How to halve a recipe

Halving is not doubling in reverse. The amounts divide fine — it's the egg, the pan and the browning that don't, and they fail in different ways from the ones that bite you scaling up.

The most-asked question, and it has a clean answer: crack the egg into a bowl, beat it until the yolk and white are properly combined, and use half by weight. A large egg is about 50 g out of its shell, so half is 25 g. Two tablespoons is close enough if you have no scale.

Don't try to separate it by eye without beating — the white and yolk do completely different jobs (water and protein versus fat and emulsifier) and half of each is not the same as half of the mixture.

When the recipe calls for three eggs, halving to one and a half is fine by the same method. And if it calls for one egg in something forgiving — pancakes, a loaf, anything with baking powder rather than structure — using the whole egg and slightly less other liquid usually works better than fussing.

The ones that don't divide into anything your spoons can measure:

Or skip the arithmetic entirely and weigh: half of 200 g is 100 g whatever the ingredient, which is the real argument for working in grams.

Half the batter in the same tin is half the depth, and depth is what sets baking time. It will be done meaningfully sooner — start checking at around two-thirds of the stated time — and if it's something that needs to rise against the sides, like a cake, it may not rise properly at all.

Better to go down a size and keep the depth. Useful equivalents, working in area:

• A 9×13 (117 sq in) halves to an 8×8 (64) or a 9×9 (81). The 8×8 is a shade over half; the 9×9 is closer to three-quarters.
• A 9×5 inch loaf tin halves to an 8×4.
• Two 9-inch round layers becomes one. Don't halve a single round tin by using a smaller one and the same depth rule — it's the one shape where you should just make one layer.

Keep the same depth and the time barely moves. Change the depth and you're baking a different thing.

• The pan you brown in. Halving up is about crowding; halving down is the opposite risk — too little in too big a pan and the fond burns before the meat colours. Drop to a smaller pan, or accept less browning.
• Cooking times on the stove. Half the soup still simmers for the stated time. It just comes to the boil faster. Braises and stews are the same: the meat takes as long as it takes.
• Item sizes. “A 3-inch cinnamon stick”, “cut into 2 cm cubes”, “a 9-inch tortilla” — those numbers describe how big something is, not how much you need. Halving them is the single most common mistake, going in either direction.
• A packet of yeast. You can halve it, but you don't need to — yeast multiplies as it works, so a half batch with a full packet just rises faster. Watch the dough, not the clock. Half a sachet is also a storage problem you didn't have before.

Baking soda and baking powder: halve exactly, and this is the one to get out the measuring spoons for. Under-leavened is a flat, dense result; over-leavened is a coarse crumb and a metallic taste. ⅛ teaspoon is a real measurement, not a rounding error.

Salt and spice: halve, then taste. Halving is the safe direction — you can always add — so unlike scaling up there's no need to hold back to 75%. Just season at the end rather than trusting the arithmetic.

Anything you reduce. Half the liquid in the same wide pan reduces much faster, because you've halved the volume without halving the surface it evaporates from. Watch it rather than timing it.

• Egg: beat it whole, use 25 g — or about 2 tbsp.
• Weigh instead of dividing fractions, if you can.
• Go down a pan size to keep the depth; otherwise check early.
• Leavening: halve exactly. Salt: halve, then taste.
• Times, item sizes and yeast: leave them alone.

Every table on this site has a ½× control, and a custom factor if you want something other than half. It divides the amounts, leaves pan dimensions and item sizes alone, and keeps a measurement and its converted twin in step so the two halves can't drift apart.

It won't halve the egg for you — that one's still a bowl and a fork. Going the other way has its own rules, or paste a recipe and try the control on it.