About 75 roasted arabica beans for a 6 fl oz cup, and about 100 for an 8 fl oz mug — with a real spread of roughly 60 to 100 beans per cup depending on bean size and roast level. The count is a consequence of weight, not something you should try to measure: dose 9.8 g of coffee per 6 fl oz cup, which is the standard 55 g per litre of water, and the bean count follows. Everything below is the arithmetic that gets you there, and the sources for each number in it.
Table of Contents
Corrections to an earlier version of this page
Three of the claims this page used to make were wrong, and one of them was an attribution that the cited body never made.
- It said “the Specialty Coffee Association defines a cup as 8oz”. It does not. The SCA’s home brewing standard, SCA Standard 310-2021, never defines a cup in ounces at all — it specifies the brew ratio by mass, as “55 g of coffee per 1.000 kg of water”, and sizes brewers by their water capacity in kilograms. The word “cup” appears in it only as a physical vessel — “sample cup”, and “an oven safe support or cup” — never as a unit of volume. The 6 fl oz coffee cup used on this site comes from the National Coffee Association’s Golden Ratio of “1 to 2 tablespoons of ground coffee for every 6 ounces of water”, not from the SCA.
- It used a 1:16 ratio. The standard reference figure is 55 g of coffee per 1.000 kg of water, which is 1:18. Every page on this site now uses that number, so that our own pages stop contradicting each other.
- It said 15 grams of coffee is “around 75 beans”. That implies a roasted bean weighing 0.2 g, which is heavier than measured green arabica beans before roasting has driven any weight off them. The bean count was roughly the right order of magnitude, but it was attached to the wrong cup size and the wrong bean mass, and arriving at a plausible answer by two cancelling errors is not the same as being right.
- Its FAQ answered “can I reuse my coffee beans” by advising fresh grinding on an aeroplane, on the grounds that “the altitude can affect the taste perception”. That paragraph was padding built around an unsupported claim, and it has been removed rather than rewritten.
Step one: how much coffee, by weight
Section 7.1.5 of SCA Standard 310-2021 reads: “The standard brew ratio of 55 g of coffee per 1.000 kg of 17±3°C water shall be used for both batch sizes as per 7.1.1.” That is 55 g per litre, or 1:18 by weight. The SCA has removed this standard from its own site; the copy linked above is an SCA-branded PDF hosted by CoffeeGeek, and we have confirmed the quoted sentence appears in it.
Apply that to the two cup sizes people actually use:
- A 6 fl oz coffee cup holds 177 g of water, so 177 × 0.055 = 9.8 g of coffee.
- An 8 fl oz mug holds 237 g of water, so 237 × 0.055 = 13.0 g of coffee.
Step two: what one bean weighs
Agronomists measure this as hundred-bean weight. Urugo, Tola, Kebede and Ogah (2024), published in Beverage Plant Research, weighed 20 green arabica samples from different Ethiopian growing areas and reported a hundred-bean weight ranging from 13.22 to 17.28 g, mean 15.49 ± 0.98 g. Divide by 100 and one green arabica bean weighs about 0.13 to 0.17 g, averaging 0.155 g.
You buy roasted beans, and roasting removes weight — mostly water, plus some dry matter as carbon dioxide and volatiles. The green coffee importer Royal Coffee puts the span this way: “Very light roasts, dropped at the beginning of the first crack, will likely lose only about 10% of their green weight, but roasts taken well past the second crack may lose as much as 25%.”
Combine the two and a roasted arabica bean weighs roughly 0.10 to 0.16 g, with a middle case — an average-sized bean at a typical medium roast loss — of about 0.13 g.
Step three: divide
| Cup | Coffee at 55 g/kg | Heaviest beans | Middle case | Lightest beans |
|---|---|---|---|---|
| 6 fl oz cup | 9.8 g | 63 beans | about 75 beans | 98 beans |
| 8 fl oz mug | 13.0 g | 84 beans | about 100 beans | 131 beans |
| 12-cup pot, 60 fl oz | 98 g | 630 beans | about 740 beans | 990 beans |
The honest headline is the spread, not the midpoint. A cup of coffee is somewhere between 60 and 100 beans, and which end you land on depends on things nobody prints on a bag — screen size, variety, growing altitude, how dark the roaster took it.
What this arithmetic does not cover
- Robusta. The bean-mass figures above are arabica, from an arabica study. We do not have a measured robusta seed mass from a source we have read, so this page does not print a robusta bean count. The earlier version of this page claimed robusta beans are “typically larger” than arabica; that has been removed rather than reversed, because we cannot source a number either way. See our page on robusta coffee beans for what robusta actually changes about a cup.
- Peaberries. A peaberry is a cherry that produced one round seed instead of the usual two, so peaberry lots have a different bean-mass distribution again. Our page on Kenyan coffee explains where the PB grade sits and why grade letters describe the bean rather than the cup.
- One study, one origin. The hundred-bean weights come from 20 Ethiopian samples. Ethiopian arabica is not the whole of arabica. Treat the range as indicative rather than universal, and treat any single-number bean count — including ours — with suspicion.
Why nobody actually counts beans
Counting is slower than weighing and less accurate than weighing, because the thing you care about is mass, and bean mass varied by about a third across the twenty Ethiopian samples above before roast level was even considered. A 0.1 g kitchen scale costs less than a bag of speciality coffee and removes the whole question. If you have no scale, use the NCA’s tablespoon version — 1 to 2 level tablespoons per 6 fl oz of water, with the strong end being the figure that matches the standard — and accept that a scoop is an approximation.
Two more things change the cup far more than a handful of beans either way. Grind size sets how fast the water pulls flavour out: too fine and the brew turns bitter, too coarse and it turns thin and sour. Water temperature sets the same thing from the other direction — see our page on the best temperature for French press coffee for the range with its source. And if what you are really measuring is a full pot rather than a single cup, how much ground coffee for 12 cups works the same numbers out for a drip carafe, including the awkward fact that a 12-cup carafe is not always the same size.
