Hydrocortisone dosing depends completely on the indication, route, and patient age/weight. Please specify what it is for, such as:

Do not self-dose injectable or oral hydrocortisone for an emergency without a clinician's plan. If there is vomiting, collapse, severe weakness, confusion, low blood pressure, or known adrenal insufficiency with inability to take oral medication, seek emergency care now.

For reference only, usual adult replacement therapy is often 15-25 mg/day orally in 2-3 divided doses, individualized by an endocrinologist. Pediatric replacement is commonly body-surface-area based, with FDA labeling for pediatric oral granules listing an initial 8-10 mg/m²/day, individualized to response (FDA prescribing information).