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Calculator Answers

How Many Ounces in a Cup

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

An ounces-in-a-cup conversion page provides liquid volume and dry weight equivalents between cups and ounces. In the US Customary system, a standard cup holds exactly 8 fluid ounces. In the British Imperial system, a cup holds exactly 10 Imperial fluid ounces (approx. 8.8 US fluid ounces). For dry ingredients, the weight in ounces depends on the ingredient's density.

Convert between cups and fluid or dry ounces instantly. Learn why standard cups differ from legal and Imperial sizes, and review dry weight conversions.

See also: Ounces to Cups, How Many Tablespoons in a Cup, and How Many Grams in a Cup.

Quick Answer

Find out exactly how many ounces are in a standard cup (8 fluid ounces) and convert cups to ounces instantly.

Direct Answer

How Many Ounces in a Cup?

There are 8 fluid ounces in a standard US cup.

For dry ingredients, the weight in ounces depends on the density of the ingredient. A baseline standard reference is 8 weight ounces per cup.

Cup Measurement Standard

Formula: 1 Cup = 8.000 fluid ounces (US Customary Fl Oz)

US Customary Cups to Ounces Table

Cups (c)Fluid Ounces (fl oz)
1/8 cup1 fl oz
1/4 cup2 fl oz
1/3 cup2.67 fl oz
1/2 cup4 fl oz
2/3 cup5.33 fl oz
3/4 cup6 fl oz
1 cup8 fl oz
2 cups16 fl oz
4 cups (1 Quart)32 fl oz
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Examples

1/2 Cup (US)

4 fl oz

1 Cup (US)

8 fl oz

2 Cups (US)

16 fl oz

How it works

Formula · 1 US customary cup = 8 US fluid ounces, exactly, by definition

In home baking and cooking, a standard US Customary cup contains exactly 8 fluid ounces:

Standard Liquid Conversion

1 Cup = 8 fl oz

Conversion Formula

Multiply the number of cups by 8 to get fluid ounces. Divide ounces by 8 to get cups.

The short answer, and which cup it assumes

A US customary cup is 8 fluid ounces, and that is not a measurement anyone made: it is the definition. The cup is defined as 8 US fluid ounces, so the conversion is exact and always will be.

That is the cup this page uses unless you change the selector. It is not the only cup in use, and the others are genuinely different sizes rather than rounding of the same one.

  • US customary, 236.5882365 mL, exactly 8 US fluid ounces. The default here and in most US recipes.
  • US legal, 240 mL, defined for nutrition labelling. That is 8.1154 US fluid ounces, about 1.4% larger than the customary cup.
  • Imperial, 284.130625 mL, which is exactly 10 imperial fluid ounces. Used in older UK and Commonwealth recipes.

By hand, both directions

Nothing here needs a calculator once you know which cup you are holding.

  1. Cups to fluid ounces: multiply by 8. Three cups is 3 × 8 = 24 fl oz.
  2. Fluid ounces to cups: divide by 8. Twelve fluid ounces is 12 ÷ 8 = 1.5 cups.
  3. Half and quarter cups fall straight out: half a cup is 4 fl oz, a quarter cup is 2 fl oz, and a third of a cup is 8 ÷ 3 ≈ 2.67 fl oz, which is why thirds are awkward to measure and eighths are not.

A note on the imperial figure

Until this revision the imperial option on this page returned 8.8 fluid ounces per cup. That number is real, but it belongs to a different cup: it is the metric cup of 250 mL expressed in imperial fluid ounces. The imperial cup is 284.130625 mL, and an imperial fluid ounce is 28.4130625 mL, so an imperial cup is exactly ten of them.

The figure is now derived from those two defined volumes rather than stored as a decimal, so the arithmetic checks itself. It is recorded here rather than quietly corrected because anyone who used the old number for a UK recipe was out by about 12%.

The metric cup, and why it keeps causing trouble

Australia, New Zealand and much modern British writing use a metric cup of exactly 250 mL. It is close enough to the US cup to look like the same thing and far enough away to matter: 250 mL against 236.6 mL is about 5.7% more.

In a cake that difference shows. In a mug of stock it does not. The practical rule is to use one set of measures for a whole recipe rather than converting halfway through, because the error compounds across ingredients that were meant to be in proportion.

Edge cases, and what this page cannot tell you

  • Ounces from a scale. Not convertible here, and not by any general factor. A weight becomes a volume only through the density of the specific ingredient: 8 ounces of water is a cup, 8 ounces of flour is closer to a cup and three quarters.
  • The dry mode is a baseline. It uses 8 as a reference point, which matches water and nothing else. It is there for arithmetic, not as a claim that dry ounces convert.
  • Packed and sifted differ. A cup of brown sugar packed and the same cup spooned loosely are different weights of the same volume. Volume measures record how much space something takes up, including the air in it.
  • Coffee cups are not cups. A coffee maker's cup is often 5 or 6 fluid ounces. It is a serving size, not the measure this page converts.

Going the other way

If you have a fluid ounce figure and want cups, the ounces to cups converter runs the same conversion from that side and carries the same distinction between fluid ounces and weight. Between them the two pages cover both directions without either guessing which kind of ounce you meant.

Your figures stay in the page

The amounts you enter are processed by this page in your browser. They are not sent to a server, not stored after you close the tab, and not visible to anyone else. There is no account and nothing to sign up for.

Fluid Ounces vs. Dry Ounces (Weight)

One of the biggest pitfalls in kitchen measurements is treating volume ounces and weight ounces as interchangeable.

While 1 cup of water happens to weigh exactly 8 dry ounces (giving rise to the old saying "a pint"s a pound the world around"), this rule fails for other ingredients:

  • 1 cup of all-purpose flour weighs about 4.2 ounces.
  • 1 cup of granulated white sugar weighs about 7.1 ounces.
  • 1 cup of honey weighs about 12 ounces.

For dry baking ingredients, always measure by weight (dry ounces or grams) using a scale for absolute accuracy.

US Customary vs. Legal vs. Imperial Cup Sizes

Different regions use different cup capacities, which changes the number of fluid ounces they hold:

  • US Customary Cup: Standard recipe size in America, equivalent to 8 US fluid ounces (approx. 236.59 mL).
  • US Legal Cup: Used on food nutrition labels in the US, defined as exactly 240 mL (equivalent to approx. 8.12 fluid ounces).
  • Imperial Cup (UK): Used in older British recipes, defined as 10 Imperial fluid ounces, which equals approx. 8.80 US fluid ounces (284.13 mL).
  • Metric Cup: Used in Australia, New Zealand, Canada, and modern British recipes, defined as exactly 250 mL (approx. 8.45 US fluid ounces).

Related Conversions

Check out other volume and kitchen conversion calculators:

How Many Ounces in a GallonHow Many Cups in a GallonHow Many Tablespoons in a Cup

Related Calculators

More tools from Conversions

Ounces to CupsConvert fluid ounces to cups instantly. Read the direct volume conversion answer, the mathematical formula, kitchen reference tables, and a live converter.How Many Tablespoons in a CupThere are 16 tablespoons in a US cup. Convert between cups and tablespoons instantly with our free converter and complete reference table.How Many Grams in a CupFind out how many grams are in a cup for common ingredients. Water is 236.6g, flour is 120g, and sugar is 200g. Convert cups to grams instantly.How Many Cups in a QuartConvert between cups and quarts instantly. Learn about dry vs liquid quarts and explore US customary vs. Imperial cooking measurements.

Frequently asked questions

There are exactly 4 fluid ounces in a half cup (US Customary) or 4 dry ounces (standard baseline).

There are exactly 2 fluid ounces in a quarter cup (US Customary) or 2 dry ounces.

Fluid ounces (fl oz) measure volume (the physical space a substance occupies), while dry ounces (oz) measure weight (force of gravity). Fluid ounces are measured with measuring cups, and dry ounces are measured on a kitchen scale.

Eight, if you mean US customary fluid ounces, and that is a definition rather than a measurement: the US cup is defined as 8 US fluid ounces, so the conversion is exact. It is 236.5882365 mL. If you mean ounces on a kitchen scale, there is no single answer, because a weight only becomes a volume once you know what is being weighed.

The US customary cup by default, at 8 fluid ounces. The selector also offers the US legal cup of 240 mL used on nutrition labels, which is 8.1154 US fluid ounces, and the imperial cup of 284.130625 mL, which is exactly 10 imperial fluid ounces. They are genuinely different sizes, not rounding of the same one.

Four fluid ounces, because half of 8 is 4. A quarter cup is 2 fluid ounces and three quarters is 6. A third of a cup is the awkward one at 8 ÷ 3, about 2.67 fluid ounces, which is why recipes tend to prefer halves, quarters and eighths.

No, and this is where the confusion bites. An imperial cup is 284.130625 mL and an imperial fluid ounce is 28.4130625 mL, so an imperial cup is exactly 10 imperial fluid ounces. In US fluid ounces it is about 9.61. An older UK recipe calling for a cup is asking for noticeably more than a US cup.

Exactly 250 mL, used in Australia, New Zealand and much modern British writing. It is about 5.7% larger than the US customary cup of 236.6 mL, which is close enough to look identical and far enough apart to change a cake. Use one system for a whole recipe rather than converting partway through.

Not with a general factor, because they measure different things. A fluid ounce is a volume and an ounce on a scale is a weight, and turning one into the other needs the density of the specific ingredient. Eight ounces of water is a cup; eight ounces of flour is closer to a cup and three quarters. Only water makes the two numbers coincide.

As a reference baseline, using 8, which matches water and nothing else. It is there so the arithmetic is available, not as a claim that dry ounces convert to cups. If your ingredient is not water, treat that mode as an approximation and weigh instead where precision matters.

Because a volume measure records how much space something takes up, including the air in it. Packing removes air, so the same cup holds more sugar. This is the general reason baking recipes that care about accuracy give weights rather than cups.

No. Coffee makers usually treat a cup as 5 or 6 fluid ounces, which is a serving size rather than a unit of measure. A twelve cup machine does not make 12 measuring cups of coffee. When following a recipe, use a measuring cup.

No. Everything you type is processed by the page in your browser. Nothing is sent to a server, nothing is stored after you close the tab, and there is no account.

A standard kitchen measuring cup holds 8 US fluid ounces. However, coffee maker manufacturers historically define a single cup of coffee as 5 or 6 fluid ounces. This represents the typical size of a porcelain teacup rather than a full mug.