How much does 10 fluid ounces weigh

Why is there a fluid ounce?

As discussed in comments:

  • A fluid ounce is a measure of that volume .
  • An ounce is a measure of Mass or weight .

The exact sizes of these measurements vary by country and historical period, as can be seen under the links.

The fact that these units have a similar name is due to a historical accident and you should be better served if you do not consider them related at all. You just measure different things.

In a recipe, the word "ounce" is ambiguous. If the recipe or source doesn't specify I would generally assume:

  • An "ounce" of something liquid or roughly liquid (sauce, sauce, syrup) should normally be measured by volume in a measuring cup (regardless of weight).
  • In the case of dry goods, an "ounce" usually refers to weight rather than volume.
  • Baking recipes sometimes include weight measurements as well in addition to Volume measurements (e.g. cups); In this case it is generally understood that an "ounce" refers to the weight measurement.
  • Professional large volume cookbooks sometimes contain recipes that are fully expressed in weight measurements. Again, the context should make this clear.

To answer the question why we instead of other volume measurements one "fluid ounce" use, the "fluid ounce" originally referred to a volume of one certain Liquid that weighed an ounce, usually wine, ale, or water. An "ounce" would therefore have a different size depending on the substance measured. A few centuries ago, both the United States and Great Britain decided to standardize the "fluid ounce" as a volume measurement equivalent in all contexts, regardless of the substance. Britain chose water as the standard; The US chose the old British wine measure as the standard size for their ounce. Regardless of this, it is now defined that all fluid ounces have a certain Have volume without requiring a relationship to the density or weight of the material.

Despite the confusion, the name stuck. For some reason it has been adopted as the standard volume measure, probably due to its size and standardization. (Pints ​​were too large and possibly inaccurate for labeling consumer goods; drams and minimals were useful for the pharmacy, but too small for labeling volumes of any size. Intermediate units like tablespoons and cups tended to vary historically. And no one seemed so to like using the gill outside of alcohol measures.)

More details on usage below.


To clarify an earlier answer: When the term "dry ounce" occurs (only generally in culinary contexts) it is ambiguous and could refer to:

  • Measure something as an ounce by weight (1/16 pound)
  • Measure a solid - usually a powder, finely chopped material, or a semi-solid butter - with a Fluid ounce volume (1/16 of a liquid Pints, equivalent to 2 tablespoons)

Large quantities of dry goods in the U.S. are measured in bushels, picks, dry quarts, and dry pints (which are about 16.4% larger than liquid Pints). A "dry ounce" (as 1/16 of a dry Pints) is NOT used as a volume measurement . (They definitely do not officially exist in the United States, the only place that still has units of volume with "dry measure".)

There is no reason for it to exist. The dry pint is the smallest official unit for dry goods. The FDA does not recognize the possibility of "dry ounces" for food labeling (see regulation 101.105 (b) (3)). Anything firmer than a dry pint must be by weight or by Liquid volume measurements be measured. Smaller units for culinary purposes (cups, tablespoons, teaspoons, and yes, fluid ounces) are all Liquid volume measurements, the ones from Fluid system are derived from (and correspond to) and do not relate to the dry goods units at all.

As we clear this up, contrary to popular lore, a "pint is NOT a pound around the world", even with water. In the traditional imperial system, one liquid ounce of water weighs exactly one avoirdupois ounce. But an Imperial pint is 20 ounces, not 16, so a pint weighs more than a pound (1.25 pounds actually). In the US system, the fluid ounce was defined as 1/128 of a wine gallon. Therefore, one liquid ounce of wine should weigh approximately one US ounce. However, because water is denser than wine, one ounce of liquid water weighs more than one ounce (by weight). Similarly, the US pint of water (16 fluid ounces) weighs more than a pound (approximately 1,044 pounds).

Incidentally, the other place of confusion is with butter, which is believed to contain 16 ounces per pound, depending on how each stick is commonly labeled in the U.S. (with 8 tablespoons = 4 (runny?) Ounces). But butter is about 5% less dense than water, and 16 fluid ounces of butter cannot be the same weight as 16 fluid ounces of water. So, a pound of butter usually contains around 33-35 tablespoons, although it is marked as containing 32 tablespoons. This discrepancy is usually not significant in culinary practice and is also approximately true for oils. (To add to the confusion, a US tablespoon is often defined as 15 milliliters for labeling purposes, rather than 14.787 milliliters, which is actually half a standard US fluid ounce. A fluid ounce is therefore also defined by the FDA in the US should 30 Milliliters when referring to nutritional information - see point 9 here.)

However, unlike butter / oil and water / wine, these relationships between volume and weight measurements do not apply at all.

In general, I would avoid equating these two units in any meaningful way, as they relate only in very specific cases, and even then only imprecisely. A fluid ounce refers to volume (and refers to cups and pints and quarts and gallons and liters); An ounce is a measure of weight (and refers to pounds and kilograms).

For culinary purposes, it's simple:

  • When using a cup to measure something, measure the volume (liquid) ounces (regardless of whether the material is liquid or not).
  • If you're using a scale, measure ounces
  • When measuring butter or shortening it on a stick, just accept what it says on the package and don't think too much about it