Cups of molasses to grams
1 US cup of molasses = 337 g (11.9 oz). A 250 ml metric cup = 356 g.
Type 1/2, 1 1/2 or 0.75. The cup size changes the volume; the weight scales by volume, so it assumes the same filling method in every cup.
What the sources say about a cup of molasses
Two published sources, side by side. Where a source lists several forms or ways of measuring, each is a row.
| Source | What was measured | Grams per US cup | Ounces |
|---|---|---|---|
| Our default | See “why this number” below | 337 g | 11.89 oz |
| USDA FoodData Central | 1 cup | 337 g | 11.89 oz |
| King Arthur Baking | Molasses (listed as 1/4 cup = 85 g) | 340 g | 11.99 oz |
Spread across sources: 1% between USDA and King Arthur for the main entry. Ingredient weights vary by brand, packing and humidity; the table is a reference, not a guarantee.
Why this number: 337 g per US cup
We use the USDA measured weight, because for liquids, fats, syrups and free-flowing grains a measured weight is more reliable than a rounded ounce value. Where the two sources disagree, both figures are in the table above and in the calculator, so you can switch to the one your recipe was written with.
Molasses is the heaviest liquid on the list: USDA lists 337 g per cup and King Arthur lists 85 g for a quarter cup (340 g a cup). The two agree to within 1%. It is about 42% heavier than water for the same volume.
Lightly oil the cup or weigh the molasses straight into the bowl; it clings to the sides, so a volume measure always leaves some behind.
UK black treacle and US molasses are related but not identical, and the weight figures here were checked for US molasses only.
Cups of molasses to grams chart
| US cups | Grams (US cup) | Ounces | Grams (metric 250 ml cup) |
|---|---|---|---|
| 1/8 cup | 42.1 g | 1.49 oz | 44.5 g |
| 1/4 cup | 84.2 g | 2.97 oz | 89 g |
| 1/3 cup | 112.3 g | 3.96 oz | 118.7 g |
| 1/2 cup | 168.5 g | 5.94 oz | 178.1 g |
| 2/3 cup | 224.7 g | 7.92 oz | 237.4 g |
| 3/4 cup | 252.8 g | 8.92 oz | 267.1 g |
| 1 cup | 337 g | 11.89 oz | 356.1 g |
| 1 1/2 cups | 505.5 g | 17.83 oz | 534.2 g |
| 2 cups | 674 g | 23.77 oz | 712.2 g |
| 3 cups | 1011 g | 35.66 oz | 1068.3 g |
| 4 cups | 1348 g | 47.55 oz | 1424.4 g |
Grams of molasses to cups
| Grams | US cups (decimal) | US cups (nearest 1/8) | Metric cups (250 ml) |
|---|---|---|---|
| 25 g | 0.07 | 1/8 | 0.07 |
| 50 g | 0.15 | 1/8 | 0.14 |
| 100 g | 0.3 | 1/3 | 0.28 |
| 125 g | 0.37 | 3/8 | 0.35 |
| 150 g | 0.45 | 1/2 | 0.42 |
| 200 g | 0.59 | 5/8 | 0.56 |
| 250 g | 0.74 | 3/4 | 0.7 |
| 300 g | 0.89 | 7/8 | 0.84 |
| 400 g | 1.19 | 1 1/8 | 1.12 |
| 500 g | 1.48 | 1 1/2 | 1.4 |
| 1,000 g | 2.97 | 3 | 2.81 |
US cup, metric cup and spoons
One US cup of molasses at our default weight is 337 g. A 250 ml metric cup, used in Australia, New Zealand, Canada and many metric recipes, holds the same volume plus 5.7%, which is 356 g. A US legal (nutrition label) cup of 240 ml is 342 g. These all assume the same packing as the US cup; read about it on US cup vs metric cup.
| Spoon | Grams |
|---|---|
| 1 tablespoon (15 ml) | 21.1 g |
| 1 teaspoon (5 ml) | 7 g |
| 1 Australian tablespoon (20 ml) | 28.5 g |
Sources and when they were checked
- USDA FoodData Central, SR Legacy (April 2018 release), food Molasses (FDC ID 168820). Gram weights per household measure as published; per-cup figures where USDA lists a different amount (such as 2 tablespoons) are scaled.
- King Arthur Baking, Ingredient Weight Chart, row(s): Molasses. Chart rows that list a quarter cup, half cup or tablespoon are scaled to a full cup on this page; the original listing is shown in the table above.
- Cup volumes: the US customary cup is exactly 236.5882365 ml; the US nutrition-label cup is defined in US law as 240 ml (21 CFR 101.9); the metric cup is 250 ml (see US cup vs metric cup).
Last checked 27 October 2026. Weights are for reference: ingredients vary by brand, humidity and how they are packed. If your recipe gives gram weights, use those.
Frequently asked questions
How many grams is 1 cup of molasses?
1 US cup of molasses is 337 g by our default (USDA). USDA lists 337 g and King Arthur lists 340 g. A 250 ml metric cup holds about 356 g.
How many grams is 1/2 cup of molasses?
1/2 US cup of molasses is 168.5 g (5.94 oz). In a metric cup it is 178.1 g.
How many grams is 1/4 cup of molasses?
1/4 US cup of molasses is 84.2 g (2.97 oz).
How many cups is 100 g of molasses?
100 g of molasses is 0.3 US cups (about 1/3 cups), or 0.28 metric cups.
How many cups is 500 g of molasses?
500 g of molasses is 1.48 US cups, or 1.4 metric cups.
How many grams is a tablespoon of molasses?
About 21 g: USDA lists 20 g per tablespoon.