Use one area basis
Record net installed square footage before comparing per-square-foot prices.
A contractor may price labor on installed area while material is billed by cartons.
Price whole packages
Material cost should use the number of full cartons actually purchased, not only net square footage times a nominal rate.
Record credits for returns only when the supplier allows them.
Separate scope lines
Underlayment, adhesive, moisture mitigation, leveling, demolition, disposal, transitions, base, stairs, and furniture moving can materially change totals.
Keep each included or excluded item visible.
Calculate comparable unit costs
Total project cost ÷ net installed area gives one comparison metric, while material-only cost ÷ adjusted purchase area answers a different question.
Label which denominator is used.
Verify quote assumptions
Tax, delivery, minimum labor, travel, markup, and warranty scope should come from the actual bid.
Do not infer missing charges from a generic national average.