Coffee Mug Sizes: How Many Oz Is a Mug?
"How many oz is a coffee mug?" has a short answer and a useful one. The short answer is 11 to 12 oz. The useful one is that mug size is the most under-considered variable in home coffee, and getting it wrong is why a lot of coffee gets poured away half-finished.
Standard coffee mug size
A standard American coffee mug holds 11 to 12 oz, which is about 325 to 355 ml filled to the brim. In practice you fill a mug to roughly 80 per cent, so an 11 oz mug delivers around 9 oz of coffee. This is the size sold as "regular" almost everywhere and the size a drip coffee machine's carafe markings assume.
The full range
- 2–3 oz (60–90 ml): espresso cup. A double espresso is about 60 ml.
- 4–6 oz (120–180 ml): cortado, macchiato, small flat white, or a traditional teacup.
- 8 oz (240 ml): a small mug. Also the volume one tea bag is dosed for.
- 11–12 oz (325–355 ml): the standard coffee mug.
- 15 oz (440 ml): large. The standard size assumed by mug cake recipes.
- 16–20 oz (475–590 ml): oversized, soup mugs, big latte mugs.
- 20 oz+ : novelty and soup territory. Heavy when full.
Oz to ml conversions
- 8 oz = 237 ml
- 11 oz = 325 ml
- 12 oz = 355 ml
- 15 oz = 444 ml
- 16 oz = 473 ml
- 20 oz = 591 ml
Note that a "cup" in an American recipe is 8 fl oz, but a "cup" marked on a coffee machine is usually 5 to 6 oz. That is why a machine that claims twelve cups fills about six mugs.
Why size changes how coffee tastes
Volume determines cooling rate, and cooling rate determines what you taste. Coffee changes flavor as it drops through its temperature range — acidity becomes more prominent, sweetness fades. A small volume in a large mug has a big surface area relative to its mass and cools fast, so by the last third you are drinking something different from what you poured.
This is the argument for matching the mug to the drink rather than owning one size for everything. It is also why espresso is served in a tiny thick cup: 60 ml of liquid needs all the help it can get.
How to measure your own mug
Fill it to the brim with water using a measuring jug and note the volume, then subtract about 20 per cent for realistic fill level. Alternatively, weigh the empty mug, fill it with water and weigh it again — water weighs 1 g per ml, so the difference in grams is the capacity in millilitres.
Frequently asked questions
How many oz is a standard coffee mug?
Eleven to 12 oz, or 325 to 355 ml. Filled normally, that delivers roughly 9 to 10 oz of coffee.
How many oz is a large coffee mug?
Large starts around 15 oz and runs to 20 oz. Above 20 oz mugs are usually sold as oversized or soup mugs.
Is a mug the same as a cup in recipes?
No. A US recipe cup is 8 fl oz. A standard mug is 11 to 12 oz, so a mug is roughly one and a half recipe cups.
What size mug do I need for a mug cake?
Fifteen ounces. The batter roughly doubles as it cooks and an 11 oz mug will overflow.
How many oz is a coffee machine "cup"?
Usually 5 to 6 oz, not 8. That is why a twelve-cup machine fills about six standard mugs.
What size mug should I buy as a gift?
Twelve ounces. It is the size most people already use and works for both coffee and tea.
Shop by size
See 11 oz mugs for the standard size, large coffee mugs from 15 oz, espresso mugs for small drinks and soup mugs at the top end.