How many onions are 70 grams?

December 1, 2025 •

4 min read

Recipe measurements for onions can be frustratingly inconsistent, with one source suggesting a "small onion" is 70 grams while another specifies 125 grams. Navigating this variation is key to ensuring consistent results, especially for recipes where the onion-to-other-ingredient ratio is critical. This guide answers the question, "How many onions are 70 grams?" and offers practical advice for precise cooking.

Quick Summary

Seventy grams of onion is roughly equal to one small onion, though actual weight varies by size and type. For recipe consistency, a kitchen scale is the most accurate tool. Approximate equivalents can be used for less precise dishes, but weighing is recommended for baking or sauces where ratios are important.

Key Points

Equivalency: One small onion is generally considered to be 70 grams.
Accuracy: For the most precise measurement, always use a digital kitchen scale.
Estimation: Visually, a 70-gram onion is about 1-2 inches in diameter, fitting in the palm of your hand.
Preparation: The 70-gram measurement refers to the peeled, trimmed, and usable portion of the onion.
Consistency: Weighing ingredients is especially important for baking and delicate sauces where ingredient ratios are crucial.
Volume: A small onion (70g) yields roughly 3/4 cup of chopped onion, but this varies with the fineness of the chop.

Understanding Onion Weight and Measurement

Recipes often call for onions in vague terms like "small," "medium," or "large," leaving home cooks to guess the intended quantity. This ambiguity is problematic because onion sizes vary significantly. For instance, a small onion might be 70 grams, while another source might classify a small one closer to 125 grams. This is where a specific weight, such as 70 grams, provides a crucial anchor for accuracy. When a recipe specifies 70 grams, you are looking for an onion that is roughly 1-2 inches in diameter, or about the size of a billiard ball.

The Variability of Onion Sizes

Produce is not standardized, which is why a single "small" onion can differ from one store to another or even within the same bag. Yellow onions, which are the most common cooking onion, follow general size guidelines, but variations are common. Sweet onions, like Vidalia, are known for being larger and less dense, which can further complicate volume measurements if you are chopping it. The best practice for achieving consistent flavor is to use a digital kitchen scale, especially when cooking dishes where the balance of ingredients is delicate, such as a vinaigrette, sauce, or a specific baking recipe.

How to Measure 70 Grams of Onion

Use a digital kitchen scale. This is the most accurate method. Place a bowl on the scale and press the tare button to zero it out. Chop your onion and add it to the bowl until the scale reads 70 grams. This eliminates all guesswork.
Estimate with a small onion. As many sources confirm, 70 grams is an average weight for a small onion. A good rule of thumb is to look for an onion that fits comfortably in the palm of your hand, about 1-2 inches in diameter.
Approximate with chopped volume. A small onion yields approximately 3/4 cup of chopped onion. However, this can be inconsistent based on how fine the chop is. Since minced onion is denser than a rougher chop, it will take less volume to reach 70 grams. For recipes that aren't overly sensitive to ingredient ratios, 3/4 cup of loosely packed, chopped onion is a fair starting point.

Whole Onion vs. Chopped Onion Weight

The weight of an onion changes depending on its preparation. A whole, unpeeled onion will weigh more than its chopped counterpart, and the cooking process can further reduce its weight due to moisture loss. When a recipe specifies "70 grams of onion," it almost always refers to the usable, peeled portion. The outer papery layers and root end are not included in the final weight. For example, if a small unpeeled onion weighs 85 grams, after peeling and trimming, it might fall right around the 70-gram mark, accounting for a typical 15-20% weight loss.

Table: Onion Weight and Volume Comparison


Onion Size	Approximate Weight (g)	Chopped Volume	Best Use Case	Notes
Small	70-115g	3/4 cup	Soups, sauces, stir-fries	Good estimate for most recipes calling for 70g.
Medium	150-175g	1 cup	Most general cooking applications	A standard size found in most grocery stores.
Large	225-275g	1.5 cups	Large-batch stews, caramelizing	Significantly larger and more pungent.
Jumbo/Extra-Large	400g+	2+ cups	Bulk cooking, making a statement	Best for recipes requiring a very strong onion flavor.

Why Accurate Measurement Matters

While many savory recipes are forgiving with minor variations in vegetable quantity, precision is crucial in baking or for delicate sauces. For example, in a caramelized onion jam, the ratio of sugar to onion is important for texture and flavor. Too much onion and the jam won't set properly; too little and the flavor will be weak. Similarly, in a foundational sauce like a soffritto, too much onion can overpower other aromatics. Measuring by weight removes the ambiguity that leads to inconsistent results and ensures your dish tastes as the recipe intended. For further reading on the science behind cooking measurements, consider visiting a resource like America's Test Kitchen.

Conclusion

So, how many onions are 70 grams? In most kitchens, 70 grams is the weight of one small, standard-sized onion, which typically measures about 1-2 inches in diameter and yields approximately 3/4 cup of chopped onion. However, for guaranteed consistency, particularly in recipes where precise ingredient ratios are important, using a digital kitchen scale is the most reliable method. By understanding the common variations in produce size and utilizing accurate tools, you can ensure that your culinary creations are consistently delicious. This knowledge not only answers the question of how many onions are 70 grams but also elevates your overall cooking precision.

Frequently Asked Questions

A 70g onion is typically a small onion, about 1 to 2 inches in diameter, which is roughly the size of a billiard ball.

No, 70g of onion is a relatively small amount, equivalent to one small onion. It's suitable for recipes serving one or two people, or as a flavorful base in a sauce.

A medium onion generally weighs between 150 and 175 grams, or around 6 ounces.

Many recipes use approximate sizes (small, medium, large) because for most savory dishes, a slight variation in onion amount won't ruin the recipe. However, this is less precise than measuring by weight.

Yes, different types of onions can have varying densities. For example, sweet onions like Vidalia tend to be less dense than standard yellow onions, meaning a 70g sweet onion might be slightly larger in volume than a 70g yellow onion.

Since there is no standard size for an onion, "half an onion" is vague. For accurate measurements, it's best to know the total weight of the onion or use a kitchen scale to measure the half, for example, 80-90g for half a medium onion.

The most accurate method is to use a digital kitchen scale. This removes all ambiguity and ensures you're adding the exact amount of onion specified by the recipe.