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Recipe Halving, Doubling, and Thirding Chart

Half, double, and a third of common cup and tablespoon amounts, using the same multiply and the same fraction list as the recipe scaler.

Paste a whole ingredient list into the Recipe Scaler when you want every line rewritten. The charts below are that scaler, run on the amounts people look up one at a time. Where the printed fraction is a snap, the cell says so and gives the exact product.

What "half," "double," and "a third" mean on this page

The scaler's factor is desired servings ÷ original servings. Every leading amount is multiplied by that factor.

• Half is a factor of 0.5. Original servings 2 and desired servings 1. Or 4 and 2.
• Double is a factor of 2. Original 1 and desired 2. Or 4 and 8.
• A third is a factor of 1/3. Original 3 and desired 1. Do not type 0.33 as the desired servings if you want exactly one third. 0.33 ÷ 1 is 0.33, which is close to 1/3 and not the same number.

The line has to start with the amount. "2 cups flour" scales. "Flour 2 cups" does not, because the parser looks for a leading number. A mixed number needs a space: "1 1/2" is one and a half. "11/2" is eleven halves. Type 1/2 with a slash. A single-character fraction glyph may not be read as a number.

How the scaler prints a fraction

After the multiply, the tool splits the result into a whole number and a remainder. It then picks the closest entry from a short list, and only if that entry is within 0.04 of the remainder:

0, 1/8 (0.125), 1/4 (0.25), 1/3 (0.333), 3/8 (0.375), 1/2 (0.5), 5/8 (0.625), 2/3 (0.667), 3/4 (0.75), 7/8 (0.875).

The 1/3 key in the code is the number 0.333, and the 2/3 key is 0.667. A true one third (0.333…) and a true two thirds (0.666…) land inside 0.04 of those keys, so they print as 1/3 and 2/3. If nothing is within 0.04, the tool prints two decimal places. That is why 1/6, which is about 0.1667, prints as 0.17: the distance to 1/8 is about 0.042, just outside the 0.04 window.

Two products fall inside the window and are not the fraction they print as. A third of 1/3 is 1/9 (about 0.111), and 0.111 is within 0.04 of 0.125, so the scaler prints 1/8. A third of 2/3 is 2/9 (about 0.222), which is within 0.04 of 0.25, so the scaler prints 1/4. The tables mark those cells. Use the exact fraction, or weigh the ingredient, when that gap matters. The Cooking Measurement Converter is the page that turns a cup into grams for the ingredients it knows.

Cups: half, double, and a third

The tablespoon figures use the cooking converter's US volume sizes: 3 teaspoons in a tablespoon, 2 tablespoons in a fluid ounce, 8 fluid ounces in a cup, so 16 US tablespoons in a US cup. They convert the exact product, not a snapped print. Half a cup is 8 tablespoons on that page, and the same 16-to-1 ratio is used for the rest.

Half of 3/4 cup is the clean row: 0.75 × 0.5 = 0.375, which is exactly 3/8, and 3/8 × 16 = 6 tablespoons. Double 2/3 cup is 4/3, which the list prints as 1 1/3. A third of 3/4 cup is exactly 1/4, so the scaler and the tablespoon count agree: 4 tablespoons. A third of 1/2 cup does not get a friendly fraction on the scaler. The exact answer is 1/6 cup, and 1/6 × 16 = 8/3 tablespoons, which is 2 and 2/3. The printed 0.17 cup is the two-decimal fallback, not a new measurement. Converting 0.17 × 16 gives 2.72 tablespoons, which is the rounded print, not 2 and 2/3. Convert the exact fraction.

The two snaps to watch are a third of 2/3 cup and a third of 1/3 cup. The scaler will say 1/4 cup and 1/8 cup. Those are the nearest names on the list, not the products. 2/9 cup is 3 and 5/9 tablespoons. 1/9 cup is 1 and 7/9 tablespoons. If the ingredient is baking powder, salt, or anything else you measure in a small spoon, the gap between the snap and the exact product is large enough to measure. Weigh it, or use the exact fraction.

Tablespoons: half, double, and a third

These rows are already in tablespoons. The scaler multiplies the number and prints with the same list. It does not convert the tablespoon into teaspoons. Four US tablespoons are one quarter cup, because 4 × 14.78676478125 milliliters equals one quarter of 236.5882365 milliliters. The 4 tablespoon row and the 1/4 cup row are the same volume.

A third of 3 tablespoons is exactly 1 tablespoon. A third of 2 tablespoons is exactly 2/3 tablespoon, and the 0.667 key catches it, so the scaler prints 2/3. Half of 1 tablespoon is 1/2. Those rows do not need a footnote. A third of 1/3 tablespoon is the same snap as a third of 1/3 cup: the scaler says 1/8, and the exact product is 1/9.

A short list, scaled three ways

The scaler's own example style is one ingredient per line, amount first. Here is that shape for a factor you can check against the chart. Original servings 2, desired servings 1, which is half:

• 2 cups flour becomes 1 cup flour.
• 3/4 cup sugar becomes 3/8 cup sugar.
• 2/3 cup milk becomes 1/3 cup milk.
• 1/2 cup butter becomes 1/4 cup butter.
• 1/3 cup oil becomes 0.17 cup oil. Exact is 1/6 cup.
• 1 tbsp vanilla becomes 1/2 tbsp vanilla.
• 3 eggs becomes 1 1/2 eggs. The scaler prints the half egg. Beating one egg and using half the volume is a kitchen step, not a second formula.

Double is original 2 and desired 4. The 2/3 cup line becomes 1 1/3 cups. The 1/3 cup line becomes 2/3 cup. A third of the same list is original 3 and desired 1. The 3/4 cup line becomes 1/4 cup. The 2/3 cup line prints as 1/4 cup and is really 2/9 cup. The 1/2 cup line prints as 0.17 cup and is really 1/6 cup.

A line with no leading amount, such as "salt and pepper to taste," comes back with a note that no amount was detected. Leave it unscaled and taste the dish. The scaler will not invent a quantity for a header.

What the chart does not change

The tool multiplies numbers. It does not convert cups to grams, does not change the oven, and does not rewrite the method or the minutes. A doubled soup in a larger pot can still need a different simmer than the original, even when every amount doubled cleanly. Yeast doughs change fermentation time as well as weight. The ingredient multiply is the start of that process, not the schedule.

Cups of flour are already a soft measure. The cooking measurement myths piece is about why a cup of flour is not one weight. If the recipe gives grams, scale the grams. The factor is the same. The unit is just honest.

A different pan is a different multiply. Floor area, not servings, is the Cake Pan Size Converter, and the pairs are written out on the baking pan conversion chart. Do the pan factor and the serving factor as two steps. They match only when the new pan holds the new yield at the original depth. Temperature, if the book and the oven disagree, is the Oven Temperature Converter.

Write the new serving count on the card. Scaling a recipe that was already doubled doubles it again. The original servings box should be the yield of the list you are looking at, not the yield of the card you started from last year.

FAQ

What is half of 3/4 cup?

3/8 cup. At 16 US tablespoons per US cup, from the cooking measurement converter, that is 6 tablespoons. The recipe scaler prints 3/8.

What is double 2/3 cup?

1 1/3 cups. The scaler prints 1 1/3. That is 2 times 2/3.

What is a third of 1/2 cup?

Exactly 1/6 cup, which is 2 and 2/3 tablespoons at 16 tablespoons per cup. The scaler does not have 1/6 on its fraction list, so it prints 0.17.

Why does a third of 1/3 cup show up as 1/8?

Because 1/9 is about 0.111, and the scaler snaps a remainder to 1/8 when it is within 0.04 of 0.125. The exact third of 1/3 is 1/9, not 1/8. Use 1/9, or weigh the ingredient, when the difference matters.

Does halving change the oven temperature?

No. The scaler multiplies the amounts at the start of each ingredient line. It does not change degrees or minutes.

Related

• Recipe Scaler to rewrite a full ingredient list
• Baking pan conversion chart when the pan changed, not the headcount
• Cooking Measurement Converter for cups, tablespoons, and grams
• Fraction, Decimal, and Percent Converter
• Cooking measurement myths

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