Dairy & Eggs
Buttermilk Conversion
Buttermilk weighs 240g per US cup.
| Amount | Grams | Ounces |
|---|---|---|
| 1 cup | 240.0 g | 8.47 oz |
| 1/2 cup | 120.0 g | 4.23 oz |
| 1/4 cup | 60.0 g | 2.12 oz |
| 1 tbsp | 15.0 g | 0.53 oz |
| 1 tsp | 5.0 g | 0.18 oz |
| 100 g | 100.0 g | 3.53 oz |
Need a different amount? Use the full Ingredient Converter tool.
Buttermilk's 240g per cup puts it right in line with regular milk's density, which makes sense since real cultured buttermilk is still mostly water and milk solids — its distinctive tang comes from live bacterial cultures, not from being a fundamentally different liquid in terms of density or weight.
Cultured buttermilk (the kind sold in US grocery stores) is different from the traditional buttermilk that's a byproduct of churning butter, which is thinner and less tangy — nearly all modern buttermilk called for in recipes is the thicker, cultured version, and this site's conversion figure reflects that.
Buttermilk's acidity does real chemical work in baking beyond flavor: it reacts with baking soda to produce lift, which is why recipes built around buttermilk often use baking soda rather than baking powder as the primary leavener, and why a buttermilk substitute needs to replicate that acidity, not just the liquid volume.
What's sold as buttermilk in a US grocery store today (thick, tangy, cultured) isn't the same product traditional buttermilk once was — the older, thinner liquid left behind after churning butter — and the modern cultured version's 245g-per-cup weight lands close to whole milk's own. Its acidity is doing real chemical work in a recipe, activating baking soda, which is why swapping in regular milk means also reconsidering the leavening.
A common homemade substitute — a tablespoon of lemon juice or vinegar stirred into a cup of milk and left to sit for a few minutes — approximates buttermilk's acidity reasonably well for baking purposes, though it doesn't fully replicate the thicker texture and more complex tang of genuinely cultured buttermilk.
Out of Buttermilk?
See real substitutes with ratios →
How long does it last?
Storage & shelf life →
Frequently asked questions
Is buttermilk the same weight per cup as regular milk?
Very close — both are around 240g per cup, since buttermilk is still predominantly water and milk solids; its tang comes from bacterial culturing, which doesn't meaningfully change its density.
Why does my buttermilk look thicker than regular milk?
Cultured buttermilk's bacteria partially ferment the milk's proteins and sugars, giving it a thicker texture and tangy flavor compared to fresh milk — this is intentional and different from the thinner, less processed buttermilk traditionally left over from churning butter.
Do I need to shake buttermilk before measuring it?
Yes — buttermilk can separate slightly on standing, and giving it a shake or stir before measuring ensures you're getting a consistent, representative cup rather than a thinner or thicker layer from an unmixed container.
Is powdered buttermilk measured the same way as liquid buttermilk?
No — powdered buttermilk is reconstituted with water at its own ratio (usually printed on the container) rather than converted using this liquid buttermilk figure, which applies specifically to the ready-to-pour product.
Does buttermilk's conversion figure change between brands?
Not meaningfully — commercial cultured buttermilk is manufactured to a fairly consistent fat and solids content across major brands, so this figure holds as a reliable average regardless of which carton is in your fridge.
Does buttermilk sold in a smaller pint container differ from a quart container?
No — container size has no bearing on this conversion; the only thing that changes the weight-per-cup figure is the product's actual formulation, not how much of it the store happens to package together.