Eggs: Does Size Matter?

One question I get asked quite regularly is whether medium eggs can be substituted for large in a recipe or vice versa. So I took to the kitchen and started experimenting to test the difference egg size makes and to answer some other egg-related baking questions.

A dozen eggs in an egg box

Jump to the question you’d like to answer…

Can I substitute medium eggs for large (or vice versa)?

How much do medium and large eggs, white and yolks weigh and how do you convert between them?

Can you bake with just eggs whites or yolks instead of whole eggs?

How do you convert between egg sizes for the EU, USA, Canada and Australia?

Can I Substitute Medium Eggs For Large (Or Vice Versa)?

One of my most popular recipes is my vanilla sponge cake and whenever I bake it I usually chuck in whatever eggs I happen to have in the kitchen whether medium or large and it’s always turned out just fine. I found it strange given that people are always saying how important accuracy is in baking that I could use pretty much any size of egg with good results.

However, I’d never baked a medium-egg cake and a large-egg cake at the same time to compare the differences, so I decided to do just that.

I made a batch of vanilla cupcakes using the smallest medium eggs and the largest large eggs and this is what I found (cupcakes are great for this type of experiment as I can bake small batches and they’re easy to compare side-by-side).

The Results

A comparison of cupcakes baked with medium or large eggs.

I preferred the cake made using medium eggs. It had a softer, fluffier and moister texture. However, on the negative side, it didn’t rise as much as the cake made using large eggs and it was more crumbly.


If you make a cake with the wrong size eggs it’s unlikely to be a disaster, but if you want the taste and texture to be as intended when the recipe was written then stick to the right size of eggs as it does make quite a big difference.

But what if I only have medium eggs and the recipe calls for large?

Then the best thing to do is to weigh your eggs.

After discovering the difference it makes using medium v large eggs in a cake I got my scales out and weighed every egg I used in the kitchen for months (yes, that’s right I’ve been planning this post for a long time!).

Not only did I weigh the egg in its shell, but I also weighed the white, yolk and both together.

The table below shows the weight of egg needed for the number of medium/large eggs called for in a recipe.

As a quick rule:

6 large eggs = 7 medium eggs

If a recipe calls for medium eggs and you only have large

Medium to large eggs weight conversion

If a recipe calls for large eggs and you only have medium

Large to medium eggs weight conversion.

As I mentioned before, as well as weighing the whole egg I also weighed the whites and yolks separately and I was surprised by the results. I’d expected large eggs to have bigger yolks and whites, but in reality, the size of egg yolks barely varies by egg size, with the large yolks weighing the same as medium when rounding to the nearest whole gram.

1 medium egg yolk = 1 large egg yolk = 18g

If a recipe calls for a medium egg yolk and you only have large (or vice versa)  then just add it in. It won’t make a difference.

What this means is that pretty much all the size difference between medium and large eggs is in the whites. The tables below show the conversion between medium and large egg whites.

As a quick rule:

11 large egg whites = 13 medium egg whites

When a recipe calls for medium egg whites and you only have large

Medium to large egg whites weight conversion.

When a recipe calls for large egg whites and you only have medium

Large to medium egg whites weight conversion.

Can you bake with just egg whites or yolks instead of whole eggs?

All this thinking about eggs got me wondering. If your eggs are more white than yolk or vice versa will the effect the cake.

To test the difference yolks and whites make to a cake I baked two more batches of cupcakes. One where I used all egg whites (increasing the number so the weight of egg in the recipe matched the weight if I were using whole medium eggs) and one where I used only egg yolks.

The results surprised me.

A comparison of cupcakes made with just egg yolks and just egg whites.

I had expected that the cake made with egg whites would be taller and fluffier as egg whites whip up so much and can hold a lot of air. The opposite was true. The yolk cake was by far the tallest. It also tasted best and had a lovely texture. However, you’ll see in the picture that it lacked structure with large air bubbles and a noticeable dip in the middle where it collapsed a little after baking.

The cake made with just egg whites had a much more uniform structure suggesting it’s the eggs whites that act as cake “glue” far more than the yolks. It was paler in colour (as expected) and sadly tasted quite bland, unlike the egg yolk cake which was full of flavour, almost like a custard.

When is a large egg not a large egg?

The answer depends on where in the world you are.

Everything I’ve written here about egg sizes is true for the UK (and the rest of the EU as eggs are categorised consistently across EU countries).

Unfortunately the same cannot be said for the rest of the world. This means that if you’re in the UK using an American recipe which calls for large eggs then you’d be better off using medium, or if you’re in Australia using a British recipe calling for large eggs then you should opt for Jumbo eggs.

I recently wrote a long post about how to convert between grams, millilitres, US cups and ounces, but it turns out you need to covert your eggs too.

The table below shows the size classifications for the UK (and the rest of the EU), USA, Canada and Australia. I chose those four countries as that’s where I know most of my readers are, but if you have a quick Google you can find the egg sizes by weight for most countries around the world.

Egg weights by size for UK, EU, USA, Canada and Australia

So if a recipe from another country calls for large eggs what size should you be using?

What size eggs you should use if an international recipe calls for large eggs.

This table is a guide. As egg sizes don’t overlap perfectly you’d be best weighing your egg before adding it to the recipe, but using the sizes in the table as a substitute for large eggs should give decent results.

A dozen eggs in a box

So there you have it, this is all I know about the impact of eggs in baking cakes. I hope it answers some of your questions and helps you to bake better cakes. If you have any other random egg related questions you’d like me to investigate then do let me know in the comments.

Pin This Egg Size Guide

Can I substitute medium eggs for large (or vice versa)? How much do eggs weigh? How do I convert between medium and large eggs? and more egg-related baking quetions answered.


  1. What wonderful dedication to experimentation and learning! Do you still have the spreadsheet of all the individual eggs you measured? It would be interesting to see the distribution, and also see the white-to-yolk ratios that all your eggs had.

    • I do, I thought about sharing all of the distribution graphs but I realised I was in danger of making the post far too technical.

  2. Very good experiment and well explained article with images.
    Removed confusion of many including me.

  3. What if the recipe doesn’t state a size?

    • Best thing to do would be to comment (if you can) asking the correct size to use. If it’s a BBC good food recipe then they usually use large in theirs unless otherwise stated. If you can’t ask then I’d weight my eggs and aim for ones that are on the larger size of medium or the smaller side of large.

  4. Hi Charlotte
    I’ve been baking for too many years to remember 40 +years & counting. Around 15 years ago I started to buy my eggs from a friend who had a small holding but the eggs varied in size dramatically as sometimes they were chicken eggs sometimes duck or even turkey eggs so I started to weigh my eggs, so for a 6oz mix flour sugar & butter I would weigh out 6oz of eggs I sometimes add a little milk to make up the weight too & this works well & cakes turn out perfect every time, so I Would agree wholeheartedly that size does matter, & thank you for sharing all your wonderful recipes & ideas I love your site & you’re never too old too learn. Keep up the good work.

  5. Thanks for the hard work Charlotte.
    I never thought it mattered to much between the sizing of eggs between medium & large,
    But i can see now how wrong I was..

  6. This is great thank you for taking the time to experiment and reporting back x

  7. This is genius!

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