From the"Summary of Product Characteristics" for doxatel
"Prostate cancer
The recommended dose of docetaxel is 75 mg/m2
. Prednisone or prednisolone 5 mg orally twice daily
is administered continuously (see section 5.1)."
The dose is calculate based on body surface area which is calculated based on height and weight which can be calculate usind different formulae. See here
Hope this helps
Tom