'I still don't know how much pizza I'll need'
'I still don't know how much pizza I'll need'
'필요할 아직도 피자를 얼만큼 몰라요'.

Is that the correct use of 얼만큼 or should it be 얼마나? Also, I'm still getting used to Korean sentence order and choosing the right forms so please correct anything else if it's wrong.

Question

'I still don't know how much pizza I'll need'
'I still don't know how much pizza I'll need' 
 '필요할 아직도 피자를 얼만큼 몰라요'.

Is that the correct use of 얼만큼 or should it be 얼마나? Also, I'm still getting used to Korean sentence order and choosing the right forms so please correct anything else if it's wrong.

Answer

피자가 얼마나 필요할지 아직 몰라.

Answer

Additionally, 얼마나, 얼마만큼, 얼마큼 may be used interchangeably to mean "how much".

얼만큼 is considered non-standard according to the dictionary, although people commonly use it in speech.