One tablespoon of cornstarch weighs 7 g (spooned and levelled, King Arthur Baking). Cornstarch is one of the lightest ingredients in the kitchen by the spoonful — a tablespoon weighs less than half a tablespoon of sugar — because it is an extremely fine, fluffy powder that traps a lot of air. That lightness is deceptive: cornstarch is also one of the most powerful thickeners you will ever use, and a single tablespoon can thicken a whole cup of liquid. The figure matters whenever you are thickening a sauce, a pie filling or a custard, and when you are converting a recipe between volume and weight. All weights on this page are approximate; cornstarch settles in the box, so verify with a scale when precision matters.
How much does 1 tablespoon of cornstarch weigh?
One level tablespoon of cornstarch weighs 7 g, spooned and levelled, according to King Arthur Baking. That is the headline number, but a single tablespoon is rarely the whole story — most recipes use several spoonfuls, or a fraction of a cup, so the table below gives the weights you will actually reach for, from a teaspoon up to a full cup. Every figure is derived from the same source value of 112 g per cup, so the whole table is consistent. Treat all of these as approximate: spooned and levelled is a technique, not a machine setting, and two cooks measuring the same ingredient can differ by a gram or two per spoonful. When the recipe matters, weigh the ingredient on a kitchen scale instead.
| Amount | Weight (approx.) |
| --- | --- |
| 1 teaspoon | 2.3 g |
| 1 tablespoon | 7 g |
| 2 tablespoons | 14 g |
| 3 tablespoons | 21 g |
| 1/4 cup (4 tbsp) | 28 g |
| 1/2 cup (8 tbsp) | 56 g |
| 3/4 cup (12 tbsp) | 84 g |
| 1 cup (16 tbsp) | 112 g |
A useful rule of thumb: there are 3 teaspoons in a tablespoon and 16 tablespoons in a cup, so you can move between any of these measures by multiplying or dividing. If a recipe calls for 2 teaspoons and you only have a tablespoon measure, that is two-thirds of a tablespoon — about 4.7 g. If a recipe calls for a quarter cup and you only have a tablespoon, that is 4 level tablespoons. Keep the tablespoons to grams converter open while you cook and you will never need to do the arithmetic in your head.
Worked examples
Thickening a stir-fry sauce
A stir-fry sauce for four uses 1 tablespoon of cornstarch — 7 g — mixed with 2 tablespoons of cold water to make a slurry, then stirred into the pan. The weight matters because cornstarch's thickening power is so concentrated: 7 g thickens about 250 ml of sauce to a glossy coating consistency, and doubling it to 14 g turns the same sauce into a jelly. Making the slurry first is essential — cornstarch added directly to hot liquid clumps instantly into lumps that never dissolve. Weighing 7 g also lets you scale the sauce: a double batch needs 14 g, and a half batch needs 3.5 g, which is half a tablespoon.
A lemon pie filling
A lemon meringue pie filling uses 4 tablespoons of cornstarch — about 28 g — to set 1 cup of lemon juice, 1 cup of sugar and 3 egg yolks into a sliceable filling. The weight is critical here because the filling's set depends on the exact starch-to-liquid ratio: too little cornstarch and the filling weeps and slides off the crust, too much and it turns rubbery and opaque. Weighing 28 g is far more reliable than spooning, because cornstarch is so light that a heaped tablespoon can weigh 10 g instead of 7 g — a 40 percent overdose that shows in the texture. The filling is cooked until it bubbles for a full minute, which is what activates the starch completely.
Lightening a sponge cake
A sponge cake recipe replaces 2 tablespoons of the flour with 2 tablespoons of cornstarch — about 14 g — to give the crumb a finer, more tender texture. Cornstarch has no gluten, so it dilutes the flour's protein and produces a softer cake, which is why it is a common trick in cakes that need to be delicate. The weight matters because the swap is small: 14 g of cornstarch against 240 g of flour is a subtle change, and getting it wrong by a tablespoon either way either does nothing or makes the cake gummy. Weighing the cornstarch keeps the substitution precise and the result consistent.
How to measure a tablespoon of cornstarch correctly
Cornstarch is measured spooned and levelled, and the technique matters because the powder is so light that it compresses easily. Spoon it into the tablespoon with a smaller spoon, letting it fall loosely, then sweep a knife across the top without pressing down. Never dip the tablespoon into the box — dipping packs the powder and can add 30 percent to the weight. Never tap the spoon to settle it, for the same reason. For sauces and fillings, weighing is better: tare a small bowl, add the cornstarch to the target weight, and mix it with cold water before it touches anything hot. The King Arthur figure of 7 g per tablespoon assumes cornstarch at room temperature, spooned and levelled; cornstarch that has been sitting in a humid kitchen can absorb moisture and weigh slightly more, so keep the box sealed and store it in a dry cupboard.
When the weight matters most
Cornstarch's tablespoon weight matters most in sauces and pie fillings, where it is doing structural work at very small quantities. A tablespoon is the difference between a sauce that coats the back of a spoon and one that runs off the plate, and between a pie filling that slices cleanly and one that floods the plate. Because cornstarch is so light, spoon measures are unusually error-prone — a heaped tablespoon can be 10 g, a level one 7 g, and that 3 g gap is a 40 percent error in a recipe that only uses one tablespoon. The weight also matters for gluten-free baking, where cornstarch is used to lighten flour blends, and for frying, where a tablespoon of cornstarch in a batter makes the coating crisper. In all of these uses, the scale turns a fiddly, inaccurate spoon measure into a single reliable number.
Common mistakes to avoid
The most common mistake is adding cornstarch directly to hot liquid, where it clumps into lumps that never dissolve. Always mix it with cold water first to make a slurry, then stir the slurry into the hot liquid. The second mistake is confusing cornstarch with cornflour: in the UK, cornflour is the same as cornstarch, but in the US, corn flour is finely ground cornmeal, which is a completely different ingredient. Check which one your recipe means. The third mistake is overcooking a cornstarch-thickened sauce: prolonged boiling breaks the starch down and thins the sauce again, so cook it just until it bubbles and thickens, then take it off the heat. Finally, do not use cornstarch to thicken a sauce that will be frozen — it turns spongy and weeps on thawing. Use flour or tapioca starch for freezer sauces instead.
Frequently asked questions
How many grams is 1 tablespoon of cornstarch?
One tablespoon of cornstarch weighs 7 g, spooned and levelled, according to King Arthur Baking. One teaspoon weighs about 2.3 g. These are approximate weights — cornstarch compresses easily, so weigh it for the most accurate result.
How many tablespoons of cornstarch are in 100 g?
There are about 14 tablespoons in 100 g of cornstarch (100 divided by 7 is 14.3). A standard 250 g box holds about 36 tablespoons.
Can I use flour instead of cornstarch?
Yes, but use twice as much. One tablespoon of cornstarch thickens about as much as 2 tablespoons of flour. Flour also makes sauces cloudy and needs longer cooking to lose its raw taste, while cornstarch gives a clear, glossy finish. For a clear sauce, cornstarch is the better choice.
Why did my sauce go lumpy when I added cornstarch?
Cornstarch clumps instantly in hot liquid. Always mix it with a little cold water first to make a smooth slurry, then stir the slurry into the hot sauce while whisking. If lumps have already formed, strain the sauce through a fine sieve.
Does cornstarch go bad?
Cornstarch keeps indefinitely in a cool, dry cupboard, sealed tightly. It does not spoil, but it absorbs moisture and odours, so keep it away from strong smells and humidity. Discard it if it smells musty or has clumped into hard lumps.
Related conversions
If you cook with this ingredient regularly, these pages will help: the tablespoons to grams converter for any amount, the cups to grams converter for larger quantities, and the full ingredient guide for storage, substitutes and the weight of a whole cup. You can also compare the cup weight on the Cornstarch cups to grams page or work backwards from a gram amount on the Cornstarch grams to cups page.
You may also want Cornmeal tbsp to grams, Baking Powder ingredients, Cornstarch cups to grams and Cornstarch grams to cups.