Funny thing is, in theory, if a fairy were born without the ability to size shift, they would be stuck in exactly the size they were born in... As they essentially don't grow as they develop.
Assuming an adult fairy has a range of about 4cm to 15 meters. Assuming linear scale, about 7.5meters (or about 24 ft 8 in). Assuming a logarithmic scale, about 77.5cm (about 2 ft 6 in).