Half of 1/3 Cup

Half of 1/3 cup in plain numbers

Half of 1/3 cup is 1/6 cup. That is the exact answer, and it is also the useless one, because almost nobody owns a 1/6 cup measure. So here is the same amount in units you can scoop:

• 1/6 cup = 2 tablespoons + 2 teaspoons
• 1/6 cup = 8 teaspoons
• 1/6 cup = 2 2/3 tablespoons
• 1/6 cup = 0.167 cup, or about 39 millilitres

Here is why it works out that cleanly. One cup is 48 teaspoons, so a third of a cup is 16 teaspoons. Half of 16 is 8. And since a tablespoon is 3 teaspoons, 8 teaspoons is 2 tablespoons plus 2 teaspoons. No rounding, no approximate, it is exact.

The rule for halving any fraction is simple: double the bottom number. Half of 1/3 is 1/6. Half of 3/4 is 3/8. Half of 2/3 is 2/6, which reduces to 1/3. You never touch the top number when you halve, you just double the denominator and then simplify if you can.

Worked example: halving a recipe that calls for 1/3 cup

Say a muffin recipe makes 12 and calls for 1/3 cup of oil. You want to make 6, so everything gets halved.

• Oil: 1/3 cup halved = 1/6 cup = 2 tbsp + 2 tsp
• Milk: 1 cup halved = 1/2 cup = 8 tbsp
• Sugar: 3/4 cup halved = 3/8 cup = 6 tbsp
• Flour: 1 1/2 cups halved = 3/4 cup = 12 tbsp
• Baking powder: 2 tsp halved = 1 tsp
• Egg: 1 large, beaten, use half, about 1 1/2 tbsp

Notice that every one of those is measurable with a standard set of spoons and cups. The only awkward item is the egg, and that is not a fraction problem, it is that eggs do not divide.

If you would rather not deal with the egg, there is a better answer for baked goods: make the full batch and freeze half. Muffins, cookies and quick breads all freeze well, and you avoid both the half-egg and the risk that halving the leavening throws off the rise. Halving works cleanly for sauces, soups and marinades; it is fussier for anything where baking powder or eggs are doing structural work.

Worked example: doubling a 1 1/2 cup batch

Now the opposite direction. A recipe calls for 1 1/2 cups of stock and you want to double it.

• Stock: 1 1/2 cups doubled = 3 cups
• Onion: 1 cup doubled = 2 cups
• Garlic: 2 cloves doubled = 4 cloves
• Tomato paste: 2 tbsp doubled = 4 tbsp (which is 1/4 cup)
• Salt: 1/2 tsp doubled = 1 tsp

Doubling whole and mixed numbers is easy, just multiply by two. The place people slip is with fractions that cross a boundary: 2 tbsp doubled is 4 tbsp, and 4 tbsp is exactly 1/4 cup, so it is cleaner to write it that way. Likewise 6 tbsp doubled is 12 tbsp, which is 3/4 cup.

One caution about doubling: salt, strong spices, alcohol and leavening do not always scale linearly. Most cooks double the salt and spices at about 1.5x rather than 2x, then adjust at the end. Baking powder is more sensitive, doubling a cake recipe and doubling the baking powder can leave a soapy taste, so it is often held to 1.75x. When in doubt, scale the base ingredients exactly and taste before you commit the seasonings.

Fractions to teaspoons: the table you need

Almost every kitchen fraction problem disappears if you convert to teaspoons, do the arithmetic, and convert back. Here is the reference table.

Keep three anchors in your head and you can rebuild the whole table: 1 cup = 16 tablespoons, 1 tablespoon = 3 teaspoons, and 1 cup = 48 teaspoons. From those, 1/3 cup is 16 teaspoons, 1/4 cup is 12 teaspoons, and 1/6 cup is 8 teaspoons.

The millilitre column is for metric measuring cups and scales. It is approximate because a US cup is 236.6 ml, not 250 ml, and because volume-to-millilitre conversions assume water. For anything you are weighing, trust the scale over the cup, see the next section on why. The National Institute of Standards and Technology publishes the official US customary volume definitions if you need the exact figures.

How to halve fractions without doing the math

There are three shortcuts that cover almost every case, and none of them require arithmetic in your head while your hands are covered in flour.

Shortcut one: double the bottom number. Half of 1/3 is 1/6, half of 3/4 is 3/8, half of 1/2 is 1/4. This works every time. If the result simplifies, half of 2/3 is 2/6, which is 1/3, simplify it at the end.

Shortcut two: convert to tablespoons first. Every cup fraction is a whole number of tablespoons except the thirds. 1/2 cup is 8 tbsp, 1/4 cup is 4 tbsp, 1/8 cup is 2 tbsp, 3/4 cup is 12 tbsp. Halving a whole number of tablespoons is easy: 8 becomes 4, 12 becomes 6. The only awkward ones are 1/3 and 2/3 cup, which land on 5 1/3 and 10 2/3 tablespoons.

Shortcut three: use the odd-number rule. If the number of tablespoons is odd, you will end up with a half-tablespoon, and half a tablespoon is 1 1/2 teaspoons. So 3 tbsp halved is 1 1/2 tbsp, which is 1 tbsp + 1 1/2 tsp. If it is even, you get a clean whole number.

When a recipe gives you grams or ounces instead of cups, none of this applies, you just divide the number. That is one of the real advantages of weighing ingredients, and it is why serious baking recipes are written in grams.

Measuring odd amounts without the right cup

Recipe calls for 1/6 cup and your smallest measure is 1/4? You have three good options, in order of preference.

Use tablespoons and teaspoons. This is the accurate method, because measuring spoons are calibrated and level. 1/6 cup is 2 tablespoons plus 2 teaspoons, and you can build almost any fraction that way. The table above gives you the breakdown for every common cup fraction.

Use a kitchen scale. This is the best method if the recipe lists weights, and it is the only method that works well when you are halving a recipe four times over. A scale to the nearest gram removes all the guesswork and, more importantly, all the accumulated error.

Eyeball it with a liquid measuring cup. If the amount is a liquid, fill a 1/3 cup measure and pour out half, but do it over a second cup and pour back what you do not need, rather than trying to judge the midpoint in a curved glass. For oil and water this is fine. For anything thick like honey or tomato paste, the residue left in the cup makes it inaccurate, so use spoons instead.

What you should not do is halve by eyeballing the dry measuring cup and hoping. Cup measures are designed to be filled level to the rim; a fraction of the cup is not marked, and people are consistently 20 to 30% off when they guess.

Weight beats volume when you halve a recipe

Here is the single biggest improvement you can make to recipe halving: stop measuring by volume for dry ingredients and start weighing them. The reason is that volume measures are inconsistent by nature, how much flour is in a cup depends on whether you scooped it, spooned it or packed it, and the same cup can hold 120 grams or 160 grams of all-purpose flour depending on technique.

That 25% swing is far larger than any error you would make halving a fraction. So a recipe that calls for 1/3 cup of flour and gets halved to 1/6 cup is somewhere between 20 and 27 grams, depending on how you filled the cup, which means the precision of your fraction arithmetic was never the limiting factor.

The fix is to convert once and then work in grams. Standard weights worth memorising: all-purpose flour is about 120 g per cup, granulated sugar about 200 g, brown sugar packed about 220 g, butter 227 g per cup (or 113 g per stick), and water 237 g per cup. Halving 120 grams gives 60 grams exactly, on any scale, every time.

For food safety rather than precision, the USDA Food Safety and Inspection Service and the FDA both publish guidance on measuring, storing and handling ingredients, worth a look if you are scaling up a batch for a crowd or freezing the extra.