1 Cup Jam in Grams

1 cup of jam weighs 320 g (spooned and levelled, USDA). Fruit preserves set with sugar and pectin. All the figures on this page are approximate conversions based on the USDA value, so when a recipe really matters, verify with a kitchen scale.

Why weighing jam beats measuring it in cups

Jam is the heaviest cup measure on this site at 320 g, because it is fruit cooked down with a large amount of sugar until it sets, leaving a dense, sticky preserve with almost no air in it. A cup of jam weighs more than a cup of honey, and that density is why jam is used by the spoonful rather than the cup in most recipes: a little goes a long way, and a cup of jam in a cake would make it overwhelmingly sweet and very wet.

The stickiness is what makes the cup measure unreliable for jam. Jam clings to the cup, traps air, and leaves a thick film behind, so the amount that reaches the bowl is less than the amount measured. A scale removes the problem: weigh the jar before and after, or spoon the jam onto the scale, and the number is exact. Different jams also weigh slightly differently per cup, because the fruit and the sugar content vary: a raspberry jam with seeds weighs a little more than a smooth apricot jam, and a low-sugar jam weighs a little less than a traditional one. The USDA figure of 320 g is medium confidence and applies to the traditional jams most people buy.

Jam cups to grams conversion table

Cups Grams Tablespoons
1/4 cup 80 g 4
1/3 cup 106.7 g 5.3
1/2 cup 160 g 8
2/3 cup 213.3 g 10.7
3/4 cup 240 g 12
1 cup 320 g 16
1 1/2 cups 480 g 24
2 cups 640 g 32
3 cups 960 g 48
4 cups 1280 g 64

One tablespoon of jam weighs about 20 g, since a cup is 16 tablespoons. That is useful when a recipe calls for a spoonful or two rather than a whole cup, though 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.

Worked examples

Jam thumbprint cookies, a batch of 24

A batch of 24 thumbprint cookies uses about 1/2 cup of jam, which is 160 g, spooned into the centres of the cookies before baking. Weigh 160 g rather than spooning from the jar, because jam clings to the spoon and a spooned measure is unreliable. Use a firm jam that holds its shape, and fill each thumbprint with a small spoonful so the jam does not run over the edges.

Jam glaze for a fruit tart

A glaze for a large fruit tart uses about 1/4 cup of jam, which is 80 g, warmed with a tablespoon of water and brushed over the fruit. Weigh 80 g and warm it gently until it is runny, then brush it over the fruit for a glossy finish. Apricot jam is the classic choice for glazing, because it is smooth and pale, but any smooth jam works.

Jam sponge filling for a layer cake

A layer cake filling uses about 3/4 cup of jam, which is 240 g, spread between the layers. Weigh 240 g so each layer gets the same amount, and spread the jam to the edges so every slice has filling. Use a jam that matches the cake: raspberry with chocolate, strawberry with vanilla, apricot with almond.

How the weight was measured

The figure on this page comes from USDA, measured spooned and levelled 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 medium. 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.

Practical guidance

Refrigerate jam after opening and use it within 3 months, because it is a fruit preserve that spoils once opened, especially in a warm kitchen. Use a clean spoon every time, and do not leave the jar out on the counter for hours. When a recipe calls for jam by the cup, weigh it rather than measuring it, because it clings to the cup and traps air. If you do not have a scale, spoon the jam firmly into the cup to remove air pockets and level the top, remembering that the 320 g figure is approximate and medium confidence. Warm the jam gently before using it as a glaze, because cold jam is too thick to brush evenly.

Common mistakes with condiments and sauces

The most common mistake is measuring thick sauces by the cup as if they poured like water. Tomato paste, mayonnaise and jam cling to the cup, trap air, and leave a film behind, so the amount that reaches the pan is less than the amount measured. A scale removes the problem entirely: weigh the jar before and after, or spoon the sauce onto the scale. The second mistake is eyeballing a tablespoon of paste or jam from the jar and calling it a cup's worth of accuracy; small errors in concentrated ingredients are large errors in flavour. The third is storing opened sauces at room temperature for weeks: most need the fridge once opened, and a sauce that has turned will spoil a whole dish. Finally, do not swap one sauce for another by volume alone: a cup of tomato paste and a cup of tomato sauce differ in concentration, salt and water, so the swap changes the recipe, not just the weight.

Frequently asked questions

How many grams is 1 cup of jam?

1 cup of jam weighs 320 g when spooned and levelled, according to the USDA. The figure is medium confidence and approximate, because the fruit and sugar content vary by brand and flavour, so verify with a kitchen scale when it matters.

Why is jam hard to measure by the cup?

Because it is dense and sticky, clings to the cup, and traps air when spooned in roughly. A cup of jam can be 20 g short of the true weight, so weighing it on a scale is far more reliable than measuring by volume.

How many grams is a tablespoon of jam?

One tablespoon of jam weighs about 20 g, since a cup is 16 tablespoons and 320 g divided by 16 is 20 g. A tablespoon is a more useful measure for jam than a cup, because most recipes use small amounts.

Is marmalade the same weight as jam?

Close, but not identical. Marmalade contains citrus peel, which changes the density slightly, so a cup of marmalade weighs a little differently from a cup of smooth jam. Weigh the preserve you are actually using rather than assuming the figure is exact.

How long does opened jam keep?

Refrigerate it after opening and use it within 3 months. An opened jar spoils faster in a warm kitchen, and mould on the surface means the whole jar should be thrown out, not just the top layer.

Related conversions

If you need a different amount, the table above scales in both directions, and the converter tool will do the maths for any quantity. When a recipe really matters, weigh the ingredient on a kitchen scale rather than trusting the cup alone, because the figures on this page are approximate and natural ingredients vary by brand, variety and moisture.