I know many of us in the British Isles find the whole cup thing confusing, annoying, or downright scary.
Although I find weighing to be much a more accurate method of measuring, I don't find cup measures at all difficult to use.
Having a set of US cup measures helps. I bought these in my local cookware shop. Supermarkets have them, M&S has them, Amazon has them.
There's a quarter cup measure, a third of a cup, half a cup and a whole cup.
A cup is 8 fluid ounces (approx 240 ml)
Half a cup is 4 fluid ounces (approx 120 ml)
A third of a cup is 2⅔ fluid ounces (approx 80 ml)
A quarter of a cup is 2 fluid ounces (approx 60 ml)
It is worth remembering that in the US a pint is not 20 fl oz, but 16 fl oz. This was also the case in Britain up until the nineteenth century. If an American recipe calls for a quart (2 pints) of something it means 32 fl oz which is 4 cups or as near-as-damn-it 1 litre.
The reason it is difficult to give simple conversions for US cup measures is simple. It all depends on what you are measuring.
One cup of oats weighs just over 4 oz.
But one cup of demerara sugar weighs just over 8 oz.
How to Make Your Own Cup Measure in 10 Minutes
If you don't have a set of cup measures I am sure you will have a measuring jug which has imperial and metric measurements on it somewhere. If you have, then it is easy to make your own measuring cup or cups.
You need a plastic container which you can cut easily with scissors. It must be able to hold more than 8 fl oz of liquid. Something like a water bottle, a cream carton or milk carton. I used a large yogurt pot, the transparent kind with a removable card sleeve. This was for the sake of clarity in my pictures but I'm sure a white pot would work just as well.
You also need a permanent marker and your measuring jug.
Pour 2 fl oz (60 ml) of water into the jug. This is your quarter cup measure.
Pour the 2 fl oz water into your container, wait for the water to settle and carefully mark on the pot where the water level comes to. Do it on the other side of the pot too to make measuring easier. Or, if you have a steady hand mark all the way round. If you are using an opaque container you may need to set it somewhere level with the light behind in order to do mark it accurately.
Tip the 2 fl oz of water out before you add the next measurement (or you will get into a right old muddle).
Continue until you have marked all four cup measures on your container.
Trim the container down so that it can be used to measure one level cup.
NB trim really carefully, my yogurt pot split as I was cutting.
If you can be bothered it would be worth making individual cups for the smaller measures. I would use small yogurt pots for these.
Some American recipes call for butter measured in sticks. A US stick is a quarter of a pound or 4 oz. So, if, for example, the recipe calls for 1½ sticks it means 6 oz.
As for teaspoons and tablespoons, apparently there is a slight difference between UK and US spoons but I've always used UK spoon measures with no problems.
I hope that helps someone, but honestly it is easier to just buy some measuring cups.