Weights of Liquids: Water, Milk, Oil and Honey

Same volume, different weight

Volume measures how much space something takes up, and weight measures how much matter is in it. The link between them is density, the weight of one milliliter. Water is close to 1 g per milliliter, which is why the idea that “a milliliter is a gram” is so popular. It is only a good rule for water and for liquids that behave very much like it.

Oil is lighter than water, milk is slightly heavier, and honey is far heavier. When a recipe is written in cups or milliliters but you would like to weigh, or the reverse, you need each liquid’s own figure. Temperature changes density slightly, but for kitchen purposes the typical figures below are close enough.

Typical figures at a glance

These typical weights per US cup (236.588 mL) are the ones used by the converter on this site. Charts differ by a few grams, so treat them as good approximations rather than laboratory values.

• Water: 237 g per cup, about 1.00 g per mL, about 14.8 g per tablespoon.
• Whole milk: 244 g per cup, about 1.03 g per mL, about 15.3 g per tablespoon.
• Vegetable oil: 218 g per cup, about 0.92 g per mL, about 13.6 g per tablespoon.
• Honey: 336 g per cup, about 1.42 g per mL, about 21 g per tablespoon.

In ounces, a cup of water weighs about 8.4 oz, milk 8.6 oz, oil 7.7 oz and honey 11.9 oz. None of these is 8 oz, even though a cup holds 8 fluid ounces. For smaller amounts, one US fluid ounce (an eighth of a cup) of honey weighs about 42 g, and three tablespoons weigh about 63 g.

Water and milk

Water is the easy reference point. A cup is about 237 g, 250 mL is about 250 g, and a liter is about a kilogram. The small differences come from rounding and from temperature, which changes density very slightly.

Milk contains dissolved sugar, protein and minerals, so it is a little denser than water: about 3% heavier. A cup of whole milk comes to about 244 g, and 500 mL to about 516 g. Skim milk, whole milk and cream differ a little from each other, so if a recipe depends on exact weight, check the product label or follow the recipe’s own figures.

Vegetable oil

Oil is less dense than water, which is why it floats on top of it. At roughly 0.92 g per milliliter, a US cup of vegetable oil weighs about 218 g, and 250 mL weighs about 230 g. Different oils vary slightly, but not by enough to matter in most home cooking.

This lighter weight explains a common surprise. A recipe that asks for 200 g of oil needs more volume than 200 g of water would: 200 ÷ 0.921 = 217 mL, or about 0.92 cup. Measured in a jug, that is a visible difference.

Honey and other syrups

Honey is dense, around 1.42 g per milliliter in these figures, so a cup weighs about 336 g and a tablespoon about 21 g. It is the liquid where assuming “1 mL equals 1 g” goes most wrong. A recipe that gives 250 mL of honey means about 355 g, not 250 g. Using 250 g would leave out roughly 105 g, nearly 30% of the honey.

Honey also varies in practice, depending on its type, its moisture content and its temperature, and it is awkward to measure by volume because it clings to the cup. Weighing is easier. Place the bowl on a scale, set it to zero, and pour the honey straight in. Lightly oiling the cup or spoon first is a common trick if you do have to measure by volume, since the honey then slides out more completely.

Converting both ways

To convert volume to weight, multiply the volume in milliliters by the density. To go from weight to volume, divide.

• 250 mL honey × 1.42 = 355 g.
• 500 mL milk × 1.031 = 516 g.
• 100 g oil ÷ 0.921 = 108.5 mL, or about 7.3 US tablespoons.
• 120 g honey ÷ 1.42 = 84.5 mL, or about 5.7 US tablespoons.

For a quick estimate, a cup of water is about 237 g, a cup of milk is slightly more, a cup of oil is roughly 20 g less than water, and a cup of honey is about 100 g more than water.

Using the converter

A cooking converter such as this one includes water, whole milk, vegetable oil and honey among its ingredients and applies the typical figures listed above. Enter a volume in cups, spoons, milliliters or fluid ounces to see the weight in grams, kilograms, ounces and pounds, or enter a weight to see the volume. As an example, one cup of honey shows as 336 g, which is 11.9 oz, and one cup of oil shows as 218 g.

Results are approximate by design, because the actual density of any particular bottle or jar is slightly different. For the vast majority of recipes that is entirely sufficient. When a recipe gives both a volume and a weight for a liquid, prefer the weight.