BMI calculators are NOT kind to people with sprinter thighs.
Well that's just too bad, innit! BMI calculators ar not supposed to be kind to anyone. They're supposed to be mean, to make you feel miserable about yourself, to shock you into action. You want kindness? Get a dog! And don't expect it from a BMI calculator.
Well, it's not. But it is something that we can easily calculate online and it (sorta) equalizes (sorta) the differences between a woman and a man who are of different heights but both trying to lose weight.
Truthfully, BMI is only a piece of it, you need body fat % as well, which isn't as easy to calculate on a quickie weekly basis.