A rental property calculator is a tool for estimating collected rent, operating expenses, debt service, and remaining cash flow.
Frequently asked questions
What is a good cash flow on a rental property?
Most experienced landlords target a minimum of $200/month per door in true cash flow, after EVERY expense — mortgage, taxes, insurance, vacancy, repairs, and management. $100/door is the floor below which a single bad month wipes out the year. The reason the bar is set so high: cash flow is your shock absorber. Cap-ex surprises (a roof, an HVAC, a sewer line) hit in 4–5 figure chunks, and you need monthly cash flow accumulating into a reserve to absorb them without selling the property at the wrong time.
What's the 1% rule and does it still work?
The 1% rule says monthly rent should equal at least 1% of purchase price — a $200,000 house should rent for $2,000+. It was a useful shortcut in the 2010s but is broken in most appreciating markets today (rents have lagged price growth). The 1% rule still works as a SCREEN — if a property hits 1%, it almost certainly cash flows. Below 1% you have to do the actual math, which this calculator does. The rule's real value now is filtering out junk before you spend time underwriting.
What's a healthy cap rate for a rental?
Cap rate (NOI ÷ purchase price) varies wildly by market. Class A in coastal cities: 4–5%. Class B in mid-cap metros: 6–7%. Class C in tertiary markets: 8–10%+. Higher cap rate ≠ better deal — it's compensation for risk (older buildings, weaker tenants, softer markets). A 9% cap rate in a market with 6% vacancy and rising property taxes can produce worse cash flow than a 5% cap rate in a stable market. Use cap rate to compare LIKE properties in LIKE markets, not as a universal goodness score.
How much should I budget for vacancy and repairs?
Default budgets that won't burn you: vacancy 5–8% of gross rent (assume 1 month vacant per year), repairs 5–10% of gross rent (higher for older properties), cap-ex reserve 5–10% of gross rent (roof/HVAC/big-ticket items not in 'repairs'), property management 8–10% of gross rent (skip this if you self-manage but understand you've replaced cash with your time). If your underwritten cash flow disappears once these are baked in, the deal didn't actually cash flow — you just hadn't done the full math yet.