The Loan Estimate is a standardized 3-page document that every lender is required by federal law to give you within 3 business days of receiving your loan application. It shows your estimated interest rate, monthly payment, total closing costs, and 5-year cost summary.
Because the format is identical across lenders, the Loan Estimate is your best apples-to-apples comparison tool. Get LEs from at least three lenders on the same day, lock the same rate scenario, and compare them line by line.
If the lender's final numbers at closing exceed the LE by more than the legal tolerance (typically 10% for most fees, 0% for lender fees), they have to pay the difference. Save your LE — it's a legal document.