You're standing in your kitchen, sleeves rolled up, flour dusting the counter, and you've got a recipe that demands a cup of butter. But you’re looking at a scale or a weirdly shaped European block instead of the standard American sticks. Now you’re stuck wondering how many ounces of butter in a cup because, let's be real, guessing leads to cookies that spread into oily pancakes.
The short, no-nonsense answer is 8 ounces.
But honestly? If you just go by that, you might still mess up your bake. Volume and weight are different beasts. One cup of butter is 8 ounces by weight (avoirdupois) and also happens to be 8 fluid ounces by volume. It's one of those rare, beautiful moments in the imperial system where things actually line up.
Why the Math Matters for Your Crust
Most people just grab two sticks of butter and call it a day. In the United States, that's exactly right. One stick is a half-cup, or 4 ounces. Two sticks equals 16 tablespoons, which is exactly one cup. But what happens if you’re using a tub of spreadable margarine? Or a high-fat Kerrygold block from Ireland?
Things get weird fast.
Weight is the only way to be certain. Professional bakers at King Arthur Baking or the folks over at America's Test Kitchen almost never talk in "cups" anymore. They talk in grams or ounces. Why? Because you can pack butter into a measuring cup and leave air pockets. Or you might use "cold" butter that doesn't settle, giving you less than you actually need. If your recipe is finicky—think puff pastry or a delicate sponge—those missing fractions of an ounce change the crumb structure entirely.
Let’s Break Down the Stick Situation
In the U.S., we have two main shapes of butter sticks. You’ve got the long, skinny ones (East Coast style) and the short, stubby ones (West Coast or "Western Stubby").
Regardless of the shape, the weight is the same. One stick is 4 ounces.
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- One stick = 1/2 cup = 4 ounces = 113 grams
- Two sticks = 1 cup = 8 ounces = 226 grams
- Half a stick = 1/4 cup = 2 ounces = 56.5 grams
If you're looking at a 1-pound box of butter, you're holding 16 ounces. That’s two cups. Basically, if a recipe asks for a cup of butter, you're using half of that entire box. It feels like a lot. It is a lot. That's why it tastes good.
The European Butter Curveball
Here is where I see people trip up. Have you ever bought those fancy gold-wrapped bricks of Kerrygold or Plugra? They don’t always come in 4-ounce sticks. Often, they come in 8-ounce blocks (which is exactly one cup) or even 250-gram blocks (which is about 8.8 ounces).
If you swap a 250g European block for a standard American "cup," you’re adding nearly an extra ounce of fat. In a cake, that extra fat might make the center sink. In a pie crust, it might make the dough too soft to handle. Always check the wrapper. Most high-end butters have measurement markings on the side of the foil, but they can be hard to read once the butter gets a little soft.
Fluid Ounces vs. Dry Ounces: A Source of Panic
Technically, butter is a solid, but we measure it like a liquid in the US.
A "cup" is a measure of volume. In the US, one cup is 8 fluid ounces. Since butter has a density very close to water, one cup of butter also weighs approximately 8 ounces on a scale.
This isn't true for everything. A cup of flour weighs about 4.25 ounces. A cup of lead would weigh... a lot more. But with butter, the "8 ounces in a cup" rule works for both weight and volume. It's a fluke of physics that makes our lives easier.
Melting Changes the Game (Sorta)
I've had people ask me if melted butter weighs less than solid butter.
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No.
Conservation of mass is a real thing. If you take 8 ounces of solid butter and melt it, you still have 8 ounces of butter. However, the volume can look different. When you melt butter, you might see some foam on top (water evaporating and milk solids separating). If you're measuring how many ounces of butter in a cup after melting it, just make sure you aren't losing half the butter to the sides of the saucepan or the microwave bowl.
Tips for the Perfect Measure
If you don't have a scale, you've got to be tactical.
- The Displacement Method: Fill a liquid measuring cup with 1 cup of water. Add chunks of butter until the water level hits 2 cups. Boom. You have exactly one cup of butter submerged. Pour off the water and you're ready. It's messy but accurate.
- The Pack and Level: If you’re using butter from a tub, use a dry measuring cup. Spoon it in. Press it down hard to get the air out. Level the top with a butter knife.
- The Scale (The Winner): Just buy a cheap digital scale. Seriously. Set it to ounces, put a piece of parchment paper on it, and slice until it reads 8.0.
Does it matter if the butter is salted?
Not for the weight. 8 ounces of salted butter weighs the same as 8 ounces of unsalted butter. But it matters for the flavor. Most sticks of salted butter contain about 1/4 teaspoon of salt per stick. So a full cup (8 oz) has about a half-teaspoon of salt. If you're using salted butter for a recipe that calls for unsalted, just leave out the extra salt the recipe asks for.
Why 8 Ounces is the Golden Number
In the world of professional baking ratios, the "Pound Cake" is the perfect example of why these numbers matter. A traditional pound cake used one pound each of flour, sugar, eggs, and butter.
That’s 16 ounces of each.
That’s 2 cups of butter.
If you're making a half-recipe, you need one cup. 8 ounces. If you get this wrong, the emulsion of fat and sugar won't hold the air bubbles created during creaming. Your cake will be heavy. It’ll be greasy. Nobody wants a greasy cake.
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Converting for International Recipes
If you're browsing a British cooking blog, they won't ask for "a cup" or "8 ounces." They'll ask for 225g or 250g.
- 8 ounces = 226.8 grams
Most Europeans just round this to 225g. If you see a recipe asking for 250g, that’s actually about 1.1 cups (or 8.8 ounces). Don’t just throw a standard cup in there and hope for the best. Use a scale or do the math. Those extra 25 grams represent about two tablespoons of butter, which is a significant difference in a batch of scones.
Real World Example: The Pie Crust Test
I recently tested a classic vodka pie crust recipe. The recipe called for 8 ounces of butter, chilled and cubed.
I measured one cup by "eye" using a tub of butter. Then I measured 8 ounces on a scale.
The "eye" cup was actually 7.2 ounces because of air gaps.
That 0.8-ounce difference made the dough crumbly and impossible to roll out. I had to add more liquid, which developed more gluten, which made the crust tough.
All because I didn't respect the 8-ounce rule.
Actionable Steps for Your Next Bake
Stop guessing. If you want to master your kitchen, follow these steps:
- Check your packaging first. Look for those 1-tablespoon markings. Remember that 8 tablespoons = 1/2 cup (4 oz) and 16 tablespoons = 1 cup (8 oz).
- Buy a digital kitchen scale. You can get a reliable one for under $20. It eliminates the "cup" debate entirely.
- Convert early. If your recipe is in cups, write "8 oz" next to it before you start. It keeps your brain focused.
- Temper your butter. If a recipe calls for a cup of "softened" butter, measure it while it's cold and firm. It's much easier to weigh or slice sticks when they are cold than when they are a mushy mess.
- Watch for "Whipped" butter. Never use whipped butter for baking unless the recipe specifically asks for it. Whipped butter is full of nitrogen or air. A "cup" of whipped butter weighs significantly less than 8 ounces. Your recipe will fail.
Knowing that there are 8 ounces in a cup of butter is the first step toward consistency. Whether you're making a roux for a gumbo or a batch of shortbread, that 8-ounce benchmark is your best friend in the kitchen.