1 Cup Corn Syrup in Grams
1 cup of corn syrup weighs 312 g (poured, King Arthur Baking). Glucose syrup that stays liquid and prevents crystallisation. All the figures on this page are approximate conversions based on the King Arthur Baking value, so when a recipe really matters, verify with a kitchen scale.
Corn syrup is a thick glucose syrup that stays liquid and stops other sugars from crystallising, which makes it a quiet workhorse of candy making, pecan pie filling and frostings. A cup weighs 312 g, poured, and it is nearly as heavy as maple syrup at the same volume. Its job is rarely to sweeten on its own: it is there to keep caramel smooth, to give pecan pie its gooey set, and to keep frostings soft instead of crusty. It is not the same as high-fructose corn syrup, which is a different product made by a different process, and the two should not be confused.
Cups lie: why corn syrup should be weighed
Sugar looks like the easiest ingredient to measure in cups, because the crystals pour cleanly and level neatly, but the weight per cup still varies a lot between types. A cup of granulated sugar weighs about 198 g, a cup of powdered sugar about 113 g, and a cup of packed brown sugar about 213 g, so swapping one sugar for another cup-for-cup changes the sweetness and the structure of a bake by a large margin. Sugar does more than sweeten: it holds moisture, tenderises crumb, feeds yeast, helps browning and sets the texture of everything from meringues to caramel. Getting the weight right is what keeps a cake moist instead of dry, a meringue crisp instead of weeping, and a jam setting instead of running. Because sugar dissolves, small errors are forgiving in drinks and sauces, but in baking they are not.
Worked examples
A pecan pie that needs 1 cup
A classic pecan pie filling asks for 1 cup of corn syrup, which is 312 g, whisked with eggs, sugar and butter and poured over pecans. The syrup is what makes the filling set into a soft, gooey layer rather than crystallising into grainy sugar as it cools. Measure it in a liquid jug at eye level, and wipe the jug with a little oil first so the syrup slides out cleanly instead of leaving a thick film behind.
Caramel that stays smooth
A caramel that calls for 1/2 cup of corn syrup needs 156 g, added to the sugar and water before the pot goes on the heat. The syrup interferes with the sugar crystals as they form, which keeps the caramel smooth and clear instead of grainy. Weigh or measure the syrup carefully, because too little and the caramel may still crystallise, and too much and it stays soft and will not set.
A glossy frosting
A buttercream or a glaze that uses 1/4 cup of corn syrup needs 78 g, and the syrup is there to keep the frosting soft and to give it a gentle shine. It also stops the sugar in the frosting from crystallising on the surface as it dries, which is why bakery frostings stay smooth for days. Scrape the measuring cup with a spatula to get every drop into the bowl, because corn syrup clings to everything it touches.
Corn Syrup cups to grams conversion table
| Cups | Grams | Tablespoons |
|---|---|---|
| 1/4 cup | 78 g | 4 |
| 1/3 cup | 104 g | 5.3 |
| 1/2 cup | 156 g | 8 |
| 2/3 cup | 208 g | 10.7 |
| 3/4 cup | 234 g | 12 |
| 1 cup | 312 g | 16 |
| 1 1/2 cups | 468 g | 24 |
| 2 cups | 624 g | 32 |
| 3 cups | 936 g | 48 |
| 4 cups | 1248 g | 64 |
One tablespoon of corn syrup weighs about 19.5 g, and a cup is 16 tablespoons, so the tablespoon column is simply the cup weight divided by 16. For small amounts, a scale that reads to the gram is far more reliable than a spoon, because a heaped tablespoon can weigh half as much again as a level one. All the values in this table are approximate, and they assume the ingredient is measured poured, exactly as the source measured it.
How the weight was measured
The figure on this page comes from King Arthur Baking, measured poured unless the method line says otherwise. Spooning means filling the cup with a spoon rather than plunging the cup into the bag, and levelling means sweeping a knife across the rim. Scooping packs the ingredient down and can add a fifth or more to the weight, which is why two bakers following the same cup-based recipe can get visibly different results. Confidence in this value is high. That reflects how consistent the ingredient is from brand to brand: a uniform, factory-packed ingredient is more predictable than a fresh, variable one. Even a high-confidence figure is still an approximation, because moisture, grind size and settling all shift the weight a little. Treat the grams on this page as a reliable starting point and check with a scale when the recipe is fussy, expensive, or being made for the first time.
When this conversion matters most
This conversion matters most in baking and preserving, where sugar controls structure as well as sweetness. In cakes it tenderises the crumb and holds moisture; in meringues it stabilises the foam; in jams it sets the pectin and preserves the fruit. It matters less in a cup of tea or coffee, where a gram or two either way is a matter of taste and you can adjust by sipping. It matters again when you scale recipes, because sugar errors multiply just like flour errors, and a doubled batch of cookies with too much sugar spreads thin and burns at the edges. When a recipe was developed by weight, matching that weight is the simplest way to match the result.
Common mistakes
The most common mistake is treating all sugars as interchangeable by volume. A cup of powdered sugar is nearly half the weight of a cup of granulated sugar, so a recipe that expects one and gets the other will be badly under- or over-sweetened. The second mistake is packing brown sugar when the recipe expects it spooned, or the reverse: packed brown sugar weighs about 213 g per cup while loosely spooned brown sugar weighs around 170 g, a difference of more than 40 g. The third is measuring sticky syrups in a dry cup and losing half of it on the sides; a light wipe of oil on the cup helps a syrup slide out cleanly. And the fourth is sifting powdered sugar before measuring it, which adds air and drops the weight per cup to around 100 g. Measure first, then sift.
What to do if you do not have a scale
If you do not have a scale, use a dry measuring cup and the method the figure on this page was measured with: spooned and levelled for free-flowing sugars, firmly packed for brown and muscovado sugars, and poured at eye level for syrups. For syrups, measure in a liquid jug at eye level and use a flexible spatula to scrape every last drop out. For powdered sugar, spoon it in lightly and level it, and do not press it down. These methods get you close, but sugar is cheap to weigh and expensive to get wrong in baking, so a scale is the better investment here than for almost any other ingredient.
Storing corn syrup
Airtight container at room temperature, up to 1 year. Keeping corn syrup properly stored matters for the conversion as well as for the flavour: an ingredient that has absorbed moisture from the air weighs more per cup than a dry one, and one that has dried out weighs less. Store it in an airtight container, away from heat and light, and measure it in the state the recipe expects, not straight from a damp or stale bag.
Frequently asked questions
Is corn syrup the same as high-fructose corn syrup?
No. Corn syrup is a glucose syrup made by breaking down cornstarch, while high-fructose corn syrup is made by converting some of that glucose into fructose. They are different products with different sweetness and different uses, and recipes that call for corn syrup mean the plain glucose syrup. Do not substitute one for the other without checking the recipe, because the flavour and the behaviour in candy making are not the same.
Why do candy recipes use corn syrup?
Corn syrup prevents crystallisation. When sugar syrup is heated and cooled, the sugar molecules want to lock together into crystals, which makes candy grainy. Corn syrup is made of longer glucose chains that get in the way of those crystals, so the candy stays smooth and clear. That is why it appears in caramels, fudge, marshmallows and glazes, where a smooth texture is the whole point of the recipe.
Can I use cups instead of a scale for corn syrup?
Yes, but a scale is more accurate. If you measure corn syrup poured, exactly as the figure on this page was measured, a cup will be close to 312 g, within a few grams. The problem is that most people scoop rather than spoon, which can add 15 to 25 percent to the weight, and that error is enough to change a bake. For everyday cooking, cups are fine. For baking, where the ratio of ingredients decides the result, weigh it and check the number on the scale.
How many tablespoons are in a cup of corn syrup?
There are 16 tablespoons in a US cup, so a cup of corn syrup is 16 tablespoons, and one tablespoon weighs about 19.5 g. A teaspoon weighs about 6.5 g. Tablespoons are useful when a recipe calls for a small amount, but they carry the same packing problem as cups: a heaped tablespoon can weigh half as much again as a level one, so level every spoon with the back of a knife, and use a scale for small amounts when accuracy matters.
Does the weight change if I pack or sift corn syrup?
Packing does not apply to corn syrup, because it is poured rather than spooned. The weight is consistent as long as the liquid is measured at eye level in a jug and the ingredient is stirred first if it separates. Temperature makes a small difference, because warm liquids expand slightly, but for ordinary kitchen use the poured weight is stable, and a cup of corn syrup weighs about 312 g whether it is cool or at room temperature.