Comprehensive Guide
Learn more in our Investing Guide.
How it works
multi-family property calculator takes your inputs and produces gross monthly income, net operating income, cap rate, monthly cash flow. Analyze duplex, triplex, or 4-plex investment property with unit-level income breakdown. You provide 6 inputs: Purchase Price (currency, in dollars) (default: 500000 dollars); Number of Units (number) (default: 4); Rent per Unit/Month (currency, in dollars) (default: 1200 dollars); Vacancy % (percent, in percent) (default: 5 percent); Monthly Expenses (currency, in dollars) (default: 2000 dollars); Down Payment % (percent, in percent) (default: 25 percent). The calculator returns 4 outputs: Gross Monthly Income (a secondary output); Net Operating Income (the primary result); Cap Rate (a secondary output); Monthly Cash Flow (a secondary output). Investment calculations rest on a few variables — principal, return rate, time, and compounding — but their interaction is non-linear enough that intuition alone gets the answer wrong more often than not. This tool runs the real formula with your inputs and shows the numbers that matter, not the rounded approximations from a textbook. With the default values, net operating income is computed from the interaction of every input field — change any one of them and the result updates immediately, so you can stress-test different scenarios without re-entering the whole form. Adjust the inputs to match your real financial situation. The defaults are realistic starting points, but every person's circumstances differ — your actual income, expenses, rates, and timelines will produce a different answer. Use the tool iteratively: start with the defaults, then change one variable at a time to see which factor has the largest impact on your outcome.Tips
- Start with the default values to see a baseline result, then change one input at a time to understand which factor matters most for your outcome.
- Replace every default with your actual number — estimates and rules of thumb produce estimates, not answers. Pull your real figures from pay stubs, statements, or account dashboards.
- Use a conservative return rate (5-6% rather than the historical 10%) for planning purposes. Markets have long flat stretches, and planning on the average sets you up for a shortfall.
Frequently asked questions
Is a 4-plex a good investment?
At $500K with 4 units at $1,200 each: $57,600 gross. After expenses: $36K NOI. Cap rate: 7.2%. Excellent for scaling.
What does the multi-family property calculator calculate?
It takes purchase price, number of units, rent per unit/month, vacancy %, monthly expenses, down payment % as inputs and computes gross monthly income, net operating income, cap rate, monthly cash flow. The primary output is net operating income. Analyze duplex, triplex, or 4-plex investment property with unit-level income breakdown.
How accurate are the calculator results?
The math is exact — the same formulas a financial professional would use by hand. The precision of the output depends entirely on how realistic your inputs are. Use your actual numbers rather than estimates when possible. The defaults are reasonable starting points, but your real income, rates, and timeline will produce a different result.