How do you say "how long"?

Question

So, I've found multiple different translations for "how long" but I can't get an answer on which is most common and when you use them. The ones I've found are چند مدتی and چقدر طول. Which of these is more common? Are they used in different situations? If neither of them really work, what should I say instead? EDIT: "How long" specifically with time, not length.

Answer 1

”چقدر طول ميكشه" or “چند وقت" its alao enough to only say “چقدر"