Cups of whole flaxseed to ounces runs on one number, 5.8202037 ounces per cup. It is a measured property of this ingredient rather than a defined conversion, which is why a generic volume-to-weight tool cannot give you it.
The density behind that figure is 0.69741 g per mL, against 1.00 for water. A cup of water weighs 236.6 g and a cup of whole flaxseed weighs 165 g, so this ingredient is 69.74% as heavy as the same volume of water — the single fact the whole page rests on.
A cup of whole flaxseed is 165 g when it is measured the standard way, but how it gets into the cup changes the answer: between about 155.1 g and 184.8 g covers the range from lightly spooned to firmly packed. That 12% spread is larger than most of the adjustments recipes fuss over, and it disappears entirely the moment the ingredient is weighed instead.
One cup of whole flaxseed is 5.82 oz. US kitchen scales usually step in eighths of an ounce, which is 3.54 g — around 2.15% of a cup of this ingredient, so the scale is precise enough for a full cup and coarse for a spoonful. That is why recipes mix the two systems: ounces for the bulk, spoons for the small amounts.
What the number depends on: Whole seeds. Ground flax is much lighter per cup and goes rancid far faster.
The formula
cups- The amount of whole flaxseed you are converting, in cups
5.82020372168- Ounces per cup for whole flaxseed, from its density of 0.69741 g/mL
ounces- The equivalent quantity in ounces
How it works, step by step
- Enter the quantity in cups.
- It is multiplied by 5.82020372168, the ounces-per-cup figure for whole flaxseed.
- The result appears in ounces, with a second reading in g beneath it.
- Use the measure table if you want a standard recipe quantity rather than a number you type in.
Worked examples
1/3 cup of whole flaxseed in ounces
Take 1/3 cup of whole flaxseed: 0.333333 × 5.8202037 gives 1.94007 ounces. Doubling the batch takes it to 3.88014 ounces, because the relationship is a straight proportion once the density is known.
3/4 cup of whole flaxseed in ounces
3/4 cup of whole flaxseed weighs out at 4.36515 ounces. Divide 4.36515 by 5.8202037 and you get back to 3/4 cup, which is the quickest check that the factor is the right way up.
3 cup of whole flaxseed in ounces
A recipe calling for 3 cup of whole flaxseed needs 17.4606 ounces on the scale. The arithmetic is 3 × 5.8202037 = 17.460611, and halving the recipe halves the weight to 8.73031 ounces.
How to read your score
Frequently asked questions
How many ounces are in 1 cup of whole flaxseed?
One cup of whole flaxseed is 5.8202037 ounces. Half that quantity is 2.9101 ounces and double it is 11.6404 ounces, so the figure scales straight up and down — there is no offset in this conversion, only the factor.
Why is a cup of whole flaxseed not 236 g like water?
Because weight per cup depends on what is in the cup. Whole flaxseed has a density of 0.69741 g per mL where water has 1.00, so a cup of it weighs 165 g rather than 236.6 g. That is a difference of 71.6 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?
Yes, and by more than most people expect. Handling changes the weight of a cup of whole flaxseed by roughly 12% — about 9.9 g either side of 165 g — because whole seeds. Weighing removes the question entirely.
Is a fluid ounce of whole flaxseed 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 whole flaxseed weighs 0.7275 oz, so the two readings differ by 27.2%. 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 whole flaxseed would weigh 174.35 g instead of 165 g — 9.35 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 12% for whole flaxseed — roughly 19.8 g on a 165 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 cups of whole flaxseed is 16 oz?
16 oz of whole flaxseed is 2.749 cups — 0.171815 cups to one ounce, so 16 × 0.171815 = 2.749. Going that way is a division by 5.8202, or a multiplication by 0.171815 if you prefer.
Whole flaxseed in cups and ounces
| Cups | Ounces | Unrounded |
|---|---|---|
| 1/8 cup | 0.727525 oz | 0.7275254652 |
| 1/4 cup | 1.45505 oz | 1.45505093 |
| 1/3 cup | 1.94007 oz | 1.940067907 |
| 1/2 cup | 2.9101 oz | 2.910101861 |
| 2/3 cup | 3.88014 oz | 3.880135814 |
| 3/4 cup | 4.36515 oz | 4.365152791 |
| 1 cup | 5.8202 oz | 5.820203722 |
| 1 1/2 cup | 8.73031 oz | 8.730305583 |
| 2 cup | 11.6404 oz | 11.64040744 |
| 3 cup | 17.4606 oz | 17.46061117 |
| 4 cup | 23.2808 oz | 23.28081489 |
Based on 165 g per cup of whole flaxseed. One cup of whole flaxseed is 5.8202037 ounces.
| Measure | Grams | Ounces | Millilitres |
|---|---|---|---|
| 1 cup | 165 g | 5.82 oz | 236.6 mL |
| 3/4 cup | 123.8 g | 4.37 oz | 177.4 mL |
| 2/3 cup | 110 g | 3.88 oz | 157.7 mL |
| 1/2 cup | 82.5 g | 2.91 oz | 118.3 mL |
| 1/3 cup | 55 g | 1.94 oz | 78.86 mL |
| 1/4 cup | 41.25 g | 1.46 oz | 59.15 mL |
| 1 tbsp | 10.31 g | 0.364 oz | 14.79 mL |
| 1 tsp | 3.438 g | 0.121 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) |
|---|---|---|---|
| Blueberries | 148 g | 5.221 oz | 0.6256 |
| Crumbled feta | 150 g | 5.291 oz | 0.634 |
| Corn kernels | 150 g | 5.291 oz | 0.634 |
| Whole flaxseed (this page) | 165 g | 5.82 oz | 0.6974 |
| Sliced strawberries | 166 g | 5.855 oz | 0.7016 |
| Chocolate chips | 170 g | 5.997 oz | 0.7185 |
| Chia seeds | 192 g | 6.773 oz | 0.8115 |
Ordered by weight. The spread across this group is why a single generic cups-to-grams factor cannot work.