how are syns worked out?

Me again.
Was just wondering how a syn is calculated? When i did ww years ago i was told that 1 point was approx 50 cals. Is it a similar thing with syns?
TIA

for sweet and savoury snacks which are not real food it is basically calories divided by 20 = syns

so for example chocolate bar = 140 cals divided by 20 = 7 syns

it doesnt work for real food though you will need to check books and website.

Hope this helps

Fab thank you so much
x