To convert fluid ounces of molasses into grams, multiply by 42.125: one fluid ounce comes to 42.125 grams. Every ingredient has its own figure here, because the units are measuring different things and only the density links them.
Water is the yardstick: 1 mL of it weighs 1 g. Molasses comes in at 1.4244 g per mL, or 142.4% of water, which is why a cup of it is 337 g rather than 236.6 g. Volume and weight only line up for water, and only in metric.
This is the pair that catches people out. A fluid ounce is a volume and an ounce is a weight, and they are only the same number for something with the density of water. One fluid ounce of molasses weighs 1.486 oz, so the two readings differ by 48.6% — worth knowing before trusting a recipe that just says "oz".
Grams are the unit this conversion is really for. A domestic scale resolves to a gram, which is 0.297% of a cup of molasses, so weighing gets an accuracy no measuring cup can reach. A 500 g pack of it is 1.484 cups, and a 1 kg pack 2.967.
The condition this weight assumes: What is left after sugar crystallises out, so almost all of its weight is dissolved solids.
The formula
fluid ounces- The amount of molasses you are converting, in fluid ounces
42.125- Grams per fluid ounce for molasses, from its density of 1.4244 g/mL
grams- The equivalent quantity in grams
How it works, step by step
- Enter the quantity in fluid ounces.
- It is multiplied by 42.125, the grams-per-fluid ounce figure for molasses.
- The result appears in grams, with a second reading in oz beneath it.
- Use the measure table if you want a standard recipe quantity rather than a number you type in.
Worked examples
3 fl oz of molasses in grams
3 fl oz of molasses weighs out at 126.375 grams. Divide 126.375 by 42.125 and you get back to 3 fl oz, which is the quickest check that the factor is the right way up.
6 fl oz of molasses in grams
6 fl oz of molasses weighs out at 252.75 grams. Divide 252.75 by 42.125 and you get back to 6 fl oz, which is the quickest check that the factor is the right way up.
12 fl oz of molasses in grams
Take 12 fl oz of molasses: 12 × 42.125 gives 505.5 grams. Doubling the batch takes it to 1011 grams, because the relationship is a straight proportion once the density is known.
How to read your score
Frequently asked questions
How many grams are in 1 fl oz of molasses?
One fluid ounce of molasses is 42.125 grams. Half that quantity is 21.0625 grams and double it is 84.25 grams, so the figure scales straight up and down — there is no offset in this conversion, only the factor.
Why is a cup of molasses not 236 g like water?
Because weight per cup depends on what is in the cup. Molasses has a density of 1.4244 g per mL where water has 1.00, so a cup of it weighs 337 g rather than 236.6 g. That is a difference of 100.4 g per cup, and it is the reason a single volume-to-weight factor cannot be applied to every ingredient.
Does how I measure it change the weight?
Barely. Molasses does not compress, so a cup of it is 337 g however it is poured — within about 1%, which is inside the accuracy of a domestic scale. This is the group where measuring by volume is defensible.
Is a fluid ounce of molasses the same as an ounce?
No. A fluid ounce is a volume — one eighth of a US cup, 29.57 mL — and an ounce is a weight. One fluid ounce of molasses weighs 1.486 oz, so the two readings differ by 48.6%. They coincide only for something with the density of water, and then only roughly.
Is this a US cup or a metric cup?
US customary: 236.59 mL, which is the cup every US recipe means. A metric cup is 250 mL, so the same cup of molasses would weigh 356.1 g instead of 337 g — 19.1 g more, or 5.67%. Australian and some European recipes use the metric cup, and the difference is large enough to matter in baking.
Do I need a scale for this, or will measuring cups do?
A scale, if the result matters. Volume measuring carries a spread of about 1% for molasses — roughly 3.37 g on a 337 g cup — while a domestic scale is accurate to a gram or two. For anything where the ratio of ingredients drives the outcome, bread and pastry above all, weigh it.
How many fluid ounces of molasses is 500 g?
500 g of molasses is 11.869 fluid ounces — 0.0237389 fluid ounces to one gram, so 500 × 0.0237389 = 11.869. Going that way is a division by 42.125, or a multiplication by 0.0237389 if you prefer.
Molasses in fluid ounces and grams
| Fluid Ounces | Grams | Unrounded |
|---|---|---|
| 1 fl oz | 42.125 g | 42.125 |
| 2 fl oz | 84.25 g | 84.25 |
| 3 fl oz | 126.375 g | 126.375 |
| 4 fl oz | 168.5 g | 168.5 |
| 6 fl oz | 252.75 g | 252.75 |
| 8 fl oz | 337 g | 337 |
| 12 fl oz | 505.5 g | 505.5 |
| 16 fl oz | 674 g | 674 |
Based on 337 g per cup of molasses. One fluid ounce of molasses is 42.125 grams.
| Measure | Grams | Ounces | Millilitres |
|---|---|---|---|
| 1 cup | 337 g | 11.9 oz | 236.6 mL |
| 3/4 cup | 252.8 g | 8.92 oz | 177.4 mL |
| 2/3 cup | 224.7 g | 7.92 oz | 157.7 mL |
| 1/2 cup | 168.5 g | 5.94 oz | 118.3 mL |
| 1/3 cup | 112.3 g | 3.96 oz | 78.86 mL |
| 1/4 cup | 84.25 g | 2.97 oz | 59.15 mL |
| 1 tbsp | 21.06 g | 0.743 oz | 14.79 mL |
| 1 tsp | 7.021 g | 0.248 oz | 4.929 mL |
US customary measures: 1 cup = 236.59 mL, 1 tbsp = 14.79 mL, 1 tsp = 4.93 mL.
| Ingredient | Grams per cup | Ounces per cup | Density (g/mL) |
|---|---|---|---|
| Peanut butter | 258 g | 9.101 oz | 1.091 |
| Sweetened condensed milk | 306 g | 10.79 oz | 1.293 |
| Maple syrup | 322 g | 11.36 oz | 1.361 |
| Corn syrup | 328 g | 11.57 oz | 1.386 |
| Agave nectar | 331 g | 11.68 oz | 1.399 |
| Molasses (this page) | 337 g | 11.89 oz | 1.424 |
| Honey | 340 g | 11.99 oz | 1.437 |
Ordered by weight. The spread across this group is why a single generic cups-to-grams factor cannot work.