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You follow an American recipe to the letter and the cake comes out dry, the cookies spread less and the bread is dense. Usually nothing is wrong with the recipe. The trouble is that the US and South Africa use different cups, and US recipes add ounces, sticks of butter, Fahrenheit and pan sizes in inches on top. This post works through each one, and the free recipe converter does all of them at once: paste the recipe, read it back in ml, grams and °C.
Convert your own recipe
The converter below starts on a typical US cookie-bar recipe. Paste your own over it - the original stays on the left and the South African version appears next to it, line by line.
Checked against a published example
- A US cup is 8 US fluid ounces, 236.588 ml; a fluid ounce 29.574 ml; an ounce 28.3495 g; a pound 453.592 g - NIST Handbook 44, Appendix C. Our recipe converter uses those factors: 1 cup gives 237 ml, 8 oz gives 227 g and 1 lb gives 454 g.
- A cup of all-purpose flour weighs 120 g and a stick of butter 113 g - King Arthur Baking ingredient weight chart. With Show grams on, the converter gives 270 g for 2 1/4 cups of flour (2.25 x 120 g).
No calculator needed a fix for this post.
Problem 1: the cup is a different size
- US cup: 236.6 ml. South African (metric) cup: 250 ml. Ours is 13.4 ml - 5.7% - bigger.
- One cup out is a tablespoon out. 250 - 236.6 = 13.4 ml, close to a 15 ml tablespoon.
- 3 cups of flour: 3 x 236.6 = 710 ml in the US, 750 ml in SA cups - 40 ml extra. At 120 g a US cup (about 0.51 g per ml) that is about 20 g more flour than the recipe was tested with.
- Liquids matter less than flour. 5.7% more milk rarely ruins anything; 5.7% more flour, on top of packing it into the cup, is what dries a cake out.
The recipe converter turns every US cup into ml and names the closest South African cup - "532 ml (about 2 1/4 SA cups less 2 tbsp)" for 2 1/4 US cups - so you can measure with the jug or adjust your cups.
Problem 2: scooping packs the flour
- A US cup of flour is 120 g when spooned in and levelled (King Arthur Baking) - and noticeably more when the cup is scooped through the bag and the flour packs down.
- This is why the converter does not guess grams for cups by default. The ml figure is exact; a weight depends on how the cup was filled.
- For baking, weigh where you can. Turn on Show grams for flour, white sugar, brown sugar, icing sugar, butter and rice - the six ingredients with well-known typical weights. For grams of other ingredients, the cups to grams converter has a longer list.
Problem 3: ounces, pounds and sticks
- An ounce (oz) is weight: 28.35 g. 8 oz of cream cheese is 227 g.
- A fluid ounce (fl oz) is volume: 29.6 ml. When a US recipe gives milk or stock in plain oz, it usually means fluid ounces.
- A pound (lb) is 453.6 g - 1 lb of mince is 454 g. The kg to pounds converter does body weights and luggage too.
- A stick of butter is 113 g, half a US cup. Our butter comes in 250 g and 500 g blocks, so "2 sticks" is 226 g - just under a 250 g block.
Problem 4: Fahrenheit and pan sizes
- 350°F = (350 - 32) x 5/9 = 176.7°C. Set 180°C, gas mark 4 - about 160°C in a fan oven.
- 425°F = 218.3°C - set 220°C, gas mark 7. The Celsius to Fahrenheit converter has the full working.
- A 9 x 13 inch pan is 23 x 33 cm (inches x 2.54). An 8 inch square tin is 20 cm.
What does not need converting
- Tablespoons and teaspoons: a US tablespoon is 14.8 ml against our 15 ml, a teaspoon 4.9 ml against 5 ml. Under 2% apart - use your normal spoons.
- Eggs, "a pinch", "to taste" and cooking times stay as they are.
Not verified from a primary source: ingredient names differ as well. US baking soda is our bicarbonate of soda, powdered or confectioners' sugar is icing sugar, heavy cream is roughly our cream, and all-purpose flour is usually swapped for cake flour. These are common kitchen swaps, not measured equivalents.
Sources
- NIST Handbook 44 (2024), Appendix C - General Tables of Units of Measurement: cup, fluid ounce, ounce and pound.
- King Arthur Baking, Ingredient Weight Chart: all-purpose flour 120 g a cup, butter 113 g a stick (half cup).
Calculators used in this post
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