Well, you didn’t specify clothes or shoes. In shoes you’d be about a three, maybe a three and a half. In clothes it varies wildly. I wear a size five and I have some shorts that are a 14 in girls. It really depends on why your a five, though. If it’s because you’ve got hips (like me) kids clothes won’t fit you all that well.
I WEAR KIDS CLOTHES i HAVE SMALL HIPS AND FLAT BELLY I AM A 32B IN BRA SIZE. I LOOKED AT A UK 4 AND THEY WERE MASSIVE SO I FIT INTO UK SIZE 2 OR SIZE 0 CLOTHES. I’M SMALL IN PANTS. I WEAR SIZE UK 8 TOPS THEY FIT ME. I CAN WEAR 13-14 YEARS IN TOPS I ONLY HAVE ONE TOP WHICH IS THAT SIZE MY BOOBS LOOK MASSIVE.