dilution fraction of 1/16? We are saying that 1 part added to 15 parts gives a total of 16 parts. The ratio 1:15 means 1 part added to 15 parts and the fraction 1/16 means 1 part in a total of 16 parts. Hence 1:15 and 1/16 are the same thing.
The word ‘part’ could be any measure you prefer. It could be grams, ounces, milliliters, or fluid ounces. Most of the time coffee and water are measured by weight but volume can also be used. Water can be measured as volume or as weight because 1 ml of water weighs approximately 1 g.
Which Brew Ratio is the Best?
It is your taste palate so you can find out the best brew ratio yourself by trial and error. However, here is what you may experience with some of the common brew ratios.
The 1:15 brew ratio uses less water which means that fewer aromatic and flavorsome compounds will be extracted from the coffee. Your cup of coffee will be strong, concentrated, rich, and acidic.
The 1:18 brew ratio uses more water which means that more aromatic compounds will be extracted from the coffee. This will result in a cup of coffee that is less strong than a 1:15 ratio, balanced, flavorsome, and slightly acidic.
The 1:16 and 1:17 brew ratios are between the 1:15 and 1:18 brew ratios in terms of strength, flavor, and acidity.
The brew ratio for you is up to you! Brew, explore, and discover your favorite brew ratio! It doesn’t mean you have to stick with the same ratio every single time.
In any case, the flavor and results of your coffee will also depend on other factors such as the brewing method (e.g. espresso, filter, drip) and the coffee beans.
How to use the brew ratios to make coffee?
Most coffee mugs have a volume of 11 fluid oz or 15 fluid oz but you don’t usually fill it to the brim. Consequently, you usually aim to make about 8 fluid oz of coffee to fit in your coffee mug.
What is the difference between ounce (oz) and fluid ounce (fl. oz)? An ounce (oz) is used to measure weight and a fluid ounce (fl. oz) is used to measure volume.
How to find your coffee to water brew ratio for one 8 fluid oz coffee.
- We usually measure coffee by weight not volume. Consequently, it is convenient to convert fl. oz to ml for calculations because ml (of water) can be converted to grams (1 ml = 1 g).
- An 8 fluid oz cup of coffee is about 237 ml of liquid. If you want to use a 1:15 brew ratio then divide your total water weight by 15 and that is the weight of coffee you need.
- 237 ml/15 = 15.8 ml = 15.8 g (assuming 1 ml = 1 g)
- Weigh 15.8 g of coffee (whole bean or ground coffee)
- Grind the coffee if you measured whole coffee beans
- Add the ground coffee to 237 ml water to give you a brew ratio of 1:15
How to find your coffee to water brew ratio for multiple cups of coffee
- Assume you want to make four 8 fl. oz (237 ml) cups of coffee for your friends
- Multiply 237 ml by 4
- 237 x 4 = 948 ml = 948 g
- Assume you want a 1:15 brew ratio
- Divide the total volume of water by 15 and that is the weight of coffee you need.
- 948/15 = 63.2 g
- Weigh 63.2 g of coffee (whole bean or ground coffee)
- Grind the coffee if you measured whole coffee beans
- Add the ground coffee to 948 ml of water to give you a brew ratio of 1:15
How to find the water you need for an amount of coffee?
- Say you have 50 g of coffee (whole bean or ground coffee)
- Multiply the amount of coffee by 15 and that is the amount of water you need
- 50 x 15 = 750 ml water
- Grind the coffee if you initially weighed whole coffee beans
- Add the ground coffee to 750 ml of water to give you a brew ratio of 1:15
The math isn’t difficult but it is easier if you have a phone or calculator!
Should I Weigh Coffee Beans or Coffee Grounds?
Should you weigh whole coffee beans or ground coffee beans for your brew ratio?
It is simpler to weigh whole coffee beans. If you were able to retain all of the coffee after grinding then it wouldn’t matter if you weighed whole coffee beans or ground coffee. Grams of coffee beans would be grams of ground coffee.
However, when you grind your beans the grinder may retain some of the coffee. The amount of coffee retained by the grinder depends on the make and type of grinder.
The Specialty Coffee Association (SCA) weighs whole coffee beans for cupping standards and tests grinders for coffee retention by weighing the coffee retained after grinding 500 g of coffee beans. The SCA uses commercial grinders is the Mahlkonig EK43S. This grinder costs about $3000 so it may not be the best choice for your home.
A better alternative for a professional home coffee grinder is the Ode Brew Grinder which was also a winner in the 2021 SCA Best New Product awards.
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Ground coffee is weighed for most other brewing techniques. Ground coffee is a bit ‘messy’ to work with but weighing ground coffee is preferred as it will give you a consistent dose in an espresso portafilter.
You will notice the word ‘dose’ in the previous sentence. This word is often used when preparing espresso coffee and refers to the standard amount of coffee contained in a portafilter basket to pour a single or double espresso.
Ground coffee is often dispensed into the portafilter and then weighed. The balance is tared for the weight of the portafilter so it would measure the weight of the coffee grounds.
How to Weigh Your Coffee Beans
The best way to measure your coffee beans is with an accurate digital kitchen scale.
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With a coffee scale, all you need to do is place the beans, coffee container, or portafilter on top of the scale, and set it to zero (tare the scale). Then add your coffee and weigh again.
Once you have measured your coffee beans or ground coffee then you can start to think about grinding and brewing.
If you don’t have a digital kitchen scale, then you can grind your coffee beans and measure your coffee with a tablespoon. A tablespoon is a measure of volume and unfortunately, the volume differs depending on your location or cooking preferences. A useful blog post listed some of the various measures of a tablespoon and the volume varied from about 14 to 25 ml!
For our purposes, we will use the following definitions.
1 US tablespoon = 15 ml.
1 Imperial tablespoon = 18 ml
1 Australian tablespoon = 20 ml
We want to measure the weight of coffee grinds not their volume. To do this we need to know the density of ground coffee to convert from milliliters (ml) to grams (g). Let us assume that the density of finely ground coffee is 0.4 g/ml. The calculation to find the weight of ground coffee is
1 US tablespoon of ground coffee = 15 ml x 0.4 g/ml = 6 g
1 Imperial tablespoon of ground coffee = 18 x x 0.4 g/ml = 7.2 g
I Australia tablespoon of ground coffee = 20 x 0.4 g/ml = 8 g
Previously we calculated that to make an 8 oz cup of coffee with a coffee to water ratio of 1:15 we would need 15.8 g of ground coffee. The number of tablespoons needed would be…
15.8/6 = 2.6 US tablespoons of ground coffee
15.8/7.2 = 2 Imperial tablespoons of ground coffee
15.8/8 = 1.90 Australian tablespoons of ground coffee.
Consequently, we would need to add 2.6 US tablespoons of ground coffee, 2 Imperial tablespoons of ground coffee, or 2 Australian tablespoons of ground coffee to 247 ml of water respectively. Alternatively, and if you are not too pedantic, you could simply round the numbers and add 2 tablespoons of finely ground coffee to 247 ml of water.
You may be wondering how I came up with the density of finely ground coffee as 0.4 g/ml? Well, I simply packed a tablespoon with finely ground medium roast coffee and weighed it. I then divided the weight by the volume of the teaspoon. Actually, my experimental value is pretty close to a calculated value of 0.36518 g/ml. Of course, the density of ground coffee will vary with the grind, the coffee bean, and the roast.
Summary
To make consistently good coffee it is best to weigh your coffee beans or coffee grinds.
If you weigh coffee beans then you need to remember that the grinder may retain some of your coffee.
It is preferable to weigh ground coffee for most other coffee brewing methods.
Despite the name, there is no ‘Golden Ratio’ (coffee to water ratio) to brew perfect coffee because your taste determines the way you make your coffee. However, there are some commonly used brew ratio ‘standards’ that are useful to get started. You can then explore different brew ratios to suit your taste.
Here is a YouTube video you may like on why coffee nerds like scales!
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