Home cooks now draw recipes from everywhere, which means a single week of cooking might involve grams, ounces, cups, millilitres and fluid ounces. Managing that without constant conversion is mostly a matter of a few decisions made once.
Why Metric Wins for Baking
The practical advantage of metric is not accuracy but arithmetic. Everything is decimal, scaling is multiplication, and there are no fractions to convert.
Halving 375 grams is trivial. Halving thirteen and a quarter ounces is not, and halving three-quarters of a cup requires a measuring set that goes down to an eighth.
Most serious baking references have moved to grams for this reason, and scales that switch between units at a button press, of the kind in the Escali range, remove the need to choose a single system.
The Conversions Worth Memorising
- 1 ounce is about 28 grams
- 1 pound is about 454 grams
- 1 US cup of water is about 240 ml, and roughly 240 g
- 1 UK pint is 568 ml; a US pint is 473 ml
- 1 fluid ounce is about 30 ml
- 250°F is about 120°C; 350°F is about 175°C; 425°F is about 220°C
Where Conversion Goes Wrong
The main hazard is converting a converted figure. A recipe originally in grams, published in cups, then converted back to grams by a reader, accumulates error at each step.
Where a recipe gives both, use the weights. They are almost always the figures the author tested with, and the volume equivalents were added afterwards.
Fluid Ounces Are Two Different Things
A US fluid ounce is 29.6 millilitres; an imperial fluid ounce is 28.4. The difference is small per unit and adds up across a pint, which is why a US pint is meaningfully smaller than a British one.
Worse, a fluid ounce is a volume and an ounce is a weight, and they are only interchangeable for water. Recipes that mix the two without specifying are a known source of confusion.
Temperature
Oven temperatures are the other recurring conversion. The formula is straightforward, but gas marks add a third system: gas 4 is around 180 degrees Celsius or 350 Fahrenheit.
Fan ovens complicate it further, generally running around twenty degrees hotter than the stated conventional temperature, which means reducing the setting rather than the time.
A Practical Approach
Pick a primary system, convert recipes into it once, and write the converted figures on the recipe. Doing the conversion once and recording it is considerably better than doing it every time from scratch.
A scale that displays both removes the pressure to commit entirely, which is useful when cooking from American sources where cup measurements are the norm and weights are not always given.