From Longman Dictionary of Contemporary Englishfactor something ↔ out phrasal verb technicalto not include something in your calculations about how long something will take, how much it will cost etc → factor→ See Verb table
Examples from the Corpus
factor out• There are a number of important factors to look out for.• Three factors stand out in explaining this harmonious relationship.• Among the factors that stand out in the Orphic construal of a cosmos is the nature of time.• As the factor came out, it shut behind him and they heard the bars and chains go on.• If any one common factor did stand out it was her tendency to play parts older than herself.• There were a number of factors for pulling out of Los Angeles.• It is important to examine each possible limiting factor by spelling out the issue of feasibility. 