Why is buttermilk slightly denser than whole milk?

Commercial lowfat buttermilk (1.036 g/ml) is denser than whole milk (1.031 g/ml) because it has less fat — and fat, at ~0.9 g/ml, is less dense than water. With less fat in the mixture, the remaining water-soluble milk solids push the overall density slightly higher. The difference is only about 1 g per cup — negligible for cooking.

Can I substitute regular milk for buttermilk by weight in baking?

By weight, the densities are close enough (1.036 vs 1.031 g/ml, <1% difference) that volume and gram substitutions are structurally equivalent. However, buttermilk's acidity is what triggers leavening when paired with baking soda. A functional substitute is 1 cup milk + 1 tablespoon lemon juice or vinegar, left to curdle — this replicates the acidity but not the protein composition.

How many grams is a cup of buttermilk?

At 1.036 g/ml, one cup (236.6 ml) of lowfat cultured buttermilk weighs approximately 245 g — the same as skim milk and about 1 g more than whole milk.

Lait, babeurre, liquide, fermenté, faible en gras : conversion mL vers grammes

Q: How many grams is a cup of buttermilk?

At 1.036 g/ml, one cup (236.6 ml) of lowfat cultured buttermilk weighs approximately 245 g — the same as skim milk and about 1 g more than whole milk.

Par Fidamen-Chefsolver Team | Révisé par Chefsolver Staff

Cultured lowfat buttermilk — the commercial version widely sold in cartons — is produced by fermenting lowfat milk (typically 1–2% fat) with lactic acid bacteria. Despite the name, it contains no butter and is thinner than sour cream or plain yogurt. At 1.036 g/ml, it is marginally denser than whole milk (1.031 g/ml) because the lower fat content leaves more dissolved water-soluble solids per unit volume. A cup weighs approximately 245 g; a tablespoon weighs about 15.3 g. Pourable like regular milk, with a tangy flavor. Its most important culinary role is its acidity: it reacts with baking soda to leaven biscuits, pancakes, cakes, and fried chicken coatings.

Quick convert

Ingrédient

Tasse US = 236,588 mL
1 c. à soupe = 14,787 mL
1 c. à café = 4,929 mL

Table de référence

Lait, babeurre, liquide, fermenté, faible en gras — de millilitres en grammes
mL	g
10	10
25	26
50	52
75	78
100	104

Comment fonctionne cette conversion

Les millilitres mesurent le volume et les grammes le poids. La densité de Lait, babeurre, liquide, fermenté, faible en gras étant de 1.036 g/mL, 10 mL pèsent 10 g — et non 10 g comme ce serait le cas pour l'eau. Ce convertisseur utilise la densité réelle de Lait, babeurre, liquide, fermenté, faible en gras pour un résultat précis.

Notes de mesure

Les valeurs sont arrondies au gramme le plus proche. Le poids réel peut varier légèrement selon le tassement, la température et la marque. Pour la pâtisserie de précision, une balance de cuisine est toujours plus fiable que les mesures volumétriques.

Questions fréquentes

Why is buttermilk slightly denser than whole milk?: Commercial lowfat buttermilk (1.036 g/ml) is denser than whole milk (1.031 g/ml) because it has less fat — and fat, at ~0.9 g/ml, is less dense than water. With less fat in the mixture, the remaining water-soluble milk solids push the overall density slightly higher. The difference is only about 1 g per cup — negligible for cooking.
Can I substitute regular milk for buttermilk by weight in baking?: By weight, the densities are close enough (1.036 vs 1.031 g/ml, <1% difference) that volume and gram substitutions are structurally equivalent. However, buttermilk's acidity is what triggers leavening when paired with baking soda. A functional substitute is 1 cup milk + 1 tablespoon lemon juice or vinegar, left to curdle — this replicates the acidity but not the protein composition.
How many grams is a cup of buttermilk?: At 1.036 g/ml, one cup (236.6 ml) of lowfat cultured buttermilk weighs approximately 245 g — the same as skim milk and about 1 g more than whole milk.