How Many Ounces In 1 3 Cup Butter? | Kitchen Math Made Easy

1/3 cup of butter equals about 2.67 fluid ounces, or 2.67 ounces by weight — a measurement often rounded to 2.7 ounces for practical cooking.

You pull out a recipe that asks for 1/3 cup of butter. Your measuring cup only shows ounces. A quick glance at the butter wrapper tells you it has tablespoon marks, but ounces? That’s a different story. It’s one of those small kitchen math moments that can stall prep, especially if you’re juggling multiple ingredients.

Here’s the honest answer: 1/3 cup of butter is roughly 2.7 ounces, whether you measure it by fluid volume or by weight. For most recipes, that rounding won’t throw anything off. This article walks through the exact math, the common confusion between sticks and cups, and a few practical ways to measure without breaking out a calculator.

The Quick Answer: 1/3 Cup Butter in Ounces

One standard US cup holds 8 fluid ounces. Divide that by 3, and you land at 2.6667 fluid ounces. For butter, fluid ounces and weight ounces are effectively the same because butter has a similar density to water — one cup of butter weighs 8 ounces on a scale.

So the conversion is straightforward: 1/3 cup of butter = approximately 2.67 ounces (or 2.7 ounces rounded). That number works whether you’re using a liquid measuring cup or a kitchen scale.

If you’re working with grams, 1/3 cup of butter comes to about 76 grams. In milliliters, it’s roughly 80 mL. These are handy benchmarks if your recipe uses metric measurements.

Why Butter Measurements Confuse Even Experienced Bakers

Butter packaging in the US follows a stick system, not a cup system. One standard stick equals 1/2 cup or 8 tablespoons. So 1/3 cup doesn’t line up neatly with a single stick mark. This mismatch trips up plenty of home cooks.

Here’s how butter’s common measurements break down:

• 1 stick of butter: 1/2 cup, 8 tablespoons, 4 ounces, 113 grams.
• 1/2 stick of butter: 1/4 cup, 4 tablespoons, 2 ounces, 57 grams.
• 1/3 cup of butter: About 5 tablespoons plus 1 teaspoon, or 2.7 ounces, or 76 grams.
• 1/8 cup of butter: 2 tablespoons, 1 ounce, 28 grams.
• 1 cup of butter: 2 sticks, 8 ounces, 227 grams.

The key is remembering that sticks are marked in tablespoons, not ounces or cups. Once you know a stick has 8 tablespoons, you can calculate that 1/3 cup (which is 5 1/3 tablespoons) lands just past the 5-tablespoon mark on the wrapper.

The Math Behind the Conversion

The core formula is simple: 1 cup equals 8 fluid ounces. Multiply 8 by 1/3, and you get 8/3, which is 2.6667. That decimal repeats, so rounding to 2.67 or 2.7 is standard in recipe writing.

For example, CK12 breaks down the math on its page about ounces in 1/3 cup, confirming the standard conversion you’ll see across cooking resources. Their calculation uses slightly different rounding, but the practical difference is negligible.

Here’s a quick-reference conversion table for common butter amounts:

Notice that ounces and grams increase linearly, so you can scale this table up or down easily. If a recipe calls for 2/3 cup, just double the 1/3 cup row: 5.33 ounces or about 152 grams.

How to Measure 1/3 Cup of Butter Without a Scale

Not everyone owns a kitchen scale, but you can still get an accurate 1/3 cup of butter. Here are three reliable methods, from easiest to most precise.

1. Use the tablespoon marks on the wrapper. One stick has 8 tablespoon lines. Cut at the 5 1/3 mark (between the 5th and 6th lines) for roughly 1/3 cup. The extra 1/3 tablespoon is small enough that you can eyeball it.
2. Use water displacement. Fill a liquid measuring cup with 2/3 cup of cold water. Add butter pieces until the water level reaches 1 cup. Drain the water, and you’re left with exactly 1/3 cup of butter. This method works for any irregular amount.
3. Use a tablespoon measure. Scoop out 5 level tablespoons, then add 1 level teaspoon. That’s the exact equivalent of 1/3 cup.

The water displacement trick is especially handy if your butter is in a block rather than sticks, or if it’s partially used. It’s also a lifesaver for shortening or cream cheese.

Butter Weight vs. Volume: Why It Matters

Weight and volume can diverge for ingredients like flour or brown sugar, but butter behaves nicely. Per the butter weight equals fluid ounces explanation on 100Daysofrealfood, one cup of butter weighs 8 ounces, matching its fluid volume. This consistency makes butter one of the easiest ingredients to convert between volume and weight.

Still, a kitchen scale gives you the most repeatable results, especially if you bake often. Room temperature, how firmly you pack a cup, and even the butter’s water content can shift volume slightly. Weight eliminates those variables.

Here’s how butter compares to other common baking fats:

Butter’s density is close to water, so its volume and weight align almost perfectly. That’s not true for most other fats, which is why measuring by weight is often recommended for precision baking.

The Bottom Line

Remember this: 1/3 cup of butter equals 2.7 ounces, 76 grams, or 5 1/3 tablespoons. The math is simple — 8 ounces per cup divided by 3 — and the measurement is consistent whether you use a liquid cup, dry cup, or scale. For most recipes, rounding to 2.7 ounces won’t make a measurable difference.

Next time your recipe calls for 1/3 cup of butter, grab a stick and slice at the 5 1/3 tablespoon mark, or set your scale to 2.7 ounces. Your cookies will bake up just as intended, no calculator required.