How Much Does an Onion Weigh? (Small, Medium & Large)

Onions, a staple ingredient in many recipes, come in various types and sizes. Have you ever wondered how much an onion typically weighs? The weight of an onion can greatly impact your culinary creations, and being familiar with these details can enhance your cooking skills.

To better grasp this aspect of onions, it’s essential to focus on the differences among the various types you might encounter in your kitchen. This article will provide insights into the average weight of onions, from the smaller ones used for garnishing to the larger ones used as a base for many dishes.

So, let’s dive into the fascinating world of onion weights and uncover the details that could make a difference in your cooking.

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The weight of an onion can vary depending on its size and variety. On average, a small onion usually weighs between 3 to 4 ounces (85 to 113 grams). A medium-sized onion typically weighs around 4.9 to 7.9 ounces (140 to 225 grams). A large onion can weigh up to 10 to 15.8 ounces (283 to 450 grams).

Types of Onions

onion weight

You might wonder about the different types of onions available and how their weights might vary. Onions come in various shapes, sizes, and colors, which can affect their overall weight. Let’s explore some of the popular types of onions.

Yellow Onions

These are the most common types of onions in grocery stores. They’re versatile and have a strong, slightly sweet flavor.

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They’re often used in cooking and can be caramelized to bring out their natural sugars. Yellow onions’ average weight is around 150 grams (5.3 ounces) to 250 grams (8.8 ounces), depending on size.

White Onions

Like yellow onions, white onions have a milder taste and a slightly more tender texture. They’re excellent for using raw in salads or salsas. The average weight of a white onion ranges from about 100 grams (3.5 ounces) to 200 grams (7 ounces).

Red Onions

Red onions are known for their vibrant purple color and slightly sweet flavor. They’re popular for adding color to salads, sandwiches, or grilled dishes. The weight of a red onion can vary between 100 grams (3.5 ounces) and 300 grams (10.6 ounces).

Sweet Onions

These onions, including Vidalia, Walla Walla, and Maui, have a milder, sweeter taste. They’re great for recipes that call for raw onions or for caramelizing. Sweet onions tend to be larger than other types of onions and can weigh around 150 grams (5.3 ounces) to 400 grams (14 ounces).


Shallots look like small, elongated onions, with a subtle, delicate flavor. They’re often used in French cuisine and can be served raw, cooked, or pickled. A shallot typically weighs between 20 grams (0.7 ounces) and 60 grams (2.1 ounces).

Now that you’re familiar with the types of onions available and their weights, you can decide which ones to use in your recipes. The weight of an onion depends on its type and size, so always check them individually when determining the weight needed in a dish.

How Much Does an Onion Weigh?

small onion weight

A medium-sized onion weighs about 4.9 ounces (140 grams). However, you might find that onions can vary quite a bit in weight depending on their size, variety, and density. Let’s look at some of the common sizes and their weights.

  • Small onion: A small onion usually weighs between 3 to 4 ounces (85 to 113 grams). These onions are perfect when you need just a hint of flavor in your dish, or when preparing a meal for one or two people.
  • Medium onion: As mentioned earlier, a medium-sized onion typically weighs around 4.9 to 7.9 ounces (140 to 225 grams). This size is the most common and versatile option, making it suitable for various recipes and serving sizes.
  • Large onion: A large onion can weigh up to 8.1 to 15.8 ounces (230 to 450 grams). These onions are great for dishes that require a significant amount of onion flavor, or when cooking for a larger group of people.
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Always remember that the weight of an onion can affect your dish’s overall flavor and texture, so make sure to choose the appropriate size and variety for your recipe.

Factors Influencing the Weight of an Onion

Onion Size

The size of an onion plays a significant role in its weight. Generally, larger onions will weigh more than smaller ones. Onions come in different sizes, such as small, medium, and large.

white onion weight

Onion Age

The age of an onion can also impact its weight. As onions mature, they become denser and accumulate more water and nutrients. This may cause them to increase slightly in weight. Additionally, the outer layers of an onion may become thicker as it ages, which can contribute to a higher overall weight.

However, it’s important to note that there isn’t a direct correlation between age and weight. Various factors, such as size and geographical factors, may influence the maturation process. This means an older onion may not always weigh more than a younger one.

Geographical Factors

Where an onion is grown can affect its weight as well. Some growing conditions and geographic factors that may influence the weight of an onion are:

  • Soil type and quality: Rich, well-drained soil can promote healthier growth and produce heavier onions.
  • Climate: Cool temperatures and consistent rainfall could produce larger onions with more substantial weights.
  • Altitude: Higher-altitude regions could produce smaller onions due to lower air pressure and less water availability.

All of these factors work together to shape the onions that you find in your local grocery store, farmer’s market, or even in your own garden. By understanding these factors, you can better appreciate the diversity of weights among different onions.

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Measurement Units for Onion Weight

medium onion weight

Metric System

When weighing onions, you can use the metric system widely used worldwide. In this system, the weight of an onion is typically measured in grams (g) or kilograms (kg).

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To give you an idea of common onion weights:

  • A small onion weighs around 85g to 113g.
  • A medium onion weighs about 140 to 225 grams.
  • A large onion can weigh 280g to 450g and sometimes more.

Remember that an onion’s weight can vary depending on the type, size, and growing conditions. So, these numbers are just a general guideline.

Imperial System

If you’re more comfortable with the imperial system, onions can also be weighed in ounces (oz) and pounds (lb). Here’s a rough conversion of common onion weights from the metric system to the imperial system:

Onion SizeMetric WeightImperial Weight
Small85g – 113g3oz – 4oz
Medium140g – 225g4.9oz – 7.9oz
Large280g – 450g10oz – 15.8oz
Jumbo454 or more16oz or more

Again, remember that these are approximate conversions, and the actual weight of an onion may vary depending on several factors.

About Kevin Jones

My name is Kevin Jones, and I'm the proud founder of this website. I'm a self-professed measurement enthusiast, and I've been passionate about measuring things for as long as I can remember. On this website, you'll find information on all aspects of dimensions, including measurements and weight of stuff.