What is the equivalent of one medium onion chopped?

Onions are a versatile vegetable used in many savory dishes across cuisines worldwide. Their flavor can range from sweet and mellow to sharp and pungent depending on the variety. When a recipe calls for a medium onion chopped, it’s referring to a specific onion size that will yield a certain amount once diced. But what exactly is the equivalent of one medium onion chopped? There are a few ways to estimate onion quantities.

Judging by Weight

One approach is to go by weight. A medium onion generally weighs around 3-4 ounces or 80-120 grams. Once chopped, a medium onion yields around 1/2 to 3/4 cup or 50-85 grams of chopped onion. So if a recipe calls for 1 chopped medium onion, you can substitute around 1/2-3/4 cup of already chopped onion.

Judging by Size

You can also estimate chopped onion amounts by the onion’s size. A medium onion is usually 2-3 inches or 5-8 cm in diameter. Larger onions tend to have morelayers and yield more once chopped. After chopping, a medium onionequates to approximately:

  • 1/2 cup of finely chopped onion
  • 3/4 cup of coarsely chopped onion
  • 1 cup of very coarsely chopped onion

So a recipe calling for 1 medium chopped onion could be replaced with 1/2-1 cup chopped onion depending on how fine they are diced.

Using Common Vegetable Chopped Amounts

Another approach is thinking in terms of common chopped vegetable amounts:

  • 2 tbsp = 1/8 cup chopped
  • 1/4 cup chopped
  • 1/3 cup chopped
  • 1/2 cup chopped

A medium onion chopped tends to yield between 1/3 and 1/2 cup. So substituting 1/3-1/2 cup chopped onion should give a similar quantity as 1 medium chopped onion.

Onion Equivalents for Common Recipes

Here are some common recipes specifying chopped onion amounts and what you can use for a 1 medium onion equivalent:

Sautéed Onions

Many recipes call for sautéed onion as flavoring. If a recipe lists:

  • 1 medium onion, chopped – Use 1/2 cup chopped onion
  • 2 medium onions, chopped – Use 1 cup chopped onion
  • 3 medium onions, chopped – Use 1 1/2 cups chopped onion

Soups, Stews, and Chilis

For dishes with lots of ingredients like soups, stews, and chilis:

  • 1 medium onion, chopped – Use 1/3 cup chopped onion
  • 2 medium onions, chopped – Use 2/3 cup chopped onion
  • 3 medium onions, chopped – Use 1 cup chopped onion

Use slightly less since the onion flavor disperses.

Salads and Salsas

For fresher items like salads and salsas:

  • 1 medium onion, chopped – Use 1/2 cup chopped onion
  • 2 medium onions, chopped – Use 1 cup chopped onion
  • 3 medium onions, chopped – Use 1 1/2 cups chopped onion

Use the full 1/2 cup per onion since onion flavor is more prominent.

Chopped Onion Equivalents for Other Alliums

Onion equivalents can also be useful for substituting other alliums like shallots, leeks, and scallions:


  • 1 medium shallot, chopped = 1-2 tbsp chopped
  • 1 medium onion, chopped = 5-6 medium shallots, chopped


  • 1 medium leek, chopped = 1/4-1/3 cup chopped
  • 1 medium onion, chopped = 2 medium leeks, chopped


  • 1 bunch scallions, chopped = 1/4-1/3 cup chopped
  • 1 medium onion, chopped = 1-2 bunches scallions, chopped

So when substituting shallots, leeks, or scallions for 1 medium chopped onion, use the equivalent amounts above.

Onion Measurement Conversions

Here are some handy onion conversion equivalents between:

  • Whole onion and chopped
  • Measurement units like cups, ounces, grams, and milliliters

Whole Onion to Chopped

Whole Onion Equivalent Chopped
1 small onion 1/4 to 1/3 cup
1 medium onion 1/3 to 1/2 cup
1 large onion 1/2 to 3/4 cup
1 jumbo onion 3/4 to 1 cup

Volume Conversions

Chopped Onion Grams Ounces Cups Milliliters
2 tbsp 10g 0.4 oz 1/8 cup 30 ml
1/4 cup 40g 1.5 oz 4 tbsp 60 ml
1/3 cup 55g 2 oz 5 tbsp + 1 tsp 75 ml
1/2 cup 80g 3 oz 8 tbsp 125 ml
3/4 cup 120g 4 oz 12 tbsp 180 ml
1 cup 160g 5 oz 16 tbsp 250 ml

Onion Measurement Equivalents in Recipes

Here are some examples of substituting chopped onion amounts in recipes:

Original Recipe

  • 1 medium onion, diced
  • 2 cloves garlic, minced
  • 1 lb ground beef

Substituting with onion measurements

  • 1/2 cup onion, diced
  • 2 cloves garlic, minced
  • 1 lb ground beef

Original Recipe

  • 1 large onion, chopped
  • 3 carrots, sliced
  • 4 cups stock

Substituting with onion measurements

  • 3/4 cup onion, chopped
  • 3 carrots, sliced
  • 4 cups stock

Original Recipe

  • 2 medium onions, finely diced
  • 1 red bell pepper, chopped
  • 14 oz can black beans

Substituting with onion measurements

  • 1 cup onion, finely diced
  • 1 red bell pepper, chopped
  • 14 oz can black beans

So depending on the original onion amount, substitute with an equivalent chopped onion measurement.

Tips for Chopping Onions

Chopping onions to a specific size can take some knife skills. Here are some tips:

Cutting Prep

  • Trim off root end and stem end of onion
  • Cut onion in half from root to stem end
  • Peel off outer layer
  • Lay flat side down to stabilize for chopping

Knife Skills

  • Use a sharp chef’s knife for clean cuts
  • Hold fingers curled in while chopping
  • Make even slices according to desired chop size
  • Chop slices crosswise into dices

Achieving Finely Chopped

  • Thinly slice onion half from root to stem end
  • Slice onion strips crosswise into tiny pieces
  • Aim for ~1/8-inch diced pieces

Achieving Coarsely Chopped

  • Cut onion half from root to stem into thick slices
  • Chop slices into ~1/4-inch pieces

With practice, you can consistently chop onions to any preferred size.

Storing Chopped Onions

To retain freshness, here are some onion storage tips:

Short-Term Storage

For using within a few days:

  • Place chopped onions in an airtight container.
  • Refrigerate for 3-5 days maximum.

Long-Term Storage

For longer storage:

  • Divide chopped onions into freezer bags or containers.
  • Lay flat in a single layer to freeze.
  • Frozen chopped onions last about 3 months.

Storage Tips

  • Avoid storing raw onions with fresh produce as they release gas that accelerates spoilage.
  • Cook raw onions within a few days for best flavor.
  • Sauté frozen onions straight from freezer.
  • Chilled cooked onions can be refrigerated 3-4 days.

Following proper onion storage helps preserve freshness and flavor.

Onion Substitutes

If you don’t have onions on hand, there are a few decent vegetable substitutes:


  • Can substitute 1:1 for onion.
  • Sweeter and more subtle flavor.


  • Swap 1 cup leek for 1 onion.
  • More delicate flavor.


  • 1 bunch scallions replaces 1 onion.
  • Use green parts only.
  • Lighter onion flavor.

Asafoetida Powder

  • Pinch substitutes for 1 onion.
  • Adds pungent onion/garlic flavor.

Onion Powder

  • 1 tsp onion powder per onion.
  • Only provides flavor, not texture.

In a pinch, these alternatives can mimic onions when cooking.

Non-Onion Substitutes

For those avoiding onions, substitute with vegetables like:


  • Provides crunch and fiber.
  • Choose celery stalks or hearts.

Fennel Bulb

  • Has a mild anise/onion flavor.
  • Use shredded or thinly sliced.


  • Adds meaty, umami flavor.
  • Chop or slice finely.


  • Use shredded or diced zucchini.
  • Soaks up surrounding flavors.

Experiment with proportions to find appropriate onion-free substitutes. Consider onion powder for flavor.

Onion Alternatives for Allergies

For those with onion allergies, safer substitutes include:


  • Look for fennel bulbs, not fronds.
  • Has a mild licorice flavor.


  • Use minced or powdered garlic.
  • Provides onion/garlic undertones.


  • Close onion relative but usually tolerated.
  • Introduce leeks cautiously.


  • Aromatic like onions but no relation.
  • Stalks or hearts work as substitute.

Discuss appropriate onion replacements with your doctor if you have an allergy.


Here are answers to some frequently asked questions:

Why do onion amounts vary in recipes?

Onion amounts vary based on personal taste and regional cuisines. Western dishes often use less onion than Indian curries, for example. Cooks may also differ on desired onion flavor strength.

Is it better to use fresh or frozen chopped onions?

Fresh onions have the best flavor, but frozen pre-chopped onions are super convenient. Use fresh when possible and cook frozen onions without thawing first.

Can dehydrated onion flakes be substituted for chopped onions?

Dried onion flakes lack texture but work in a pinch. Rehydrate in water first or use onion powder to add flavor instead.

What is the difference between shallots and onions?

Shallots are small, elongated onions with purple skin and milder flavor. Substitute 1 small shallot for 1 tablespoon onion.

Why do onions make you cry when cutting them?

Onions produce a sulfur compound that creates an irritating gas when cell walls are damaged. This gas wafts into eyes and triggers tears.


When a recipe calls for a medium chopped onion, you can estimate the amount as 1/2-3/4 cup chopped or 50-85 grams based on weight. Chopping onions uniformly takes knife skills; aim for 1/4-inch dices for coarse chopping. For storage, raw onions last 3-5 days refrigerated; frozen chopped onions keep for months. If you lack onions, shallots, leeks, and onion powder make decent substitutions depending on the dish. Non-onion stand-ins like fennel, mushrooms, and celery work for those avoiding onions. With the right techniques and conversions, it’s easy to work with chopped onion amounts in your cooking.

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