Why the Same Recipe Works for Everyone Except You

If your baking is inconsistent — the same recipe dry one week and fine the next — the most likely cause is not technique. It is that you are measuring flour by volume, and a cup of flour is not a fixed quantity.

A cup of flour is not a cup of flour

Depending purely on how it is filled, a cup of plain flour weighs anywhere from about 120 g to 160 g.

• Spooned and levelled — flour spooned lightly into the cup, then levelled with a straight edge: around 120–125 g.
• Scooped — the cup pushed into the bag, compacting the flour: 140–160 g.
• Sifted first: closer to 115 g.

That is a spread of up to 33%. In a recipe calling for three cups, the difference between spooning and scooping is over 100 g of flour — the difference between a tender cake and a dense one, entirely invisible while you work.

Nothing about your oven, your technique or your ingredients has to change for a recipe to fail this way. Two people can follow identical instructions correctly and produce different food.

Professional and commercial baking works in weight for exactly this reason. It is not fussiness.

Cups are not the same size internationally

Even ignoring how you fill it, the container differs:

A metric cup is about 6% larger than a US cup. Across a recipe with several cup measurements, that compounds.

The tablespoon that catches everyone

Australia's tablespoon is 20 ml. Everywhere else it is 15 ml.

An Australian tablespoon is four teaspoons; a US, UK or Canadian one is three.

This matters most where a tablespoon is a significant quantity of something potent: baking powder, bicarbonate of soda, salt, yeast, spices. A recipe from an Australian source calling for a tablespoon of baking powder, measured with a US spoon, is a third short — and in the other direction, a third over, which is enough to taste.

Teaspoons are 5 ml essentially everywhere, so they are safe.

Pints, and the other divergences

A UK pint is 20% larger than a US pint. For a recipe using a pint of stock or milk, that is a substantial difference in a sauce.

Fluid ounces are close enough that the difference rarely matters in cooking, but the gallon difference is large and shows up in brewing and preserving recipes.

Common weights, for when you need them

Approximate, and worth confirming against the recipe's own source if it gives one:

Two things stand out. Butter and honey are far heavier than flour for the same volume, which is why "a cup" is such an unreliable unit across ingredient types. And a US stick of butter is 113 g — half a cup, four ounces — which is the conversion most often needed outside the US.

What to do about it

Buy a digital scale. They cost very little, they take up no space, and they eliminate this entire category of problem. You can also weigh directly into the mixing bowl using the tare button, which means fewer measuring cups to wash — the practical advantage that converts most people faster than the accuracy argument does.

When a recipe gives both, use the weights. Where an author has provided gram measurements, those are what they actually used. The cup figures are a conversion, often done with a generic table.

When converting, note the ingredient. A general-purpose "1 cup = 240 ml" is right for liquids and wrong for everything dry.

Liquids can stay in volume. Water, milk and oil are consistent enough by volume that measuring jugs are fine. It is dry ingredients — flour above all — where volume fails.

The cooking converter handles ingredient-specific weight conversions rather than assuming a single density, and covers the US/metric/Australian spoon and cup differences. If you are also changing the quantity, the recipe scaler adjusts ingredients while leaving temperature alone — temperature does not scale, which is the other half of why scaled recipes go wrong.