Article — mL to Grams Converter
Milliliters to Grams: a Cook's Density Guide
One millilitre of water weighs exactly one gram at 4°C, which is how the kilogram was originally defined in 1795. For any other ingredient, the conversion needs that ingredient's density: honey is 1.42 g/mL, all-purpose flour is 0.53 g/mL, olive oil is 0.91 g/mL. Multiply mL by the density to get grams.
This is the single most useful rule in a metric kitchen, and the source of the most common substitution errors. Recipes that travel between countries often switch from volume to mass and back without telling the cook which density they assumed. The result is bread that does not rise, sauces that split, and cakes that come out heavy. The converter above and the tables below give the corrected values for fifteen ingredients that turn up in roughly 90% of home recipes.
When 1 mL equals 1 gram
One millilitre of pure water at 4°C weighs one gram. That is not a coincidence, and it is not a measurement. It is a definition, written down by the French Academy of Sciences in 1795 and refined in 1799, that anchored the entire metric system to a substance every kitchen had on tap.
The choice was deliberate. The team picked water because it was universal, reproducible, and free. They picked 4°C because that is where water reaches its maximum density, which made the standard temperature-stable. From that one decision came a chain of equalities: 1 cm³ = 1 mL, 1 mL of water = 1 g, 1 L of water = 1 kg. The kilogram was redefined in 2019 in terms of the Planck constant, but the water-gram relationship still holds at the level of accuracy any cook needs.
The kilogram was the last SI unit defined by a physical object. From 1889 to 2019, the official mass was a platinum-iridium cylinder kept in a vault outside Paris, called Le Grand K. Copies aged at different rates over the century, by tens of micrograms. The 2019 redefinition replaced the cylinder with a fundamental constant of nature, but the water-gram-millilitre relationship is unchanged.
The density table that runs the converter
The dropdown in the calculator switches between fifteen ingredient densities drawn from USDA FoodData Central, the FAO/INFOODS database, and the King Arthur Baking ingredient-weight chart. These are average room-temperature values; the real density of a specific bag of flour or jar of honey can vary by a few percent.
- Water 1.00 g/mL (definition, at 4°C)
- Whole milk 1.03 g/mL (heavier than water due to protein and lactose)
- Heavy cream 1.01 g/mL (fat lowers density, milk solids raise it)
- Yogurt 1.02 g/mL (mostly milk, slightly denser when set)
- Honey 1.42 g/mL (the densest common kitchen ingredient)
- Maple syrup 1.33 g/mL (sugar concentration sets the value)
- Olive oil 0.91 g/mL (lighter than water, like all edible oils)
- Vegetable oil 0.92 g/mL (canola, sunflower, soybean cluster here)
- Melted butter 0.91 g/mL (matches olive oil; solid butter is similar)
- All-purpose flour 0.53 g/mL (loosely packed; varies by 30% with technique)
- Granulated sugar 0.85 g/mL (uniform crystals pack predictably)
- Brown sugar, packed 0.92 g/mL (moisture binds the crystals)
- Powdered sugar 0.56 g/mL (cornstarch and fine particles trap air)
- Cocoa powder 0.40 g/mL (the lowest density in the list)
- Peanut butter 0.95 g/mL (close to water, mostly oil and protein)
The flour problem
Flour is the single ingredient that breaks the converter's assumptions most often. The 0.53 g/mL density listed above is the spoon-and-level value, where the flour is gently spooned into a measure and the top is struck off with a straight edge. If you scoop the measure directly into the flour, the act of pushing through the bag packs the grains and the density rises to about 0.65 g/mL. A sifted measure, on the other hand, drops to 0.45 g/mL.
That is a 44% spread for the same ingredient and the same volume. It is the reason a recipe that worked perfectly in one kitchen can fail in another. The cup of flour in the original recipe might have weighed 110 g; the cup in the new kitchen might weigh 150 g.
If the original recipe gave volume measurements and you are converting to grams using this calculator, check whether the recipe was American or European. American recipes typically assume scooped flour (closer to 130-150 g per cup), while European recipes assume spooned or weighed (around 110-130 g per cup). The same number in cups can mean different things by mass.
Liquid versus dry measuring cups
American kitchens have two types of measuring cup. The liquid cup is a glass or plastic jug with markings up the side, used to measure pours up to the indicated line. The dry cup is a metal or plastic cup with a flat rim, used to scoop and level. Both are nominally 240 mL. They give different results.
The liquid cup is read at eye level and depends on the meniscus being lined up with the mark, which most home cooks do not do exactly. The dry cup depends on how the cook fills it. The two cups can disagree by 15-25% for the same volume of the same ingredient. Switching to a kitchen scale eliminates both problems.
If your recipe gives American volume measurements but you want metric weights, do not just multiply the cup count by 240 mL. Pull up the converter, pick the ingredient, and read the gram value directly. A cup of flour is not 240 g; it is closer to 125 g.
Temperature, humidity, and other small corrections
The density values used in the converter assume room temperature, around 20°C. Real-life cooking moves through a much wider range, and density follows.
Liquids expand when warm. Water density drops from 1.000 g/mL at 4°C to 0.958 g/mL at 100°C, a 4% change. Cooking oils expand faster, about 0.07% per °C. Oil hot enough to fry, around 180°C, is approximately 11% less dense than the same oil at room temperature. The reverse holds for chilled liquids: fridge-cold milk is slightly denser than the labelled value.
Granular solids are sensitive to humidity. Flour stored in a humid kitchen absorbs moisture and gains weight per cup without changing volume; the same flour in a dry winter kitchen loses moisture and loses weight. Brown sugar dries out and pulls in moisture in the opposite direction, which is why it hardens in the box.
Worked examples for popular recipes
The most-asked conversions on the Internet, with the math shown:
250 mL whole milk × 1.03 = 257.5 g240 mL flour × 0.53 = 127.2 g200 mL sugar × 0.85 = 170.0 g100 mL honey × 1.42 = 142.0 g150 mL olive oil × 0.91 = 136.5 g50 mL maple syrup × 1.33 = 66.5 gWhy bakers weigh instead of measure
Professional bakeries weigh every ingredient, every time. The reason is the variation discussed above: the same volume of flour can hold 30% more or less mass depending on technique. For bread, where the hydration ratio determines whether the dough hooks correctly and whether the final loaf holds its shape, that variation breaks the recipe.
The home equivalent is a USD 20 digital kitchen scale. It tares to zero, reads in grams or ounces, and gives the same answer every time regardless of how you scoop. King Arthur Baking, the oldest US food company (founded 1790), recommends weighing as the single most useful change a home baker can make. The mL to gram converter on this page is a stopgap for recipes that were written in volume; the long-term fix is the scale.
The shift from volume to weight in professional baking is not as old as it sounds. Before standardized flour grades arrived in the late 19th century, bakers had no good reason to expect two bags of flour to behave the same way, so they adjusted by feel. Weighing only became universal in the 1920s, when industrial-scale flour mills started producing consistent product and recipes could finally be specified in grams.