How to find out the pipe cut(raw material) length for a but welded elbow

[sushant297]

Hi guys
Greetings

is there any formula or reference to know the raw material length that need to be cut from the mother pipe to form an elbow (90 or 45 deg)

[sushant297]

Help Needed

guys is there any formula or reference to know the raw material length that need to be cut from the mother pipe to form an elbow (90 or 45 deg)