Each country started its own sizing convention.
Here is the Bella Materna size conversion for international sizes.
UK has double FF, which is a half size between F and G, therefore we do not list these double sizes
We use the European method of sizing where DD=E, DDD=F - we like to keep it straightforward! Our bras are known for their comfort and longevity, the back closure is longer, so it is easier to fit, and last - as long as when you first get it - you are on the 3rd - 6th hooks --- this way your investment will last longer for you!