Powdered Sugar Cups to Grams

How many grams in a cup of powdered sugar

One US cup of powdered sugar weighs about 120 grams when you spoon it into the cup and level it off. That is the number most US recipe charts use, and it is the default in the calculator above. In ounces it is about 4.2 oz, and in tablespoons a cup is 16, so 1 tablespoon is about 7.5 grams.

The number is not fixed, because powdered sugar holds a lot of air. The same cup can weigh 100 grams or 155 grams depending on how it was handled. The table below shows the three common cases.

Pick the row that matches what you did. If you scooped straight from the bag with the measuring cup, you packed it, so use the 150 gram row. If you spooned it in and swept off the top, use 120 grams. If you sifted it, use 100 grams.

Why a cup of powdered sugar weighs so little

Weight per cup comes down to density, or how much sugar fits in the same space. Powdered sugar is ground into particles far smaller than the grains in granulated sugar, and a little cornstarch is blended in to keep it from caking. Those fine particles settle with more air between them, so a cup holds less actual sugar.

The gap is large. A cup of granulated sugar weighs about 200 grams, and a cup of packed brown sugar can reach 213 grams. Powdered sugar comes in at about 120 grams, roughly 40% lighter than granulated for the same volume. That is why a frosting recipe that looks like it uses a huge pile of sugar still balances with only a small amount of liquid.

This is also why measuring powdered sugar by volume is the least reliable measure in baking. The spread from 100 to 155 grams is more than 50%, which is enough to turn a smooth frosting stiff or runny. A scale removes the guesswork, and the USDA FoodData Central database lists weights for confectioners' sugar if you want the source figures. The FDA labeling rules are the reason the box lists net weight in grams, which is the number to trust over any cup chart.

Worked example: buttercream for a two layer cake

Say a buttercream recipe calls for 4 cups of powdered sugar and you want to weigh it. Using the 120 gram figure, 4 cups is 4 times 120, which is 480 grams. That is about 16.9 ounces, a little over 1 pound.

Now check the other ingredients the same way.

• 1 cup butter, 227 grams
• 4 cups powdered sugar, 480 grams
• 2 tablespoons milk, about 30 grams
• 1 teaspoon vanilla, about 4 grams

The ratio that matters is sugar to butter. Here it is 480 to 227, close to 2 to 1, which gives a medium buttercream. Add 60 grams more sugar, half a cup, and the frosting stiffens enough for piping. Add 30 grams of milk and it loosens for a crumb coat.

If you had measured by scooping and packed the sugar, your 4 cups could have weighed 600 grams instead of 480. That extra 120 grams is a full cup of sugar, and it would make the frosting far too stiff. Weighing the sugar is the single step that keeps the result the same every time.

Cups to grams for common amounts

This table covers the amounts that come up most in frosting, glaze and dusting recipes. The grams use the spooned and leveled figure of 120 grams per cup.

Read down the grams column when your scale is set to grams, and across to ounces if you are using an older recipe. For sifted sugar, take 20% off the grams. For packed sugar, add about 25%.

Sifted, spooned or packed: which number to use

The single biggest mistake with powdered sugar is mixing up sifted and unsifted numbers. Recipes written in grams almost always mean unsifted, spooned and leveled, which is the 120 gram cup. Recipes that say "1 cup sifted powdered sugar" mean you sift first, then measure, which lands near 100 grams.

Here is how to read the three cases.

• Sifted, then measured: about 100 g per cup. Use this when the recipe says "sifted powdered sugar".
• Spooned and leveled: about 120 g per cup. This is the default for most charts and the safest general number.
• Packed: about 150 g per cup. This happens when you scoop with the cup itself.

When a recipe gives both cups and grams, trust the grams. They were written to match the exact batch the recipe writer tested. When a recipe gives only cups, spoon the sugar into the cup, level it with a straight edge, and use 120 grams per cup as your conversion.

Measuring powdered sugar without a scale

If you do not own a scale, you can still get close. Fluff the sugar with a fork first to break up lumps. Spoon it into the measuring cup rather than scooping with the cup, then sweep the top level with the back of a knife. Do not tap the cup on the counter, since that settles the sugar and adds weight.

For small amounts, spoons are more accurate than cups. One tablespoon is about 7.5 grams and one teaspoon is about 2.5 grams. A recipe that needs 15 grams is easier to hit with 2 tablespoons than with an eighth of a cup.

A basic digital scale costs little and pays for itself the first time a frosting comes out right. Weigh the bowl first, note the number, then add sugar until the total rises by the amount you need. That method works for every ingredient in the recipe, not just the sugar.