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Egg sizes explained: what medium, large and extra-large really mean in a recipe

By BakePen Editorial · Last updated 31 Aug 2026 · 5 min read

‘3 eggs’ is the least precise line in most recipes. Egg sizes are legal categories with weight bands, and the bands differ between countries: a British large egg is not an American large egg. Across three eggs, cooking with mediums where larges were intended can quietly remove half an egg's worth of liquid, protein and lift from a recipe — enough to sink a sponge and puzzle its baker.

This article gives the actual weights behind the labels, explains what eggs contribute to a bake (it is more than ‘binding’), and shows how to correct for the eggs you have, including the white-and-yolk arithmetic that meringues and custards depend on.

The labels and the grams behind them

In the UK and EU, eggs are graded by weight in shell: small under 53 g, medium 53–63 g, large 63–73 g, very large above 73 g. In the US the bands run lower: a large egg is 56.7 g minimum per egg by the dozen-weight system, and jumbo reaches 70.9 g. So a recipe written in New York for large eggs assumes about 57 g an egg; one written in London assumes about 68 g. Same word, nearly 20% apart.

The shell is about a tenth of the weight. Shelled, a UK large egg gives roughly 58–60 g of egg, split about two-thirds white to one-third yolk — a large yolk is around 18–20 g, the white 38–40 g. These are the numbers the egg converter uses, and the numbers to weigh by when a recipe is written in grams of egg, as professional pastry recipes often are.

What eggs do in a bake

Eggs are four ingredients in a shell. The water (about three-quarters of the egg) hydrates flour and makes steam. The proteins set with heat, giving cakes and custards their structure — the sponge's scaffold once flour's starch joins it. The yolk's fat and lecithin emulsify, holding fat and liquid in a smooth batter and enriching flavour and colour. The white, whipped, is baking's cheapest aeration: a foam that can triple in volume and carry an entire flourless cake.

Each role has a temperature and handling preference — whites whip best at room temperature, yolks emulsify willingly, whole eggs set batters around 70–80 °C — which is why eggs reward being understood rather than merely counted. A recipe balanced for three large eggs and given three small ones loses a little of every role at once.

Correcting for the eggs you have

The correction is arithmetic and takes a scale. If a recipe wants 3 large eggs (about 174 g shelled, UK) and your box is mediums (about 51 g shelled each), three give you 153 g — beat a fourth egg, weigh out the missing 21 g, and use the rest in an omelette. The same method fixes any mismatch, including the reverse: a recipe in mediums, a box of very larges, solved by weighing out the right total of beaten egg.

Where a recipe counts whites or yolks separately — meringues, macarons, custards — weigh the parts. Meringue ratios are sugar-to-white by weight; a ‘3 egg whites’ instruction with small eggs can be 15 g light on white, and the meringue will not forgive it even if the baker never learns why.

Freshness, storage and the floating test

Eggs age through their shells: whites thin, yolks flatten, and the air cell grows — which is the physics behind the float test (old eggs float; fresh ones sink and lie flat). For baking, middling-fresh eggs are versatile; very fresh whites whip slightly less willingly, and older whites whip fast but make a less stable foam. A pinch of acid — cream of tartar — steadies white foams regardless of age.

Store eggs cool and consistent; the fridge door's temperature swings are worse than a cool larder's steadiness for most home timelines. And bring them to room temperature before baking — not from folklore but because cold eggs split batters and whip slowly, as the temperature article on this site explains in full.

Egg sizes in grams

Half an egg missing

A sponge written for 3 large eggs is made with 3 mediums because the box was there. Total shelled egg: 153 g instead of 174 g — the sponge is short 21 g of liquid and protein, roughly a third of an egg and yolk. It bakes a shade lower, a shade drier, and entirely ‘not quite’. Nothing in the method was wrong; the ingredient list, read in grams, was short. Weighing beaten egg to the recipe's total is a thirty-second habit that makes egg size a non-event forever.

Common mistakes

Assuming ‘large’ is universal. US large (≈57 g in shell) and UK large (≈68 g) differ by nearly a fifth. Recipes crossing the Atlantic inherit the gap; gram totals dissolve it.

Splitting whites by count in meringue. ‘4 whites’ can vary by 20 g between boxes. Weigh whites for meringue and macarons; the sugar ratio depends on it.

Cracking eggs straight into the batter. One bad egg ruins a bowlful. Crack into a cup first, every time — the cheapest insurance in baking.

Questions, answered

Can I use duck eggs instead?

Duck eggs are larger and richer in fat and protein; one replaces roughly one large hen’s egg plus a yolk in richness. They shine in sponges and enriched doughs; weigh them the same way.

What does ‘egg wash’ assume?

Usually one beaten egg, any size, often thinned with a spoon of milk or water. Size hardly matters here; shine and colour are the point.

Are brown eggs different inside?

No — shell colour is breed, not content. Weight for weight, brown and white eggs bake identically.

The short version

Count eggs and you inherit every country's grading quirks; weigh them and the recipe gets exactly what its author meant. Keep the bands in mind, crack into a cup first, and ‘3 eggs’ becomes what it should have been all along — a quantity.

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