Produce
Chopped Onion Conversion
Chopped Onion weighs 160g per US cup.
| Amount | Grams | Ounces |
|---|---|---|
| 1 cup | 160.0 g | 5.64 oz |
| 1/2 cup | 80.0 g | 2.82 oz |
| 1/4 cup | 40.0 g | 1.41 oz |
| 1 tbsp | 10.0 g | 0.35 oz |
| 1 tsp | 3.3 g | 0.12 oz |
| 100 g | 100.0 g | 3.53 oz |
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Chopped onion's 160g per cup is one of the more variable figures in the produce category in practice, because "chopped" spans a real range — a coarse, large chop packs looser into a measuring cup than a fine dice, so this figure represents a medium, standard chop rather than an exact universal constant the way a fixed-composition ingredient like sugar has.
One medium onion yields roughly one cup of chopped onion, which is a genuinely useful rule of thumb beyond the precise gram figure — most recipes that call for "one onion, chopped" are implicitly assuming this same rough equivalence, which is part of why onion is one of the few produce items where a cup-based recipe instruction and a whole-item instruction are treated as roughly interchangeable in practice.
Onion's water content is high enough that its weight can shift noticeably between varieties (a sweet Vidalia onion vs. a standard yellow storage onion) and even by season, but not enough to meaningfully change this conversion for typical recipe purposes — the 160g figure is a reliable working average across common cooking onion varieties.
Chopped onion weighs about 160g per cup, though dice size shifts that somewhat — the bigger practical fact is how much water onions lose during a long, slow caramelization, where a large raw pile can collapse down to a small fraction of its starting volume as the sugars concentrate.
Yellow, white, and red onions differ meaningfully in sharpness and sweetness despite weighing about the same per cup chopped — yellow onions are the standard all-purpose cooking onion in most US recipes, while red onions are milder raw and more commonly used uncooked in salads.
Chilling an onion in the fridge for 15-30 minutes before cutting it, or slicing it under running water, are two common ways cooks cut down on the eye-watering sulfur compounds released when its cells rupture, without changing the flavor or texture of the finished dish.
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Frequently asked questions
Does the onion variety (yellow, white, red) change this conversion?
Not meaningfully — common cooking onion varieties are close enough in water content and density that this figure works as a reliable average across them; the differences between onion varieties matter more for flavor and sweetness than for weight.
How many cups of chopped onion does one medium onion yield?
Roughly one cup — a useful rule of thumb for recipes that specify "one onion" rather than a cup measurement, and part of why the two instructions are often treated as interchangeable in home cooking.
Does finely dicing versus roughly chopping change the weight in a cup?
It can shift it somewhat — a fine dice packs more densely with fewer air gaps than a rough chop, so a cup of finely diced onion may weigh slightly more than this figure, which represents a standard medium chop.
Does caramelizing onions change how much a cup weighs?
Dramatically — caramelized onions lose most of their water content during slow cooking, so a cup of caramelized onion weighs far less than a cup of raw chopped onion, even from the same starting quantity.
Does pearl onion or cocktail onion measure the same as standard chopped onion?
No — those are a different variety entirely, smaller and used mostly whole rather than chopped, so this page's chopped-cooking-onion figure isn't a meaningful reference for them.