Half of 2/3 Cup

Half of 2/3 cup in plain numbers

Half of 2/3 cup is 1/3 cup. That is the exact answer, and it happens to be the easy one, because a third of a cup is marked on every standard measuring cup set. If your set is missing it, here is the same amount in units you can scoop:

• 1/3 cup = 5 tablespoons + 1 teaspoon
• 1/3 cup = 16 teaspoons
• 1/3 cup = 5 1/3 tablespoons
• 1/3 cup = 0.333 cup, or about 79 millilitres

The arithmetic behind that is short. One cup holds 48 teaspoons, so 2/3 cup holds 32. Half of 32 is 16. Since one tablespoon is 3 teaspoons, 16 teaspoons is 5 tablespoons plus 1 teaspoon. Nothing is rounded and nothing is estimated.

The rule for halving any fraction is to double the bottom number and leave the top one alone. Half of 2/3 is 2/6, and 2/6 reduces to 1/3. The same rule turns half of 3/4 into 3/8 and half of 1/2 into 1/4. Once you know the rule, you stop reaching for a chart.

Worked example: halving a sauce that calls for 2/3 cup

A stir-fry sauce calls for 2/3 cup of soy sauce and serves 4. You are cooking for 2, so the whole recipe gets halved.

• Soy sauce: 2/3 cup halved = 1/3 cup = 5 tbsp + 1 tsp
• Rice vinegar: 1/4 cup halved = 1/8 cup = 2 tbsp
• Brown sugar: 3 tbsp halved = 1 tbsp + 1 1/2 tsp
• Sesame oil: 2 tsp halved = 1 tsp
• Cornstarch: 1 tbsp halved = 1 1/2 tsp
• Garlic: 2 cloves halved = 1 clove

Every item on that list is measurable with the spoons in a standard set. The only thing that does not divide cleanly is the garlic clove, and a small clove is close enough for a sauce. Notice how the awkward 2/3 cup became the easy 1/3 cup, and the 1/4 cup became 2 tablespoons, a spoon measure rather than a cup measure.

If you would rather not think in fractions at all, do the halving in tablespoons. Two thirds of a cup is 10 2/3 tablespoons, and half of that is 5 1/3 tablespoons, which is 5 tablespoons plus 1 teaspoon. Working in the smaller unit keeps the numbers whole and takes the guesswork out of it.

Worked example: doubling and thirding 2/3 cup

The same 2/3 cup shows up when you scale up or down. Here is what happens at the other common multipliers.

• 2/3 cup doubled = 1 1/3 cups (1 cup + 5 tbsp + 1 tsp)
• 2/3 cup tripled = 2 cups, exactly
• 2/3 cup cut in thirds = 3 tbsp + 1 2/3 tsp (about 2/9 cup)
• 2/3 cup cut in quarters = 8 tsp (about 1/6 cup)

Tripling 2/3 is the cleanest of the group, because three times two thirds is six thirds, which is exactly 2 cups. Doubling is a little messier at 1 1/3 cups, but you can build it as one full cup plus 5 tablespoons plus 1 teaspoon with no special measure.

Cutting 2/3 cup into thirds is the one that trips people up. One third of 2/3 cup is 2/9 cup, and that comes out to about 3 tablespoons plus 1 2/3 teaspoons. Convert to teaspoons before you divide: 2/3 cup is 32 teaspoons, a third of 32 is 10.67, and 10.67 teaspoons is 3 tablespoons plus 1 2/3 teaspoons. The fractions look ugly, the measuring does not.

Cup fractions in tablespoons and teaspoons

Almost every recipe-scaling question gets easier once you convert the cup fraction to teaspoons. Here is the reference table for the fractions that come up most often.

Three anchors rebuild the whole table: 1 cup is 16 tablespoons, 1 tablespoon is 3 teaspoons, and 1 cup is 48 teaspoons. From those, 2/3 cup is 32 teaspoons, 1/3 cup is 16 teaspoons, and 1/6 cup is 8 teaspoons.

The millilitre column is approximate, because a US cup is 236.6 ml rather than a round 250 ml, and volume-to-millilitre figures assume water. The National Institute of Standards and Technology publishes the official US customary volume definitions if you want the exact values. For anything you can weigh, a scale beats a cup every time.

Why thirds are the awkward fraction in the kitchen

Halves, quarters and eighths are easy because the numbers stay whole. A half cup is 8 tablespoons, a quarter cup is 4, an eighth cup is 2. Thirds are the odd ones out: a third of a cup is 5 1/3 tablespoons, and that repeating third is what makes 2/3 cup feel hard even though the arithmetic is identical to halving 1/2 cup.

The fix is to stop thinking in cups for a moment. Convert to teaspoons, divide there, and convert back only if you need to. Two thirds of a cup is 32 teaspoons. Half of it is 16. A third of it is 10.67, which you round to 10 2/3 teaspoons or write as 3 tablespoons plus 1 2/3 teaspoons. The number stays manageable because teaspoons are small.

Measuring spoons usually come in 1 tablespoon, 1/2 tablespoon, 1 teaspoon, 1/2 teaspoon and 1/4 teaspoon. That set can build any of these amounts to the nearest quarter teaspoon, which is finer than the accuracy of the cup measure you would have used anyway. Nobody notices a quarter teaspoon in a sauce, and most recipes have more slack than cooks assume.

Weigh it instead: the reliable way to halve 2/3 cup

Volume measures are inconsistent by design. How much all-purpose flour sits in a 2/3 cup depends on whether you scooped it from the bag, spooned it in, or packed it down, and the same cup can hold anywhere from 80 to 100 grams. That swing is wider than any rounding you would introduce by halving a fraction, which means the fraction was never the real source of error.

If you own a kitchen scale, convert once and work in grams. Useful anchors: all-purpose flour is about 120 grams per cup, granulated sugar about 200 grams, brown sugar packed about 220 grams, butter 227 grams per cup, and water 237 grams. So 2/3 cup of flour is about 80 grams and half of it is 40 grams, on any scale, every time.

For the storage side of scaling a recipe, the USDA Food Safety and Inspection Service and the FDA both publish guidance worth a look, especially if you plan to freeze half the batch for later.