We don't know how to exactly define or calculate the size of the habzone.
But due to inverse square law, we know exactly how that size (whatever it turns out to be) will vary due to the luminosity of the star. The brighter the star, the wider the habzone. Some stars have luminosities over a million times that of our sun, so their habzones will be a thousand times wider (and a thousand times farther out) than sol's.