A quart carton of buttermilk holds 4 cups. A US quart is 32 fluid ounces, and since 1 cup is 8 fluid ounces, the conversion is exact: 32 divided by 8 is 4. Buttermilk is a liquid, so the volume conversion holds for every brand — a quart is a quart. By weight, a quart is about 946 ml, and at the USDA figure of 245 g per cup, 4 cups weigh about 980 g. The gram figure is slightly higher than the millilitre figure because buttermilk is denser than water, and King Arthur Baking rounds the cup weight to 227 g, which would put a quart at about 908 g. Either way, the cups are the same: 4.
Buttermilk is the secret ingredient of Southern baking — pancakes, biscuits, fried chicken, ranch dressing — and it is almost always sold by the quart while recipes measure it in cups. A pancake recipe for four uses 2 cups, which is half the carton. A biscuit recipe uses 1 cup, a quarter of the carton. A fried chicken marinade for eight uses 3 cups, three quarters of the carton. Knowing the carton is 4 cups lets you plan a weekend of baking around one carton, and it tells you when the quart is too much: if you only need 1 cup for a single batch of biscuits, three quarters of the carton will be left, and buttermilk goes off faster than milk.
Carton of buttermilk conversion table
The table below breaks a quart carton into fractions, with tablespoons and fluid ounces alongside. Buttermilk is a liquid, so the volume fractions are exact.
| Amount | Cups (approx.) | Tablespoons | Fluid ounces |
|---|---|---|---|
| 1/4 container | 1.00 cups | 16.0 tbsp | 8.0 fl oz |
| 1/2 container | 2.00 cups | 32.0 tbsp | 16.0 fl oz |
| 3/4 container | 3.00 cups | 48.0 tbsp | 24.0 fl oz |
| Full container | 4.00 cups | 64.0 tbsp | 32.0 fl oz |
| 2 containers | 8.00 cups | 128.0 tbsp | 64.0 fl oz |
By weight, 1 cup of buttermilk is about 245 g (USDA), so a full quart carton is about 980 g. King Arthur Baking rounds the cup weight to 227 g, which would make a quart about 908 g — treat either figure as approximate.
Worked examples
Pancakes for four
A pancake recipe for four people uses 2 cups of buttermilk — half a quart carton — whisked with two eggs, flour, sugar, baking powder and baking soda. The acid in the buttermilk reacts with the baking soda to give the pancakes their lift, which is why buttermilk pancakes are fluffier than milk pancakes. Whisk the wet ingredients together, pour them into the dry ingredients, and stir only until combined — lumps are fine, and overmixing makes tough pancakes. Cook on a medium-hot griddle for two minutes a side. The remaining 2 cups will keep for a few days and are enough for a second batch of pancakes or a batch of biscuits.
Fried chicken marinade for eight
A fried chicken marinade for eight people uses 3 cups of buttermilk — three quarters of a quart carton — with hot sauce, garlic, salt and pepper. The buttermilk tenderises the chicken and helps the coating stick, and the acid works gently, so the chicken can marinate overnight without turning mushy. Submerge the chicken pieces completely, cover and refrigerate for at least four hours, and let the chicken come to room temperature for thirty minutes before dredging and frying. Discard the used marinade — it has been in contact with raw chicken and cannot be reused.
Biscuits for a weekend breakfast
A biscuit recipe for eight biscuits uses 1 cup of buttermilk — a quarter of a quart carton — stirred into flour, baking powder, salt and cold butter. The buttermilk gives the biscuits their tang and their tender crumb, and the acid reacts with the baking powder for lift. Keep everything cold: cold butter, cold buttermilk, and a cold bowl if your kitchen is warm. Cut the biscuits straight down without twisting the cutter, because twisting seals the edges and stops them rising. Bake at 220°C for 12 to 15 minutes until golden.
How the figure is worked out
The figure above is worked out by simple division, not by guessing. The package weight is a quart carton of cultured buttermilk. Divide that weight by the grams in one cup and you get the number of cups in the package. Because cup weights for dry ingredients depend on how the cup is filled, the result is approximate, and the honest way to use it is as a planning figure: it tells you how many batches a bag will cover, not the exact cup count to the last spoonful. The cup weight used here is 245 g per cup, poured, sourced from USDA. USDA lists cultured buttermilk at about 245 g per cup; King Arthur Baking rounds it to 227 g, so the gram figures are approximate.
Practical guidance
Buttermilk is cultured milk, not the liquid left over from churning butter — that is a common misunderstanding, and the modern product is made by adding cultures to low-fat milk. It is thick, tangy and acidic, and that acidity is the point: it reacts with baking soda to leaven pancakes and biscuits, and it tenderises meat in a marinade. If a recipe calls for buttermilk and you do not have any, you can make a substitute by adding a tablespoon of lemon juice or vinegar to a cup of milk and letting it sit for ten minutes — it will curdle slightly and taste tangy, and it works well in baking, though it is not identical to real cultured buttermilk.
A quart carton of buttermilk keeps for about a week to ten days after opening if refrigerated and sealed, but always check the date on the carton. Buttermilk is supposed to smell tangy, so a sour smell alone does not mean it has gone off — but if it smells bitter, tastes unpleasant, or has mould, throw it away. Do not freeze buttermilk you plan to use in a marinade or a dressing, because freezing changes the texture. Frozen buttermilk is usable in baking, where the texture change is hidden. If you only need 1 cup, buy the pint carton instead — it holds 2 cups and wastes less.
Frequently asked questions
How many cups are in a pint of buttermilk?
2 cups. A US pint is 16 fluid ounces and a cup is 8 fluid ounces, so a pint is exactly 2 cups. A quart is twice a pint, which is why a quart carton holds 4 cups. If your recipe needs 2 cups or less, a pint carton is the right size.
How many grams are in a quart of buttermilk?
About 980 g, using the USDA figure of 245 g per cup. King Arthur Baking rounds the cup weight to 227 g, which would make a quart about 908 g. The difference comes from rounding and from small variations between brands, so treat either figure as approximate.
What can I use instead of buttermilk?
Add a tablespoon of lemon juice or white vinegar to a cup of milk and let it sit for ten minutes until it curdles slightly. This works well in pancakes, biscuits and cakes, where the acid is what matters. It is not identical to cultured buttermilk — the flavour is less complex — but it is a reliable substitute in baking.
Is buttermilk the liquid left over from making butter?
Not any more. Traditional buttermilk was the liquid left after churning butter, but modern cultured buttermilk is made by adding bacterial cultures to low-fat milk. It is thicker and tangier than the traditional liquid, and it is the product sold in cartons and used in recipes.
How long does an opened carton of buttermilk keep?
About a week to ten days in the fridge, sealed, if it was fresh when opened — but always check the date on the carton. Buttermilk is supposed to smell tangy, so do not judge it by smell alone. Discard it if it smells bitter, tastes unpleasant, or has any mould.