Fix and flip loans are sized against two limits, and the smaller one wins. Loan-to-cost (LTC) is the loan as a share of your total cost, meaning the purchase price plus the renovation budget. The after-repair value (ARV) cap is the loan as a share of what the property should be worth once the work is done, based on comparable sales.
Here is a simple example with round numbers. You buy a house for $200,000 and plan $60,000 of work, so the total cost is $260,000. At 90% LTC, the loan could be up to $234,000. If the appraiser puts the ARV at $360,000, a 75% ARV cap allows up to $270,000. The lower number, $234,000, is the loan. You bring the remaining $26,000 plus closing costs. If the ARV came in at $300,000 instead, the 75% cap would drop the loan to $225,000 and you would need to bring more cash.
This is why the ARV matters so much. A deal that looks fine on cost can come up short if the comparable sales do not support the finished value.