Quick Answer
One medium onion is generally considered to be around 1 cup chopped or sliced. However, onion sizes can vary, so the exact cup amount may be slightly more or less depending on the specific onion. A good rule of thumb is that a medium onion yields approximately 1 cup chopped.
Onion Sizes
Onions come in different sizes that are categorized as small, medium, large, jumbo, and colossal. The most common onion sizes used for cooking are:
- Small – 1-2 inches diameter
- Medium – 2-3 inches diameter
- Large – 3-4 inches diameter
The medium onion is the most frequently used size in recipes. When a recipe simply calls for “1 onion” without specifying a size, it is generally referring to a medium onion.
Onion Cup Measurements
When chopped or sliced, different onion sizes yield different cup amounts:
| Onion Size | Cups Chopped |
|---|---|
| Small | Around 1/2 cup |
| Medium | Around 1 cup |
| Large | Around 1 1/2 cups |
As you can see, a medium onion falls right around the 1 cup mark when chopped. However, onions can vary a bit in density and moisture content, so you may get a little over or under 1 cup depending on the specific onion.
Chopping Onions for Precise Measurements
If a recipe calls for a very precise onion measurement like 1 cup or 3/4 cup chopped onion, here are some tips to hit the target amount:
- Weigh the onion first – You can get a sense for how large an onion you need by weighing it. A medium onion weighs approximately 4-5 ounces.
- Chop precisely – Chop the onion into uniform pieces for the most accurate yields.
- Pack lightly – When measuring the chopped onion, pack it lightly into the measuring cup without compressing.
- Adjust as needed – If you are a little under or over the needed amount, finely chop another small piece of the onion or set aside a spoonful to adjust to the precise measurement.
Getting an exact cup measurement for onions takes a little bit of prep work and precision chopping, but it can be done with some care and adjustment.
Common Uses for 1 Medium Onion
Here are some of the most popular ways that 1 medium onion (around 1 cup chopped) is used in recipes:
- Sauteed onions – Caramelizing 1 chopped medium onion is the base for countless dishes.
- Onion soup – A French onion soup recipe will start with at least 1 medium sliced onion as the foundation.
- Salad topping – Diced onions make a flavorful addition to green, pasta, potato, and grain salads.
- Quesadillas & tacos – 1/2 cup each of chopped onions and bell peppers are commonly sautéed for quesadilla and taco fillings.
- Onion dip – Mixing 1 cup of chopped onions into sour cream makes a classic onion dip.
- Pizza topping – 1/2 cup each of chopped onions, peppers, and mushrooms is a popular homemade pizza topping combo.
These are just a few examples of popular recipes that call for a medium chopped or sliced onion. Adapt the amount up or down depending on how much onion flavor you want in a given dish.
Onion Equivalents
If you don’t have a fresh onion on hand, here are some substituted equivalents for 1 medium onion:
- 1/4 cup dried minced onion
- 1/2 cup frozen chopped onion
- 1 cup leek, chopped (using just the white parts)
- 1 medium shallot, chopped
These all provide a similar oniony punch of flavor. Leeks and shallots have a milder, more delicate taste, so you may want to use the full 1 cup substitution to get an equivalent flavor.
Storing Onions
Here are some tips for storing fresh onions:
- Whole, unpeeled – Store whole dry onions in a cool, dry, well-ventilated place out of direct sunlight. They will last for 1-2 months.
- Chopped – Place chopped onions in an airtight container in the refrigerator. They will stay fresh for 4-5 days.
- Frozen – Chop and freeze onions in an airtight freezer bag or container for 4-6 months.
Proper storage keeps onions fresh longer and prevents sprouting and spoilage. Use refrigerated chopped onions within a few days for the best flavor.
Common Onion Varieties
There are many types of onions ranging in flavor from sweet and mild to sharp and pungent. Here are some of the most popular varieties:
| Onion Variety | Flavor | Best Uses |
|---|---|---|
| Yellow | Balanced, mildly sweet | Great all-purpose onion for cooking |
| White | Very mild, slightly sweet | Good raw, salads, Mexican cuisine |
| Red | Sharp, spicy | Grilling, caramelizing, sandwiches |
| Shallots | Mild, sweet, delicate | Sautéing, vinaigrettes, fish |
| Sweet/Vidalia | Very sweet and mild | Eating raw, sandwiches, salads |
The variety you choose can make a big difference in the overall flavor profile of a dish. Consider the taste you want when deciding which type of onion to use.
Onion Nutrition Facts
Onions are very low in calories but provide vitamin C, vitamin B6, folate, potassium, and other essential nutrients. Here are the nutrition facts for 1 cup of raw chopped onion (around 1 medium onion):
| Nutrient | Amount |
|---|---|
| Calories | 64 |
| Carbohydrates | 15g |
| Fiber | 3g |
| Sugars | 7g |
| Fat | 0g |
| Protein | 1g |
| Vitamin C | 12mg |
| Vitamin B6 | 0.2mg |
| Folate | 27mcg |
| Potassium | 180mg |
Onions provide anti-inflammatory quercetin, sulfur compounds, and other beneficial plant nutrients. Their high flavonoid content offers antioxidants.
Health Benefits of Onions
Eating onions, especially raw, provides many potential health benefits:
- Cancer prevention – Quercetin and other antioxidants may help prevent certain cancers like stomach, colon, prostate, and ovarian cancer.
- Heart health – Onions contain compounds that help improve cholesterol levels and blood pressure.
- Anti-inflammatory – The quercetin in onions acts as a potent anti-inflammatory that may ease arthritis pain.
- Immune support – Onions are high in vitamin C and B6, which boost the immune system.
- Gut health – The prebiotics in onions promote good bacteria in the gut for improved digestion.
Add more onions to your recipes to boost the nutritional value and reap the many health benefits these flavorful bulbs provide.
Risks and Food Safety
Onions are very safe but there are a few risks and safety tips to know:
- Allergies – Some people are allergic to onions and can have reactions. Severe onion allergy is rare.
- Gas and bloating – Onions contain FODMAPs that can cause gas and bloating in some people, especially with overconsumption.
- Foodborne illness – Onions can become contaminated with bacteria that cause food poisoning. Practice food safety when handling.
- Cooking decreases nutrients – Some of onions’ beneficial compounds are lost when cooked. Eat raw onions regularly too.
Introduce onions into your diet gradually to identify any digestive issues. Practice safe onion storage and handling to avoid bacterial contamination.
Cost of Onions
Onions are very inexpensive, typically costing between:
- Around $1 – $2 per pound for conventional onions
- Around $2 – $3 per pound for organic onions
Specialty sweet onion varieties like Vidalias cost more, generally $2 – $4 per pound. Pricing can vary based on location and time of year. Onions are an affordable and economical ingredient for most budgets.
Conclusion
One medium onion does yield right around 1 cup chopped or sliced. Exact amounts may vary slightly based on onion size, density, and moisture content. Onions provide a healthy dose of nutrients and plant compounds for little caloric cost. They make great additions to all types of savory dishes and provide flavor and nutrition. Look for firm, dry onions without sprouts or spots. Store and handle onions properly for safety, and incorporate more onions into your cooking routine. Enjoy the versatility and health benefits that this handy vegetable provides.