According to Google, a cup is 8 oz.

According to Wikipedia, a cup of coffee as measured on the coffee maker is only 5.07 oz.

Every brand of coffee I buy shows directions for 1 tbsp. per 6 oz.

So, why is a cup of coffee only 5.07 oz when nobody (that I know of) uses a cup that small? In fact and in most establishments, you can't even buy a "small" cup of coffee that is less than 8 oz.

Is this just a conspiracy so that the coffee maker companies can exaggerate their capacity while the coffee companies dupe people into using too much coffee per cup, or is there another reason?

Why not just make it 6 oz?

  • if you make yourself a cup of coffee, do you fill the cup to the brim? and has the cup the size of a measuring cup?
    – ths
    Jul 17, 2019 at 8:42
  • @ths Thanks but the point is that the coffee maker companies use a measurement of roughly 5 oz of water before brewing whereas the coffee bean companies use a measurement of 6 oz of water before brewing. This means that I have to use my own measurements (6 oz) to make a proper cup of coffee and the measurements used by most coffee makers are essentially useless.
    – mchid
    Jul 17, 2019 at 20:02
  • I imagine that 12 gr. coffee is a rather common amount of coffee to start brewing. Also, we know that 1:12 ratio fits most of the situations for a delicious brew. So, it is normal that a cup is defined as 144 gr. It could be a problem if you want to be exact with unusual units. On the other hand, the world cannot save US on this issue. This is something for US citizens to deal with. :)
    – MTSan
    Oct 5, 2021 at 7:50

6 Answers 6


Do not blame the coffee makers for what has always been an ambiguous measure - or rather, not a unit for measuring at all. Only in some areas of the world a "cup" has evolved into a fixed unit.

First and foremost, a cup is a drinking vessel for usually hot beverages and usually with a handle.

How big a cup is, is primarily a cultural thing. To showcase two extremes:

An espresso cup (source: Wikipedia):

enter image description here

vs. a jumbo coffee mug (source: Amazon) :

enter image description here.

I am from Germany. We typically use [ml] for volumetric measurements. Whenever I come across a recipe quoting "cups" I start my research: Where did it originate? Is it from the US? I use 245 ml. From current Germany? Probably 200 ml. From my Granny's time? 150 to 180 ml probably fits the bill.

Similar rues apply for coffee, from a small espresso or mokka cup in southern Europe or the Arab world to a mug of filtered coffee in the US.

There seems to be one correlation though - the "stronger" (=more concentrated) a coffee is customarily prepared, the smaller the cup. The amount of ground coffee per "serving unit" seems surprisingly constant for the various preparation styles - about a heaping teaspoon per "cup". The rest is a matter of taste.

  • 2
    You have to understand that a cup is an actual unit of measurement here in the US.I agree that it is not the coffee makers fault and I think the coffee machine makers should display the industry standard of 6 oz. instead of 5 which is not even the standard 8 oz that is an actual and very commonly used unit.
    – mchid
    Nov 30, 2015 at 8:39
  • @mchid While what you say is true (except for that you mix up fluidic ounces and regular weight ounces - a cup is 8 fl.oz., and not 8 oz - note that 8 fl.oz. of water does not weigh 8 oz, so this is not equivalent), the origin of the ~5.07 fl.oz. cup is likely to come from indeed "cup, the container" - a classical porcelain cup in Europe has ~200 ml of volume, and if you leave some space for milk, that is roughly 5.07 fl.oz. In offices nowadays, however, many people use mugs, which are indeed way larger.
    – DCTLib
    Nov 30, 2015 at 9:16
  • @DCTLib I'm sorry I thought it would be understood that fluid was implied. Especially since we are discussing volume and not weight :)
    – mchid
    Nov 30, 2015 at 9:19
  • 1
    @DCTLib Actually 1 fl.oz. of water is exactly 1 oz. of water. For most water based liquids you can interchange it. Tomato sauce, milk, juice or yoghurt for example. Oils are generally lighter, so 1 oz. of olive oil e.g. is more than 1 fl.oz of olive oil. Maybe something like 105-110 fl.oz. Anyways coffee is just as water roughly convertible 1 to 1 from oz. to fl.oz.
    – avocado1
    Oct 14, 2018 at 15:08
  • 1
    @avocado1 I am assuming US units of measurements in that statement (for Imperial ounces, your statement appears to be true). According to en.wikipedia.org/wiki/Fluid_ounce, one US fluid ounce is 29.5735295625 mL. A weight ounce is 28.349523125 g (again, according to Wikipedia). The weight of a litre of water is "0.999975 kg at 4 °C, and 0.997 kg at 25 °C" (again, according to Wikipedia: en.wikipedia.org/wiki/Litre), which leads to a difference of 3.8-4.32%.
    – DCTLib
    Oct 15, 2018 at 9:18

The exact liquid measurement of a "cup" as noted on the side of a coffee maker is subjective since there is no industry wide standard unit of measure. Lee Denny explains this in his article:

One thing is for sure: a "cup" of coffee does not fill up the typical 12 oz. coffee mug found in most American homes.

Ounces per Cup in Popular Coffee Maker Brands

Bunn: 5 oz

Bodum (Vacuum): 5.7 oz

Capresso: 5 oz

Cona: 5.5 oz to 5.7 oz

Cuisinart: 5 oz

Krups: 5 oz

Proctor Silex: 4.5 oz

Technivorm: 4.2 oz

Zojirushi: 5.1 oz

To complicate things even further, coffee brewing instructions frequently tell you how much ground coffee to add for every 6 ounces of water. You'll see this metric on the back of a can of Maxwell House as well as published by coffee authorities such as the National Coffee Association of U.S.A., Inc. Further proof of the lack of standardization.

That being said, neither is their an internationally recognized standard measure for what a "cup" is since American uses cup measurements while many other countries use kitchen scales to mete out ingredients by weight. This entertaining article Sue Quinn wrote for The Telegraph explores this difference:

Here in the UK, we love your food, we really do. We guzzle your dirty burgers, crave your Cronuts and scoff your hot dogs like there’s no tomorrow. But your recipes are giving us heartburn. Why on earth do your cookbooks and food websites cling to cup measures when kitchen scales are much easier, more precise and infinitely less faff?

Quinn provides an excellent cups - metric weight guide if you are interested in eliminating the cup conundrum by buying a kitchen scale for use going forward. If you do make the switch to weights, then try the National Coffee Association's recipe:

A general guideline is one to two tablespoons of ground coffee for every six ounces of water. This can be adjusted to suit individual taste preferences.

Be sure to check the “cup” lines on your brewer to see how they actually measure. And remember that some water is lost to evaporation in certain brewing methods.

If you are still interested in pursuing cup measurement, it may interest you to know that Fannie Farmer is given much credit for establishing the American way of measuring ingredients as noted by Bill Daily in this Chicago Tribune article:

Fannie Merritt Farmer was an influential New England cooking teacher with a flair for marketing and promotion whose 1896 "The Boston Cooking-School Cook Book" and myriad subsequent editions have made her a household name for more than a century.

Often called the "mother of level measurements" for her insistence on the use of measuring cups and spoons in cooking and in recipes, Farmer shaped the appetites of a nation through her cookbook.

If you want an up close and personal look at how Farmer popularized the use of the cup measurement system, check out her cookbook here at Internet Archive.


I'm with you. I was so confused by all of the inconsistencies that we see. All of my coffee makers use a different amount of fl. oz when they mark their pots.

I would go out on a limb and call my self a some what conspiracy theorist and agree with you! They are in cahoots! (partially kidding!)But it does seem like something that should have a standard to it.

The easiest way to make sure you get great coffee is to measure everything in grams and use ratios IMO.

I don't even pay attention to the marks anymore.

  • Thank's for the link to the mass measurements as those are always preferred when measuring dry material like this. I'll have to check it out whenever I can afford a cheap scale.
    – mchid
    Jun 30, 2017 at 23:50

The 6oz water measure is before brewing, not afterward. The brew process results in about 5oz in whatever cup you use.

  • Thanks for the answer but according to the Wikipedia article referenced in my question: "a customary "cup" of coffee in the U.S. is usually 4 fluid ounces (118 mL), brewed using 5 fluid ounces (148 mL) of water". It seems the 5.07oz per cup also takes this into consideration as the article states that a 12 cup coffee maker only makes 57.6oz of coffee whereas 12*5.07=60.84oz. However, 12*4 is only 48 so, again, there is still no consensus here.
    – mchid
    Jul 17, 2019 at 7:05

In the U.S., two cups make a pint. Two pints make a quart. and four quarts make a gallon. There is no ambiguity. The manufacturers of the coffee machines are not using what is clearly a well known standard (in the U.S.). When I buy a 5 gallon container for gasoline, I don't have to guess how much gasoline it will hold. When I buy a pint of milk, there is likewise no ambiguity. It does not surprise me that in other parts of the world, the word "cup" may have different meanings, but I still think the manufacturers are deceiving the U.S. public.

  • Welcome to Coffee! Can you elaborate a bit more? When you order a cup of coffee in the US, do you normally get the volumetrically accurate amount? Over here in Europe a cup of coffee is like a glass of milk, it varies how big the glasses are and how much the put in. I understand that you need accurate measurements when buying fuel, but with a cup of coffee I'm not sure if that's the key measurement. You can add more water to a cup of coffee to get more but that doesn't make the coffee better. Of course, you can't do that with fuel, that ruins it.
    – JJJ
    Oct 8, 2021 at 17:58
  • @JJJ I don't think they're talking about buying a cup of coffee, but how many cup servings of coffee are in the container of ground coffee and how many cups of coffee are produced by the machine. Although, coffee shops typically sell different sizes based on mL or fl. oz. However, restaurants don't usually sell coffee by volume. When you buy a "cup of coffee" they usually give you a cup of any random size and provide endless refills.
    – mchid
    Oct 8 at 4:55

The 8oz cup measurement is a standard Imperial volume. The smaller drink “cup” was typically used for tea, and traditionally held roughly 6oz of liquid. This carried over to coffee drinking until people decided one coffee drink wasn’t enough. It’s unfortunate they shared the same name which leaves some room for confusion. And the ambiguity left room for advertisers to “skim” their definition to get people to buy their products.

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