Max offer calculator
Stop asking whether the asking price works. Set your minimum cash flow and returns, and this free tool works backwards to the highest price at which the deal still clears your bar, with real per-state property tax and insurance in the math. No signup.
Default targets mirror a conservative buy bar (cap rate above 7%, cash-on-cash above 8%, positive cash flow). Set your own. Fixed reserves: 8% vacancy, 10% maintenance, 10% management, plus real per-state tax and insurance.
Estimates only. Verify rent comps, taxes and condition before making an offer. This is not financial advice or an appraisal.
Screening a lot of listings?
The Mortar Chrome extension runs this exact analysis automatically on any Zillow listing. No typing. Free to start.
Why work backwards from targets
Anchoring on the asking price is how investors talk themselves into thin deals. Working backwards inverts the negotiation: the rent, the real local costs and your own thresholds produce a number, and that number is your ceiling. If the seller is $60k above it, you know the gap before you spend an evening underwriting.
The same discipline applies across every deal you screen: fixed assumptions, honest local taxes and insurance, and thresholds you chose calmly in advance. The only variable left is the property.
Frequently asked questions
What is a maximum allowable offer (MAO)?
The maximum allowable offer is the highest price you can pay for a property and still hit your investment targets. Instead of asking whether the asking price works, it flips the question: given the rent and your minimum cash flow and returns, what price makes this deal work?
How does this calculator find the max offer?
It runs the same deterministic analysis as every Mortar tool (mortgage, real per-state property tax and insurance, vacancy, maintenance and management reserves) across prices, and finds the highest price where the deal still clears every one of your minimums. Because each metric falls as price rises, there is exactly one crossover point.
Is this the same as the 70% rule?
No. The 70% rule is a flipper's shortcut based on after-repair value and rehab costs. This calculator is for buy-and-hold rentals: it works backwards from rent, expenses and your cash flow and return targets, which is the number that matters when you plan to hold the property.
What targets should I use?
The defaults mirror a conservative screening bar: cap rate above 7%, cash-on-cash above 8% and positive monthly cash flow. Your own bar should reflect your market and strategy. The point is to pick your thresholds before you fall in love with a house, then let the math name the price.
Is this financial advice?
No. Every figure is an estimate to help you screen deals and frame offers quickly. It is not financial, investment or real estate advice, and it is not an appraisal. Verify rent comps, taxes and condition before making an offer.
More free calculators
The full screen: cap rate, cash flow, cash-on-cash and a verdict, with real per-state taxes and insurance.
Net operating income over price, computed with real per-state property tax and insurance.
What the cash you actually put in earns, with your own down payment, rate and term.
Monthly rent minus mortgage and every honest expense line, including reserves.
Prefer the full write-up? Read the Mortar blog on analyzing rentals.