The REI Vault Pro Fix and Flip Calculator: How to Project Profit, ROI, and MAO Before You Buy

Fix-and-flip investing looks simple on paper: buy low, renovate, sell high. In practice, the gap between your projected profit and your actual profit is almost always determined by how thoroughly you modeled costs before you bought. Experienced flippers who consistently earn strong returns do not rely on rough estimates — they run a complete P&L projection on every deal before submitting an offer.

The REI Vault Pro Fix and Flip Calculator is that projection. It accounts for every cost category between purchase and sale, so you know your net profit, ROI, and Maximum Allowable Offer before you are under contract.

The Real Cost Structure of a Fix-and-Flip

Every flip has five distinct cost buckets, and most new investors only account for two or three of them. Missing any one category can turn a projected profit into a break-even — or a loss.

Purchase Price — what you pay to acquire the property. This is your starting point and the variable you have the most control over.

Estimated Repair Costs — the full scope of renovation required to bring the property to retail-ready condition. This should be a line-item estimate, not a round number.

Holding Costs — every dollar the property costs you while you own it: property taxes, insurance, utilities, HOA fees, and — critically — the interest on your hard money or private money loan. For a 6-month flip at $150,000 borrowed at 10%, holding costs from interest alone are $7,500. Most new investors forget this.

Financing Costs — origination points, loan fees, and any other lender charges associated with acquiring and carrying the property. A 2-point origination fee on a $150,000 loan is $3,000 that reduces your profit.

Closing Costs — two sets of closing costs: the buy-side closing costs when you purchase (title, escrow, recording fees, inspections) and the sell-side closing costs when you sell (agent commission, title, transfer taxes, seller concessions). Sell-side costs are the larger number and the more commonly underestimated.

What the Fix and Flip Calculator Takes as Input

The Fix and Flip Calculator accepts all five cost buckets as separate line items:

Purchase Price — your acquisition cost. Estimated Repair Costs — total renovation budget. Holding Costs — total carrying costs for the projected hold period. Financing Costs — loan origination and fees. Buy-Side Closing Costs — title, escrow, and acquisition-related fees. Sell-Side Closing Costs — title, transfer taxes, seller concessions. Agent Commission % — the total real estate agent commission on the sale side (typically 5–6%). Expected Sale Price (ARV) — your After Repair Value, the projected sale price after renovation is complete.

What the Calculator Returns

Net Profit

Your bottom-line result: Sale Price minus total all-in cost (purchase plus all expense categories). This is the dollar amount you earn from the flip after every cost has been deducted. It is the only number that matters when evaluating whether a deal is worth doing.

ROI and Profit Margin

Return on Investment is your net profit divided by total cash invested. Profit Margin is net profit as a percentage of the sale price. These two metrics together tell you the efficiency of the capital deployed — a $30,000 profit on a $150,000 all-in cost is a 20% ROI, which is excellent for a 4–5 month hold.

Agent Commission in Dollars

The calculator isolates the agent commission as a standalone line item, which helps you see exactly what that cost category is eating into your margin and evaluate whether a 5% versus 6% commission negotiation is worth pursuing.

Total All-In Cost

Every cost category summed into a single number. This is your true cost basis — the number you compare against sale price to determine profitability.

Using the Calculator to Find Your MAO

The most powerful use of the Fix and Flip Calculator is working backward from a target profit to your Maximum Allowable Offer. Enter your ARV and every cost except purchase price. Then adjust purchase price until the net profit hits your target — say, $30,000 minimum. The purchase price at that point is your MAO.

This is how professional flippers approach every deal: the offer price is the output of the P&L model, not the starting point for negotiation. If a seller will not meet your MAO, the deal does not work at that price — and you walk, regardless of how much you like the property.

Stress-Testing Before You Commit

Before closing on any flip, run three scenarios through the calculator: your base case (current estimates), a conservative case where repairs come in 15% over and sale takes 60 days longer, and a pessimistic case where you hit both cost overruns and a price reduction to move the property.

If all three scenarios produce positive profit, the deal has real margin. If the pessimistic case goes negative, your cushion is thin and the deal is a risk, not a certainty.

Try It on Your Next Deal

Open the Fix and Flip Calculator, enter a property you are currently evaluating or one you have recently analyzed manually. Compare what the calculator produces against your rough estimate. The gap — if there is one — is usually the holding costs, the financing costs, or the sell-side closing costs that were not fully accounted for.

Available to Core and Pro members. Start your 7-day free trial and run a complete flip P&L on a live deal this week.