One ounce of whole flaxseed is 0.17181529 cups, so converting ounces of whole flaxseed to cups means multiplying by 0.17181529. That factor is specific to this ingredient — it comes from its density, not from any relationship between the two units.
Water is the yardstick: 1 mL of it weighs 1 g. Whole flaxseed comes in at 0.69741 g per mL, or 69.74% of water, which is why a cup of it is 165 g rather than 236.6 g. Volume and weight only line up for water, and only in metric.
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.
How the figure is arrived at: Whole seeds. Ground flax is much lighter per cup and goes rancid far faster.
The formula
ounces- The amount of whole flaxseed you are converting, in ounces
0.171815291667- Cups per ounce for whole flaxseed, from its density of 0.69741 g/mL
cups- The equivalent quantity in cups
How it works, step by step
- Enter the quantity in ounces.
- It is multiplied by 0.171815291667, the cups-per-ounce figure for whole flaxseed.
- The result appears in cups, with a second reading in tbsp beneath it.
- Use the measure table if you want a standard recipe quantity rather than a number you type in.
Worked examples
2 oz of whole flaxseed in cups
Take 2 oz of whole flaxseed: 2 × 0.17181529 gives 0.343631 cups. Doubling the batch takes it to 0.687261 cups, because the relationship is a straight proportion once the density is known.
4 oz of whole flaxseed in cups
4 oz of whole flaxseed weighs out at 0.687261 cups. Divide 0.687261 by 0.17181529 and you get back to 4 oz, which is the quickest check that the factor is the right way up.
12 oz of whole flaxseed in cups
Take 12 oz of whole flaxseed: 12 × 0.17181529 gives 2.06178 cups. Doubling the batch takes it to 4.12357 cups, because the relationship is a straight proportion once the density is known.
How to read your score
Frequently asked questions
How many cups are in 1 oz of whole flaxseed?
One ounce of whole flaxseed is 0.17181529 cups. Half that quantity is 0.0859076 cups and double it is 0.343631 cups, 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 much does 2 cup of whole flaxseed weigh?
2 cup of whole flaxseed comes to 330 g, or 11.64 ounces. This page runs that calculation in reverse — enter a weight and it returns the volume — and the cups-to-ounces page does it in the direction the question is usually asked.
Whole flaxseed in ounces and cups
| Ounces | Cups | Unrounded |
|---|---|---|
| 1/2 oz | 0.0859076 cup | 0.08590764583 |
| 1 oz | 0.171815 cup | 0.1718152917 |
| 2 oz | 0.343631 cup | 0.3436305833 |
| 3 oz | 0.515446 cup | 0.515445875 |
| 4 oz | 0.687261 cup | 0.6872611667 |
| 6 oz | 1.03089 cup | 1.03089175 |
| 8 oz | 1.37452 cup | 1.374522333 |
| 12 oz | 2.06178 cup | 2.0617835 |
| 16 oz | 2.74904 cup | 2.749044667 |
Based on 165 g per cup of whole flaxseed. One ounce of whole flaxseed is 0.17181529 cups.
| 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.