How much does one glass in a recipe actually hold?

The glass and spoon measures used in recipes differ from home to home; the same recipe can give a different result in two kitchens. That does not show that the recipe is wrong but that the measure being used is personal.

Why is it so variable?

The vessel called a su bardağı (water glass) comes in clearly different volumes from kitchen to kitchen. The difference between two glasses known by the same name can be large enough to change the consistency of a recipe directly.

The same problem exists with spoons. The spoons used as tablespoons vary in depth and width; and whether it was taken level or heaped is never stated in the recipe either.

That uncertainty changes the result especially in baking. A difference of a few spoonfuls can be made up for in a dish with sauce, while in a dough the same difference takes the consistency somewhere else entirely.

Which recipes does it matter in?

Precision of measure matters in recipes where the ratio between the ingredients decides the result. Bread, cake and baked goods come first in that group; there the difference between glasses becomes directly visible.

In dishes with sauce, soups and sautés the flexibility is high. In these recipes the measure is a starting point and is adjusted while cooking by eye and by taste; a difference of a few spoonfuls does not spoil the result.

Rice sits between the two. The ratio between grain and water decides it, but using the same glass for both the grain and the water keeps the ratio by itself and largely solves the problem.

What does using the same glass solve?

Using the same glass for both the solid and the liquid in a recipe makes the glass's real volume beside the point. What matters is not the absolute amount but the ratio between the ingredients.

That method helps especially in rice, soup and dough recipes. Whether the glass is large or small, as long as the ratio holds the result comes out close to what was expected and the recipe becomes repeatable.

The same principle holds for the spoon. Always using the same spoon in a recipe also removes the question of level or heaped; as long as you take it the same way every time.

How do you settle on your own measure?

Measuring the real volume of the glass and the spoon at home once gives you information that holds for every recipe. That measurement is done once and stays valid as long as the kitchen does not change.

Writing the measured value down somewhere makes it easier too. A short note stuck to the inside of a cupboard door means you do not have to remember how much the glass holds while trying an unfamiliar recipe.

Buying a measuring jug is the most direct answer. A vessel with markings on it translates both recipes and measures coming from other kitchens into a common language and makes them repeatable.

What do you gain by measuring by weight?

Weight is a far more stable measure than volume. The same amount of flour fills the same glass differently when it is packed and when it is loose; the weight is the same in both cases.

This is why baking recipes are increasingly written by weight. A recipe written by weight gives the same result in whichever kitchen it is followed and removes the argument about glasses entirely.

The second gain of measuring by weight is the washing-up. Putting the bowl on the scale and adding the ingredients one after another makes separate measuring vessels unnecessary and cuts the work in the kitchen.

What do you do when a recipe does not work?

When a recipe does not work, the first place to look is the measure, because that is where the most likely difference is. Noting the glass and the spoon used while trying the same recipe a second time usually solves the problem in one go.

The second place to look is the consistency. Looking at how the result should appear, rather than at the directions in the recipe text, can be a far more reliable guide than a numerical measure.

And a recipe that has found its own measure is written down. Writing down what a recipe you have got right comes to in your own kitchen makes it permanently repeatable.