340 g of molasses is 1 cup. Molasses is the heaviest common ingredient in the kitchen, denser even than honey, because it is a concentrated syrup left over from sugar refining. It pours slowly, clings to everything, and its strong, bitter-sweet flavour means it is used in small amounts, usually a quarter of a cup or less at a time.
All figures on this page are approximate, and they come from King Arthur Baking, measured poured. When a recipe has to work the first time, verify with a kitchen scale.
How the measurement works
The figure on this page comes from King Arthur Baking, measured poured. Thick, dark syrup left after sugar refining; strongly flavoured. Gingerbread, baked beans, barbecue sauce and rye bread.
All results on this page are approximate. Ingredient weights vary with brand, humidity, temperature and how firmly you pack the cup, so when a recipe has to work the first time, weigh the ingredient on a kitchen scale and use the numbers here as a guide.
Conversion table
| Cups | Grams of molasses |
|---|---|
| 1/4 cup | 85 g |
| 1/3 cup | 113.3 g |
| 1/2 cup | 170 g |
| 2/3 cup | 226.7 g |
| 3/4 cup | 255 g |
| 1 cup | 340 g |
| 1 1/2 cups | 510 g |
| 2 cups | 680 g |
| 3 cups | 1020 g |
| 4 cups | 1360 g |
Quick reference: 100 g of molasses is about 0.29 cups, and 50 g is about 0.15 cups. All figures are approximate; verify with a kitchen scale when it matters.
Three real kitchen examples
Gingerbread for the holidays
A gingerbread recipe uses 170 g of molasses, half a cup, with flour, spices and butter. The molasses gives the gingerbread its dark colour, its chew, and its deep flavour. Warm the molasses slightly before measuring so it pours more easily, and oil the measuring cup so it slides out cleanly.
Baked beans for a barbecue
A baked bean recipe uses 85 g of molasses, a quarter of a cup, stirred into the beans with mustard and brown sugar. The molasses adds sweetness and a dark, smoky note that balances the salt pork. A quarter of a cup is easy to measure in a jug, and the exact amount is forgiving.
A rye bread with a dark crumb
A rye bread recipe uses 42 g of molasses, about 2 tablespoons, to darken the crumb and feed the yeast. The molasses is a small part of the recipe, but it changes the colour and the flavour noticeably. Measure it with a tablespoon rather than a cup, because the amount is small and a spoon is more accurate.
Getting it right in your kitchen
Granulated sugar is forgiving to measure, but brown sugar is not: it must be packed firmly into the cup, because loosely spooned brown sugar weighs about 170 g per cup instead of 213 g, a gap that will leave cookies flat and sauces thin. Powdered sugar goes the other way: sifted powdered sugar is about 100 g per cup against 113 g unsifted, so always measure it unsifted unless the recipe says otherwise. Honey and syrups should be measured in a lightly oiled cup or jug so they slide out cleanly, and weigh them if you can, because sticky sweeteners cling to every measuring surface.
Scaling is straightforward once you know the cup weight. Doubling a recipe that calls for 340 g of molasses means measuring 680 g, or 2 cups, and tripling it means 1020 g, or 3 cups. Halving is just as easy: half a cup is 170 g. The key is to scale every ingredient by the same factor, because changing one ingredient without changing the others throws the recipe out of balance. A cake scaled by half still needs half the flour, half the sugar, half the butter and half the molasses, not just half of one of them. If you are scaling a recipe by an awkward factor, like two thirds, weigh the molasses rather than trying to measure two thirds of a cup in a jug, because the jug markings are not precise enough for fractions of a cup.
When should you weigh molasses instead of measuring it? Whenever the recipe has to work the first time, and whenever the amount is large. A kitchen scale costs less than a single failed cake, and it removes the biggest source of variation in home cooking: the way ingredients pack into a cup or a spoon. Put the bowl on the scale, press tare, and add the molasses until the display shows the number you need. There is nothing to wash afterwards except the bowl, and the result is the same every time. For small amounts, a level spoon is accurate enough, and for liquids, a jug is fine, but for anything where precision matters, the scale is the tool to reach for.
Storage. Airtight jar, cool and dark, up to 1 year.
- Oil the measuring cup so molasses slides out.
- Warm it slightly to make it pour more easily.
- Weigh it straight into the bowl to avoid the mess.
Frequently asked questions
Why is molasses so heavy per cup?
Molasses is a concentrated syrup with very little water left in it, so a cup contains more dissolved sugar than a cup of honey or maple syrup. A cup of molasses is 340 g, against 336 g for honey and 312 g for maple syrup.
How do I measure molasses without a mess?
Lightly oil the measuring cup or jug first, so the molasses slides out. Warm it slightly to make it pour more easily, and weigh it if you can: pouring it straight into the bowl on the scale is the cleanest method of all.
What is the difference between light and dark molasses?
Light molasses comes from the first boiling of sugar cane and is sweeter and milder. Dark molasses comes from the second boiling and is stronger and less sweet. Blackstrap molasses comes from the third boiling and is very bitter and high in minerals. All three weigh about 340 g per cup.
Can I substitute honey for molasses?
You can, but the flavour will be different: honey is sweeter and milder, while molasses is darker and more bitter. Use the same weight, not the same volume, because a cup of honey is 336 g and a cup of molasses is 340 g, which is close enough to swap by weight.
How long does molasses keep?
About a year in an airtight jar in a cool, dark place. It is very high in sugar, so it does not spoil easily, but it can crystallise over time. Warm the jar in hot water to dissolve the crystals.
Keeping a conversion note in the kitchen: if you cook from American recipes often, write the gram weights of the ingredients you use most on a card and stick it inside a cupboard door. A short list covering flour, sugar, butter, milk and oil will handle most recipes, and it saves you looking up the same number every time. Update the card when you buy a new ingredient, and note the method next to the weight, because a number without a method is only half a conversion.