It’s very important that your new flamenco shoes fit properly.
All dance shoes must be snug, but flamenco and Irish dancing shoes are the hardest to get right. Dancers often buy ballroom and ballet shoes a fraction too tight, knowing they’ll stretch to a perfect fit with wear. However, flamenco shoes are rigid and have less “give”, so if you buy a pair that’s slightly too small, they may never be comfortable. Too-small shoes will affect your balance, because you don't have a secure platform to dance on if your toes are curled up.
Shoes that are too big can be even worse because they can cause injuries. If your foot is able to slide around inside the shoe, you're more likely to go over your ankle or step out of the shoe while you’re dancing. The movement means your foot will rub against the inside of the shoe and cause blisters. If your shoe doesn’t feel like part of your foot, it’s distracting, too.
Unfortunately it’s not as simple as looking up your street shoe size on a conversion table. We all know clothes sizes vary from manufacturer to manufacturer, and shoes are no different. Similarly, people with the same size of foot can have surprisingly different foot shapes, in much the same way as two women may wear the same size jeans, but one may be able to wear slim fit whereas the other needs relaxed fit.
For instance, you can have two people with the same length of foot, but the ball of one person’s foot will be further back than the other’s. Since that’s where the shoe has to bend, that can be important. The width of feet varies, too, but not necessarily through the whole length: some people have a wide forefoot and narrow heels, and so on.
Of course, shoe manufacturers can’t cater for all these variations, so they build to an average instead. Each manufacturer makes their own choice as to what constitutes “average”, and make their lasts (the forms on which they build their shoes) accordingly. Have you noticed that some makes of street shoe always fit you better than others? That’s because that manufacturer’s lasts happen to be more like your foot.
If you're buying shoes on the internet, be prepared to send them back if they don't fit. Better to pay a bit of extra postage than be stuck with shoes you can't wear!